By Jay Schmuecker
A MEMORIAL TO A HYDROGEN ADVOCATE
My father was an advocate of using hydrogen as a fuel to replace fossil fuels. A couple of years after he died in 2005, I started considering installing a hydrogen system on the 1500 acres of farmland that our family has in Eastern Iowa.
I was interested in seeing if we could get back to having farms that could provide self-sustaining sources of fuel that were carbon-emission free. I ran some numbers and found that the costs of installing something that could be used to farm the entire 1500 acres would be prohibitive. So I focused on the 320 acres of the Pinehurst Farm, my father’s birthplace and childhood home, that I own with my three children. They agreed that the Solar-Hydrogen Project would be a memorial to my father and their grandfather.
I wanted a hydrogen-powered tractor that could be used on the farm. I found that Pinehurst Farm is in a marginal wind turbine area, as the average wind velocity is around 12 mph. I decided to install solar panels which, as a result of my spacecraft experiences working for NASA, I preferred as they do not have many moving parts. I wanted solar energy to power a hydrogen generator, which uses electric current to break down water into hydrogen and oxygen.
Sizing the System
About 5 gallons of diesel are needed to farm an acre/year for corn and 3.5 gallons for beans. A kilogram of hydrogen gas has about the same energy content as a gallon of diesel. A pound (.45kg) of hydrogen at atmospheric pressure is about 194 cu. ft. in volume.
As a result, I calculated that we would need 3000 pounds of hydrogen a year to farm the 320 acres when half was in corn and the other half in beans. This would require 77 kilowatts of electrical power, assuming that over a year the solar panels provide power on an average of 5 hours a day. Dennis Crow, who farms the land, estimated that he uses half of his fuel for planting in the spring and half in the fall at harvest time. The growing season is about 150 days, which meant that I would need to generate 10 pounds of hydrogen a day and be able to store 1500 lbs. in tanks. I figured that during the other 215 days we could generate enough hydrogen for spring planting.
After looking at what the costs of an operational system would be, and the quality of the numbers that were used in sizing the system, I concluded that I would install a demonstration solar-hydrogen system that provided 10% of what would be required to fuel all the farm operations. From the actual data we would gather we could refine what would be required for an operational system.
A Hydrogen Fueled Tractor
Dennis was interested in having a tractor that he would use under full power in the field rather than just to drive in parades. Because of the limited hydrogen generated, our hydrogen tractor is capable of being used for 10% of the farm operations.
I started out assuming that I could obtain a diesel tractor and have it modified to run on hydrogen. Companies are working on having diesels run on hydrogen, but are years away from having a product. New Holland has developed an award-winning fuel cell powered tractor, but the costs of obtaining a tractor powered by fuel cells is prohibitive. We contacted the Hydrogen Engine Center (HEC) in Algona, Iowa, who has been making Internal Combustion Engines that are modified to run on hydrogen gas. They agreed to provide a Ford 460 cu. in. V-8 engine design that could be installed in a tractor and used in the field. We selected and purchased a John Deere 7810 tractor. The four hydrogen tanks are sized to contain enough fuel to operate the tractor at full power for four hours before refueling.
Adding Ammonia to the System
We initially agreed to include a small propane tank on the tractor that could be used as “back-up” if Dennis ran low on hydrogen fuel while in the field. The engine would operate on either hydrogen or propane. In later meetings we agreed that we would instead include a small back-up ammonia tank on the tractor and have the ability to switch between powering the tractor with hydrogen or ammonia/hydrogen.
I wanted to have a completely renewable fuel generation capability rather than purchasing ammonia. In late 2013, I discussed with Doug Carpenter his idea of generating ammonia from solar power. I found that we annually apply nitrogen based fertilizers to the corn cropland. If all the fertilizers were ammonia, 5600 pounds of hydrogen would be applied. I decided to have Doug make the ammonia reactor and added the other ammonia subsystem hardware. The demonstration ammonia generation subsystem makes ammonia from hydrogen and nitrogen, that is separated from the air, and is stored in a small tank that can be used is use to fuel the tractor or be applied to the corn cropland.
Safety a Priority
Maximizing personnel and equipment safety has been paramount during the design and development of the system.
Historically the public is afraid of hydrogen because of the “H” word: Hindenburg. The newly issued National Fire Protection Association Document 2 “Hydrogen Technologies Code 2011 Edition” has provided the safety related guidance in the 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 did leak inside a building should be small enough to not impact normal oxygen levels. Nitrogen also rises and vents quickly.