Wayne....here's a discussion about fuel cells and GTL fuels that I recently posted on the Raging Bull RTK thread.
"As far as directly using GTL fuels for fuel cell applications, here's what I know. ALL types of fuel cells basically run on hydrogen, although solid oxide fuel cells (SOFC) can also use CO for fuel as well. SOFCs (like those made by Global Thermoelectric) and molten carbonate fuel cells (MCFC) made by companies like FCEL (!) are very tolerant of contaminants like CO, sulfur, aromatic hydrocarbons and trace metals due to their high operating temperatures and the lack of exotic catalysts which may be contaminated by them. These types of fuel cells can essentially run on the hydrogen stream of any reformed hydrocarbon source (coal gas, syngas, methane, methanol, propane, diesel, petrol, gasoline, etc.), although the less contaminated the fuel, the better for the fuel cell’s stack efficiency and longevity. MCFCs actually reform the fuel from within the fuel cell and others (like our ITN) are working with SOFCs and ceramics to be able to DIRECTLY use methane and liquid hydrocarbons (like diesel fuel) without prior reforming. Essentially, both these types of fuel cells would be very happy using GTL fuels because of its lack of contaminants, but currently these fuels need to be reformed first (the hydrocarbon chain broken down into hydrogen and CO).
On the other hand, PEM fuel cells, made by the likes of Ballard, need a completely pure hydrogen stream to function and can be quickly contaminated with a fast reduction in efficiency if exposed to sulfur, CO or other contaminants. The quality of the fuel going into the reformer is very important for PEM fuel cells, especially since PEM fuel cells are considered to be the top candidates for fuel cell vehicles in the future. Here, clean fuels like methanol, low or no sulfur gas and GTL fuels would ideally work since the reformer can be built smaller and more efficiently if it doesn't have to scrub out sulfur and high amounts of CO prior to generating the clean hydrogen stream. Of note, there's such a thing as a DIRECT methanol PEM fuel cell that can directly use methanol without prior reforming. The issue of what will be the ultimate fuel for future cell vehicles of the future is currently very hot in alternative energy circles.
The real question, though, is whether GTL would make good fuel for fuel cell applications like PEM fuel cell vehicles (via Ballard) and stationary fuel cell applications (like power plants envisioned by FCEL). Here are some of the potential the advantages for using GTL fuels for these applications:
-- being able to use the existing petroleum storage and distribution infrastructure for GTL diesel fuel would be a HUGE cost savings. Building a hydrogen infrastructure would be a multi-billion dollar proposition, but probably is evitable.
-- GTL fuels are "technology neutral" meaning that they could be used essentially without modification in today's diesel engines, new hybrid engines (diesel and electric) and tomorrow's fuel cell vehicles. They can also be used by the military for their ships, submarines and other vehicles without modification.
-- GTL fuels store very well and don't decompose in storage tanks (for example, on islands which use diesel-driven electric generators) unlike conventional diesel fuels
-- Unlike gasoline, DTE or methanol, GTL fuels are biodegradable and non-toxic according to the EPA
-- GTL fuels are VERY easy to reform due to their straight hydrocarbon (paraffinic) chains and complete lack of contaminants. Reformers can be built smaller and more efficiently.
-- GTL fuels contain TWICE the hydrogen carrying capacity as methanol meaning that a fuel cell vehicle can go TWICE as far before refueling
-- GTL fuels can derived (as we know) from gasified coal stranded or flared natural gas, refinery bottoms, gasified biomass and other industrial hydrocarbon waste products and gases.....thus giving us a tremendous fuel from NEGATIVE VALUE FEEDSTOCKS!
-- The use of GTL fuels in the future also has other potential advantages such as greatly reducing our dependency on OPEC and allowing the Trans-Alaskan Pipeline System (TAPS) to keep operating when they run out of petroleum up there." |
