Daihatsu Investigating Hydrazine Fuel for Fuel Cell Vehicles
16 Apr 2012
Japanese domestic car manufacturer Daihatsu, part-owned by Toyota, is investigating the use of hydrazine as an alternative to hydrogen for future fuel cell electric vehicles (FCEV), such as its ShoCase concept, above. Hydrazine, N2H4, is a compound with chemical properties similar to those of ammonia, from which it is synthesised. Approximately 260,000 tons of hydrazine is produced annually for use in a number of industrial and process applications including in the steam cycles of conventional and nuclear power plants.
Hydrazine is toxic in its pure form but is most commonly handled in solution. Daihatsu proposes to transport and store the fuel as hydrazine hydrate, which chemically fixes to special polymer coated fuel tanks; hydrazine hydrate, which is a liquid and far less volatile than compressed hydrogen gas, may be transported and delivered in the same way that gasoline is today, under the same general safety conditions, but with no flammable fumes – potentially increasing forecourt safety.
Furthermore, unlike hydrogen, hydrazine works best in alkaline electrolyte solutions, meaning that expensive acid-resistant metal catalysts used in conventional PEM fuel cells, principally platinum, are not required. Cheaper and more readily available metals may be used instead, reducing the overall system cost; Daihatsu has successfully used both cobalt and nickel as catalysts. Lack of acidic electrolytes may also simplify the disposal and recycling of the fuel cell.
Daihatsu has been working on alternative fuel solutions for fuel cell vehicles since 2007. To date Daihatsu engineers have produced an output density of 0.5 watts per square centimetre from its hydrazine fuel cell, comparable to current hydrogen PEMFC.
Image: Daihatsu ShoCase concept car (Source: Gizmag)