The Browning Automatic Rifle (BAR) is a family of American automatic rifles and machine guns used by the United States and numerous other countries during the 20th century. The primary variant of the BAR series was the M1918, chambered for the .30-06 Springfield rifle cartridge and designed by John Browning in 1917 for the American Expeditionary Forces in Europe as a replacement for the French-made Chauchat and M1909 Benét–Mercié machine guns that US forces had previously been issued.

The BAR was designed to be carried by infantrymen during an assault advance while supported by the sling over the shoulder, or to be fired from the hip. This is a concept called "walking fire"—thought to be necessary for the individual soldier during trench warfare. The BAR never entirely lived up to the original hopes of the War Department as either a rifle or a machine gun.

The US Army, in practice, used the BAR as a light machine gun, often fired from a bipod (introduced on models after 1938). A variant of the original M1918 BAR, the Colt Monitor Machine Rifle, remains the lightest production automatic firearm chambered for the .30-06 Springfield cartridge, though the limited capacity of its standard 20-round magazine tended to hamper its utility in that role.

Although the weapon did see very little action in late 1918 during World War I, the BAR did not become standard issue in the US Army until 1938, when it was issued to squads as a portable light machine gun. The BAR saw extensive service in both World War II and the Korean War and saw limited service in the Vietnam War. The US Army began phasing out the BAR in the 1950s, when it was intended to be replaced by a squad automatic weapon (SAW) variant of the M14, and as a result the US Army was without a portable light machine gun until the introduction of the M60 machine gun in 1957.

History

The US entered World War I with an inadequate, small, and obsolete assortment of domestic and foreign machine gun designs, due primarily to bureaucratic indecision and the lack of an established military doctrine for their employment. When the United States declaration of war on Germany was announced on 6 April 1917, the high command was made aware that to fight this trench war, dominated by machine-guns, they had on hand a mere 670 M1909 Benét–Merciés, 282 M1904 Maxims and 158 Colt-Browning M1895s. After much debate, it was finally agreed that a rapid rearmament with domestic weapons would be required, but until that time, US troops would be issued whatever the French and British had to offer. The arms donated by the French were often second-rate or surplus and chambered in 8mm Lebel, further complicating logistics as machine gunners and infantrymen were issued different types of ammunition.

Development
Browning began to design the weapon later known as the BAR in 1910. He demonstrated the prototypes to the US military, which did not see an immediate use for the weapon until 1917.

In 1917, prior to America's entry to the war, John Browning personally brought to Washington, D.C. two types of automatic weapons for the purposes of demonstration: a water-cooled machine gun (later adopted as the M1917 Browning machine gun) and a shoulder-fired automatic rifle known then as the Browning Machine Rifle or BMR, both chambered for the standard US .30-06 Springfield (7.62×63mm) cartridge. Colt and the Ordnance Department arranged for a public demonstration of both weapons at a location in southern Washington, D.C. known as Congress Heights. There, on 27 February 1917, in front of a crowd of 300 people (including high-ranking military officials, congressmen, senators, foreign dignitaries and the press), the Army staged a live-fire demonstration which so impressed the gathered crowd, that Browning was immediately awarded a contract for the weapon and it was hastily adopted into service (the water-cooled machine gun underwent further testing).

Additional tests were conducted for US Army Ordnance officials at Springfield Armory in May 1917, and both weapons were unanimously recommended for immediate adoption. In order to avoid confusion with the belt-fed M1917 machine gun, the BAR came to be known as the M1918 or Rifle, Caliber .30, Automatic, Browning, M1918 according to official nomenclature. On 16 July 1917, 12,000 BARs were ordered from Colt's Patent Firearms Manufacturing Company, which had secured an exclusive concession to manufacture the BAR under Browning's patents (Browning's  was owned by Colt). However Colt was already producing at peak capacity (contracted to manufacture the Vickers machine gun for the British Army) and requested a delay in production while they expanded their manufacturing output with a new facility in Meriden, Connecticut. Due to the urgent need for the weapon, the request was denied and the Winchester Repeating Arms Company (WRAC) was designated as the prime contractor. Winchester gave valuable assistance in refining the BAR's final design, correcting the drawings in preparation for mass production. Among the changes made, the ejection pattern was modified (spent casings were directed to the right side of the weapon instead of straight up).

Initial M1918 production

Since work on the weapon did not begin until February 1918, so hurried was the schedule at Winchester to bring the BAR into full production that the first production batch of 1,800 rifles was delivered out of spec; it was discovered that many components did not interchange between rifles, and production was temporarily halted until manufacturing procedures were upgraded to bring the weapon up to specifications. The initial contract with Winchester called for 25,000 BARs. They were in full production by June 1918, delivering 4,000 units, and from July were turning out 9,000 units per month.

Colt and Marlin-Rockwell Corp. also began production shortly after Winchester got into full production. Marlin-Rockwell, burdened by a contract to make rifles for the Belgian government, acquired the Mayo Radiator Co.'s factory and used it exclusively to carry out production of the BAR. The first unit from this source was delivered on 11 June 1918 and the company's peak output reached 200 automatic rifles per day. Colt had produced only 9,000 BARs by the time of the armistice due to the heavy demands of previous orders. These three companies produced a combined daily output of 706 rifles and a total of approximately 52,000 BARs were delivered by all sources by the end of the war. Between 1918 and 1919, 102,174 BARs had been manufactured jointly by Colt, Winchester, and Marlin-Rockwell.

By July 1918, the BAR had begun to arrive in France, and the first unit to receive them was the US Army's 79th Infantry Division, which took them into action for the first time on 13 September 1918. The weapon was personally demonstrated against the enemy by 2nd Lt. Val Allen Browning, the inventor's son. Despite being introduced very late in the war, the BAR made an impact disproportionate to its numbers; it was used extensively during the Meuse-Argonne Offensive and made a significant impression on the Allies (France alone requested 15,000 automatic rifles to replace their Chauchat machine rifles).

US Marines briefly took possession of the BAR. Troops from the First Battalion of the Sixth Marines had talked the "doggies" of the US Army's 36th Division into trading their BARs for their Chauchats. However, complaints from officers of the 36th resulted in the issuance of a command from Marine Lt. Col. Harry Lee on 9 October 1918: All Browning guns and equipment in Marine possession were to be turned in.

Design details and accessories
The M1918 is a selective-fire, air-cooled automatic rifle using a gas-operated, long-stroke piston rod actuated by propellant gases bled through a vent in the barrel. The bolt is locked by a rising bolt lock. The weapon fires from an open bolt. The spring-powered cartridge casing extractor is contained in the bolt and a fixed ejector is installed in the trigger group. The BAR is striker-fired (the bolt carrier serves as the striker) and uses a trigger mechanism with a fire selector lever that enables operating in either semi-automatic or fully automatic firing modes. The selector lever is located on the left side of the receiver and is simultaneously the manual safety (selector lever in the "S" position – weapon is safe, "F" – fire, "A" – automatic fire). The "safe" setting blocks the trigger.

The weapon's barrel is screwed into the receiver and is not quickly detachable. The M1918 feeds using double-column 20-round box magazines, although 40-round magazines were also used in an anti-aircraft role; these were withdrawn from use in 1927. The M1918 has a cylindrical flash suppressor fitted to the muzzle end. The original BAR was equipped with a fixed wooden buttstock and closed-type adjustable iron sights, consisting of a forward post and a rear leaf sight with 100 to 1,500 yard (91-1,372 m) range graduations.

As a heavy automatic rifle designed for support fire, the M1918 was not fitted with a bayonet mount and no bayonet was ever issued, though one experimental bayonet fitting was made by Winchester.

Variants and subsequent models

During its lengthy service life, the BAR underwent continuous development, receiving many improvements and modifications. The first major attempt at improving the M1918 resulted in the M1922 machine rifle, adopted by the United States Cavalry in 1922 as a troop-level light machine gun. The weapon used a new heavy profile ribbed barrel, an adjustable spiked bipod (mounted to a swiveling collar on the barrel) with a rear, stock-mounted monopod, a side-mounted sling swivel and a new rear buttplate, fixed to the stock retaining sleeve. The hand guard was changed, and in 1926 the BAR's sights were redesigned to accommodate the heavy-bullet 172-grain M1 .30-06 ball ammunition then coming into service for machinegun use.

In 1931, the Colt Arms Co. introduced the Monitor Automatic Machine Rifle (R 80), intended primarily for use by prison guards and law-enforcement agencies. Intended for use as a shoulder-fired automatic rifle, the Monitor omitted the bipod, instead featuring a separate pistol grip and butt stock attached to a lightweight receiver, along with a shortened, , barrel fitted with a  Cutts compensator. Weighing  empty, the Monitor had a rate of fire of approximately 500 rpm. Around 125 were produced; 90 were purchased by the FBI. Eleven went to the US Treasury Department in 1934, while the rest went to various state prisons, banks, security companies and accredited police departments. Although available for export sale, no examples appear to have been exported.

In 1932, a greatly shortened version designed for bush warfare was developed by USMC Maj. H.L. Smith and was the subject of an evaluative report by Capt. Merritt A. Edson, ordnance officer at the Quartermaster's Depot in Philadelphia, Pennsylvania. The barrel was shortened nine inches (229 mm) at the muzzle and the gas port and gas cylinder tube were relocated. The modified BAR weighed  and was only  long overall. Though it proved superior to the M1918 in accuracy when fired prone in automatic mode and equal in accuracy to the standard M1918 at ranges of 500–600 yards (460–550 m) from a rest, it was less accurate when fired from the shoulder, and had a loud report combined with a fierce muzzle blast. Attaching a Cutts compensator materially reduced the muzzle blast, but this was more than offset by the increase in smoke and dust at the muzzle when fired, obscuring the operator's vision. Nor did it improve control of the weapon when fired in bursts of automatic fire. Though the report recommended building six of these short-barreled jungle BARs for further evaluation, no further work was done on the project.

The M1918A1, featuring a lightweight spiked bipod with a leg height adjustment feature attached to the gas cylinder and a hinged steel butt plate, was formally approved on 24 June 1937. The M1918A1 was intended to increase the weapon's effectiveness and controllability firing in bursts. Relatively few M1918s were rebuilt to the new M1918A1 standard.

In April 1938, work commenced on an improved BAR for the US Army. The army specified a need for a BAR designed to serve in the role of a light machine gun for squad-level support fire. Early prototypes were fitted with barrel-mounted bipods as well as pistol grip housings and a unique rate-of-fire reducer mechanism purchased from FN Herstal. The rate reducer mechanism performed well in trials, and the pistol grip housing enabled the operator to fire more comfortably from the prone position. However, in 1939 the army declared that all modifications to the basic BAR be capable of being retrofitted to earlier M1918 guns with no loss of parts interchangeability. This effectively killed the FN-designed pistol grip and its proven rate reducer mechanism for the new M1918 replacement.

The final development of the M1918A2 was authorized on 30 June 1938. The FN-designed pistol grip and rate-reducer mechanism with two rates of automatic fire was shelved in favor of a rate-reducer mechanism designed by Springfield Armory, and housed in the butt stock. The Springfield Armory rate reducer also provided two selectable rates of fully automatic fire only, activated by engaging the selector toggle. Additionally, a skid-footed bipod was fitted to the muzzle end of the barrel, magazine guides were added to the front of the trigger guard, the hand guard was shortened, a heat shield was added to help the cooling process, a small separate stock rest (monopod) was included for attachment to the butt and the weapon's role was changed to that of a squad light machine gun. The BAR's rear sight scales were also modified to accommodate the newly standardized M2 ball ammunition with its lighter, flat-base bullet. The M1918A2's walnut butt stock is approximately one inch (2.5 cm) longer than the M1918 BAR's butt stock. The M1918A2's barrel was also fitted with a new flash suppressor and fully adjustable iron sights. Towards the end of the war a barrel-mounted carrying handle was added.

Because of budget limitations initial M1918A2 production consisted of conversions of older M1918 BARs (remaining in surplus) along with a limited number of M1922s and M1918A1s. After the outbreak of war, attempts to ramp up new M1918A2 production were stymied by the discovery that the World War I tooling used to produce the M1918 was either worn out or incompatible with modern production machinery. New production was first undertaken at the New England Small Arms Corp. and International Business Machines Corp. (a total of 188,380 new weapons were manufactured). In 1942 a shortage of black walnut for butt stocks and grips led to the development of a black plastic butt stock for the BAR. Composed of a mixture of Bakelite and Resinox, and impregnated with shredded fabric, the stocks were sandblasted to reduce glare. The Firestone Rubber and Latex Products Co. produced the plastic butt stock for the US Army, which was formally adopted on March 21, 1942. The M1922 machine rifle was declared obsolete in 1940, but they were used by Merrill's Marauders in Burma later in the war as a slightly lighter alternative to the M1918A2.

Production rates greatly increased in 1943, after IBM introduced a method of casting BAR receivers from a new type of malleable iron developed by the Saginaw division of General Motors, called ArmaSteel. After it successfully passed a series of tests at Springfield Armory, the Chief of Ordnance instructed other BAR receiver manufacturers to change over from steel to ArmaSteel castings for this part. During the Korean War  M1918A2 production was resumed, this time contracted to the Royal McBee Typewriter Co., which produced an additional 61,000 M1918A2s.

A bullpup prototype existed as the Cook automatic rifle during the 1950s. It was developed at Benicia Armoury by US Army ordnance officer Lauren C. Cook. It used the gas operation of the M1918 BAR with the trigger group in front of the magazine. The operation fired from a closed bolt. The Cook automatic rifle was 30 inches retaining the barrel length of 18 inches.

The last US-made variant was produced in 7.62×51mm NATO, as T34 Automatic rifle.

International and commercial models

Export models
The BAR also found a ready market overseas and in various forms was widely exported. In 1919 the Colt  company developed and produced a commercial variant called the Automatic Machine Rifle Model 1919 (company designation: Model U), which has a different return mechanism compared to the M1918 (it is installed in the stock rather than the gas tube) and lacks a flash hider. Later the Model 1924 rifle was offered for a short period of time, featuring a pistol grip and a redesigned hand guard. These Colt automatic rifles were available in a number of calibers, including .30-06 Springfield (7.62×63mm), 7.65×53mm Belgian Mauser, 7×57mm Mauser, 6.5×55mm, 7.92×57mm Mauser and .303 British (7.7×56mmR). All of the 6.5×55mm-caliber Colt automatic rifles appear to have been sold directly to FN.

An improved version of the Model 1924, the Model 1925 (R75), achieved the highest popularity in export sales. It is based on the Model 1924 but uses a heavy, finned barrel, a lightweight bipod and is equipped with dust covers in the magazine well and ejection port (some of these features were patented: US patents #1548709 and #1533968). The Model 1925 was produced in various calibers, including .30-06 Springfield (7.62×63mm), 7.65×53mm Belgian Mauser, 7×57mm Mauser, 7.92×57mm Mauser, and .303 British (7.7×56mmR) (no Colt-manufactured Model 1925 rifles in 6.5×55mm appear to have been sold). A minor variant of the Model 1925 (R75) was the R75A light machine gun with a quick-change barrel (produced in 1942 in small quantities for the Dutch army). Between 1921 and 1928 FN Herstal imported over 800 Colt-manufactured examples of the Colt Machine Rifles for sale abroad.

All of the Colt automatic machine rifles, including the Colt Monitor, were available for export sale. After 1929 the Model 1925 and the Colt Monitor were available for export sale in Colt's exclusive sales territories per its agreement with FN. These Colt territories included North America, Central America, the West Indies, South America, Great Britain, Russia, Turkey, Siam (Thailand), India and Australia.

Belgium

A variant known as the FN Mle 1930 was developed in 7.65×53mm Belgian Mauser by FN Herstal and adopted by the Belgian army. The Mle 1930 is basically a licensed copy of the Colt Automatic Machine Rifle, Model 1925 (R 75). The Mle 1930 has a different gas valve and a mechanical rate-reducing fire control mechanism designed by Dieudonné Saive, located in the trigger guard-pistol grip housing. Some of these FN rate reducer mechanisms and pistol grip housings were later purchased by Springfield Armory for evaluation and possible adoption on a replacement for the M1918. The weapon also had a hinged shoulder plate and was adapted for use on a tripod mount. In 1932 Belgium adopted a new version of the FN Mle 1930 allocated the service designation FN Mle D (D—demontable or "removable"), which had a quick-change barrel, shoulder rest and a simplified take-down method for easier cleaning and maintenance. The Mle D was produced even after World War II in versions adapted for .30-06 Springfield (for Belgian service) and 7.92×57mm Mauser ammunition (for Egyptian service). The final variant in Belgian service was the Model DA1 chambered for the 7.62×51mm NATO cartridge and feeding from the 20-round magazines for the FN FAL battle rifle.

France

In 1922, the French Army considered the introduction of the BAR or of the Fusil-mitrailleur MAS modèle 1922, a copy of the BAR produced by the Manufacture d'armes de Saint-Étienne. The FM 24/29 light machine gun was eventually adopted.

Poland

Production of the BAR in Belgium began only after signing an agreement with Poland (on 10 December 1927) involving the procurement of 10,000 wz. 1928 light machine guns chambered in 7.92×57mm Mauser, which are similar to the R75 variant but designed specifically to meet the requirements of the Polish army. Changes to the base design include a pistol grip, different type of bipod, open-type V-notch rear sight and a slightly longer barrel. Subsequent rifles were assembled in Poland under license by the state rifle factory (Państwowa Fabryka Karabinów) in Warsaw. The wz. 1928 was accepted into service with the Polish army in 1927 under the formal name 7,92 mm rkm Browning wz. 1928 and—until the outbreak of World War II—was the primary light support weapon of Polish infantry and cavalry formations (in 1939 Poland had a total of approximately 20,000 wz. 1928 rifles in service). Additional detail modifications were introduced on the production line; among them were the replacement of the iron sights with a smaller version and reshaping the butt to a fish tail.

In the mid-1930s, Polish small-arms designer Wawrzyniec Lewandowski was tasked with developing a flexible aircraft-mounted machine gun based on the Browning wz.1928. This resulted in the wz. 1937. Changes included increasing the weapon's rate of fire to 1,100 rounds/min, eliminating the butt stock, adding a spade-type grip to the rear of the receiver, moving the main drive spring under the barrel and, most importantly, changing the feed system. Sustained fire was practically impossible with the standard 20-round box magazine, so a new feed mechanism was developed that was added to the receiver as a module. It contains a spring-loaded, bolt-actuated lever that would feed a round from a 91-round pan magazine located above the receiver and force the round into the feed path during unlocking. The machine gun was accepted in 1937 and ordered by the Polish Air Force as the karabin maszynowy obserwatora wz. 1937 ("observers machine gun model 1937"). Eventually 339 machine guns were acquired and used as armament in the PZL.37 Łoś medium bomber and the LWS-3 Mewa reconnaissance aircraft.

Sweden

In 1920, Belgian arms manufacturer Fabrique Nationale (FN) acquired sales and production rights to the BAR series of firearms in Europe from Colt. The first BAR model sold by FN was the Kg m/21 (Kg—Kulsprutegevär or "machinegun rifle") chambered for the 6.5×55mm m/94 cartridge. The m/21 is a variant of the Model 1919 designed to Swedish specifications and manufactured initially by Colt's and later under license at the Carl Gustafs Stads Gevärsfaktori in Eskilstuna. Compared to the Model 1919, the Swedish weapon has—apart from the different caliber—a spiked bipod and dust covers for ejection. The m/21 would become one of Sweden's main support weapons in the interwar years together with the water-cooled, belt-fed Ksp m/1914 medium machine gun (Swedish adaptation of the Austrian M07/12). Dissatisfied with the rapidly overheating fixed barrel of the m/21, Carl Gustaf began to design a new quick-detach mechanism for the barrel that mates the externally grooved chamber to a series of rotating flanges in the receiver operated by a locking lever. The barrel also received cooling fins along its entire length. These enhancements were incorporated into the fm/1935 prototype, which was favorably evaluated during trials in 1935. The final version was the Kg m/37, adopted for service in 1937, which uses a smooth-contour, unfinned barrel. Numerous m/21 guns were retrofitted with the screw-on receiver extension and quick-change barrel and renamed the Kg m/21-37. The m/37 remained in service until replaced by the FN MAG, but was still in second-line use until 1980. Carl Gustaf also developed a belt-fed prototype; however, it was never adopted.

China
The Chinese Nationalist Army used the FN M1930 throughout the Second Sino-Japanese War. 29,550 were bought from Belgium between 1933 and 1939. The Chinese BAR was chambered for the German 7.92×57mm Mauser round, the standard rifle cartridge of the National Revolutionary Army. After the outbreak of the Pacific War, the Chinese Expeditionary Army in Burma was equipped with American BARs. Towards the end of World War II, small quantities of American equipment, including the BAR, made their way into mainland China.

Civilian use

Colt Monitor
With the cessation of WWI hostilities, Colt Arms Co. received the Browning patents to produce the BAR that had been withheld from issue during the war. This allowed Colt to make the BAR available for commercial sale, including to civilian owners. The Colt Automatic Machine Rifle Model 1919, initially made up of overruns from the M1918 military production contract, was the first of several commercial Colt BARs that would follow. However, the high price of the weapon and its limited utility for most civilian owners resulted in few sales. Ad Topperwien, a famous trick shooter of the early 1920s, purchased one of the first Colt-produced BARs to perform aerial target shooting exhibitions. Occasional BAR sales were made to civilian owners through distributors such as the Ott-Heiskell Hardware Co.

In 1931, the new Colt Monitor was made available to civilians during the Depression at $300 each, including a spare parts kit, sling, cleaning accessories and six magazines, but Colt records indicate no domestic sales to individuals.

Post National Firearms Act
After passage of the National Firearms Act of 1934, civilian BAR ownership was restricted even further. Importation of machine guns for transfer between civilians was prohibited in 1968 and the production of machine guns for civilian transfer was banned in 1986. However, machine guns produced prior to 1986 are still transferable, and fully-automatic BAR models exist and occasionally come up for sale to qualified buyers.

21st century
Some companies continue to manufacture semi-automatic copies for sale to civilians, such as Ohio Ordnance Works, Inc., in Chardon, Ohio. Ohio Ordnance Works produces a contemporary semi-automatic variant of the M1918 called "1918A3-SLR", and a much modified lightened version called HCAR (Heavy Counter Assault Rifle), which are legal for civilians without an FFL (federal firearms license) to own.

Criminal and law enforcement use
Although the Colt Monitor version of the BAR failed to interest US civilian buyers in the midst of the Depression, the underworld was a lot more interested: in 1936 the price of a black-market Colt Monitor was $5,000, with military BARs going for somewhat less. The army's M1918 was a favorite of gangster Clyde Barrow, who obtained his through periodic robberies of Army National Guard armories in the Midwest. Barrow liked to use armor-piercing (AP) .30-06 ammunition he obtained from armory stores, and frequently modified his BARs to suit his own needs. Barrow taught his girlfriend Bonnie Parker to fire the M1918 as well, and by all accounts she was an excellent BAR operator. She used an M1918 on full-automatic to pin down unsuspecting law officers after they confronted the gang at a house in Joplin, Missouri. A Missouri highway patrolman at the scene, forced to dive for cover behind a substantial oak tree after Bonnie Parker opened up on him, later stated, "That little red-headed woman filled my face with splinters on the other side of that tree with one of those damned guns."

As the use of automatic weapons by criminal elements in the US became more widespread, FBI Director J. Edgar Hoover ordered the agency to acquire and commence regular training with automatic shoulder weapons, including the Thompson submachine gun and the BAR. For its BARs the FBI turned to Colt, which sold 90 Colt Monitor automatic machine rifles to the agency. Some of the FBI's Monitors were distributed to field offices for use as support weapons if needed on a particular operation, while the remainder were retained at the FBI Academy in Quantico, Virginia, for training purposes. Colt sold an additional 11 Colt Monitors to the US Treasury Department in 1934, while 24 guns were sold to state prisons, banks, security companies and accredited city, county and state police departments. At least one member of the ambush team that killed Bonnie and Clyde was armed with a Colt Monitor.

Although it has sometimes been alleged that the M1918 or M1918A2 BAR was used by members of the Symbionese Liberation Army (SLA) in a shootout with Los Angeles police on May 17, 1974, no SLA members ever used such a weapon. The confusion arose out of Browning's decision in the 1970s to also designate its semi-automatic hunting rifle the Browning BAR. The SLA converted a .30-06 Browning BAR hunting rifle and a .243 Remington Model 742 to automatic fire by filing down the sear, and it was these weapons that were used in the shootout.

In US military service

World War I

At its inception, the M1918 was intended to be used as a shoulder-fired rifle capable of both semi-automatic and fully automatic fire. First issued in September 1918 to the American Expeditionary Forces, it was based on the concept of "walking fire", a French practice in use since 1916 for which the CSRG 1915 (Chauchat) had been used accompanying advancing squads of riflemen toward the enemy trenches, as regular machine guns were too cumbersome to move with the troops during an assault.

In addition to shoulder-fired operation, BAR gunners were issued a belt with magazine pouches for the BAR and sidearm along with a "cup" to support the stock of the rifle when held at the hip. In theory, this allowed the soldier to lay suppressive fire while walking forward, keeping the enemy's head down, a practice known as "marching fire". The idea would resurface in the submachine gun and ultimately the assault rifle. It is not known if any of the belt-cup devices actually saw combat use.

The BAR only saw minor action in France during World War I, being brought into action only as late as September 1918, less than three months before Armistice Day. The intentional delay had been inspired by General Pershing, the AEF commander, in order not to let the BAR fall into enemy hands too early. Fifty-two thousand BARs were available by the end of the war in November.

Interwar use

During the interwar years, as the U.S. Army was reduced significantly in size, the BAR remained in the smaller extant Regular Army and by the 1930s, was also issued to state national guard units to be maintained at their armories.  Given the part-time nature, smaller manning and lesser security of these national guard armories when compared to regular army installations, some BARs were subject to plunder by domestic civilian criminal elements.

The BAR was also standard issue to US naval landing forces during the period. The weapon was a standard item in US warship armories, and each BAR was accompanied by a spare barrel. Large capital ships often had over 200 BARs on board, with many of the US Navy BARs remaining in service well into the 1960s.

The BAR also saw action with US Marine Corps units participating in the Haitian and Nicaraguan interventions, as well as with US Navy shipboard personnel in the course of patrol and gunboat duty along the Yangtze River in China. The First Marine Brigade stationed in Port-au-Prince, Haiti, noted that training a man to use the BAR proficiently took a full two days of range practice and instruction, compared to half a day with the .45 caliber Thompson submachine gun.

Prior to World War II, both the US Army and Marine Corps had a separate BAR squad together with three rifle squads in the "square" organisation of the time.  When converting to the "triangular" organisation the separate BAR squad was eliminated with BARs going to each rifle squad.

World War II

When the threat of a new war arose, Ordnance belatedly realized that it had no portable, squad light machine gun, and attempted to convert the M1918 BAR to that role with the adoption of the M1918A2 by the US Army on 30 June 1938. The BAR was issued as the sole automatic fire support for a twelve-man squad, and all men were trained at the basic level how to operate and fire the weapon in case the designated operators were killed or wounded. At the start of the war, infantry companies designated three-man BAR teams, a gunner, an assistant gunner, and an ammunition bearer who carried additional magazines for the gun. By 1944, some units were using one-man BAR "teams" with the other riflemen in the squad detailed to carry additional magazines or bandoliers of .30 ammunition. Contrary to certain claims, the BAR was issued to soldiers of various heights.

As originally conceived, US Army tactical doctrine called for one M1918A2 per squad, using several men to support and carry ammunition for the gun. Fire and movement tactics centered on the M1 riflemen in the squad while the BAR man was detailed to support the riflemen in the attack and provide mobility to the riflemen with a base of fire. This doctrine received a setback early in the war after US ground forces encountered German troops, well-armed with automatic weapons including fast-firing, portable machine guns. In some cases, particularly in the attack, every fourth German infantryman was equipped with an automatic weapon, either a submachine gun or a full-power machine gun.

In an attempt to overcome the BAR's limited continuous-fire capability, US Army divisions increasingly began to specify two BAR fire teams per squad, following the practice of the US Marine Corps. One team would typically provide covering fire until a magazine was empty, whereupon the second team would open fire, thus allowing the first team to reload. In the Pacific, the BAR was often employed at the point or tail of a patrol or infantry column, where its firepower could help break contact on a jungle trail in the event of an ambush. After combat experience showed the benefits of maximizing portable automatic firepower in squad-size formations, the US Marine Corps began to increase the number of BARs in its combat divisions, from 513 per division in 1943 to 867 per division in 1945. A thirteen-man squad was developed, consisting of 3 four-man fire teams, with one BAR per fire team, or three BARs per squad. Instead of supporting the M1 riflemen in the attack, Marine tactical doctrine was focused around the BAR, with riflemen supporting and protecting the BAR gunner.

Despite the improvements in the M1918A2, the BAR remained a difficult weapon to master with its open bolt and strong recoil spring, requiring additional range practice and training to hit targets accurately without flinching. As a squad light machine gun, the BAR's effectiveness was mixed, since its thin, non-quick-change barrel and small magazine capacity greatly limited its firepower in comparison to genuine light machine guns such as the British Bren and the Japanese Type 96. The weapon's rate-reducer mechanism, a delicately balanced spring-and-weight system described by one ordnance sergeant as a "Rube Goldberg device", came in for much criticism, often causing malfunctions when not regularly cleaned. The bipod and buttstock rest (monopod), which contributed so much to the M1918A2's accuracy when firing prone on the rifle range, proved far less valuable under actual field combat conditions. The stock rest was dropped from production in 1942, while the M1918A2's bipod and flash hider were often discarded by individual soldiers and marines to save weight and improve portability, particularly in the Pacific Theater of war. With these modifications, the BAR effectively reverted to its original role as a portable, shoulder-fired automatic rifle.

Due to production demands, war priorities, subcontractor issues, and material shortages, demand for the M1918A2 frequently exceeded supply, and as late as 1945 some Army units were sent into combat still carrying older, unmodified M1918 weapons.

After a period of service, ordnance personnel began to receive BARs with inoperable or malfunctioning recoil buffer mechanisms. This was eventually traced to the soldier's common practice of cleaning the BAR in a vertical position with the butt of the weapon on the ground, allowing cleaning fluid and burned powder to collect in the recoil buffer mechanism. Additionally, unlike the M1 rifle, the BAR's gas cylinder was never changed to stainless steel. Consequently, the gas cylinder frequently rusted solid from the use of corrosive-primered M2 service ammunition in a humid environment when not stripped and cleaned on a daily basis. While not without design flaws (a thin-diameter, fixed barrel that quickly overheated, limited magazine capacity, complex field-strip/cleaning procedure, unreliable recoil buffer mechanism, a gas cylinder assembly made of corrosion-prone metals, and many small internal parts), the BAR proved rugged and reliable enough when regularly field-stripped and cleaned.

During World War II, the BAR saw extensive service, both official and unofficial, with many branches of service. One of the BAR's most unusual uses was as a defensive aircraft weapon. In 1944, Captain Wally A. Gayda, of the USAAF Air Transport Command, reportedly used a BAR to return fire against a Japanese Army Nakajima fighter that had attacked his C-46 cargo plane over the Hump in Burma. Gayda shoved the rifle out his forward cabin window, emptying the magazine and apparently killing the Japanese pilot.

Korean War

The BAR continued in service in the Korean War. The last military contract for the manufacture of the M1918A2 was awarded to the Royal Typewriter Co. of Hartford, Connecticut, which manufactured a total of 61,000 M1918A2s during the conflict, using ArmaSteel cast receivers and trigger housings. In his study of infantry weapons in Korea, historian S.L.A. Marshall interviewed hundreds of officers and men in after-action reports on the effectiveness of various U.S. small arms in the conflict. General Marshall's report noted that an overwhelming majority of respondents praised the BAR and the utility of automatic fire delivered by a lightweight, portable small arm in both day and night engagements. In his autobiography Colonel David Hackworth praised the BAR as 'the best weapon of the Korean War'.

A typical BAR gunner of the Korean War carried the twelve-magazine belt and combat suspenders, with three or four extra magazines in pockets. Extra canteens, .45 pistol, grenades, and a flak vest added still more weight. As in World War II, many BAR gunners disposed of the heavy bipod and other accoutrements of the M1918A2, but unlike the prior conflict the flash hider was always retained because of its utility in night fighting.

The large amounts of ammunition expended by BAR teams in Korea placed additional demands on the assistant gunner to stay in close contact with the BAR at all times, particularly on patrols. While the BAR magazines themselves always seemed to be in short supply, Gen. Marshall reported that "riflemen in the squad were markedly willing to carry extra ammunition for the BAR man".

In combat, the M1918A2 frequently decided the outcome of determined attacks by North Korean and Chinese communist forces. Communist tactical doctrine centered on the mortar and machine gun, with attacks designed to envelop and cut off United Nations forces from supply and reinforcement. Communist machine gun teams were the best-trained men in any given North Korean or Chinese infantry unit, skilled at placing their heavily camouflaged and protected weapons as close to UN forces as possible. Once concealed, they often surprised UN forces by opening fire at very short ranges, covering any exposed ground with a hail of accurately sighted machine gun fire. Under these conditions it was frequently impossible for US machine gun crews to move up their Browning M1919A4 and M1919A6 guns in response without taking heavy casualties; when they were able to do so, their position was carefully noted by the enemy, who would frequently kill the exposed gun crews with mortar or machine gun fire while they were still emplacing their guns. The BAR gunner, who could stealthily approach the enemy gun position alone (and prone if need be), proved invaluable in this type of combat.

During the height of combat, the BAR gunner was often used as the 'fire brigade' weapon, helping to bolster weak areas of the perimeter under heavy pressure by communist forces. In defense, it was often used to strengthen the firepower of a forward outpost. Another role for the BAR was to deter or eliminate enemy sniper fire. In the absence of a trained sniper, the BAR proved more effective than the random response of five or six M1 riflemen.

Compared to World War II, US infantry forces saw a huge increase in the number of night engagements. The added firepower of the BAR rifleman and his ability to redeploy to 'hot spots' around the unit perimeter proved indispensable in deterring night infiltration by skirmishers as well as repelling large-scale night infantry assaults.

While new-production M1918A2 guns were almost universally praised for faultless performance in combat, a number of malfunctions in combat were reported with armory-reconditioned M1918A2s, particularly weapons that had been reconditioned by Ordnance in Japan, which did not replace operating (recoil) springs as a requirement of the reconditioning program. After decades of complaints, ordnance addressed the problem of maintaining the problematic gas piston on the BAR by issuing disposable nylon gas valves. When the nylon valve became caked over with carbon, it could be discarded and replaced with a fresh unit, eliminating the tedious task of cleaning and polishing the valve with wire brush and GI solvent (frequently in short supply to line units).

Vietnam War

The M1918A2 was used in the early stages of the Vietnam War, when the US delivered a quantity of "obsolete", second-line small arms to the South Vietnamese Army and associated allies, including the Montagnard hill tribespeople of South Vietnam. US Special Forces advisors frequently chose the BAR over currently available infantry weapons. As one Special Forces sergeant declared, "Many times since my three tours of duty in Vietnam I have thanked God for ... having a BAR that actually worked, as opposed to the jamming M16 ... We had a lot of Viet Cong infiltrators in all our [Special Forces] camps, who would steal weapons every chance they got. Needless to say, the most popular weapon to steal was the venerable old BAR."

Post-Vietnam use
Quantities of the BAR remained in use by the Army National Guard up until the mid-1970s. Many recipients of US foreign aid adopted the BAR and used it into the 1980s and 1990s.

Users

: Adopted in 1930, built under licence by Fabrique Nationale
: Two Colt Automatic Rifles were used in the 1923 revolution in Rio Grande do Sul by Loyalist forces. Used by the Brazilian Expeditionary Force in WWII <ref>{{cite book|last1=Maximiano|first1= Cesar|last2=Bonalume|first2= Ricardo N|url=https://books.google.com/books?id=6q6HCwAAQBAJ|title=Brazilian Expeditionary Force in World War II|publisher=Osprey Publishing|year= 2011|isbn=9781849084833|series=Men at Arms 465|page=45}}</ref>

: A large number were seized from the Republic of China during the Chinese Civil War.
: Used by nationalist forces during the Second Sino-Japanese War and subsequent Chinese Civil War, most of them armed with FN Mle 30s

: Colt commercial BAR and M1918A2 BAR, used by Castro's rebels during the Cuban Revolution. Anticastrists machine gunners of the Brigade 2506 were also equipped with M1918A2 BARs.

: FN type D in 7.92 Mauser
: FN Mle 30 and M1918 BAR
: FN Mle 30 and Swedish m/21
: Supplied to Free French forces during World War II and later used during Indochina War and Algerian War. Known as the Fusil-mitrailleur 7 mm 62 (C. 30) M. 18 (B. A. R.).
: The Wehrmacht captured a number of Polish-made Browning wz. 1928 guns and used them until the end of World War II under the designation IMG 28(p): FN Model D in limited service.
: Used FN Model Ds.
: Used the M1918A2 as the Fucile Mitragliatore Browning (B.A.R.) cal. 7,62.
: Used some FN Mle 30s. Most of them were taken from disarmed Chinese forces with original markings removed to use Japanese markings. Used M1918A2 post-war by National Police Reserve.
: The Armed Forces received 1,198 M1918A2 before the Korean War, and 11,768 were in service with the Army by the end of the war. Also used as squad automatic weapon in early years of the Vietnam War by the ROK Forces in Vietnam.
: Received from US Government during Laotian Civil War and Vietnam War.

: Introduced to the Korps Mariniers in 1943 with the creation of the Mariniersbrigade. Known as the Browning Automatisch Geweer M.1918 A2'', 243 BARs were in use with the Mariniersbrigade. The Koninklijke Landmacht also used the M1918A2 whilst fighting in the Korean War under United Nations command.
: The Guardia Nacional de Nicaragua used the BAR, first supplied by the US Marines and later by the US Military Assistance Program (MAP) continuously from 1932 to 1979.

: used during the anti-Japanese guerillas and by the Armed Forces of the Philippines during the Hukbalahap Rebellion

: Ex-French BARs used by the Viet Cong and the North Vietnamese Army.
: Used by the ARVN, most provided as surplus
: Bought some Colt commercial BARs. Some ex-Polish wz. 1928s also used during the war.

: 25,000 bought from 1940, issued to the Home Guard units

:FN Model D

See also
FM 24/29 light machine gun
Lewis automatic machine gun, British support gun
Kg m/40 light machine gun
Mendoza RM2
Model 45A
Ribeyrolles 1918 automatic carbine
Weibel M/1932

Notes

References
 .
 .
 .
 .
 .
 .
 .

 FM 23–15: Basic Field Manual — Browning Automatic Rifle, Caliber .30, M1918A2 (27 Aug 1940).
 .

External links

FM 23-15 Basic Field Manual Browning Automatic Rifle, Caliber .30, M1918A2 with Bipod

 YouTube animation showing mechanism of BAR 1918

.30-06 Springfield battle rifles
.30-06 Springfield machine guns
.303 British battle rifles
.303 British machine guns
6.5×55mm battle rifles
6.5×55mm machine guns
7.92×57mm Mauser battle rifles
7.92×57mm Mauser machine guns
Firearms by John Browning
Gas-operated firearms
Light machine guns
Rifles of the United States
United States Marine Corps equipment
Weapons and ammunition introduced in 1918
Weapons of the Philippine Army
World War I infantry weapons of the United States
World War I machine guns
World War II infantry weapons of the United States
World War II machine guns
World War II infantry weapons of Brazil

M1918 Browning Automatic Rifle


Geothermal energy is thermal energy in the Earth's crust. It combines energy from the formation of the planet and from radioactive decay. Geothermal energy has been exploited as a source of heat and/or electric power for millennia.

Geothermal heating, using water from hot springs, for example, has been used for bathing since Paleolithic times and for space heating since Roman times. Geothermal power, (generation of electricity from geothermal energy), has been used since the 20th century. Unlike wind and solar energy, geothermal plants produce power at a constant rate, without regard to weather conditions. Geothermal resources are theoretically more than adequate to supply humanity's energy needs. Most extraction occurs in areas near tectonic plate boundaries.

The cost of generating geothermal power decreased by 25% during the 1980s and 1990s. Technological advances continued to reduce costs and thereby expand the amount of viable resources. In 2021, the U.S. Department of Energy estimated that power from a plant "built today" costs about $0.05/kWh.

In 2019, 13,900 megawatts (MW) of geothermal power was available worldwide. An additional 28 gigawatts provided heat for district heating, space heating, spas, industrial processes, desalination, and agricultural applications as of 2010.

As of 2019 the industry employed about 100 thousand people. Pilot programs like EWEB's customer opt-in Green Power Program suggest that customers would be willing to pay a little more for renewable energy.

The adjective geothermal originates from the Greek roots  (), meaning Earth, and  (), meaning hot.

History

Hot springs have been used for bathing since at least Paleolithic times. The oldest known spa is at the site of the Huaqing Chi palace. In the first century CE, Romans conquered Aquae Sulis, now Bath, Somerset, England, and used the hot springs there to supply public baths and underfloor heating. The admission fees for these baths probably represent the first commercial use of geothermal energy. The world's oldest geothermal district heating system, in Chaudes-Aigues, France, has been operating since the 15th century. The earliest industrial exploitation began in 1827 with the use of geyser steam to extract boric acid from volcanic mud in Larderello, Italy.

In 1892, the US's first district heating system in Boise, Idaho was powered by geothermal energy. It was copied in Klamath Falls, Oregon in 1900. The world's first known building to utilize geothermal energy as its primary heat source was the Hot Lake Hotel in Union County, Oregon, beginning in 1907. A geothermal well was used to heat greenhouses in Boise in 1926, and geysers were used to heat greenhouses in Iceland and Tuscany at about the same time. Charles Lieb developed the first downhole heat exchanger in 1930 to heat his house. Geyser steam and water began heating homes in Iceland in 1943.

In the 20th century, geothermal energy came into use as a generating source. Prince Piero Ginori Conti tested the first geothermal power generator on 4 July 1904, at the Larderello steam field. It successfully lit four light bulbs. In 1911, the world's first commercial geothermal power plant was built there. It was the only industrial producer of geothermal power until New Zealand built a plant in 1958. In 2012, it produced some 594 megawatts.

In 1960, Pacific Gas and Electric began operation of the first US geothermal power plant at The Geysers in California. The original turbine lasted for more than 30 years and produced 11 MW net power.

A binary cycle power plant was first demonstrated in 1967 in the USSR and introduced to the US in 1981. This technology allows the generation of electricity from much lower temperature resources than previously. In 2006, a binary cycle plant in Chena Hot Springs, Alaska, came on-line, producing electricity from a record low temperature of .

In 2021 Quaise Energy announced the idea of using a gyrotron as a boring machine to drill a hole 20 kilometers in depth. The technique used frequencies of 30-300 GHz to transfer energy to rock 1012 (1 trillion) times more efficiently than a laser. Lasers would be disrupted by the vaporized rock, which would effect the gyrotron's longer-wavelength much less. Drilling rates of 70 meters/hour were claimed to be possible with a 1 MW gyrotron.

Resources

The Earth has an internal heat content of 1031 joules (3·1015 TWh),  About 20% of this is residual heat from planetary accretion; the remainder is attributed to past and current radioactive decay of naturally occurring isotopes. For example, a 5275 m deep borehole in United Downs Deep Geothermal Power Project in Cornwall, England, found granite with very high thorium content, whose radioactive decay is believed to power the high temperature of the rock.

Earth's interior temperature and pressure are high enough to cause some rock to melt and the solid mantle to behave plastically. Parts of the mantle convect upward since it is lighter than the surrounding rock. Temperatures at the core–mantle boundary can reach over 4000 °C (7200 °F).

The Earth's internal thermal energy flows to the surface by conduction at a rate of 44.2 terawatts (TW), and is replenished by radioactive decay of minerals at a rate of 30 TW. These power rates are more than double humanity's current energy consumption from all primary sources, but most of this energy flux is not recoverable. In addition to the internal heat flows, the top layer of the surface to a depth of  is heated by solar energy during the summer, and cools during the winter.

Outside of the seasonal variations, the geothermal gradient of temperatures through the crust is 25–30 °C (45–54 °F) per km of depth in most of the world. The conductive heat flux averages 0.1 MW/km2. These values are much higher near tectonic plate boundaries where the crust is thinner. They may be further augmented by combinations of fluid circulation, either through magma conduits, hot springs, hydrothermal circulation.

The thermal efficiency and profitability of electricity generation is particularly sensitive to temperature. Applications receive the greatest benefit from a high natural heat flux most easily from a hot spring. The next best option is to drill a well into a hot aquifer. An artificial one may be built by injecting water to hydraulically fracture bedrock. This last approach is called hot dry rock geothermal energy in Europe, or enhanced geothermal systems in North America.

2010 estimates of the potential for electricity generation from geothermal energy vary sixfold, from  depending on the scale of investments. Upper estimates of geothermal resources assume wells as deep as , although 20th century wells rarely reached more than  deep. Wells of this depth are common in the petroleum industry.

Geothermal power

Geothermal power is electrical power generated from geothermal energy. Dry steam,, flash steam, and binary cycle power stations have been used for this purpose. As of 2010 geothermal electricity was generated in 26 countries.

As of 2019, worldwide geothermal power capacity amounted to 15.4 gigawatts (GW), of which 23.86 percent or 3.68 GW were in the United States.

Geothermal energy supplies a significant share of the electrical power in Iceland, El Salvador, Kenya, the Philippines and New Zealand.

Geothermal power is considered to be renewable energy because the heat extraction is insignificant compared with the Earth's heat content. The greenhouse gas emissions of geothermal electric stations are on average 45 grams of carbon dioxide per kilowatt-hour of electricity, or less than 5 percent of that of coal-fired plants.

Geothermal electric plants were traditionally built on the edges of tectonic plates where high-temperature geothermal resources approach the surface. The development of binary cycle power plants and improvements in drilling and extraction technology enable enhanced geothermal systems over a greater geographical range. Demonstration projects are operational in Landau-Pfalz, Germany, and Soultz-sous-Forêts, France, while an earlier effort in Basel, Switzerland, was shut down after it triggered earthquakes. Other demonstration projects are under construction in Australia, the United Kingdom, and the US. In Myanmar over 39 locations are capable of geothermal power production, some of which are near Yangon.

Geothermal heating

Geothermal heating is the use of geothermal energy to heat buildings and water for human use. Humans have done this since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ of geothermal heating in 2004. As of 2007, 28 GW of geothermal heating satisfied 0.07% of global primary energy consumption. Thermal efficiency is high since no energy conversion is needed, but capacity factors tend to be low (around 20%) since the heat is mostly needed in the winter.

Even cold ground contains heat: below  the undisturbed ground temperature is consistently at the Mean Annual Air Temperature that may be extracted with a ground source heat pump.

Types
Geothermal energy comes in either vapor-dominated or liquid-dominated forms. Larderello and The Geysers are vapor-dominated. Vapor-dominated sites offer temperatures from 240 to 300 °C that produce superheated steam.

Liquid-dominated plants
Liquid-dominated reservoirs (LDRs) are more common with temperatures greater than  and are found near volcanoes in/around the Pacific Ocean and in rift zones and hot spots. Flash plants are the common way to generate electricity from these sources. Steam from the well is sufficient to power the plant. Most wells generate 2–10 MW of electricity. Steam is separated from liquid via cyclone separators and drives electric generators. Condensed liquid returns down the well for reheating/reuse. As of 2013, the largest liquid system was Cerro Prieto in Mexico, which generates 750 MW of electricity from temperatures reaching .

Lower-temperature LDRs (120–200 °C) require pumping. They are common in extensional terrains, where heating takes place via deep circulation along faults, such as in the Western US and Turkey. Water passes through a heat exchanger in a Rankine cycle binary plant. The water vaporizes an organic working fluid that drives a turbine. These binary plants originated in the Soviet Union in the late 1960s and predominate in new plants. Binary plants have no emissions.

Enhanced geothermal systems

Enhanced geothermal systems (EGS) actively inject water into wells to be heated and pumped back out. The water is injected under high pressure to expand existing rock fissures to enable the water to flow freely. The technique was adapted from oil and gas fracking techniques. The geologic formations are deeper and no toxic chemicals are used, reducing the possibility of environmental damage. Drillers can employ directional drilling to expand the reservoir size.

Small-scale EGS have been installed in the Rhine Graben at Soultz-sous-Forêts in France and at Landau and Insheim in Germany.

Economics

As with wind and solar energy, geothermal power has minimal operating costs; capital costs dominate. Drilling accounts for over half the costs, and not all wells produce an exploitable resources. For example, a typical well pair (one for extraction and one for injection) in Nevada can produce 4.5 megawatts (MW) and costs about $10 million to drill, with a 20% failure rate, making the average cost of a successful well $50 million.

Drilling geothermal wells is more expensive than drilling oil and gas wells of comparable depth for several reasons:
 Geothermal reservoirs are usually in igneous or metamorphic rock, which is harder to penetrate than the sedimentary rock of typical hydrocarbon reservoirs.
 The rock is often fractured, which causes vibrations that damage bits and other drilling tools.
 The rock is often abrasive, with high quartz content, and sometimes contains highly corrosive fluids.
 The rock is hot, which limits use of downhole electronics.
 Well casing must be cemented from top to bottom, to resist the casing's tendency to expand and contract with temperature changes.  Oil and gas wells are usually cemented only at the bottom.
 Well diameters are considerably larger than typical oil and gas wells.

As of 2007 plant construction and well drilling cost about €2–5 million per MW of electrical capacity, while the break-even price was 0.04–0.10 € per kW·h. Enhanced geothermal systems tend to be on the high side of these ranges, with capital costs above $4 million per MW and break-even above $0.054 per kW·h.

Heating systems are much simpler than electric generators and have lower maintenance costs per kW·h, but they consume electricity to run pumps and compressors.

Development
Geothermal projects have several stages of development. Each phase has associated risks. Many projects are canceled during the stages of reconnaissance and geophysical surveys, which are unsuitable for traditional lending. At later stages can often be equity-financed.

Sustainability
Geothermal energy is considered to be sustainable because the heat extracted is so small compared to the Earth's heat content, which is approximately 100 billion times 2010 worldwide annual energy consumption. Earth's heat flows are not in equilibrium; the planet is cooling on geologic timescales. Anthropic heat extraction typically does not accelerate the cooling process.

Wells can further be considered renewable because they return the extracted water to the borehole for reheating and re-extraction, albeit at a lower temperature.

Replacing material use with energy has reduced the human environmental footprint in many applications. Geothermal has the potential to allow further reductions. For example, Iceland has sufficient geothermal energy to eliminate fossil fuels for electricity production and to heat Reykjavik sidewalks and eliminate the need for gritting.

However, local effects of heat extraction must be considered. Over the course of decades, individual wells draw down local temperatures and water levels. The three oldest sites, at Larderello, Wairakei, and the Geysers experienced reduced output because of local depletion. Heat and water, in uncertain proportions, were extracted faster than they were replenished. Reducing production and injecting additional water could allow these wells to recover their original capacity. Such strategies have been implemented at some sites. These sites continue to provide significant energy.

The Wairakei power station was commissioned in November 1958, and it attained its peak generation of 173 MW in 1965, but already the supply of high-pressure steam was faltering. In 1982 it was down-rated to intermediate pressure and the output to 157 MW. In 2005 two 8 MW isopentane systems were added, boosting output by about 14 MW. Detailed data were lost due to re-organisations.

Environmental effects

Fluids drawn from underground carry a mixture of gasses, notably carbon dioxide (), hydrogen sulfide (), methane () and ammonia (). These pollutants contribute to global warming, acid rain and noxious smells if released. Existing geothermal electric plants emit an average of  of  per megawatt-hour (MW·h) of electricity, a small fraction of the emission intensity of fossil fuel plants. A few plants emit more pollutants than gas-fired power, at least in the first few years, such as some geothermal power in Turkey. Plants that experience high levels of acids and volatile chemicals are typically equipped with emission-control systems to reduce the exhaust.

Water from geothermal sources may hold in solution trace amounts of toxic elements such as mercury, arsenic, boron, and antimony.  These chemicals precipitate as the water cools, and can damage surroundings if released. The modern practice of returning geothermal fluids into the Earth to stimulate production has the side benefit of reducing this environmental impact.

Construction can adversely affect land stability. Subsidence occurred in the Wairakei field. In Staufen im Breisgau, Germany, tectonic uplift occurred instead. A previously isolated anhydrite layer came in contact with water and turned it into gypsum, doubling its volume. Enhanced geothermal systems can trigger earthquakes as part of hydraulic fracturing. A project in Basel, Switzerland was suspended because more than 10,000 seismic events measuring up to 3.4 on the Richter Scale occurred over the first 6 days of water injection.

Geothermal power production has minimal land and freshwater requirements. Geothermal plants use  per gigawatt of electrical production (not capacity) versus  and  for coal facilities and wind farms respectively. They use  of freshwater per MW·h versus over  per MW·h for nuclear, coal, or oil.

Production

Philippines

The Philippines began geothermal research in 1962 when the Philippine Institute of Volcanology and Seismology inspected the geothermal region in Tiwi, Albay. The first geothermal power plant in the Philippines was built in 1977, located in Tongonan, Leyte. The New Zealand government contracted with the Philippines to build the plant in 1972. The Tongonan Geothermal Field (TGF) added the Upper Mahiao, Matlibog, and South Sambaloran plants, which resulted in a 508 MV capacity.

The first geothermal power plant in the Tiwi region opened in 1979, while two other plants followed in 1980 and 1982. The Tiwi geothermal field is located about 450 km from Manila. The three geothermal power plants in the Tiwi region produce 330 MWe, putting the Philippines behind the United States and Mexico in geothermal growth. The Philippines has 7 geothermal fields and continues to exploit geothermal energy by creating the Philippine Energy Plan 2012-2030 that aims to produce 70% of the country's energy by 2030.

United States

According to the Geothermal Energy Association (GEA) installed geothermal capacity in the United States grew by 5%, or 147.05 MW, in 2013. This increase came from seven geothermal projects that began production in 2012. GEA revised its 2011 estimate of installed capacity upward by 128 MW, bringing installed U.S. geothermal capacity to 3,386 MW.

See also

2010 World Geothermal Congress
Earth's internal heat budget
Geothermal activity
Hydrothermal vent
International Geothermal Association
Relative cost of electricity generated by different sources
Renewable energy by country
Thermal battery

References

External links

 Energy Efficiency and Renewable Energy – Geothermal Technologies Office
 International Energy Agency Geothermal Energy Homepage
 NREL – Geothermal Research
 2022 discussion of geothermal energy advantages and challenges

Power station technology
Sustainable energy
Volcanism

Geothermal energy


The Wind River Range (or "Winds" for short) is a mountain range of the Rocky Mountains in western Wyoming in the United States. The range runs roughly NW–SE for approximately . The Continental Divide follows the crest of the range and includes Gannett Peak, which at , is the highest peak in Wyoming; and also Fremont Peak at , the third highest peak in Wyoming. There are more than 40 other named peaks in excess of . With the exception of the Grand Teton in the Teton Range, the next 19 highest peaks in Wyoming after Gannett are also in the Winds.

Two large national forests including three wilderness areas encompass most of the mountain range. Shoshone National Forest is on the eastern side of the continental divide while Bridger-Teton National Forest is on the west. Both national forests and the entire mountain range are an integral part of the Greater Yellowstone Ecosystem. Portions of the east side of the range are inside the Wind River Indian Reservation.

History
Indigenous peoples of the Great Basin, such as the Shoshones and Absarokas (Crow) Native Americans, lived in the range beginning 7000 and 9000 years ago. Villages as high as  in elevation, dating from 700 to 2000 BC, have recently been studied by archaeologists. These villages were established by the Sheepeater band of Shoshone during pine nut harvesting season. One, dubbed "High Rise", has 60 lodges over a space of 26 acres and was recently added to the National Register of Historic Places.

One of the men from the Lewis and Clark expedition, John Colter, is thought to be the first European American person to view the range when he visited the area around 1807, though little is known about his travels through the area. In 1812, a party led by Wilson Price Hunt were the first to cross South Pass, at the southern end of the range, the pass which marked the continental divide and crest of the Rocky Mountains and became an important portion of the Oregon Trail.

Climbing was pursued in the mid to late 1800s by men such as John C. Fremont, typically for the purpose of surveying the region. Early climbers to come purely for recreation began arriving in the 1920s. Gannett Peak, the range and Wyoming's tallest, was first climbed by Arthur Tate and Floyd Stahlnaker in 1922. Most of the early climbing in the region focused around the Titcomb Basin, slowly radiating outwards. Today, the Titcomb Basin remains one of the area's busiest recreation attractions along with the Cirque of the Towers to the south.

Much of the Wind River Range received federal protection as National Forest primitive areas during 1931–32. The Wind River Range is now largely protected by three federal wilderness areas. These include the Bridger Wilderness on the western slope, designated in 1964, and the Fitzpatrick Wilderness and Popo Agie Wilderness on the eastern slope, designated in 1976 and 1984 respectively.  Together these wilderness areas protect , making the Wind River Range one of the largest road-free areas in the continental United States. Part of the eastern slope of the Wind River Range is also under the protection of the Wind River Indian Reservation.

Geology
The Winds are composed primarily of a granitic batholith which is granite rock formed deep under the surface of the Earth, over one billion years ago. Over hundreds of millions of years, rocks that were once covering this batholith eroded away. As the land continued to rise during the Laramide orogeny, further erosion occurred until all that remained were the granitic rocks.  The ice ages beginning 500,000 years ago began carving the rocks into their present shapes. Within the Winds, numerous lakes were formed by the glaciers and numerous cirques, or circular valleys, were carved out of the rocks, the most well known being the Cirque of the Towers, in the southern section of the range. Shoshone National Forest claims that there are 16 named and 140 unnamed glaciers just on the east side of the range for a total of 156, with another 27 reported by Bridger-Teton National Forest for the western slopes of the range. Several of these are the largest glaciers in the U.S. Rocky Mountains. Gannett Glacier which flows down the north slope of Gannett Peak, is the largest single glacier in the Rocky Mountains of the U.S., and is located in the Fitzpatrick Wilderness in Shoshone National Forest.

Hydrology
Several major rivers have headwaters on either side of the range. The Green and Big Sandy rivers drain southward from the west side of the range, while the Wind River drains eastward through the Shoshone Basin. The Green is the largest fork of the Colorado River while the Wind River, after changing its name to the Bighorn River, is the largest fork of the Yellowstone River. The range includes several canyons on either side, including Silas Canyon and Sinks Canyon both on the eastern side. The canyons are carved by rivers such as the Middle Fork of the Popo Agie which feeds the Wind River.

The Bridger Wilderness contains over 1,300 lakes. These lakes range in size from less than  to over , with an average size of about .  Historically, the lakes and streams of the Bridger Wilderness were devoid of fish, as were most alpine lakes throughout the Rocky Mountains.  The first known transplant of fish into the area took place in 1907 when Colorado River cutthroat trout were introduced into North Fork Lake.  Considerable fish stocking by individuals, the U.S. Forest Service, and the Wyoming Game & Fish Department, occurred between 1924 and 1935.

Ecology

The Winds are known to have a small grizzly bear population, primarily in the northernmost areas. Other mammals include the black bear, elk, moose, mule deer, pronghorn, bighorn sheep, mountain lion and wolverine. Bald eagles, falcons and hawks are just a few of the 300 species of birds known to inhabit the region. The streams and lakes are home to Yellowstone cutthroat, rainbow, brook, brown, lake, and golden trout—about 2.5 million of which were stocked by a local explorer named Finis Mitchell and his wife during the Great Depression. The forests are dominated by lodgepole pine, whitebark pine, subalpine fir, and Engelmann spruce.

The range sits alongside many of the animal migration routes in the United States and contains several important passes, notably South Pass, , at the south end of the range, which was one of the more important passes on the Oregon Trail as it passed through the Rockies. Aside from South Pass, which is at the southernmost tip of the range, no roads cross the mountains until Union Pass,  at the northern terminus of the range. There are many passes between tall peaks across the continental divide, which runs through the entire range.

Recreation
The Winds are a popular recreation destination and the vast wilderness areas attract hikers, climbers and skiers.  The Winds have many back country areas that see heavy use despite the relative remoteness of many of the trail-heads and the long approaches from those trail-heads to reach routes.  Two of the more popular backpacking destinations are the Titcomb Basin (commonly accessed via the Elkhart Park Trailhead) and the Cirque of the Towers (commonly accessed via the Big Sandy Trailhead). The exposed granite in the higher elevations of the range is particularly attractive to climbers and areas such as Cirque of the Towers in the southern portion of the range are facing overuse issues as a result.  According to the White Pine Ski Resort website, the Winds are home to one ski area, White Pine, the only lift-accessible skiing and snowboarding in the range.  Located near Pinedale, it is the oldest ski area in Wyoming.

Trails
The Wind River Range has a number of trailheads for backpackers to explore, including:

 Big Sandy (elevation )
 Boulder Lake (elevation )
 Burnt Lake (elevation )
 Elkhart Park (elevation )
 Green River Lake (elevation )
 Half Moon Lake (elevation )
 Meadow Lake (elevation )
 New Fork (elevation )
 Scab Creek (elevation )
 Spring Creek Park (elevation )

A longtime popular destination for outdoor enthusiasts, the Wind River Range has also played host to a number of wilderness and outdoor education programs. The number of trailheads and terrain variety have made it an ideal stage for learning and exploration.

Hazards

Encountering bears is a concern in the Wind River Range. There are other concerns as well, including bugs, wildfires, adverse snow conditions and nighttime cold temperatures.

Importantly, there have been notable incidents, including accidental deaths, due to falls from steep cliffs (a misstep could be fatal in this class 4/5 terrain) and due to falling rocks, over the years, including 1993, 2007 (involving an experienced NOLS leader), 2015 and 2018. Other incidents include a seriously injured backpacker being airlifted near SquareTop Mountain in 2005, and a fatal hiker incident (from an apparent accidental fall) in 2006 that involved state search and rescue. The U.S. Forest Service does not offer updated aggregated records on the official number of fatalities in the Wind River Range.

See also
 List of mountain peaks of the United States
 List of mountain ranges in Wyoming
 List of Ultras of the United States

Notes

External links

 General Information on the Wind River Range
 Climbing the Wind River Range (more)
 Glaciers in the Wind River Range
 Shoshone National Forest Federal website
 Continental Divide Trail information

Bridger–Teton National Forest
Greater Yellowstone Ecosystem
Green River (Colorado River tributary)
Landforms of Fremont County, Wyoming
Mountain ranges of Wyoming
Mountains of Fremont County, Wyoming
Mountains of Wyoming
Ranges of the Rocky Mountains
Shoshone National Forest

Wind River Range


Atlantic Crossing is a historical drama in the form of a television miniseries set in Norway and the United States during World War II.  The series is wide-ranging but pays special attention to interactions between Crown Princess Martha of Norway and President Franklin Roosevelt during the period when Martha was a war refugee in the United States after fleeing the 1940 Nazi Invasion of Norway.

Some portions with Norwegian, Danish or Swedish spoken dialogue are subtitled in English. It premiered on 25 October 2020 on NRK in Norway. The series premiered 4 April 2021 on Masterpiece Theatre on PBS.

Production
The eight part series was co-produced by the Norwegian independent production company Cinenord, Norway's public broadcaster NRK and the US Public Broadcasting Service (PBS). Most of the series was filmed in the Czech Republic and Norway.

Reception
The series created controversy in Norway by repeatedly portraying the President and the Crown Princess as romantically involved, a claim that is not supported by historical evidence.

Main cast
Sofia Helin as Crown Princess Märtha of Norway
Tobias Santelmann as Crown Prince Olav of Norway
Kyle MacLachlan as Franklin Delano Roosevelt, President of the United States
Søren Pilmark as King Haakon VII of Norway
Anneke von der Lippe as Ragni Østgaard, Crown Princess Märtha's lady-in-waiting

Recurring
 Harriet Sansom Harris as Eleanor Roosevelt, First Lady of the United States
 Daniel Betts as Harry Hopkins, Roosevelt's closest advisor on foreign policy affairs during the war
 Lucy Russell as Missy LeHand, Roosevelt's private secretary
 Suzanne Bertish as Florence Harriman, U.S. ambassador to Norway
 Leonora Eik as Princess Ragnhild of Norway
 Amathea Eik as Princess Astrid of Norway
 Justýna Brozková as Prince Harald of Norway
 Michael Pitthan as King George VI of the United Kingdom
 Abigail Rice as Queen Elizabeth of the United Kingdom
 Lasse Kolsrud as Nikolai Ramm-Østgaard, Olav's aide-de-camp
 Petr Meissel as Oswald Nordlie, King Haakon's aide-de-camp
 Terje Ranes as Johan Nygaardsvoll, Prime Minister of Norway
 Stig Ryste Amdam as General Carl Gustav Fleischer, commander of the Norwegian infantry brigade based in Scotland
 Trond Teigen as Wilhelm Morgenstierne, Norwegian Ambassador to the United States

Guest
 Erik Hivju as General Otto Ruge, Commander-in-chief of the Royal Norwegian Armed Forces
 Marianne Høgsbro as Princess Ingeborg, Duchess of Västergötland, Crown Princess Märtha's mother
 Jan Tiselius as Prince Carl, Duke of Västergötland, Crown Princess Märtha's father
 Carl-Magnus Dellow as King Gustaf V of Sweden, Crown Princess Märtha's uncle
 Oscar Töringe as Prince Carl Bernadotte, Crown Princess Märtha's brother
 Fredrik Dolk as Per-Albin Hansson, Prime Minister of Sweden
 Hartmut Krug as Victor Prinz zu Wied, German Ambassador to Sweden
 Fridtjov Såheim as Alfred Isaksen, a double amputee and survivor of the Arctic convoys
 Dan Cade as Private Joseph L. Lockard, a soldier manning the radar station at a hilltop at Opana Point, Oahu
 Stanislav Callas as Private George R. Elliot Jr., Lockard's colleague and fellow radio operator

References

External links

 Rabinowitz, Dorothy. 'Atlantic Crossing' Review: Harboring Royals and Passions, wsj, March 31, 2021
 Norwegian Government in Exile
 "Norway's crown princess fled the Nazis with her children and lived in Maryland" The Washington Post

Cultural depictions of Eleanor Roosevelt
Cultural depictions of Franklin D. Roosevelt
Cultural depictions of George VI
Masterpiece Theatre
NRK original programming
2020 Norwegian television series debuts
2020 Norwegian television series endings
2020s Norwegian drama television series
Television shows set in Norway
Television shows set in Washington, D.C.
World War II television series
Television shows set in Finland
Television shows set in London
Television shows set in Stockholm
Television shows filmed in the Czech Republic
Television shows filmed in Norway

Atlantic Crossing (TV series)