Um, how much hydrogen could the $2.2 billion Ivanpah solar thermal plant produce?

[NNadir]

6. You are on to something; and so are many of the world's scientists.

The literature is full of papers on the subject of the gasification of biomass, both in the presence and absence of water. In the presence of water, either subcritical or supercritical, the processes are often called "hydrothermal" gasification.

One can get a sense of the scale of this work by going on google scholar and entering the words "hydrothermal" and "biomass." I got 57,000 hits. The word "hydrothermal" is usually used in subcritical situations where at least some of the water is in the liquid phase, usually under pressure to significantly raise the boiling point of water.

Supercritical water is sometimes referred to as "SWO" supercritical water oxidation.

SWO processes give syn gas, of varying quality.

There are also pyrolytic processes, in which biomass is heated in a vacuum to its decomposition point. Historically this was how methanol was discovered by the "destructive distillation" of wood. This is why one can still hear methanol referred to as "wood alcohol."

There is also - and this is a very important process I think - carbon dioxide driven reforming. In this case biomass is heated in a carbon dioxide atmosphere wherein carbon dioxide is reduced to carbon monoxide. The controlled addition of hydrogen made either by the water gas reaction or by thermochemical hydrogen cycles - there are many examples of these - can be used to make syn gas, which again, can be used to make, well, anything.

There is also partial oxidation in oxygen. Many of these processes are already industrial. A very interesting approach to this partial oxidation is "chemical looping" in which a metal oxygen carrier is used as an oxidant, resulting in very high and contained concentrations of carbon oxides, monoxide and dioxide, which can then be utilized synthetically.

An issue in these processes are the formation of asphaltenes, which as the name sounds, is tar. Much work has been done on the cracking of asphaltenes, which are also found in petroleum, particularly heavy oils. They are, obviously, a huge constituent of "tar sands."

From my perspective, I'm not totally against biomass asphaltenes, since their use in road pavement and roofing and other applications represent sequestered carbon, carbon fairly well permanently sequestered as opposed to all those stupid "sequestration" dumps people are always talking about, either as EOR (enhanced oil recovery) schemes or as, simply, dumps. Like so called "renewable energy" they have not worked, are not working and will not work.

The scientific community is largely moving away from CCS, carbon capture and storage, to CCU, carbon capture and utilization. There is no intrinsic reason why carbon capture need involve dangerous fossil fuels; it is worth studying for its applications to biomass.

In general the above described processes have some major drawbacks, the low energy density of biomass compared with dangerous fossil fuels, the need to transport them, the corrosive nature of some of the inorganic species, in particular alkali metals, but other metals, silicates, sulfur compounds and phosphorous residues. This is a challenge for materials scientists - and I am very proud that my youngest son, a high school senior, is considering a career in materials science - but we have made significant advances in addressing them.

One of the journals I regularly read is the ACS's Energy and Fuels. The journal contains a large amount of material about the disgusting and deadly fuels coal, oil and natural gas that the so called "renewable energy" industry couldn't live without, although some of it is worth reading, but it also contains more and more material about biomass processing.

Our fear and ignorance has put us in a very dangerous place such that as we wait around for the "renewable energy" miracle that never comes, just like people wait for Jesus to come back and save us from our sins, we are rapidly approaching a point at which it will become necessary not merely to stop dumping carbon dioxide into the atmosphere, but rather to find ways to remove it.

This is an extremely challenging engineering and thermodynamic problem, and may actually have no solution, I regret to say. However, it is my opinion as I reach the end of my life, that if there is a route to doing this, it will and must involve biomass. Direct engineered capture from the air will involve huge amounts of energy.

I'm not sure that "biomass" is really "renewable energy" inasmuch as we have a big problem with the phosphorous cycle we're ignoring even as we ignore climate change or offer stupid and expensive band aid proposals that sound wonderful to airheads, but have proved useless to address it. (I'm of course referring to the damned fool fantasies about solar and wind energy.) However, since biological systems are self replicating and involve huge surface areas, they're our best shot, and in combination with uranium, plutonium, thorium and, to a lesser extent the actinides neptunium, americium and curium, they really are our last best hope.

Sometime ago I wrote a fun little riff elsewhere giving my thoughts on biofuels and their relation to nuclear energy: Better Chemistry, Better Biofuels?: The Glycerol Glut, Solketal, and other Floating Ideas. This is not the original site on which I wrote the article, but these people have seemed to copy it with attribution, which is fine with me.

Thank you for asking a very intelligent question. There's plenty of stuff to read on these points, if you look.