The Hydrogen Problem
by Jim Lane (Biofuels Digest) A numbers of readers responding to “Biofuels from a raging fireball” (Friday’s Top Story, on research work with the raging fireball, Pyrococchus furiosus, to make biofuels and renewable chemicals from hydrogen gas and CO2) raised the question, where is all the hydrogen going to come from?
As many know, hydrogen is not found in a free state in nature in much quantity — and we supply most of our hydrogen needs through steam reformation of natural gas, or cracking fossil petroleum. In other words, renewable fuels made using external hydrogen may well have a hidden fossil fuel dependency.
It all comes down to cost. There are alternative ways to make hydrogen gas, and renewable pathways for sure — if society is not using them, it is generally due to cost issues. In there, to some extent because the costs associated with renewable hydrogen are generally internalized in the process, while many of the social costs of fossil fuels are externalized — e.g. the venting of sequestered CO2.
The hydrogen dependency
Hydrogen gas is a dependency in a number of processes that make renewable fuels — most notably, those that have a hydrotreating step to remove excess oxygen. That includes the upgrade of pyrolysis oils, and even the production of aviation biofuels from renewable oils (the HEFA pathway that is currently powering most of the current flight activity).
Those beyond H2.
Now, hydrogen gas is not a required production element. Fermentation of biomass to produce an alcohol fuel does not require it. The production of diesel and jet fuels fuels using the processes pioneered by Amyris and LS9 do not. Neither does Joule’s process, not Cool Planet’s drop-in fuels (we think). We’ll get to the interesting case of LanzaTech shortly. Upgrading alcohol fuels to hydrocarbons can be accomplished without hydrogen gas — ORNL has developed such a process.
The process? Hydrogen can be produced from water, and routinely is, using an electrolytic process that you can demonstrate in a high school lab.
The problem? The process will chew up some 35-50 kilowatt hours of electricity per kilo of hydrogen.
The process? Here, microbes chew waste materials and produce biogas, rich in methane.
The problem? Costs have been the issue. But systems have been getting bigger, and options for producing hydrogen from them are there, using essentially the same processes by which hydrogen is produced from natural gas.
Steam reformation or other catalytic processes from biogas or biooil
The process? Cracking hydrogen from biomass using heat and catalysis.
The problem? Cost, again. Steam reformation itself has struggled with high costs associated with the high temperatures at which the system operates. But it has been a technology worth chasing, for in the development of F-T plants it eliminates both the need for expensive oxygen plants and larger footprints needed to deal with nitrogen dilution from air, lowering capex and space requirements.
In California last week, HyperSolar announced its plan to build renewable hydrogen generators for commercial use. Named the H2Generator, the company’s first commercial product is expected to sell at a substantially lower price than other renewable hydrogen systems that rely on expensive and energy intensive electrolyzers to split water.
…There are multiple paths to renewable hydrogen — all a matter of cost. Our take: look for symbiotic systems, of the LanzaTech type we discussed above, where hydrogen or electricity becomes available as a residue from another process. In terms of bolting on to a second technology, there’s no better way to be capital light, and get closer, faster, to parity costs with fossil pathways to hydrogen. READ MORE