and Östergötland) are in service in Sweden as the , and two others are in service in Singapore as the (Archer and Swordsman). Kockums also delivered Stirling engines to Japan. Ten Japanese submarines were equipped with Stirling engines. The first submarine in the class, , was launched on 5 December 2007 and delivered to the navy in March 2009. The eleventh of the class is the first one that is equipped with lithium-ion batteries without a Stirling engine. This submarine may have a range from AIP of 6500 nautical miles and can remain submerged for 40 days. The new Swedish has the Stirling AIP system as its main energy source. The submerged endurance will be more than 18 days at 5 knots using AIP. Fuel cells Siemens has developed a 30–50 kilowatt fuel cell unit, a device that converts the chemical energy from a fuel and oxidiser into electricity. Fuel cells differ from batteries in that they require a continuous source of fuel (such as hydrogen) and oxygen, which are carried in the vessel in pressurized tanks, to sustain the chemical reaction. Nine of these units are incorporated into Howaldtswerke Deutsche Werft AG's 1,830 t submarine , lead ship for the Type 212A of the German Navy. The other boats of this class and HDW's AIP equipped export submarines, , Type 209 mod and Type 214, use two modules, also from Siemens. The Type 212 can remain submerged for 21 days; one such submarine conducted a 1600 nautical mile journey solely on AIP in 2016. After the success of Howaldtswerke Deutsche Werft AG in its export activities, several builders developed fuel-cell auxiliary units for submarines, but as of 2008 no other shipyard has a contract for a submarine so equipped. The AIP implemented on the of the Spanish Navy is based on a bioethanol-processor (provided by Hynergreen from Abengoa, SA) consisting of a reaction chamber and several intermediate Coprox reactors, that transform the BioEtOH into high purity hydrogen. The output feeds a series of fuel cells from Collins Aerospace (which also supplied fuel cells for the Space Shuttle). The reformer is fed with bioethanol as fuel, and oxygen (stored as a liquid in a high pressure cryogenic tank), generating hydrogen as a sub-product. The produced hydrogen and more oxygen is fed to the fuel cells. China has been researching fuel cell engines for AIP submarines. The Dalian Institute of Chemical