Carbonscape: The Potential for Fixing Carbon

 By Chris Turney, author of Ice, Mud and Blood: Lessons from Climates Past

carbonscapeAs with all great stories it began with a potato. Longer ago than I care to admit, there was a time when I was a young and foolish teenager. Left at home on one of the rare occasions my parents went out, I got it into my thick skull to microwave a potato. Having no idea what to do, the timer was set to a shockingly high 40 minutes. The inevitable result was a dead microwave and a glowing black lump where the potato had once been. It was one of those painful experiences in life that one tries to forget but years later it opened up a line of thought. We need to get the amount of greenhouse gases in the atmosphere down, and fast. Could microwaving plant material help? Using patented technology, I’ve been working with a team to set up a new company called Carbonscape which is doing just that.

As many readers will know, technology now exists to capture carbon dioxide (CO2) direct from any major source that emits the offending gas. The crucial point is that the carbon dioxide can be captured and stored underground; an approach commonly referred to Carbon Capture and Storage (or CCS). This does sound rather wonderful but unfortunately there are still major problems. There are very real concerns that CCS may not be the environmental solution it’s cracked up to be: this technology only deals with greenhouse gas emissions produced by large single sources, such as power stations, while the captured gases that are supposedly stored have the potential of escaping back to the atmosphere. If this wasn’t enough, CCS won’t become commercially available for at least another decade and can only capture carbon dioxide being released in the future; it does nothing to claw back the CO2 that is already in the atmosphere.

Using photosynthesis, plants are remarkably efficient absorbers of carbon dioxide. One alternative approach is to utilise natural sinks for sequestering carbon. Forests are one possibility. The potential of the terrestrial biosphere is enormous. Consider the figures. Each year we emit 8 billion tonnes of carbon. In contrast, 120 billion tonnes of carbon are sucked out of the atmosphere each year by photosynthesis on land. Unfortunately for us, all of this is pretty much returned to the atmosphere through respiration and decomposition of plant material.

charcoalFortunately, however, we know from scientific studies that charcoal can store carbon for thousands of years. Ancient fires preserved in archaeological sites, including those found with ancient human remains, show carbon can be stable for thousands of years. This is because charcoal is highly resistant to microbial breakdown. Once formed, the charcoal effectively keeps the carbon out of the atmosphere and ocean for virtually indefinite periods.

We’ve taken this idea a step further at Carbonscape. Developing an industrial-scale unit, we’re converting wood waste and other biomass into charcoal. Our proprietary industrial microwave technology means that in spite of the energy used during production, the carbon captured draws down significantly more carbon dioxide from the atmosphere than it produces. Each industrial-scale unit converts 40-50% of wood debris into charcoal; one tonne of carbon dioxide can be fixed as charcoal per day. By converting carbon in organic material to charcoal, it can be then put into the ground where it does the most good.

At Carbonscape we hope we’re adding a new commercial reason for reforestation. Once wood has been turned into charcoal, the cleared area can be replanted, allowing us to repeat the process when the plants have matured, effectively sucking yet more carbon dioxide out of the atmosphere. A great example is the USA: if the 200 million hectares of forest used for timber production were turned to charcoal instead, each crop rotation would help bring carbon dioxide levels down by some 10 parts per million. And it’s not just potatoes or wood that can be turned into charcoal: other organic material (even sewage) can be turned into a permanent carbon sink. 

The possibilities for fixing carbon are truly enormous.  


If you see any unhelpful comments, please let us know immediately.

C Robb W. 429°

Interesting idea, have you looked into Terra Preta?

Does your product have the same beneficial effects on soil fertility? What about a comparison between intact diverse living forests, not tree farms, and your operation. Ancient temperate forests sequester huge quantities of carbon. I assume you are not suggesting replacing them with tree farms. Does your energy balance calculation include the petrochemical input and environmental damage caused by the tree farm; herbicides, pesticides, seedling producing operations, logging and transport, etc?
Why not manufacture the charcoal or biochar in the traditional way?

Written in October 2008


Absolutely. For those Celsias readers who are interested in Terra Preta and other charcoal applications, there’s a number of links at the Carbonscape site ( The key thing here is the microwave technology allows us to efficiently convert organic material into charcoal. Ideally, this method could be used at sites where natural regeneration has taken place. And because the technology can be taken to forests and other sites of organic matter, it reduces the need to transport the material off-site to be processed, maximising the environmental benefits.

Best wishes,


Written in October 2008

Jeff (anonymous)

You have a nice efficient technology for producing charcoal, which has the potential to benefit agriculture, but selling it as a form of carbon sequestration is wrong. Storing carbon for thousands of years is not good enough. People will still be around thousands of years from now. I'm sure they will be really happy when all of the greenhouse gas our generation has sequestered escapes into the atmosphere and wrecks their environment. Additionally, you have to cut down trees to make the charcoal. You can claim that the forests will be sustainably harvested, but replacing an old-growth forest with a continuously harvested forest will result in a net release of carbon into the atmosphere because the disrupted soil of a sustainably harvested forest will not hold as much carbon as an old-growth forest. Charcoal is a good agricultural resource, but I hope you are not allowed to sell it as a carbon credit. The only proposed form of sequestration that is not a fraud is the production of artificial limestone. Reforestation is necessary too, but it does not offset the carbon released by fossil fuels, because it can only offset the carbon released by the original act of tearing down the forest.

Written in October 2008

Hi Jeff,
By making charcoal, it's possible to double the carbon content of biomass, and lock carbon away that would otherwise readily decompose and return to the atmosphere. Thorugh reforestation, we can start sucking the carbon out of the atmosphere; once mature, the wood can be converted to charcoal, locking the carbon away. Even fixing carbon for a thousand years would be a significant contribution. We need to get greenhouse gas levels down and fast.


Written in October 2008

Nick (anonymous)

The Carbon sequestered in natural forests is relatively static as the forest reaches a mature state. Some forests even reach a point where they emit more carbon than they sequester. The use of farmed trees (not the design whereby trees are grown in even aged monoculture to be clearcut which presents many pressures on the envoronment) can provide truly sustianable/renewable products within the natural carbon cycle and byproducts that can be used for energy production combined with biochar production. This is also able to help offset the overuse and leaching of chemical fertilisers in agriculture, further benefitting the environment. Tree cropping can be environmentally, culturally and economically sustainable.

Written in January 2009

I have spent several years developing new applications for industrial microwave. Based on that background it does't seem to make a lot of sense to use the unique heat exchange properties of microwave to heat up biomass to 500 deg C. Why would anyone want to use heat from electricity at a overall conversion efficiency of 20% when one can use heat directly on biomass for making charcoal at around 80%. By the way, I have patents on microwave biomass gasification and I have done the lab work as well as run the economics.

Written in March 2009

Roderick Williams (anonymous)

If you use electricity you will produce more biogas. You could even use the biogas as an energy store, if the electricity is generated from a unpredictable source, for example wind. You could even use the process to convert from electricy to a liquid fuel or chemical feedstock.

All of this assume you aren't generating the electricity by burning fossil fuels.

Written in March 2009

Harold (anonymous)

I am confused about why there is no mention of the gases driven off when heating the wood and their potential uses. For example, using those gases to make the charcoal instead of/in concert with the microwaves. Or at least using the gases to generate electricity for the grid/microwave. Seems like the gases are a major part of the benefit here...

Written in March 2009

Alan Free (anonymous)

I feel the same as Harold, what happens to the gasses? If they are collected they could be used to make electricity. The talk is about making bigger and bigger microwaves which obviously is intended to make money. Why not make smaller ones as well so that people like me could make my own charcal. I like the idea of developing a terra preta garden. I do make my own charcoal, but it is a bit like driving a pedal car when a real car would be easier. I can't drive a bus which is what is currently on offer. Getting gardeners interested would be easier as they only have a few square yards to worry about. Farmers would worry about acreage being lost to research the product and harder to convince.

Written in July 2009

Simon Wong (anonymous)

I have read a few passages about biochar in these few days, and I am wondering what kinds of "input" these biochar machines accept? Could it be food wastes generated by human?

Written in December 2009

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