Green Tech

A new machine dubbed the "Black Phantom" can turn biomass into manmade coal.

Carbonscape, a New Zealand-based start-up, describes its invention as an industrial-sized microwave that can cook plant waste, wood waste, and "even sewage" into coal.

Carbonscape also claims that the machine captures and stores more carbon than the amount of carbon generated by the electricity needed to power it for the process.

Why would anyone want to make more coal when humans are desperately trying to get out from under the carbon dioxide mess we've been making since the Industrial Revolution?

The invention combines two popular environmental efforts: using biochar for carbon capture and storage (CCS), and developing alternative fuel sources from biomass.

While there are issues to be worked out on carbon capture and storage (CSS), it's seen by energy utilities and governments as a possible tool in reducing greenhouse gas emissions. Biochar is coal made from biomass that can be buried in soil as a carbon sink or for use in farming, rather than letting decaying plants release carbon dioxide back into the atmosphere.

Biomass--agricultural and wood byproducts that can be used to make ethanol, or electricity directly--is considered by the EU, the U.S. and others as a possible answer to reducing oil dependence while providing a cleaner and more efficient way to produce and consume energy.

As reported by the Financial Times, Carbonscape's machine turns biomass into a kind of biochar to be stored underground.

Though it's unclear just how clean it would burn, Carbonscape's biochar can also be burned as fuel.

Whether or not the invention is scalable remains to be seen, but judging from who is involved Carbonscape's claims seem legit.

The company's board includes Nick Gerritsen, the director of Aquaflow Bionomic, one of the companies developing algae biodiesel; and Tim Flannery, former Harvard University professor and environmental activist known for his books "The Future Eaters" and "The Weather Makers."

On paper, it sounds pretty good. You take the carbon dioxide pollution from paper production and transform it into a paper additive.

Carbon Sciences on Monday announced that it intends to target its carbon recycling technology toward paper manufacturers.

The company has developed a process that treats carbon dioxide gas with heat and pressure, then mixes it with other chemicals to produce calcium carbonate. For a video of the equipment in a solar-panel equipped van, click here.

Calcium carbonate, or chaulk, is used in many many industrial processes. Precipitated Calcium Carbonate, or PCC, is used to add gloss or brighten paper.

Technologies to recycle carbon dioxide waste are being seriously pursued. Large polluters, such as factories or power plants, are anticipating regulations to restrict their greenhouse gas emissions.

Several routes are being pursued, including growing algae at power plants and making baking soda. Government research in the U.S. is focused on pumping carbon dioxide underground at power plants.

Carbon Sciences' strategy is to start with the paper industry and then optimize its technology for power producers. It also envisions using its equipment at mining operations which can use calcium carbonate.

"We believe that by focusing our efforts on the existing multibillion-dollar PCC industry, we will be well-positioned to be a major player in the even larger $400 billion CO2 mitigation market in the future. This strategy is in line with our corporate mission of enabling a carbon-neutral world by transforming CO2 into high value products, one industry at a time," company CEO Derek McLeish said in a statement.

McLeish said that the main competitor to carbon recycling is carbon storage underground, an approach that has raised concerns over safety and costs.

BP has proposed capturing carbon dioxide underground. A start-up in Texas called Skyonic says it can capture the gas and turn it into baking soda.

And now Carbon Sciences says it will turn carbon dioxide emissions from power plants and factories into calcium carbonate, otherwise known as limestone or chalk. The company combines the gas with fine calcium powders in a way that doesn't require a lot of heat and pressure, or that much calcium for that matter. For every ton of carbon dioxide, you only need three tons of raw materials, says CEO Derek McLeish.

The good news is that a lot of the raw materials exist as leftover tailings from mines, says McLeish. (Side note: McLeish also has set several land speed records at the Bonneville Salt Flats; it's a hobby.) So you are essentially taking environmental garbage, mixing it with pollution, and churning out a product that can then be sold to industrial manufacturers, who in turn won't have to ask miners to dig new holes in the ground to get calcium carbonate.

McLeish, in fact, showed us a prototype of how Carbon Sciences' system will work. It's in a van he drives around (See video). The chemical reaction that takes place in the van is powered by a solar panel on the roof.

Carbon sequestration will likely be inevitable--all three leading presidential candidates favor a cap-and-trade system, after all. The question now is how. Many believe that storing it underground will likely be the most practical way to do it, particularly when you think of the millions of tons of carbon dioxide that get produced. The gas will be liquefied before being inserted into the ground to increase storage. Some of the carbon dioxide can be pumped into oil fields to extract crude oil. However, a large percentage of the gas will just sit underground.

Converting carbon dioxide into solids does take raw materials and energy. McLeish (and Joe Jones of Skyonic), though, point out that the public isn't keen on storing a gas that can be hazardous to your health in large, underground caves. Still, carbon dioxide is a low-energy molecule. Converting it to other substances does require time, money, and energy. The efficiency of the processes will determine whether or not Skyonic or Carbon Sciences can become viable.

One sequestration technology you probably won't see, however, is using carbon dioxide to grow plankton in the ocean. , the people who had that idea, have run out of money.

Here's a novel twist on curbing greenhouse gases. Some scientists and companies are examining ways of using captured carbon dioxide to extract fossil fuels.

It works like this. Carbon dioxide from smokestacks would be captured and compressed, and then shuttled into pipelines to oil fields. The gas would then be forced into oil wells to extract more fossil fuels.

The scenario solves two major problems in the energy field. First, what do you do with all of the carbon dioxide? The leading idea is to store it underground in depleted mines or saline aquifers. By being forced into oil fields, the gas will at least perform an economic function. Second, it would help ameliorate one of the age-old problems facing the oil industry: oil companies only get about 30 percent or so of the oil out of a field. (iRobot is contemplating creating a robot that can help free up captured oil.)

Granted, some of the benefits of sequestration are lost by using it to extract fossil fuels, but conventional cars are going to be with us for a while. Better to use carbon dioxide for this than leave it in the atmosphere and burn oil. Getting permits to lay pipelines will also take quite a bit of time.

Duke Energy is currently building a power plant in Indiana that will come with a carbon sequestration facility. One of the ideas the utility is contemplating is using the gas for enhanced oil recovery, said CEO Jim Rogers at the Clean Tech Investor Summit, held this week in Indian Wells, Calif. Duke is working with Princeton University on sequestration research.

Oil giant BP is also examining a way to pipe carbon dioxide from a hydrogen power plant to oil fields. Hydrogen and BP? It created a hydrogen business last year and has launched experiments.

Steven Koonin, BP's chief scientists (and a former California Institute of Technology professor), noted that underground storage--whether used in oil recovery or not--seems to be the most viable for sequestration. Transforming carbon dioxide into baking soda, which has been proposed by some companies, or other solids, he noted, requires quite a bit of additional raw material and energy.

"There is a good reason CO2 is the end product of combustion. It is a low energy molecule," he said. " Getting rid of CO2 by burying it underground may be the best option."

Still, even there, scientists still don't know if room exists underground to store it all.

Some start-ups are trying to convert the gas into a fuel.

The cleantech sector has developed as a major player in the fight against climate change. One of my friends, Dan Whaley, has founded a company called Climos to attack global warming in a new way, sinking massive amounts of carbon into the ocean depths using ocean iron fertilization. The approach has seen significant scientific study, but as he acknowledges, still has a ways to go to prove its effectiveness. That is where Climos comes in. The exciting part is the sheer scale of the potential carbon sequestration (on the order of a billion tons) and the low cost (possibly on the order of $5 to 7 per ton, according to Dan). Dan and Climos believe that they can use iron fertilization to sequester tremendous amounts of carbon, play a big part in reducing global warming, and use the carbon trading markets to finance the projects. I was also intrigued to learn more from Dan given the quality of the companies, like DNV and Ecosecurities (LSE:ECO.L), that Climos is working with to help design the carbon abatement methodology, and the care that Climos is taking to understand the environmental science. Like our own efforts in carbon, Dan believes in science and standards first. (On a personal note, I do not have a lot of choice in that matter, as my wife is an environmental scientist and statistician.) As a result, we asked Dan to do an interview with Cleantech Blog and tell us how they believe harnessing the power of the sea can play a big role in the fight against climate change.

Dan, you are one of the new class of technology entrepreneurs who is moving into cleantech. Can you share some of your background, and why you chose carbon?

In 1995 I founded the first company to commercialize travel reservations over the net, GetThere.com. We went public in 1999 and sold to Sabre in 2000. If you've booked a ticket on United Airlines' website, you've used an example of the infrastructure we built.

I think that entrepreneurs by nature love big challenges. We like to find opportunities where key technologies, services or business transformations can make a profound difference to the world. We understand that the missing ingredient we provide is the vision and the sheer will to make those transformations happen. We are perhaps at our best when the odds are against us, and when most people say we're crazy.

A few years ago, I drove from here down to Buenos Aires. Somewhere along the way, I think I woke up and really fully realized that there were some extraordinary challenges out there facing us that were much more pressing than most people had been giving them credit for. Challenges that were much more important than whether people could book their travel online, for instance. GetThere was a powerful lesson to me that I could set my mind to something and achieve it, but it was also a little numbing at times too--sometimes I wondered just exactly what I was really contributing to the world.

By contrast, the energy and environmental challenges we face as a species are exactly the kind of thing an entrepreneur likes to tackle head on. Plus it actually makes a difference whether we succeed or not.

Tell me a bit more about the concept of ocean fertilization and how it could abate C02? Why iron?

Ocean Iron Fertilization (OIF) was first proposed nearly 20 years ago by an oceanographer here in California named John Martin, at the time he was the Director of Moss Landing Marine Labs. He was the first to discover that iron was the trace nutrient limiting photosynthesis, and hence primary production, in most of the world's oceans.

Photosynthesis uses freely available sunlight to convert CO2 to organic material, which higher level organisms consume directly or which sinks into deep waters of the ocean to be sequestered for up to 1000 years. Clearly we need to lower our emissions dramatically, and immediately, but if atmospheric CO2 that we have already put into the atmosphere is ever to decline, it will be photosynthesis that eventually does the work.

Over the last billion years, phytoplankton (the micro algae that grows ubiquitously in the ocean) have helped to concentrate over 80% of all mobile carbon on the planet into the deep ocean. This process is referred to as the Biological Pump, where after plankton bloom, mature and die, they sink to the deep ocean, carrying carbon along with them. The deep ocean recirculates over very long time periods. The lag between downward flux and eventual recirculation creates an extremely effective trap. This process is probably easily 20-30x more effective at storing carbon than plant growth on land, which returns most carbon back to the atmosphere on short time scales (10-100 years).

A tiny amount of iron can stimulate a lot of phytoplankton growth. 12 publicly-funded, open ocean experiments over 15 years have shown this. The science community is now proposing the next generation of experiments, at moderate as opposed to small scale and potentially funded by private sources. We hope to answer the question just how much carbon is sequestered (not just grown), at what scale can this be done safely, and whether this can fit in to the market mechanisms that have evolved worldwide to fund the mitigation of carbon dioxide.

Who else is doing this and what exactly do you do differently as far as ocean fertilization goes?

Up until now, it has been purely been a research effort, with cruises funded by public agencies such as the National Science Foundation. There are now a few companies proposing to do this, though the primary competitor, Planktos, appears to be winding down operations due to problems fundraising. We decided to pursue this because we feel like this is one of the largest potential tools mankind might have to address global warming. Perhaps our primary differentiator is that we want to make sure that if this is done, it is done credibly and scientifically.

Our Chief Science Officer, Dr. Margaret Leinen left NSF in January. She was the head of Geosciences there and managed a $700M research budget. Her research career was in paleoceanography and biogeochemistry. Our Science Advisory Panel includes people such as Dr. Rita Colwell, the former Director of NSF, Dr. Tim Killeen, the Director of the National Center for Atmospheric Research and the recent President of the American Geophysical Union, Dr. Bob Gagosian, the former President of Woods Hole Oceanographic Institute, Dr. Tom Lovejoy, the President of the Heinz Center, and so forth.

What is different about what is happening now is that the demonstrations of OIF will be larger, focused on different questions and also funded in part by the private sector. The carbon market is the mechanism that the world has chosen to fund emissions reductions and carbon mitigation, and so if OIF can be an effective way to safely remove CO2 from the atmosphere, that will probably be financed via the carbon market.

How will you verify that the abatement is happening?

To quantify the carbon removed, we deploy a range of sensors, the most important of which are called "Neutrally Bouyant Sediment Traps" to measure the amount of carbon falling past a certain depth in the ocean. Identical measurements are taken both inside the project area as well as outside the project area--this gives us an idea of what would have happened if we hadn't been there.

There are further nuances which are important to account for, such as how much carbon really ends up coming out of the atmosphere to replace that which is being used at the ocean's surface. Also, we will need to model the impact on nutrient stocks before they are replenished via deep winter mixing, etc. There many important other details, but this probably illustrates the basic concept.

Can you go into some more detail on the questions of permanence, always a major concern in new carbon reduction methodologies.

The permanence of storage is measured in choosing the depth we place the sensors at. This depth is determined by looking at what is called the ventilation or residence time of water at difference depths in the project area. Because the oceans circulate so slowly, most of the world's water mass, in fact the majority, has not seen the surface since before fossil fuels began being combusted in the late 1800s. I think that is a fairly surprising fact to most people. By sampling water at depth for signs of human activity which also have a known history, such as tritium from bomb testing in the 1950s or from CFCs that began being released in the 1920s, oceanographers can tell how long any cubic meter of water has been away from the surface.

Putting this to practice, if you sink carbon past water that hasn't seen the surface for 300 years, and if you know the directionality of circulation in that place in the ocean, you can be fairly sure that this carbon won't see the surface for at least 300 years moving forwards. This is how we understand permanence in addition to quantity.

The IPCC defines permanence as at least 100 years, so we will likely use this definition--but ultimately the carbon market will decide what that number is, not us. Keep in mind that significant amounts of carbon are stored for timeframes which are shorter as well, i.e. 75 years, 50 years, etc. This timeshifting of carbon is meaningful and helpful as well, but we won't claim credit for this. Also, the minimum (i.e. 100 years) is just that, the minimum. Much of the carbon will be stored for much longer--hundreds to even thousands of years.

Many people question the value of 'timeshifting' carbon. They wonder if we're creating a problem for ourselves later when this carbon comes back. There are several important things to consider here. First, we really have no other options--other than emissions reductions, which are important--but really separate. There is no other way to 'dispose' of the carbon that we've put up in the atmosphere already. Nature timeshifts carbon--at some point, nearly all carbon will see the atmosphere again, the question is on what timeframe. The effectiveness of sequestration in the ocean is the reason that the majority of 'mobile' carbon has ended up there over time. Second, this approach gives us time to address our emissions problem. People have likened this to a concept called 'oscillation damping', where if you have a pulse that takes time X (as in the number of years we have been adding too much CO2 to the atmosphere) then it may take you 2X or 3X or 4X to 'dampen' that pulse, depending on its amplitude. So if we've been creating this problem for 100 years, and it takes us another 25 years to solve, then we may have to mitigate for several multiples of that. This is an unscientific quantification, but perhaps a useful illustration--and I think it also serves to highlight what a huge challenge we have ahead of us.

Aren't you worried about the impact on the environment on "adjusting" ocean nutrients? I know that has been a concern of some environmental groups.

I think there are a number of distinct concerns rolled up in your statement. One is the fear that OIF is 'messing with mother nature.' Many people feel that humans simply can't get anything right, and that we if we try to fix what we've already broken, we're likely to make it worse. This is an unscientific attitude, and one that I think also fails to appreciate some of the unique aspects of this concept.

Other concerns are whether a change in the level of iron is potentially harmful, or whether the drawdown of existing macronutrients such as nitrates, phosphates and silicates (which is what the addition of iron triggers) could result in permanent shifts, or deplete productivity elsewhere--i.e. no net benefit. There are a number of answers for this.

First, this is already happening. Iron naturally fertilizes phytoplankton blooms--and these are the largest source of carbon sequestration happening as we speak. About three billion tons of CO2 is stored safely at depth in the ocean every year, and has been for a long time. Iron is a benign mineral. It in and of itself is simply not harmful.

Second, nature has already done more aggressive iron fertilization at scales much larger and for periods much longer than we are contemplating. During the last million years on at least five or six separate occasions between the major ice ages, natural iron inputs to the ocean increased by many times what they are now for thousands of years at a time. Productivity (i.e. plankton) increases appear strongly correlated with these times of increased iron. A recent paper by Cassar, et al this year has linked nearly 40ppm of the 80-100ppm swing of carbon in the last interglacial to increased iron enrichment of ocean waters by aerosol and other transport mechanisms. If iron fertilization simply removes nutrients that would have eventually been used elsewhere, then you would not have seen sustained productivity increases in the paleo record. Where we are now is a result of all of these previous episodes--and more than likely this will happen naturally again in the future, whether humans do it on purpose or not.

Lastly, OIF will be done gradually, over decades. It can be stopped at any time.

The key is to continue to explore this as a potential mitigation mechanism and to see whether it can be both effective and safe. Demonstrations run by scientists, and funded by the private sector which can deploy the capital required for the larger projects, are probably our best chance of this.

You intend to sell carbon credits based on this process. What standard will you use, and who do you expect will be the likely buyers?

Long term if this is to be meaningful it will need to be accepted in regulated markets, in the short term the voluntary market can help provide the bridge financing to get us there. We think the Voluntary Carbon Standard (VCS) is probably the best current standard, but there are others as well. We'll target as many standards as appropriate. The methodology we are currently developing is designed around the UN Clean Development Mechanism (CDM) specification--though since it takes place in the middle of the ocean it will never qualify for those credits without changes to the regulatory framework.

You mentioned you approached the problem from the science, standards and measurement & verification end first. That's an approach I definitely agree with. Can you go into some more detail? I know you had mentioned working with DNV, among others.

A number of things need to be done before larger demonstrations like the one we propose.

First, the key science questions that will to be asked of this next generation of experiments need to be asked. We will be proposing a series of science workshops with the community this year to help facilitate that. One of the conferences will be on long term modeling. Another will be on measurement and verification techniques. We will be announcing these over the next several months.

Second, a comprehensive Environmental Impact Assessment needs to be performed by an outside party that reviews concerns in detail and against the peer-reviewed literature, identifying which are likely not an issue, which are questions of appropriate project design, and which need more study. We will be initiating this process over the next several months.

After these processes are complete we will begin to structure our proposed cruise, and publish this ahead of time. This also involves applying for appropriate international permits, etc.

DNV, or a company like that, will be involved in validating the Project Design Document (PDD) after we select a specific operating site, and before we actually go to sea. They will also come on the cruise to provide direct verification of the results.

Many of these general activities are called for by a document we produced last year which we call a Code of Conduct. We think that it is vital that companies like ours operate in a scientific, responsible and transparent manner.

So this process is kind of like planting trees, except in the ocean?

Yes, except it happens faster and the storage is more permanent. Forests store carbon in the form of standing biomass--in other words, you get storage for as long as the forest is managed and preserved. If it burns down, or gets harvested, a large part of that carbon is returned to the atmosphere. Also, if the tree dies and is not replaced, nearly all of that carbon is returned on short time scales (< 100 years). This is not to say that we shouldn't be planting trees. We should, and we are--the UN just finished planting a billion trees the week before the recent Bali conference. We need to be doing a lot more of that. Two of the most attractive aspects of ocean fertilization are low cost and large scale. Can you give us some insight into where ocean fertilization fits on the spectrum of cost and potential abatement levels?

We think credits from OIF can be delivered for about $5-7 a ton long term. No one knows what the annual global capacity might be. Certainly three billion tons a year (CO2) are already being done naturally. It is possible that another billion tons annually might be able to be added to this number, but that is pure speculation. Some people have quoted numbers that are much higher than this, but I think that's probably not a constructive exercise right now.

And of course, when do you expect to be able to offer credits off of this platform, now that the VCS has been released?

We have just received the first draft of the methodology back from Ecosecurities and DNV (Det Norske Veritas) is in the process of a formal assessment. After their comments, and possible revisions, we will submit the methodology to the VCS steering committee. They have told us they will require a 2nd formal review by a qualified verifier, after which it would qualify to be accepted as a VCS methodology.

We will also be asking other peers in the science community to help us evaluate and refine the methodology. They will certainly be the most important check. We expect it will be refined many times as measurement and modeling approaches improve.

The credits of course will be dependent on the successful completion of our first cruise. We expect this in 2009.

Dan, your OIF approach is certainly exciting given the scale and low cost of the potential CO2 abatement, and I wish you the best. It is certainly not a easy task.

Neal Dikeman is a founding partner at Jane Capital Partners LLC, a boutique merchant bank advising strategic investors and startups in cleantech. He is founding contributor of Cleantech Blog, a Contributing Editor to Alt Energy Stocks, Chairs Cleantech.org, and a blogger for the CNET Cleantech Blog.

Scientists are starting to consider planet-scale engineering projects to slow the pace of climate change--anything from causing massive plankton growth in the ocean to putting a giant mirror in space above Greenland to stop ice from melting.

These ideas to alter the earth's environment at large scale, called "geoengineering," are increasingly being articulated and seriously evaluated even though they are likely to be controversial.

Earlier this month, climate scientists held a conference in Cambridge, Mass., to discuss the importance of geoengineering projects. The overall consensus was that geoengineering deserves further study, according to one of the organizers and news reports.

Beyond that general agreement, though, there was a wide diversity of views on the potential effectiveness of these proposals and the impact they could have on how people address climate change, according to a report in Science magazine. Some feared that geoengineering could dampen efforts to address global warming in other ways, such as using less energy and investing in renewable energies.

One of the summit organizers is Harvard University Professor Daniel Schrag, a geochemist who studies climate changes over the Earth's history. Last Wednesday in Cambridge, he gave a brief outline of some of the techniques being considered and his feelings on the subject during an MIT Enterprise Forum on energy.

Most of all, Schrag is scared of the risks that undertaking these projects pose.

"We don't understand the climate system very well and so trying to engineer a system that is probably unknowable and almost certainly uncontrollable is a very frightening thing," Schrag said.

Large-scale geoengineering concepts go back decades but they appear to be gaining more currency as concerns about global warming heighten. During a presentation, Schrag noted that greenhouse gas emissions over the last two years have been higher than the "business as usual" scenario created by the Intergovernmental Panel on Climate Change.

"This may be a terrible idea but it might be better than the alternative, which is to let greenhouse-gas forming run away," he said.

Capturing carbon
Some efforts led by commercial companies are already going ahead.

Planktos and Climos are two companies that intend to "seed" the ocean with iron to stimulate the growth of plankton. During a plankton "bloom," or large-scale growth, plankton metabolize carbon dioxide.

The idea behind these ocean fertilization companies, which have already been sharply criticized, is that plankton growth can sequester large amounts of carbon dioxide in the ocean. Planktos, which launched its vessel from Florida earlier this month, has said it intends to sell carbon credits for the captured carbon dioxide.

Although not generally considered geoengineering, another technology being seriously pursued is carbon capture and sequestration at coal-fired power plants.

The U.S. Department of Energy is sponsoring a project called FutureGen to build a power plant with integrated sequestration and hydrogen production.

Commercial efforts are now getting started as well, although financing them is a significant hurdle, according to Phillip Boyle, president and chief operating officer of Powerspan. The company has developed scrubbing technology, now in testing, that it says removes 90 percent of carbon dioxide from coal power plants, along with other pollutants.

Other carbon-sequestration plans call for pumping carbon dioxide under the sea.

Artificial volcanoes
Schrag mentioned other approaches being considered, including releasing sulfur into the atmosphere in an attempt to mimic large volcanic eruptions. When sulfate aerosols are released into the atmosphere, they cool the climate; the eruption of Mount Pinatubo in the Philippines had a measurable downward effect on temperatures. Sulfur could act as a "crude" substitute for sulfate aerosols, he said.

"You could get more technical and actually put in things that are more sophisticated than sulfur that actually would hover over Greenland and reflect light away from Greenland to keep the ice sheet from melting," Schrag said. "All these ideas are actually being discussed."

Another concept put forth by Columbia University Professor Klaus Lackner is making artificial trees that would be designed to capture carbon dioxide from the air.

Apart from the technical challenges and environmental risks, geoengineering poses difficult questions over control.

"This is exactly the opposite of greenhouse gas reductions. Greenhouse gas reductions--we can't do it alone. We can do it but we need everybody to do it--China, India, and Europe and Russia and lots of other countries to participate," Schrag said.

"With climate engineering, we're not the only ones that can do it. There are any one of 25 countries that could do it. Who gets to control it? Who gets to decide?" he said. "This is a really scary thing."

Electricity generator NRG Energy and Powerspan announced on Friday a plan to create one of the largest projects to capture and bury the carbon dioxide from coal-burning power plants.

The companies said the facility in Sugar Land, Texas will capture and sequester the emissions equal to a 125 megawatt generator. That would make it a commercial-scale demonstration of the technology, one the biggest thus far.

Experts have singled out carbon capture and sequestration as an important technology to reduce greenhouse gas emissions from coal, one of the dirtiest and abundant fuels. The idea is to build the carbon capturing operations as an adjunct to coal-fired plants.

Plans at the NRG Energy plant call for capturing the pollution from its generators and then pumping it underground in the Houston area to help oil drilling.

The unit is designed to get 90 percent of the carbon dioxide emissions from the coal and be operational in 2012.

The Powerspan process, called Electro-Catalytic Oxidation, filters out nitric oxide, sulfur dioxide, mercury and fine particles from smokestacks. The remaining carbon dioxide is captured by an ammonia-based solution, which is later recovered.

Powerspan is backed by venture firm NGEN and has raised $60 million.