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MJ Grieve / AHEAD Energy 501c3
Rochester, NY
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MicroEra Power is riding this wave! Natural Gas, Biogas and Ammonia Hybrid Fuel Cell systems and novel Thermal Energy Storage are on the roadmap for a cost-effective energy transition.
A small, near-zero emission APU is a huge enabler for practical EVs in sub-freezing weather. The key questions are: what fuel? and what APU technology? I’d argue for Propane/DME/Ammonia as a trio of low pressure gaseous fuels - based on no evaporative emissions, low cost tank and refueling infrastructure, long shelf life and near zero emission potential (both in burner modes and CHP modes). Ammonia is the zero carbon emission option, of course. For larger APUs, a small high CR internal combustion engine can target 45% fuel to electric efficiency. For very small APUs for urban cars, a small SOFC (5-15 kW) can target 60% or more, with inherently zero emissions and nearly silent operation.
Producing hydrogen or ammonia as longer term storage of renewable electricity is a great idea, but I see decentralized reversible SOFC as the way to go because: - higher blends of carbon free fuel can be used, avoiding the limitations of the natural gas network. - byproduct heat can be stored and used (for heating, cooling, hot water and dehumidification). - hydrogen can be delivered to urban FCEVs.
This seems like a poor approach. Changing to heat pumps and electrification of heating brings much more flexibility. Retooling to use carbon free fuels like hydrogen and ammonia can cover most of the cases where supplemental fuel is needed. Using these carbon free fuels in fuel cells, as a high efficiency CHP approach, is about twice as efficient as burning these fuels for heat...
Efficiency and emissions are the downfall of the Microturbine range extender. A gasoline, propane or natural gas internal combustion engine (ICE) can easily and robustly meet near-zero emissions and can exceed 45% fuel to mechanical. Add series/parallel transmission and efficient highway cruises and charge sustaining operation become straightforward. My understanding is that a C65 is only about 30% efficient and while emissions are low, NOx and HC emissions are much higher than the near-zero potential of spark ignition engines with state-of-the-art 3-way catalysts. The ICE is hard to beat for higher power plug-in hybrids. SOFC hybrids are the emerging alternative for range extension in urban/low average power electric vehicles...
In an off-grid situation this might be viable, because the surplus renewable energy can be zero marginal cost. But in a developed country application with a mature electric grid it is hard to find an economic justification for this in terms of operating cost (cost of electricity and water to supply the electrolyzer per kW-h) and amortization of capital cost (operating an electrolyzer, dryer and compressor a few hour a day...) The capital cost for small scale H2 production, purification and compression seems like a huge barrier.
I think there is a flawed assumption in the comments suggesting that going from 70% to 100% will be especially difficult and expensive based on intermittency. Hawaii could certainly generate a meaningful amount of dispatchable power from sugarcane, biomass and biomethane. There is also significant hydroelectric and pumped storage potential. Demand side management can also significantly flatten the daily load variation. If necessary, carbon free hydrogen and ammonia could be imported to supplement the biofuels. 100% is a lofty goal, but 30 years seems like an adequate time to transition to an optimal system.
Much of the hydro-electric capacity is in the far North, so I expect the transmission capacity south is sometimes the bottleneck. Storage in and around Montreal may be quite useful for managing the daily swing in demand and improving power quality for hospitals, data centers etc. Of course developing the larger market for the battery technology in support of renewables is also a motivation.
In our minds there are only 2 choices for massively scaleable carbon-free synthetic fuel: hydrogen and ammonia. All the otherwise attractive synthetic hydrocarbons are carbon intensive in the molecule. Making hydrogen or ammonia from any feedstock allows full capture of process CO2 emissions for value added functions like CO2 Enhanced Oil Recovery. There are many other methods to make these fuels, so the use of coal and natural gas in the immediate term (using sequestration) is just the first step. In the longer term, when fossil fuels are depleted or no longer cost competitive (50+ years from now) we will have perfected bio, renewables and nuclear methods of sythesizing hydrogen and ammonia.
Ammonia (NH3) is the low cost, carbon-free fuel that seems to meet all the criteria as an important fuel for shipping. Ammonia is (1) low cost, (2) available worldwide and easy to make, transport and store (3) carbon-free (using a variety of cost effective processes), (4) very safe (when handled appropriately and it already is in shipping). LNG (1) is expensive in parts of world, (2) has costly infrastructure for storage and handling, (3) is only marginally less carbon intensive than diesel fuel and however small the probability, has risk for catastrophic accidents. With all due respect, we think LNG is a bridge fuel to nowhere.
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Feb 11, 2014