much less loss (<0.1%) than in a power network (8%). The use of the existing natural gas pipelines for hydrogen was studied by NaturalHy The power-to-ammonia concept The power-to-ammonia concept offers a carbon-free energy storage route with a diversified application palette. At times when there is surplus low-carbon power, it can be used to create ammonia fuel. Ammonia may be produced by splitting water into hydrogen and oxygen with electricity, then high temperature and pressure are used to combine nitrogen from the air with the hydrogen, creating ammonia. As a liquid it is similar to propane, unlike hydrogen alone, which is difficult to store as a gas under pressure or to cryogenically liquefy and store at −253 °C. Just like natural gas, the stored ammonia can be used as a thermal fuel for transportation and electricity generation or used in a fuel cell. A standard 60,000 m³ tank of liquid ammonia contains about 211 GWh of energy, equivalent to the annual production of roughly 30 wind turbines. Ammonia can be burned cleanly: water and nitrogen are released, but no CO2 and little or no nitrogen oxides. Ammonia has multiple uses besides being an energy carrier, it is the basis for the production of many chemicals, the most common use is for fertilizer. Given this flexibility of usage, and given that the infrastructure for the safe transport, distribution and usage of ammonia is already in place, it makes ammonia a good candidate to be a large-scale, non-carbon, energy carrier of the future. Hydroelectricity Pumped water In 2008, world pumped storage generating capacity was 104 GW, while other sources claim 127 GW, which comprises the vast majority of all types of grid electric storage – all other types combined are some hundreds of MW. In many places, pumped storage hydroelectricity is used to even out the daily generating load, by pumping water to a high storage reservoir during off-peak hours and weekends, using the excess base-load capacity from coal or nuclear sources. During peak hours, this water can be used for hydroelectric generation, often as a high value rapid-response reserve to cover transient peaks in demand. Pumped storage recovers about 70% to 85% of the energy consumed, and is currently the most cost effective form of mass power storage. The chief problem with pumped storage is that it usually requires two nearby reservoirs at considerably different heights, and often requires considerable capital