Advice by Anthony Ricigliano: Hydrogen has long been thought to have the potential to replace fossil fuels and ultimately eliminate carbon based emissions completely. With water as its only post-combustion byproduct, hydrogen could deliver an ideal solution to the problem of greenhouse gas emissions as a plentiful, environmentally friendly, and zero carbon emission fuel. High hopes aside, the promise of hydrogen has been stunted by challenges on multiple fronts. These challenges include:
- Cost and availability – Hydrogen is a relatively expensive fuel alternative. Outside California, availability is extremely limited. Even there, access points are few and far between.
- Prohibitive technology and vehicle costs – Fuel cells, and the vehicles which incorporate them, are extremely expensive. Additionally, the experience of user has not been great.
- Onboard Storage - In volume comparisons, hydrogen delivers much less energy than gas and diesel which limits range. Another issue is that onboard hydrogen storage systems have yet to meet size, weight, and cost objectives for commercialization purposes.
A solution to some of these hydrogen related issues is provided by ammonia, known as “the other hydrogen”. A compound consisting of nitrogen and hydrogen, ammonia can be used today as fuel in internal combustion engines, diesel engines, and fuel cells. Internal combustion engines can be adapted to run on ammonia with only minor modifications. The byproducts of combustion are water and nitrogen, with no carbon emissions.
Ammonia, which serves essentially as the delivery system for hydrogen, solves a couple of problems that exist with using hydrogen on its own. The combination of nitrogen and hydrogen results in a more stable compound, which can be liquefied at ambient temperatures and moderate pressure. This eliminates the primary difficulty of storing and transporting hydrogen. Another solution provided by ammonia is that it is widely accessible due its use across the country in fertilizers.
The issue which ammonia has not yet solved is its cost. Synthesized from hydrogen and nitrogen via the Haber-Bosch process, the production of ammonia is an extremely energy intensive undertaking, requiring high temperatures and pressures. The energy requirements for ammonia production represent about 2% of the total energy consumption in the world.
Like other fossil fuel alternatives, the biggest challenge to ammonia’s use as a mainstream fuel lies in its cost of production. One possible solution comes from another alternative energy source; wind. There are currently several pilot programs around the country using wind power for the synthesis of ammonia. Using wind farms’ excess power generated during low times of demand such as night and early morning hours, the lower cost energy is used to power the production process for ammonia instead of being put out to the electrical grid. There is still much that needs to be accomplished but the other hydrogen could play an important future role in our search for clean fuel alternatives.