I’m a mechanical engineer with experience in the nuclear industry. As one trained in the burning of fossil fuels, I became interested in the climate change issue about twenty years ago. That interest evolved into participation in  Canada’s studies of   means  to reduce greenhouse gas emissions as taken on under the Kyoto Protocol. I represented the Canadian Nuclear Association on several committees a decade ago. We are still a long way from deciding how to cope with climate change.  It seems we have some doubts about the need to reduce atmospheric carbon dioxide and just how that might be done. I’m here to seek your help with one more process which could remove carbon dioxide from the atmosphere and might simultaneously improve the planets soil. It depends on tweaking the carbon cycle to enhance the soil carbon sink. Is it possible we could turn our carbon emissions into an asset toward a sustainable future?

Many ideas have been considered to manage greenhouse gases. Most have to do with emissions reduction. A few focus on removing carbon dioxide from the atmosphere. My agricultural colleagues on the Kyoto watch proposed doing that  with growing plants.

Some carbon absorbed by plants via photosynthesis is deposited by natural processes in the soil. Large quantities have been trapped over millennia. No-till farming practices and composting are cited as means of keeping more  carbon in the soil. This seems fraught with uncertainty though. How much carbon containing plant material simply decays quickly and returns as carbon dioxide  to the atmosphere? Will soil reach an equilibrium carbon content and then absorb no more? Likely some of you are involved in advancing the science.

Nuclear energy is essentially emissions free. My task with the greenhouse management committees was to promote the idea  nuclear generated electricity just as a means of avoiding CO2 emissions. I began to wonder if it could be used in a way to go beyond that and  actually help absorb CO2 from the atmosphere. Indeed it could. As an example, I considered a scheme to pump water from northern Alberta to irrigate southern growing regions  and thus enhance plant growth there. I found half the water from the Slave river could grow enough carbon dioxide absorbing vegetation to  meet Canada’s Kyoto commitment. Conversion of the plant material to charcoal was identified as a way  ensure it stayed intact  for hundreds or thousands of years, thus becoming  an enduring  carbon sink. Crazy idea? Yes!  Remember though,  that  we are in a province where we are seriously planning to capture carbon dioxide from smokestacks and pump it underground at tremendous expense.

I finally found and went to  a relevant conference, in Georgia. About 50 people attended including archeologists, soil scientists, and experts in bioenergy. I learned that archeologists had long known of an ancient civilization in South America that apparently incorporated charcoal in soil with a variation of slash and burn agriculture. Very rich soil known as Terra Preta resulted. It is  still there hundreds of years after the civilization collapsed – possibly from disease introduced by European explorers. The researchers had gathered to discuss the implications on  carbon dioxide mangement as well as soil enrichment. The sense of discovery at this little conference was palpable. It seemed to me these people were onto something useful.

I came home enthused by the excitement to make more people aware of the possibilities. This land portion of the carbon cycle indicates plants cycle some 120 billion tonnes of carbon through the atmosphere annually. Growing plants absorb carbon dioxide  from the atmosphere via photosynthesis into carbon bearing materials. Most is returned to the atmosphere as carbon dioxide through consumption by plants themselves and various animals from microbes to elephants - and  burning of plant materials. Humans control about 24 billion tonnes of this cycle by my estimate. Emissions from fossil fuel are about 8 billion tonnes. This simple analysis suggests the potential is there to counter fossil fuel emissions through conversion of plant material to charcoal. Could we modify agricultural techniques to ensure a much larger portion of carbon is retained in the soil? More specifically,  could we convert a portion of the plant growth we manage to charcoal and place it in the soil to serve as a carbon sink and a soil enhancer?

Later on, in 2007, an Internet discussion list was established. Individuals involved tirelessly spread information on the concept and try to coordinate experimental work on biochar production and soil enhancement studies. Now, the concept  has “gone viral”. Many enthusiasts are trying it out the concept in their backyards and farms. Internet searches in 2004  came back essentially empty. Now a search on “Terra Preta” or “Charcoal in Soil” yields hundred of thousands - or more - “hits”.

Scientists and engineers are  involved. This diagram from a 2009 article in Nature Communications provides an overview. It identifies potential sources of carbon from agricultural wastes and forestry activities. It shows that a combination of oils, fuel gases and char could be produced. The char portion would be  added to soil sequestering the carbon there.  The anticipated improvement in soil fertility feeds back into the process and further enhances primary production of biomass. The stage is set for an agricultural  process which removes carbon dioxide from the atmosphere – and improves soil and agricultural production. Not many global warming solutions provide such a double benefit.

There is substantial evidence that charcoal can last for hundreds to thousands of years. Indeed, it often provides the material for carbon dating related to archeological  and other studies. Carbon dating is central to understanding the Terra Preta soils found in South America and elsewhere. A credit scheme could be developed and factored into cap and trade policies currently studied as a means of carbon dioxide management.

Researchers are working on methods to produce char cleanly and efficiently. Most use energy from biomass itself to drive the process and many propose to co-produce fuel from excess flammable gas . This process from Danny Day and the Eprida Foundation in Georgia adds other nutrients to the biochar based fertilizer product as well. As a  mechanical engineer, I  can imagine there are many ways to conserve energy and reduce pollution. As a mechanical engineer with nuclear experience, I contemplate that the needed energy might even come from nuclear generated electricity. The production of biochar and fuels could thus be increased to  conserve  organic material and provide more fuel for transportation and other uses.

My experience with soil is limited to being raised on a farm in central Alberta. I encountered various types of soil on the farm and wondered how they came to be formed. How essential is organic matter to soil fertility? I certainly need your help to understand this. To quote Henry Janzen, of Agriculture and Agri – Food Canada here in Lethbridge, “ Soil organic matter is far more than a potential tank for impounding excess CO2; it is a relentless flow of carbon atoms, through a myriad of streams – some fast, some slow – wending their way through the ecosystem driving biotic processes along the way” through provision of energy and nutrients. It is thought that charcoal acts to help bacteria and fungi drive the soil building processes that Henry refers to. How far can we go in converting organic matter to char before we starve the microorganisms which maintain soil health?

Can we really be confident that the addition of charcoal to soil will help increase it’s fertility. Studies of the Terra Preta soils over the years have provided substantial evidence that fertility is improved – at least in the tropics. There is evidence of  human caused soil improvement here in Canada too - going back thousands of years to the last ice age. Many hobbyists and researhers are now experimenting with a lot of enthusiasm. However, It seems to me it will take a long time and a lot of controlled science based work to evaluate  the process in terms of increased fertility and productivity over the long term. Several decades of discovery seems warranted in view of the potential for climate change we are facing – whether warming or cooling is associated with it.

In summary, we may need to control climate change, through greenhouse gas control or other means,  if human development is to be sustained. The carbon cycle provides insight as to one way nature does it. Humans can help.   We’ve considered a revised  agricultural  process today. It presents a promise to turn carbon dioxide emissions into a long term agricultural asset. I’m hoping some of you will turn your attention to this and undertake some evaluation. If the promise pans out, the side benefit of soil improvement might even turn out to be a more important bridge to sustainable agriculture than the initial goal of carbon dioxide removal from the atmosphere.