Sunday, April 07, 2013

Percival Zhang: cheap hydrogen fuel from any plant

Joseph S. has sent me links to articles (e.g. UPI, Forbes) about an energy breakthrough claimed by Percival Zhang, a bio-engineer from Virginia Tech.

He claims to have completed a system of biotechnologies that produce a large enough amount of hydrogen out of plants.

He used the second most important sugar in plants (xylose, the simplest among abundant sugars that is named after wood [in Greek] from which it was first isolated) and some enzymes to prevent the microorganisms from practicing their main hobby – reproduction – which increases the amount of produced hydrogen three-fold or so.

If you have ever cared about rocket propellants (or even hydrogen fuel cell-powered cars), I don't have to explain to you how cutely clean hydrogen is as a fuel. Its oxidation produces something of order an electronvolt per atom, a huge amount of energy, especially if you realize how light a single hydrogen atom is.

Needless to say, it's nearly mandatory for the newspaper articles written about this topic to discuss how "environmentally friendly" this possibility is and how it would reduce the "dependence on fossil fuels". Sometimes, this type of propaganda leads to nearly comical inaccuracies and mistakes in the press releases and articles, for example:
This environmentally friendly method of producing hydrogen utilizes renewable natural resources, releases almost no zero greenhouse gases and doesn't require costly or heavy metals, a university release reported Wednesday.
Well, when you burn the hydrogen, you combine hydrogen and oxygen to produce water – which actually not only is a greenhouse gas but it is the most important greenhouse gas in our atmosphere, one that is raising the average temperature by something like 33 °C. What they wanted to write is that the process releases no greenhouse gases with long residence times (of order decades or longer) – and long residence times are needed for the greenhouse effect to be strong enough and "accumulating". Note that the residence time of water vapor in the atmosphere is estimated as 9 days while the same figure is 30-95 years for carbon dioxide.

At any rate, it would be cool if hydrogen were the stuff in which we store the useful energy. But because fossil fuels – and even biofuels, if we talk about "renewable" fossil fuels – only differ by their replacement of water vapor by another beneficial gas, carbon dioxide, the new technologies must really become cheaper for them to fairly prevail.

Imagine they will. The Forbes article in particular is full of interesting technical semi-details but it also unmasks the attitudes of U.S. secretaries of energy who are expected to wisely support similar research. Both Steven Chu and his successor Ernest Moniz have trash-talked (and in Chu's case, slashed 70% of the funding for) hydrogen fuel cell research because the solutions that existed at that time produced CO2 at the same moment. Their viewpoints seem foolish and unworthy of visionaries, right? It's one of the main points of a proper energy research (and research in general) to show that certain technical assumptions we are making today aren't really necessary.

TriHyBus, a triple hybrid bus from Pilsen.

This is just an example showing how utterly foolish it is for the not-quite-experts in the government to selectively throw large amounts of money to various kinds of fashionable research. Chances are huge that they will throw it to wrong places, hopeless research directions that will get uselessly overfunded, and those promising ones actually end up being overlooked and underfunded, anyway. The main obstacle in this energy research surely isn't the shortage of net funding. Extra funding that is decided by politicians because they have to decide in some way – instead of investors who invest because they were intrigued by a particular idea and are willing to put their own money at risk – is pretty much guaranteed to be nothing else than the waste of the taxpayers' money.

I am not saying that Chu or Moniz are stupid. But general expectations just like the particular evidence above suggests that they – and government bureaucrats in general – just can't see "all promising potential paths to the future" that emerge in an industry as large as the energy industry. When the funding decisions are effectively made by one person and his or her hierarchy, many promising directions inevitably remain underfunded and the bulk of the money is inevitably spent unwisely. The government is 1) narrow-minded, 2) not guaranteed to have some of the most qualified people who are responsible for various decisions (no genuine market competition or natural selection operates within the government to achieve this outcome), and 3) unmotivated to make the decisions really well – carefully yet creatively. These three disadvantages combine to make up the public spending inferior relatively to the spending by the private sector. When we talk about the applied research that is supposed to produce economically attractive results within years or a decade, we should simply leave it to the invisible hand of the free markets as purely as we can.


  1. Minor point but if you are ranking plant sugars by importance then D-ribose and D-deoxyribose should probably take first two places (their order is debatable, though i'd go with ribose as no1) before glucose. DNA, RNA, ATP, NAD and FAD are all based on them and are all absolutely critical to life as we know it. Glucose while crucial to metabolism would be much easier to replace (way less enzymes and processes depend on it's exact shape and properties).

  2. Apparently, the people at Virginia Tech haven't heard about conservation of mass and energy. If xylose is a reactant, the liberation of carbon dioxide is manadatory. Furthermore, the production of polyphosphate and xylose requires more energy than is released by hydrogen oxidation. A chemical engineer knows all this and knows the press release is a pack of lies.

    Anyway, the chief problem with any biomass energy scheme is the diversion of farm land from food production to fuel production. America's asinine corn to ethanol program has driven up food prices world-wide. These policies are a return to the world that existed before the industrial revolution and the fossil fuel revolution. They are not only idiotic they are morally depraved.

  3. I don't see how the residence time for CO2 could be 30 - 95 years. The Mauna Loa rise and fall shows changes every year due to vegetation. In fact the CO2 levels fall every year in the northern hemisphere summer. This to me suggests that the CO2 lifetime for extra CO2 over 300 ppm would be taken down very quickly.

    The argument here seems reasonable, and shows a 5 year half life.

  4. You also need to calculate the total energy that is actually stored in plants and what percentage of our crop land would have to be devoted to this particular purposes (instead of others) before deciding if this approach is really promising. My guess is that it isn't off the top of my head.

  5. Hydrogen-burning fuel cells have their place in a spacecraft, but hydrogen storage is still too expensive and dangerous for everyday use. Methanol and ethanol are much easier to work with. True, their energy density is lower than that of gasoline, but then a fuel cell is much more efficient than any combustion engine. To your knowledge, is any work being done on alcohol fuel cells?

  6. Are you sure that they're making these trivial errors? It's plausible but I still find it hard to imagine that...

    Isn't the energy simply going from the Sun? And plants are typically *using* CO2 instead of emitting it, aren't they?

  7. A little off topic, but I learn more from reading this blog and the accompanying comments then any other. It's the only blog where I thoroughly read and digest the comments. Just love it. The whole quality vs. quantity thing. Thanks

  8. From what I have read we are introducing into the air each year an amount of CO2 that is equal to 4% of what is already there but the actual measured increase in atmospheric CO2 is just 1.9% per year, i.e. 2.1% is being removed each year by surface phenomena. If we were to totally stop our addition the 2.1% decline would still be there and this corresponds to a CO2 residence half-life of about 30 years. The Mauna Loa variation may be partly due to local, not global, effects.

  9. The Soviet Union tried to make central planning work but it miserable failed because they limited the amount of intellectual brain power to solve problems by putting bureaucrats in charge of making decisions and implementing ideas.

  10. You are right. Further reading of the link I included above says much the same thing. IPCC uses something close to 100 years in their work.

  11. I think you are right. Sunlight is a very diffuse, non-concentrated energy source and the ratio of power out to power in must be low. There are many steps in this process that lose some of that, already diffuse, power.
    Solar, photovoltaic power, when carried all the way through to vehicle propulsion, is well under five percent efficient and I’ll bet that this new method is no better and, likely, even worse. Our methanol experience demonstrates the futility of the general approach.

  12. Nancy B. HultquistApr 8, 2013, 7:22:00 AM

    Written by John, not Nancy

    “ . . . especially if you realize how light a single
    hydrogen atom is.”

    By “light” you also mean small and that is a big problem. It is so small it doesn’t behave nicely:

  13. Could you comment on the viability of Photolysis of water for Hydrogen production? Supposedly it is possible now by using common and more economical elements.
    Thank You

  14. Hydrogen can be obtained directly from water with a catalyst and sunlight, however I don't know the cost/benefit etc ratio in comparison, but can be done in desert areas. There are problems with hydrogen that make it less than the wonder-fuel of the future. These are mainly related to difficulty of storage.

    Currently, the pundits seem to be crossing their fingers over Joule Unlimited, a company which uses a genetically modified bacteria to produce bio-ethanol and bio-diesel directly from water, CO2 and photosynthesis. This process can also be operated in desert areas.

  15. Dear John, I am no chemist. In general, you may produce hydrogen by hydrolysis - separation of water to oxygen and hydrogen - except that you must spend lots of energy, the same energy that you get by burning the hydrogen later (plus a fee for inefficiency). This conservation of energy - impossibility to get the split hydrogen "for free" holds generally, regardless of the tools and catalyzers you use.

    Living forms are able to do hydrolysis as a part of many other processes that consume the energy from sunlight and also involve ATP, sugars, etc., but I am really not the right person to ask what is possible in any detail.

  16. Lubos
    People forget, regardless of where the energy comes from to produce it, Hydrogen is only a way to store and transport the energy. A Hydrocarbon is much more energy dense and easier to store and transport. A hydrocarbon infrastructure is already in place.

    It is an incredible waste to produce Hydrogen for fuel from petroleum or the electric grid.

    I am just a welder, a machinist and avid reader. It is several years since my reading into Photosynthesis and Photo hydrolysis. It was my impression that there are some quantum level probabilistic issues to understand in Photosynthesis. Seemed like they could use a good Physicist working on the problem of developing practical Photo Hydrolysis.

    It is my hope that we can bypass the food chain in trying to harvest energy from the Sun. Sunlight + catalyst + water + air -> Hydrogen or Hydrocarbon fuel.

    Thank you for your time in replying.