The X-15 aircraft used ammonia as one component fuel of its rocket engine.

I’ve long argued on this blog that that fossil fuel replacement this century could, on technical grounds, be achieved via a mix of nuclear fission, renewables and perhaps also fossil fuels with carbon sequestration, with a high degree of electrification; nuclear would probably end up supplying over half of final energy.

A key component of this energy revolution would be to find feasible ways of converting clean electricity (or heat) into a usable liquid fuel, to replace oil. Although biomass will provide for some of this demand, it is unrealistic to expect vast areas of arable land to be turned over to ethanol production, and as such, various synfuels (e.g., hydrogen and hydrogen-nitrogen or hydrogen-carbon derivatives such as ammonia, hydrazine and methanol) will necessarily be required, manufactured using energy inputs to liberate free hydrogen from water, plus atmospheric or concentrated gas streams to provide the other constituent elements (C, N, O). (A useful recent overview of this topic is Forsberg 2009, Is hydrogen the future of nuclear energy?).

The hydrogen used in synfuel production will likely come from either electrolysis at ~30 % electricity-to-hydrogen conversion efficiency, or via direct nuclear (or solar) heat via high-temperature thermochemical water decomposition, catalysed using the hybrid S-I or Cu-Cl cycles, at a 60 % heat-to-hydrogen conversion efficiency (Orhan et al., 2010). The ratio of future (c2100) direct electricity use to the final energy used in synfuel manufacture (via electrolysis and nuclear heat) was estimated to be 0.4 by Eerkens (2006, pg 135), although this figure did not include battery electric vehicles or biofuels.

Okay, enough background from me. What I really want to highlight here is a recent presentation by Darryl Siemer (in collaboration with Kirk Sorenson and Bob Hargraves) at the 8TH Annual NH3 Fuel Conference 19-21Sep11, Portland OR. It’s entitled “Nuclear Ammonia – A Sustainable Nuclear Renaissance’s ‘Killer App‘”. Darryl notes that:

The case it makes for a US nuclear renaissance implemented with LFTRs would apply with equal force to one implemented with S-PRISMs [IFR]. There never will be a “second nuclear era” if we can’t/won’t convince people that it’s got some unique “killer apps”.

Above is an example slide. There were 50 slides presented in his main talk, plus another 64 kept in reserve for questions! You can view the lot here. It is well worth reading carefully through the whole deck — it is packed with useful information. (My only significant critique is the conflation of “uranium” with the once-through fuel cycle — the sustainability advantage of LFTRs/thorium are equally applied to uranium if the spent fuel is recycled in fast reactors).

After presenting at the conference, Darryl told me the the following:

My talk went great – 49 slides in 27 minutes (just two minutes over) followed up by ten minutes of question-answering during the subsequent break. During the 8 years that this conference has been going on, it was only the second talk given about how nuclear power could make it all actually come true… One thing that the audience seemed to appreciate was its explanation of how nuke-powered cement kilns could make the GHG-neutral “CHx”-type synfuels needed for applications (aviation, chainsaws, etc) that ammonia wouldn’t be much good for.

By the way, who is Darryl Siemer? Here is a brief bio: Darryl Siemer, Ph.D., is a retired Idaho National Laboratory “Consulting Scientist” and an expert in virtually all of the technical aspects of radioactive waste management. Dr. Siemer has  76 journal publications in subjects including electronic circuit design, “wet” analytical methods development,   atomic spectrometry, chromatographic instrumentation, cement/concrete formulation,  and  chemical engineering/materials science related to nuclear fuel reprocessing and waste management. He earned his doctorate in chemistry from Montana State University in 1974 and was an assistant professor of chemistry at Marquette University from 1974-1978. Since then he has served as an affiliate/adjunct professor at the University of Umea (Sweden), Pennsylvania State University, the University of Idaho, and Idaho State University.

This is also interesting — a video of a car that runs on ammonia:

It’s not just about ammonia, of course. As another potential vehicle fuel, you can read about the boron car concept in the online chapter on that topic from Prescription for the Planet (by Tom Blees). And for further details on boron, see these articles by Graham R.L. Cowan at the SCGI site. In short, there are some really exciting possibilities for decarbonising the transport sector in addition to stationary electricity, once we have in place the clean electricity and heat sources such as nuclear fission. I hope that these slides and articles help you better grasp that important holistic view.

Editor: I've added this additional, relevant slideshow link (5 years old) from Los Alamos: Nuclear-Power Ammonia Production