Feb 16 2010
Making Gasoline from Carbon
This week on the SGU I discussed a company, Carbon Sciences, Inc., who plans to make gasoline from atmospheric carbon dioxide (CO2). I focused on the particular application discussed in the news report, but the story raised many more questions than I answered, and so I would like to delve into this potential new technology in more depth.
These kinds of applications always fascinate me – it’s the game of follow the energy, the rules of which are the laws of thermodynamics. For quick review, essentially the first law of thermodynamics is that energy cannot be created or destroyed, it can only change forms. In other words, in any isolated system, the total energy will remain constant.
The second law of thermodynamics states that in any process of converting energy from one form to another, entropy must increase. Therefore, heat will flow from a relatively warmer system to a connected cooler system, not the other way around. Your coffee tends to cool down to room temperature – it does not spontaneously heat up, taking energy from the cooler surrounding air. The second law also means that any time you convert energy from one form to another, some of that energy is lost to entropy – it’s still there, it has just dissipated as heat or some other form and is no longer in a stored usable form.
With that as background, we can begin to think about the energy systems off of which we run our civilization, and also evaluate proposed new “green” energy systems to see if they make sense. Do biofuels, for example, make sense? Can we run our society off of hydrogen?
The next basic principle we have to consider is whether or not any energy medium is being used as a source of energy or as a way to store and transport energy. To give a simple example, when I charge a battery, the battery is not a source of energy, it is solely a way of storing energy in a usable form. Gasoline (and fossil fuels generally) is both a source and a convenient way to store energy.
An finally, we can evaluate energy systems based upon their environmental impact, and here I will focus on their effect on CO2 in the atmosphere.
Let’s take a quick look at the coming (heh) hydrogen economy. It seems this has hit a few technical snags, but that aside – can we even theoretically run our world on hydrogen? The answer is no – hydrogen is not a source of energy, because there is no free hydrogen on the earth. We must therefore obtain our hydrogen from other sources. If we split hydrogen from water that requires energy, and the second law tells us it requires more energy than we will get back from burning the hydrogen. We will need an actual source of energy to split off the hydrogen in the first place. If we obtain hydrogen from natural gas, then we are essentially using the fossil fuel as a source of energy.
So either way – hydrogen is not a source of energy. It is purely a storage medium. It may turn out to be a convenient storage medium, but then we still have the problem of where our energy is coming from. Creating and burning hydrogen may itself be carbon neutral, but you have to consider the carbon footprint of the energy production.
Biofuels are a bit more complex, because they can be both a source and way of storing usable energy. They are not as energy dense as gasoline, but close enough to be suitable for the internal combustion engine. They also have desirable properties in terms of stability vs combustibility, and temperature tolerance. So they are a reasonable storage medium.
The question of biofuels is – are they a net source of energy. The answer depends on how they are produced. Ethanol from corn, the way it is currently grown (which often involves fossil fuel-based fertilizer) is close to being energy neutral. If you consider growing, fertilizing, harvesting, and processing the plant material in order to make ethanol, biofuels are not energy efficient. There is also the separate factor of displacing farm land from food production.
Biofuels by themselves are carbon neutral – but they are only really carbon neutral to the extent that they give back more energy than they take to create. If I burn a gallon of gas to produce an equivalent energy of ethanol, I still burned the gas.
But biofuels are a potential source of energy, because part of their energy comes from the sun – plants trap solar energy through photosynthesis, and then we can harvest the chemicals they produce which store some of that energy – usually cellulose. We just need to find a plant that efficiently uses land and is sufficiently energy dense. Then we need to find a process that is energy efficient enough that at the end of the day we end up with more energy in ethanol (or some similar storage medium) than went into the entire process (not including the sunlight, which is the true ultimate source of the energy). There are labs and companies who claim to be able to do this, but the process needs to be scaled up to industrial mass production. We’ll see.
What about the question at hand – making gasoline from atmospheric CO2? Carbon Sciences claimed a year ago that they had a process for taking carbon from the air and making it into a stable solid form, which can then be used to make paper, plastics, and similar products. This is just using carbon as a raw material, and does not have to be energy efficient to make sense – as long as it’s competitive to other manufacturing processes. There is the added bonus of taking carbon out of the atmosphere, so we would need to consider what that is worth also.
But now the company is claiming they can use their process to make commercial grade gasoline or even jet fuel.
The company announced last week that it has developed a “breakthrough technology” that converts atmospheric carbon dioxide into commercial-grade gasoline, diesel fuel and jet fuel. Founded in 2006, Carbon Sciences had previously converted CO-2 into low-grade methanol using an enzyme-based technology. Now, it said, it has combined chemical and biological engineering in a bio-catalytic process that transforms carbon emissions into “a cost-efficient” energy resource.
I find this hard to believe. But I note the term “energy resource” is a bit vague – do they mean energy source, or just energy storage medium? Let us first consider this technology as an energy source. The proposed plan is to take the exhaust of coal-burning power plants (where carbon will be dense), take the carbon and use their process to make gasoline. Thermodynamics tells us that this process must take a considerable input of energy – more energy than you can possibly get out of burning the resulting gasoline. So it is trivial to conclude that this process cannot be a source of energy.
One proposal is to dedicate a nuclear power plant to providing the energy to make the gasoline. This seems absurd to me. Essentially this process will use nuclear energy to make electricity, while simultaneously burning coal to make electricity for the grid. The nuclear electricity will be used to take carbon from the coal-burning process and make it into gasoline, which can then be burned in cars. That is a lot of energy conversions – very thermodynamically inefficient.
You would be better off simply hooking the nuclear power plant into the grid and never burning the coal in the first place – that’s just one energy conversion. Or, we would be better off developing electric cars and using electrical energy to run them, charged off the nuclear power-plant supplied grid, then burning gasoline from this process.
From a carbon perspective this accomplishes nothing – because you eventually burn the gasoline you make . That carbon which was sequestered for millions of years in the coal still winds up in the atmosphere. From a carbon perspective, you are better off using this process to make solid material that will sequester the carbon for a long time.
So really the net effect of this process is to turn nuclear power into gasoline. This process itself is carbon neutral. But you are still burning coal to generate electricity, and that carbon is still winding up in the atmosphere.
If we consider this process as a way of storing energy, however, it can make sense. When you think about it – all energy production must generate usable energy, and preferably store it in a stable medium. Power generation generally does not store or buffer much energy – they simply supply what is needed moment to moment. As we explore sustainable power generation – solar, wind, geothermal, tidal, and hydroelectric – one of the challenges is that many of these energy sources are variable over time, and so to be really useful we need to store energy for when it is needed. Batteries are not a great option – they are expensive, inefficient, and usually involve a great deal of raw materials, some of which are toxic.
One option being explored is compressing gas in a large underground cavern. This is an interesting idea, but just in the theoretical stage.
Making gasoline or something similar (like ethanol) is actually a reasonable idea. If we could convert solar or wind power into gasoline, using exhaust or atmospheric carbon as raw material – we would have a carbon neutral method for storing that energy. We already have a gasoline-based infrastructure as well.
However, I don’t think this is a good idea in the short term. It is more efficient to use that electricity directly than to convert it into another form (thermodynamics again). It would probably be far better to use electricity from renewable sources to displace coal-burning power plants.
It may be a good idea in the future – it depends. Right now it is difficult to compete with the cost-efficiency of burning fossil fuels – the energy is there in a convenient form. And what carbon neutral or sustainable energy we can produce is probably best used on the grid. (The other factor that needs to be considered here is the efficiency of the grid itself – how much energy is lost in transport. I acknowledge that using electricity locally to make gasoline may be more efficient than transporting that electricity a long distance before being used. That calculation needs to be done. And, of course, the other solution, which is being talked about, is both upgrading the grid, and distributing energy production so it is more local.)
If over the next 20 years we shift our automobile fleet into one that is mostly electric, then this process of turning CO2 into gasoline may never become useful. If, however, we are burning gas indefinitely and one of two things happen, then this technology may see its day. If we begin to run out of oil, then finding alternative sources of gasoline will become crucial. Some technologies, like jets and industrial vehicles, may remain dependent on energy-dense fuel. We may have no choice, therefore, than to make jet fuel out of an energy inefficient process because we need the energy stored in that form.
Also – if we develop sustainable energy sources that more than meet the needs of the power grid (let’s say fusion power becomes feasible, or solar power comes into its own) so that in essence we have excess power generation capacity, we can store that excess power as gasoline made from CO2.
This does raise another point – current power companies do have excess power generation capacity – off peak. This is a source of inefficiency, as power plants needs to be able to make energy for immediate use during peak hours, and this extra capacity sits idle during off peak hours. This is because there is no way to efficiently store all that energy – it has to be used immediately. Extra capacity is therefore wasted. So another idea to explore is using off-peak wasted power generation capacity to store energy in this kind of process. If this would make power plants more efficient – because they have a way of leveling off their power generation (any unused power being shunted into making gasoline) that might be feasible.
Conclusion
This topic is a good example of the relative strengths and weaknesses of podcasts vs blogs for the discussion of various topics. The podcast is more entertaining and personal, and people like the convenience of listening while doing other things. Reading blogs requires a bit more of a commitment.
But writing a blog allows for getting into more depth and detail than the spoken (especially unscripted) format.
When I discussed this topic on the SGU I focused on the core claim of using a nuclear power plant to make gasoline from the exhaust of a coal-burning power plant. This makes no sense, for the reasons I discussed above. However it seemed as if I was dismissing this technology in all its possible applications. This blog post is therefore a nice companion piece to the podcast discussion, because I have the time to explore more of the nuances of this story.
In the end, I do not know if this technology will ever see the light of day. It is still a laboratory phenomenon, not ready for industrial use. The company, I suspect, is either looking for investors or to pump up its stock price. At the moment this technology seems to be mainly industry hype.
If the technology itself pans out, then we will need to think carefully about how best to apply it – which includes thinking through every step of energy production and use, and how these might compare to the alternatives. In the end, we are slaves to the laws of thermodynamics and we ignore them at our peril.
19 Responses to “Making Gasoline from Carbon”
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A ‘bio-catalytic’ process I’ve seen a documentary on some time ago that does make sense is to run factory’s “CO2 exhaust” through what amounts to algea-filled solar packs – algae could, presumably after some genetic engineering, efficiently combine CO2, water and solar power into substances that can act as an energy store.
No nuclear power needed, and it sounded like a very attainable goal (after all, that’s what algea do – they would only need to be coaxed in producing excesses of whatever photosynthesis can output…)
You are absolutely right to consider hydrogen an energy storage system rather than an energy generation system. I think it will only be practical if we can produce either a self-recharging fuel cell (NASA was working on this under the Helios project, which sorta petered out after the loss of the aircraft), which takes an electrical input to crack water into hydrogen and oxygen, then recombines those to produce electricity later, or a system where filling stations drain off stored water from fuel cells, crack it into hydrogen and oxygen, and load that up into other fuel cells. Otherwise, it’s just a way of making electricity generation cheaper for the consumer at somebody else’s expense.
Steve -
Ethanol is only one biofuel – however, you should take a second look at biodiesel. Biodiesel contains almost the same energy density as petroleum based diesel (though are about equivalent overall considering that biodiesel is a better lubricant so generate less friction in an engine.)
The energy to extract the oils from plants (and hopefully algae in the future) is much less than the processes needed to create ethanol – not mechanically breaking down cell walls, etc. Also, the corn based ethanol market, IMHO, has more to do with subsidies than good energy production. When you run the numbers and learn how much clean water is required to create one gallon of ethanol from corn, you really have to wonder what people were thinking.
Fuel cells are wonderful energy storage devices – however, as you point out, the cost to charge them is unreasonable except for the uses (satellites, etc.) where alternatives don’t readily exist. (The costs for the fuel cells themselves should also be considered!)
There was some great research into algae to biodiesel funded in the 70′s after the gas crisis which supports the idea that we could use algae as a feedstock. There are now other non-food crop feedstocks being looked at including Jethropa which, in theory, could be used to create a reasonable biodiesel product.
Biodiesel, from my perspective is a pretty cool solar energy product. Using solar energy to create a fuel that will release enough CO2 to grow more fuel! (There are no modifications needed to run a diesel engine on biodiesel – the only change one has to do is to warm up the biodiesel since viscosity curves are very different at lower temperatures.)
Anyway – keep up the good work – always a pleasure to read.
Bob
While listening to your comments on the SGU the other day, I was thinking that you may have been missing a vital point: i.e. that using nuclear power to convert atmospheric carbon to gasoline might be highly inefficient, but it would allow people to carry on using their gas-guzzling cars in a ‘carbon-neutral’ manner. A short-term solution for sure, but surely better than using oil. Nice to see you expand on the theme here.
Carbon Sciences Inc looks like a scam to me.
Dr Novella is completely correct, the key is the source of the energy to convert the CO2 into a fuel plus O2. If that source of energy is electricity, it will always be more efficient to use that electricity directly than convert it into fuel.
In looking at their press releases, they have been having breakthroughs every few months for almost 3 years now, but nothing seems to have come from it. The only patent application I see
http://www.wipo.int/pctdb/en/wo.jsp?WO=2008140821&IA=US2008006091&DISPLAY=DESC
is what they describe in this press release
http://www.carbonsciences.com/01/view_news.php?id=16
is one on making fine particle carbonates which has nothing to do with making fuels. This is a very expensive way to sequester CO2. They talk about saving money by using “tailings” as the source, but that only works for low volume applications. For every ton of coal burned, about 3 tons of CO2 are produces, requiring 7 tons of MgSiO3 to sequester it as over 5 tons of MgCO3. How can handling all that solid be cheaper than pumping a liquid (CO2) underground?
This explanation
http://www.carbonsciences.com/01/view_news.php?id=26
is nonsense. Catalysts only accelerate spontaneous reactions. There is no spontaneous reaction that breaks H2O into H and OH. The inventor of their technology discussed above, joined the company
http://www.carbonsciences.com/01/view_news.php?id=18
only a few months earlier, long after they had already gone public
http://www.carbonsciences.com/01/view_news.php?id=6
claiming to already have what their newly hired chief technical advisor just invented.
I am afraid that this looks like a scam. Which is a shame. It will make the market dubious of people who actually have real breakthroughs which unfortunately will never be as good as the fantasies the scammers can make up.
I doubt that pure hydrogen will ever be used directly because of storage and safety problems. There was a claim a few years ago that leakage could pose a risk to the ozone layer. Hydrogen combined with carbonaceous waste to create liquid fuels seems to be a good way to go. Algae has been developed that will produce hydrogen from sunlight, however, I sure would not want it to get into the wild. Zeolites have been developed to efficiently turn methane into methanol, maybe that method could be extended to a more complex liquids.
Something I’m suddenly curious about: Are there any good numbers on the amount of fossil fuels the Earth tends to produce over a given period of time? Like, a thousand gallons’ worth of petroleum every million years, or something?
(This is obviously a way-over-simplified model, but I think what I’m asking is clear. My assumption is that technically, if the human use of fossil fuels were restricted to something ludicrously low, fossil fuels would be “renewable”, assuming that the human race exists for all time.)
Making carbon rich fuel out of atmospheric CO2 is not a crazy chemistry. After all trees are doing exactly that all the time.
cdegroot (post#1) may well be on the right lines. Or perhaps we should just plant more trees…
Since America can’t even produce enough food to feed itself, I do wonder who is going to produce all this cheap bio-fuel. I also wonder whether America can actually afford it.
It should also be noted that considerable fossil fuels in the form of transport, fertilizer and running planting/harvesting machinery are needed for large scale farms to be efficient.
You are therefore burning fossil fuels to provide bio-fuels. While reducing the space needed for growing your food.
If they are using algae to convert the power plant carbon I would ask whether the algae could ever do it fast enough to be worth it, how they will deal with contamination of the algae etc… There is also the no-small matter of mutations within the algae itself. Something that could be both a blessing and a curse.
Personally, I don’t think it will scale well and will fall down there.
I think its time we invented the “infinite improbability generator” with a really good cup of earl grey tea!.
Since peak oil and related things are currently in the news, do you guys have any plans to look at that in your podcast?
It’s actually quite interesting because like climate change its got conspiracy theories, scientific validity but huge ranges (so they know it will happen, just not when). You have to know a lot of disparate facts. It ties in with global warming and its got “end of civilisation” features.
All good stuff.
eiskrystal:
America certainly can produce enough food to feed itself, due to having an impressively vast amount of arable land. (Heck, we export huge quantities of grain, and the main reason the corn ethanol exists is to use up the surplus, thereby providing corn farmers with price relief. It’s certainly not because corn ethanol is efficient. It’s because corn farmers wanted better market conditions.) America does import large quantities of food, but this is more because of desire than need. We don’t really *need* to have fresh strawberries in January, for instance, but we import them anyway because we *want* them. We could just go back to older, more traditional methods and do a lot of canning and preserving. We just don’t want to, since fresh alternatives exist.
I would note that there is already a simpler way of storing off-peak excess energy in active use: pumped-storage hydroelectric. Of course it requires an appropriate location and may not be as widely deployable as a hypothetical generated-fuel storage model. http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
Dr. Novella, I listen to your podcast religiously…
ha!
Anyway, I’m having issues with a friend of mine who just can’t shut up about denying climate change. Now he states that the ‘leading scientist’ professing global warming, Phil Jones, has resigned and admitted it’s all a fraud, based upon my friend’s reading of articles in The Washington Times and the New York Post. It’s driving me crazy!!
Can you PLEASE give me sources as to the dubious journalistic merits of these publications and the fact that Phil Jones is not the answer.
I don’t want to have to commit a crime.
Thank you,
An easy-going fan
Indeed, man cannot live on bread alone. So its just as well that America has consistently for the last ten years increased its intake of processed foodstuffs from other countries. It’s food exports have changed little though. It is also heavily, heavily dependent on wheat it seems.
There is also (I believe) a growing mandate on ethanol to produce an increasing amount each year. It is only a tiny amount of the actual oil used, but represents a lot of meals.
There are of course other considerations, with the price of oil rising can that arable land be fertilised, watered and machined. What is the quality of that land currently? Do you have farmers available and skilled to make use of that land? If the land is used organically, does that mean lower yields? What will be the environmental effects of this?
How has the recent run of bad weather affected the crops? I have had farmers complaining that its been really bad, yet strangely its going to be the best year ever for wheat according to where you look. Unfortunately (and much to my annoyance) I have yet to find any “good” info on this apparent anomaly.
While I will not go as far as labeling Carbon Sciences, Inc. as a definitive scam, it does sound to me like they are trying to patent trees and other plant life.
Extracting CO2 from the atmosphere and changing it into solids or even (bio-)fuel. That is what plants do.
And I would consider plant life a fairly useful “invention”, in spite of plants not being energy sources in and of themselves. I don’t think a patent will hold up, though.
While I agree that it’s nonsensical from a net energy standpoint to use nuclear power to capture carbon from a coal station (as you say, just turn off the coal station and use the nuclear power directly), this is not the only consideration.
Petrol has a very high energy density, takes a short time to put into a tank, and is easily stored, making it a great fuel for cars. Electric vehicles are not there et in terms of the right combination of cost, range and performance, so if this technology worked it could let us keep being able to move around while reducing our impact on the environment, while we wait for battery technology to get close enough to petrol technology to allow us to switch without too much pain.
What about the feasibility of hemp biodiesel? There isn’t much data available on it, because the ability to research it is limited due to cannabis laws in nearly every country. Not to sound like a pot activist, but it seems to me there should be some reform of the laws restricting hemp to allow laboratories to grow and study it, seeing as how it is an amazing fiber with many uses.
Mat Alford – I just love the way your mind works!