Scientists Recycle CO2 with Sunlight to Make Fuel

An anonymous reader brings us this article from Wired about a new method to produce fuel with the help of concentrated sunlight and carbon dioxide. The process "reverses" combustion, breaking down the CO2 into carbon monoxide, which is then used as a building block for hydrocarbons. Quoting: "The Sandia team envisions a day when CR5s are installed in large numbers at coal-fired power plants. Each of them could reclaim 45 pounds of carbon dioxide from the air daily and produce enough carbon monoxide to make 2.5 gallons of fuel. Coupling the CR5 with CO2 reclamation and sequestration technology, which several scientists already are pursuing, could make liquid hydrocarbons a renewable fuel."

More Technical Info

[jcaldwel (935913)]

Here is a link for more technical information on how this works http://www.greencarcongress.com/2007/12/sandia-applying.html [greencarcongress.com]

Vaporware

[by Anonymous Coward]

This sounds a lot like vaporware, in both senses of the word.

Re:Vaporware

[myc (105406)]

You may have missed the part about requiring sunlight. Also, a common misconception about photosynthesis is that plants need "nutrients" to synthesize glucose from CO2. In terms of the biochemical pathways, the only "nutrient" that are required are water and CO2; the free energy required for photosynthesis and de novo glucogenesis is provided by photons from sunlight. ATP and NADPH, energy intermediates that are consumed during the dark reactions of photosynthesis (the Calvin cycle), are generated during the light reactions of photosynthesis.

Re:

[evanbd (210358)]

I suppose you neglected to read the whole "solar energy" part of the article? The point of all these things, be they this plan or biofuels, isn't some magic pixie dust source of free energy. It's that the easiest way of getting solar energy into a useful form might be to take a detour through plants or CO or steam or something else.

Fortunately, some people are actually trying to solve these problems rather than bitching on /.

Re:

[evanbd (210358)]

The energy content that comes from the solar input is renewable. Certainly the system isn't completely renewable energy, but improvement is a good thing. It would replace some of our oil use with reprocessed CO2 from coal. "It isn't perfect" is a really, really horrible reason to not do something that's far better than the current plan.

underwhelming

[macurmudgeon (900466)]

2.5 gallons of fuel produced per plant, per day? It's nice that it might scrub pollutants but it seems the solar energy could be more profitably used to directly produce electricity.

Re:underwhelming

[by Anonymous Coward]

2.5 gallons of fuel produced per plant, per day, per installed Counter-Rotating Ring Receiver Reactor Recuperator (CR5).

Re:

[FudRucker (866063)]

that was my first thought too, 2.5 gallons of fuel per plant a day amounts to all the coal fired plants in the USA can get together and sell one person a tank of gas for their car...

Re:

[by Anonymous Coward]

Uh... I think you need to re-read the quote.

  "CR5s are installed in large numbers at coal-fired power plants. Each of them could reclaim 45 pounds of carbon dioxide from the air daily and produce enough carbon monoxide to make 2.5 gallons of fuel"

Each of the CR5s produce 2.5 gallons... large numbers of CR5 means 2.5 x "large number" per plant per day.

Re:underwhelming

[xaxa (988988)]

It would seem easier to pipe the CO2 into a greenhouse and grow some food.

Re:underwhelming

[evanbd (210358)]

And steam locomotives would seem easier than high-temperature turbines. "Seems easier" is not what I'd call a good metric for evaluating such a technology.

Re:

[misleb (129952)]

Correction: I messed up the calculation, the actual number is 240,000 units - but stil, a ridiculous quantity.

Not to mention that even if you did convert all the CO2 from the coal plants... you'd just be burning it again in cars (or something else). The entire process would not be carbon neutral. You're merely reusing the carbon once. In the end, you're releasing the exact same net amount of CO2 into the atmosphere.

Might as well just use the solar energy to create electricity directly and reduce the amoun

Re:

[PReDiToR (687141)]

if you did convert all the CO2 from the coal plants... you'd just be burning it again in cars (or something else)

And what would the cars be burning otherwise?

Oil is a fossil fuel too, using coal twice saves on burning gasoline once.

Re:underwhelming

[pla (258480)]

It's nice that it might scrub pollutants but it seems the solar energy could be more profitably used to directly produce electricity.

Great idea in the equatorial region, but solar really doesn't count as an option in the polar two-thirds of the planet (at least not until we have near-100% efficient PV panels that cost a pittance).

I would also point out that very few companies seem to want to build solar power plants, even in ideal places such as the vast tracts of desert wasteland in the US SouthWest. I presume this results because the long term costs might look great, but the books would take a big hit up front, and most companies (or at least, their current boards) couldn't care less beyond next quarter.

Given those two facts, we can either talk endlessly about why we don't use cool-tech-X, or we can deal with the reality we have now: We use a LOT of cheap and dirty coal power plants. And it costs considerably less to retrofit them with spiffy scrubbers such as TFA mentions than it does to rebuild new clean plants.

Also, who says only power plants can use this? Why couln't I (and everyone else who might care enough to give something like this a try) buy one (probably a scaled-down version to make it affordable) and toss it in my backyard? Five or ten tons a year, times a few hundred thousand people who want a free gallon or two of gasoline per day, could really make a difference.

No one renewable energy source will solve all our problems. Between them all, however, perhaps we can at least keep the planet habitable for a few more generations of humans.

Re:underwhelming

[Jimithing DMB (29796)]

Interesting? Mods.. please. I really hope the poster was joking.

[...] the solar energy could be more profitably used to directly produce electricity

As if we have a limited supply of solar energy. Yes, we better not do this because we might drain the sun.

The sad thing is that I think there are far too many people on this forum who are completely uninterested in technologies like this. Yeah, sure, we'd love to be able to grab all the energy we need from the sun and we'd love to be able to store during dark periods or transmit it with relatively low loss from lit areas to unlit areas. And it'd be great if we could harvest energy from the winds (hey, I'm a sailboat racer.. I do it all the time) or from the natural water flows.

However, until we can get all of these technologies working, something we may never see in our lifetimes, wouldn't it be nice if we could reduce the amount of pollution we produce and start harvesting at least some amount of energy from the sun? It's basically free energy. Every little thing we can do to use it will greatly improve our ability to continue the lifestyles we enjoy while reducing our environmental footprint.

We've got at least a few generations and probably many more to work this out and come up with creative ways to both meet our demands for energy and reduce our environmental footprint.

Re:underwhelming

[Diego_27182818 (174390)]

Not only that, but the size of a dish required to focus the sunlight on the "barrel" is not mentioned.

It is mentioned, from the article

An 88-square meter solar furnace will blast sunlight into the unit, heating the rings to about 2,600 degrees Fahrenheit.

i dunno

[wwmedia (950346)]

aint that like recycling dung from a big white elephant in a room?

Doesn't make sense

[SiliconEntity (448450)]

It doesn't make sense to me: first you burn coal, which basically creates energy by oxidizing carbon and creating CO2; then you use solar energy to undo that and turn the CO2 back into CO. Wouldn't it make more sense to make electricity directly from the solar energy and not involve the coal at all? Besides which, if the CO is later used as fuel as they say, then eventually you're going to oxidize that anyway and create the same CO2 you would have in the first place. It seems like a very roundabout way to add solar energy into the mix.

Re:Doesn't make sense

[vakuona (788200)]

It enables people to not have to change everything overnight. We have a big investment in carbon based fuel processes, so having away to create hydrocarbons which we then burn, and create CO2, then use solar energy to repeat the process means that hydrocarbons are now just an intermediate step, and that we have a dynamic equilibrium, and can forgo the pain of trying to get rid of all our petrol engines and replace them with fuel cell engines. At least, this won't have to be done overnight, and we actually do stop the increase in greenhouse gases, because we recycle them.

If it works, it is a clever solution.

Re:

[Martin Foster (4949)]

If you are going to burn the coal in order to produce the large quantities of energy required to warm and light homes. Then you can alleviate its impact to the environment and reuse some of that waste to make the system more efficient overall.

Solar power as of yet, is not effective enough to produce the energy of a major coal plant (with the same density of land area used). Coal plants however, pollute en-masse and this addition makes them more efficient and less hazardous to the environment as a whole.

N

Re:Doesn't make sense

[Znork (31774)]

"Wouldn't it make more sense to make electricity directly from the solar energy and not involve the coal at all?"

To some extent, yes. The main problem is that electricity produced needs to be (almost) instantly consumed. Chemical storage of the energy avoids that problem. As such, there are various forms of chemical energy storage, ranging from batteries, through hydrogen, through ammonia to hydrocarbons, all with their own problems and advantages.

With batteries, the main trouble is they store too little and they (comparatively) rapidly break down.

Fuel cells can run on hydrogen or ammonia, with varying success. Hydrogen is a PITA to store, but perhaps ammonia is a simpler compromise.

Or hydrocarbons. Which have the advantage of being easy to store and fairly stable.

The thing about the energy crisis is there is no lack of energy (in fact, global warming is in essense an excess of it, and provides excesses of it in the form of weather). There's just a huge problem of extracting, transporting and, above all, storing that energy so you can use it when and where you need it.

Re:Doesn't make sense

[Fear the Clam (230933)]

perhaps ammonia is a simpler compromise

And unlike gasoline, you wouldn't have to clean up an ammonia spill. In ammonia-fueled car, fuel spill cleans you!

Re:

[Dirtside (91468)]

So... in Soviet Russia, I guess that means you DO clean ammonia spills?

Re:

[ignavus (213578)]

Why not use the solar energy to compress air?

Then you use the compressed air to drive compressed air engines - even small cars for urban use (http://en.wikipedia.org/wiki/Air_car).

If compressed air leaks out of its storage, you get ... plain old air in the air. No pollution problems.

Homes could compress air during the day and consume it at night - or during the next day in their cars.

Compressed air is energy stored in a readily available, non-polluting medium. When it is used, it just returns into the atmos

Re:Doesn't make sense

[Eivind (15695)]

Some natural energy-sources (all energy-sources are "natural" by the way, why don't you use the standard terminology and refer to them as "renewable" energy-sources?) are very well able to accomodate fluctuations in demand and produce when we need the power, infact better than nuclear. (most of the cost in nuclear is constructing, safety and decommision, fuel is a pittance, which mean if you throttle down a nuclear powerplant you save essentially nothing. Yes you can do it, but the cost of producing at 25% is going to be 95% of the cost of producing at full-throttle)

For example, in Norway we produce much of our power using hydroelectric powerplants that run water coming from large magazines in our high mountains trough turbines attached to generators. Very nice:

• The magazines are re-filled automagically by a process known as "rain" (solar-powered!)
  
• The magazines store enough energy for like half a YEAR of use, so even longish periods of drougth are no problem.
  
• The powerplants can be ramped up or down according to need inside of less than a minute. Significantly faster than most fossil-fuel-burning powerplants.
  
• Efficiency is high, about 90% in a modern powerplant.
  
• Low impact: some lakes have water-levels that vary more than is natural, a few dams, some rivers have less water in them then they would naturally have. That's about it, the powerplant itself is typically in a mountain-cave and neither visible nor hearable.
  

It's an excellent thing for combining with other renewables: When the sun shines, use that. When the wind blows, use that. When tides are strong, use those. When neither produces much, dial up a hydroelectric or two.

Better still:

With modest investment, the things can be used as batteries: If you've at any time got to -much- power from other sources, use excess power to pump water uphill to one of the magazines, where it can be stored safely for months until needed. (yeah, this pump-turbine cycle will waste like 40% of your power, but that's true for most other kinds of batteries too)

Sucks if you live somewhere -flat- with no or little rainfall, I guess.

Re:

[dvice_null (981029)]

> For example, in Norway we produce much of our power using hydroelectric powerplants that run water coming from large magazines in our high mountains

1. Get a high mountain
2. Build hydroelectric powerplants
3. Sell electricity
4. Profit

I never realized it was that easy. So now I only need a mountain...

Re:

[by Anonymous Coward]

Norway may have an abundance of craggy valleys and the like, but the reservoir required in most places to generate hydroelectric power is a considerable cost. For example, the Hoover Dam, a large, but not monstrous project, covered 640 km. That is a significant cost, especially in populated regions where people have to be moved. Furthermore, river bottom land is usually the most agriculturally productive, so the cost of hydro power is fairly high, not to mention the environmental costs of damming a river

Re:

[ross.w (87751)]

# The magazines store enough energy for like half a YEAR of use, so even longish periods of drougth are no problem.

So six months without filling the lake is a drought is it?

Warragamba Dam near Sydney stores enough water for five years and hasn't been full since 1987.

<Crocodile Dundee>

Now that's a drought!

</Crocodile Dundee>

Renewable not!

[bradbury (33372)]

So long as any of the carbon in the cycle is coming from sources currently in the ground or oceans (e.g. coal, oil, natural gas, or methane clathrates). I.e. we are harvesting energy by oxidizing previously reduced carbon -- it is NOT RENEWABLE or SUSTAINABLE!

The only cycles which potentially work over the long term are: (a) solar; (b) fusion reactors; (c) breeder reactors; (d) thorium fuel cycle reactors. That is probably in decreasing order of length of time we could sustain our civilization off of those sources (your opinions may differ).

The coal power plant output conversion of CO2 to liquid fuels simply shifts the problem from an CO2 source one can easily sequester (coal plant smokestacks) to one which is much less easy to sequester (automobile exhausts). You have a fundamental problem here which is when are we going to incorporate the cost of "full sustainability" into our energy costs? That means any carbon you put into the atmosphere you pay to take back out of the atmosphere. Ideally you do more than that to reduce atomospheric CO2 levels back to pre-industrial levels [1], i.e. you are taking more CO2 out of the atmosphere than you are putting into it. We are currently very far from being able to do that.

So long as we continue to live off of the reduced carbon sources (stored solar energy harvested by plants hundreds of millions of years ago) and don't fully pay for them we have a real problem.

Robert

1. Or humanity makes a decision to allow the glaciers and icecaps to melt, the sea levels rise a bit, some islands and low lying areas get flooded, weather patterns to change a bit *and* spends the money necessary to mitigate the negative effects of these processes.

Short term, long term, one size doesn't fit all

[Per Abrahamsen (1397)]

At the short term, it seems to make coal based energy production more efficient. That is significant, no matter what your long time goals are, coal is going to be a very important source of energy for the next many years.

At the long term, they hope to develop the technology further so it can extract the CO2 needed directly from the atmosphere, and then it will be a renewable if successful.

A problem with the energy and climate discussion is the idea that we should have one solution to all our needs. Short

Re:

[bradbury (33372)]

I'm not saying it is impossible to use CO2 from the atmosphere as an input. Plants do it. But they have a *lot* of surface area to harvest CO2 which is only present at hundreds of ppm levels. We have the same problem with harvesting CO2 from the atmosphere that we have with harvesting solar power from the sun -- one has to produce relatively complex molecular structures, which are hopefully lightweight, at high surface area to mass (cost) ratios.

If we solve those problems for solar cells, we may be on th

Not carbon neutral

[Joce640k (829181)]

All it adds up to is getting a bit more energy out of the coal.

In the middle of the process there's a small C02 -> CO ->CO2 stage.

Probably better to use all those mirrors to heat some water and drive a turbine.

Re:

[xaxa (988988)]

The caption for the picture in the article reads "Sandia researcher Rich Diver checks out the solar furnace which will be the initial source of concentrated solar heat for converting carbon dioxide to fuel. Eventually parabolic dishes will provide the thermal energy." so it seems he is concentrating the solar energy anyway.

A New Kind of Cracker

[TheHawke (237817)]

Instead of attempting to make hydrocarbon based fuels the article toots about, crack CO down even further using an Old School catalytic cracker containing platinum, breaking CO into the base components of ultra-pure carbon (graphite) and high levels of oxygen.
Now I'd release the oxygen since atomic oxygen is the most corrosive element on the table, recover the graphite and sell it off.'
This would give the high polluting coke refineries something to grieve about since this would put a ding in their profits.

Summary a bit too rosy ...

[ScrewMaster (602015)]

Scientists Recycle CO2 with Sunlight to Make Fuel

They're leaving the production of actual liquid fuel to other people ... all this thing does right now is produce carbon monoxide.

Re:

[IamTheRealMike (537420)]

Right. IIRC you'd need to split water to get hydrogen, and then combine the CO and H2 in the Fischer-Tropsch process [wikipedia.org] to actually get liquid fuels. So it'd take a lot of energy to do, but if you can suck CO2 out of the atmosphere (a hard, hard problem), voila, you have renewable petroleum.

More steps, more energy loss

[Veramocor (262800)]

Or you could use solar energy directly (photovoltaics or solar thermal) to generate electricity and not use as much coal decreasing Carbon dioxide emissions that way. Instead they generate electricity using coal, then use solar energy to convert the CO2 back, which is dumb because each processing step has inefficiencies associated with it and adds unneeded complexity to the system.

In the best case it takes as much energy to break the CO2 bonds as you get from generating the CO2, in reality it will take much more.

Same process as wood gasification?

[bear_phillips (165929)]

Is this basically the same process used in wood gasification? In a wood gasifier, wood turns to charcoal, to CO2 then to CO. This seems to be the same thing but using the sun as the heat source instead of hot burning charcoal.

Old Technology

[PPH (736903)]

Convert CO2 to fuel with sunlight. We've had that for years. They're called plants.

Amazing!

[mqduck (232646)]

An anonymous reader brings us this article from Wired about a new method to produce fuel with the help of concentrated sunlight and carbon dioxide.

The scientists inventing this method are calling it "tree".

This vs biofuels, sustainability & how to do i

[cgraves (1213828)]

I am working [columbia.edu] on a similar process that synthesizes hydrocarbon fuels from carbon dioxide, water, and non-fossil energy (could be solar) and should eventually have some publications out about this. There are several ways to go about this. But first, let me comment on some of the comments:

Regarding the "They're leaving the production of actual liquid fuel to other people ... all this thing does right now is produce carbon monoxide." comment [slashdot.org], reducing CO2 to CO is the hardest part of the process. Once you have concentrated CO, you can follow the coal-to-liquids processes and water-gas shift (CO + H2O => CO2 + H2) to get hydrogen and run the syngas (CO + H2 mixture) into Fischer-Tropsch [wikipedia.org] reactors. They've been doing this for 50 years in South Africa to produce synthetic diesel.

Regarding the "Renewable not!" comment [slashdot.org] and using power-plant flue gas CO2 as the input to this process, this would indeed not be sustainable. However, if industrial capture of CO2 from the air [columbia.edu] is available, one can fully close the loop and have a sustainable hydrocarbon fuel cycle. Flue gas CO2 could be a good option in the short term, however. For instance, if solar and other nearly-carbon-free energy sources begin to rapidly take over, coal plants will not immediately be shut down. Other CO2-emitting industrial plants such as aluminum smelters, etc, will also have CO2 emissions to deal with, and this form of using it to store non-fossil energy by recycling it once as a liquid fuel would be worthwhile. One comment [slashdot.org] discussed this transition well.

Related, other comments [slashdot.org] say "why not just use the solar energy to produce electricity". These intermittent resources need storage, and liquid fuel storage is not a bad method (and very versatile). Others responded [slashdot.org] about storage.

So, processes like this are a way to store non-fossil energy as a convenient energy-dense fuel which can be used in our existing petroleum fuel infrastructure and vehicles (as opposed to hydrogen and batteries). Biofuels can do the same, and there are many comments above ("I saw something like this... it's called a tree") mentioning biofuels and how this process replicates it with much more complexity; indeed you could call this whole process including the Fischer-Tropsch fuel synthesis "artificial photosynthesis". However, this process cuts out the middle-man of the plant in biofuels processes, which has much lower sunlight-to-fuel efficiency than industrial solar collectors (PV or thermal) and requires a lot of fertilizers and pesticides to boost growth rate. Such land- and resource-intensive agriculture is not sustainable [sciencemag.org] in its current form and may not ever be on the scale we will need it.

TFA discusses a solar-heat-driven thermochemical process that has potential. A somewhat similar solar-heat thermolytic process splits CO2 directly [www.lare.us] at higher temperatures. There are many other methods of accomplishing this that are at different levels of development and being researched, including electrochemical (pdf link1 [risoe.dk], pdf link2 [confex.com]), photoelectrochemical, photo(bio)chemical...

Grampa's biotech solution

[Harmonious Botch (921977)]

My grandfather used to be an employee in a biotechnology venture in the 30's. It was a two stage process. The first was a corn - or sometimes a potato - plant. The second was a still. ( He was a tinsmith. ) The input was CO2 and sunlight, the output was ethanol.

Re:

[arivanov (12034)]

Not a lot have changed. Then the economics were perverted by the prohibition, now the economics are perverted by subsidies. In either case the process does not make sense neither for booze (grapes are better) nor for fuel (oil plants are better).

Re:

[arivanov (12034)]

Neither.

I am referring to the massive subsidies received by the corn farmers in the USA and the sugar beet farmers in Europe.

Re:

[edwardpickman (965122)]

Yeah but this time they are hoping to run a car with the fuel instead of running your grandfather.

Re:This is

[x2A (858210)]

Seems to be a couple years old though, this page [sandia.gov] (second story down) which includes the same photo is dated feb 2006, and includes a much better description of how it works, including how they use alternate direction rotation rings for heat conservation within the drum, although it looks like they've more recently been trying it with CO2 instead of H20. This page [greencarcongress.com] contains more info and diagram [typepad.com] of the counter rotating drum. Very interesting stuff though.

Re:

[x2A (858210)]

"this does not remove CO2 from the atmosphere"

Well technically it does, it's just that burning it puts it back into the atmosphere. Anybody who feels strongly enough could bury it instead.

Re:

[homer_ca (144738)]

Oil is already too expensive to use for power plants. Liquid fuels sell at a premium because all our transport runs on internal combustion, and the fuel produced by this process goes into a completely different market from the one for grid electricity. Electricity is probably still more efficient for harnessing solar energy, but as long as we need liquid fuels for transport, we'll need to consider ways like this to reduce oil usage.

Personally, I'll worried more about the production rate of 2.5 gal of fuel p

Re:What could possibly go wrong...

[Cyberax (705495)]

You can immediately use CO for synthesis of more complex chemicals. No need to store it.

BTW, chemical plants have a lot more nasty compounds than CO.

Urban myth

[MyNymWasTaken (879908)]

http://www.snopes.com/business/genius/spacepen.asp [snopes.com]
Claim: NASA spent millions of dollars developing an "astronaut pen" which would work in outer space while the Soviets solved the same problem by simply using pencils.
Status: False.