The Solar-Hydrogen-Ammonia System
A renewable energy alternative for the next century.
The C-Free Renew system is the first of its kind.
Three 2-axis solar arrays generate electricity that power an electrolyzer that makes hydrogen from water. The demonstration system is sized to generate one pound of hydrogen a day.
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- About 3000 pounds of hydrogen are needed to fuel the vehicles used to farm the 320 acre farm.
- About 5500 pounds of hydrogen are needed for the generation of ammonia to fertilize the 150 acres of corn cropland on the farm.
The solar-generated electricity also powers two air compressors that drive the hydrogen, nitrogen and ammonia mixture pumps, the air conditioner, and instrumentation and control assembly.
Any excess electricity is fed to the grid.
The solar-hydrogen system is composed of nine subsystems:
1. Electrical Power. Three two-degree-of-freedom solar trackers, each carrying 12 solar panels, are contained in a fenced area. The combined output is rated at 8.1 kilowatts. The average daily power available from panels is roughly equivalent to that available during a clear midday five-hour time period. Each array feeds its Direct Current power to an inverter in the equipment room where it is converted to alternating current power. Power not used is fed to the grid.
2. Gases Generation.Water from a nearby well flows through a deionizer for purification before entering a hydrogen generator. A nitrogen generator receives compressed air and makes pure nitrogen that flows to the nitrogen pump. At lower solar power levels, less hydrogen is generated. The oxygen is vented and the hydrogen flows to the hydrogen storage tanks, and the nitrogen flows to the ammonia shed where it is compressed and is retrained in the nitrogen storage tank.
3. Air Compressors and Air Tanks.Air, compressed by commercial electric air compressors, is used to drive the two hydrogen, nitrogen, gas mixture pumps and nitrogen generator. The air is routed through a storage tank, desiccant and refrigeration dryers, and surge tanks.
4. Hydrogen Pump Assembly. A small, vented steel building houses two compressed air driven pumps and a surge tank. The storage pump is used to pump hydrogen from the staging tank into the storage tanks. After hydrogen is bled into the tractor tanks, the tractor pump is used to pump hydrogen from the storage tanks into the tractor hydrogen tanks.
5. Large Tanks and Piping. Stainless steel piping connects the 1000-gallon steel hydrogen staging tank, eight 10-ft.-long composite hydrogen storage tanks, and the 1000-gallon steel nitrogen storage tank. The ammonia storage tank contains 100 gallons of liquid ammonia that can be used for fueling the tractor or fertilizing three acres of corn cropland. The tractor contains four 10-ft.-long composite tanks containing 80 pounds of hydrogen and one ammonia tank containing 50 gallons of ammonia. The ammonia tank contains half of the energy that’s in the hydrogen tanks.
6. Ammonia Generation. A small, vented steel building houses part of the instrumentation and control assembly and the components used to generate ammonia from nitrogen and hydrogen. Specifically: nitrogen and mixed gas pumps, surge tanks, inlet cylinders, feed cylinder, N2 pressure cylinder, outlet cylinder, collector tanks and control valves.
7. Control and Instrumentation. The unit’s control panel enables the selection of only solar or a combination of solar and grid power to operate the air compressors, air drying equipment, hydrogen and nitrogen generators, ammonia reactor and electronics. The air compressors, pumps, generators and reactor can be set for manual or automatic operation. The computer uses solar, gas pressure, temperature and collector tank data to control system functions. A display panel showing system performance information can be monitored via the internet.
8. Tractor and Tractor Fueling. The John Deere 7810 tractor is outfitted with a 9.4-liter OX Power engine based on a Ford 460 cu-in V-8 design. It runs on hydrogen gas or a mixture of hydrogen and ammonia gases. The tractor tanks are fueled by first bleeding hydrogen from the storage tanks and after the tank pressures have been equalized, the tractor pump is used. A commercial ammonia pump is used to fuel the tractor ammonia tank from the ammonia storage tank.
9. Facility. The overall facility includes four main areas:
- Equipment Room: Houses the power inverters, one air compressor, the air storage tank and moisture removal components, water purification hardware, most of the instrumentation and control subsystem, and the environmental control equipment that keeps the temperature in the gas generation and equipment room above 40 degrees.
- Gas Generation Room: Hydrogen and nitrogen generators.
- Tractor Storage Room: Adjacent to the above rooms and contains elevated tractor workstand, the second air compressor and space for storing the tractor.
- Fences: Enclose the solar array area and separately the ammonia related hardware and hydrogen storage, pumping and fill area.
Safety Measures
Maximizing personnel and equipment safety has been paramount during the design and development of the system.
The electrolyzer contains interlocks to shut off the unit should hydrogen escape and the insulated electrolyzer room is designed to allow any hydrogen that could escape to easily vent out a roof opening. All the hydrogen is stored outdoors. There is no electrical power in the hydrogen storage area as the pumps are driven by compressed air. The room in which the tractor can be stored is vented through a rotary vent in the roof.
Respectful use of ammonia, and avoiding unnecessary risks is also important. Unlike fossil fuels or other gases, it does not easily combust. Ammonia is commonly used as a cropland fertilizer and as a result, we have extensive experience and knowledge about handling ammonia safely. The system is designed to contain the ammonia or allow any residual amounts from fueling to quickly and safely evaporate and exhaust through vents.
Nitrogen generated by the system is also well-confined within tubes and pressure vessels. As a natural component of the air we breathe, any nitrogen that might leak inside a building should be small enough to not impact normal oxygen levels. Nitrogen also rises and vents quickly.