A Solar-Hydrogen Energy Conversion Scheme for Agricultural Use

A solar energy activated system is presented which can produce hydrogen and hydrogen-derived fuels (methanol) for use on farms. The device, named solar-kine , also can produce fertilizer (anhydrous ammonia) as a byproduct of the hydrogen. A cost analysis shows that solar-kine may be mass-producible and sold to farmers for between $7,200 and $14,700. This is equivalent to giving the fanner energy at a price of $1.79 to $3.66 per million BTU\u27s (in 1974 dollars). Presently (Spring, 1974) regular gasoline used in tractors at 43¢ per gallon, represents a cost to the farmer of $3.77 per million BTU\u27s. As oil-based fuels increase in price in the next few years, solar-kine may represent a reasonable alternative to keep food prices down. The solar-kine system uses concentrated solar energy which can be converted into a high-density electric current by means of a thermionic heat engine. The rejected heat and electric current from the thermionic converter is supplied to an electrolysis cell which, in turn, produces hydrogen and oxygen gas. Chemical process equipment will use the hydrogen and oxygen to produce a methanol (CH3OH) fuel supply for internal combustion engines used on farm machines. The hydrogen can also be used to manufacture ammonia, ammonium nitrate (NH4NO3), and ammonium sulfate [(NH4)2SO4)] fertilizers. The following materials can be produced which are useful to the farmer: a) hydrogen gas, b) oxygen gas, c) liquid tractor fuel, d) fertilizer, e) ammonia, f) electricity, and e) heat energy We feel that any unconventional energy system, such as solar-kine, must interface and serve the conventional use of fuel energy if it is to have lasting merits. This is why we feel that it is desirable to have the complete conversion of solar energy into a liquid fuel that is safe to handle and store, and which also can be used in any conventional fossil-fuel burning system with minimum modifications. Solar energy is compatible with our environment; it is free, and its supply cannot be exhausted. It is also available at any geographic location without requiring transportation to the user\u27s site (See Fig. 2). Its major advantage over fossil fuel comes from the fact that it does not add any net heat content to the earth [5,6]. A small on-site energy system is best for the farmer because, a) It can be mass produced at 106 or more, units per year,b) Power levels needed by farms are low, 100-500 KW, c)Farm energy is used over a large geographical area, d)The main source of energy (the sun) is everywhere available,e) Heat rejected from the heat engine (thermionic) is used in other portions of the system to increase overall efficiency, and may be used in part to heat buildings,f) The farmer would be energy-independent from the price and supply undulations of the industrial complex,g) Legal considerations which regulate the large energy distribution systems would not apply, or affect, the proposed system as used by the farmer,h) Last, and possibly most important, the farmer would have a dependable fuel supply at the lowest possible cost. In the future, the proposed system will supply energy at a cost much lower than petroleum-derived energy