The world is losing its battle against global warming.
Even in Europe, where they have valiantly fought to reduce greenhouse gas
emissions, the imbalance gets worse every day. Biofuels are the biggest disappointment.
They still emit CO2 when burned and require fertilizer, processing and
transportation which all emit even more CO2.
The justification for biofuels is that the growing plants take CO2 out
of the air. However, plants growing on the land before planting were
already capturing CO2, so only the increase
in CO2 capture (if any) should be counted
The natural balance of the earth has always included
carbon storage in the plants and soil. The problem is that we have disrupted
that balance. We have burned in one century much of the carbon that nature
sequestered over millions of years. Coal is almost pure carbon, gathered by
plants and sequestered by natural processes. We need to stop burning it!
Though growing plants take CO2 from the air and fix it in
their cells, the carbon is only borrowed: 99% of that carbon ends up back
in the atmosphere as the plant is eventually burned or consumed by
animals, termites, funguses, nematodes or worms which then return the carbon to
the atmosphere. Pyrolysis
is a way to grab the carbon in plants before it can become a meal for these
creatures and return it to the soil as pure carbon biochar.
Pyrolysis
mimics the natural process that turned ancient plants into coal: When biomass
is heated up with no oxygen supply it melts into carbon, syngas and biooil.
Pyrolysis was used thousands of years ago by the natives of Brazil to enrich
their poor, acidic soil into Terra
Preta, one of the richest, most productive soils known to man.
Terra Preta still contains as much as 9% carbon. It is
always found with pottery shards and other evidence that it was man made. It is
so productive that it is bagged up and sold today as potting soil. We’re still
trying to match their superb results. If we succeed, we will solve world
hunger, global warming and our energy shortage in one stroke.
The Amazon culture that made these soils was killed by
conquest and disease. The primitive people in the area today practice slash
and burn agriculture, which quickly depletes the soil and spews CO2 and
pollutants into the atmosphere. The Terra Preta was created by slash
and char, which involves cutting off oxygen to the burning biomass by
covering it with dirt. Without oxygen, little CO2 is produced and the biomass
melts into carbon with a very fine structure called biochar. The hydrogen in
the plant molecules produces heat and water as it combines with oxygen from the
plant molecules.
The buried biochar is like activated charcoal with very
high surface area. It can hold water and nutrients and gradually release them
as needed. Even more important, the nanoscale structure of biochar, like a
coral reef, hosts a whole ecosystem of soil fungi and bacteria that feeds the
roots of plants. This part of the terra
preta story is still not fully understood. It takes some time for this
microscopic biological culture to develop and produce the amazing increases in
yield for the soil.
Experiments have shown that burying biochar in the soil
can increase productivity significantly. For poor acidic soil it has sometimes
been known to double
or triple production! The pyrolysis
process converts cellulosic matter into biooil and biochar by heating in
the absence of oxygen. The biooil produced can be used like low-grade diesel
fuel for heating and power generation.
The energy in the biooil produced is much greater than
what is obtained by fermentation to ethanol. For example, Miscanthus, a wild
grass can produce 340
GJ/hectare/year of biooil. For
comparison, corn only produces 120
GJ/hectare/year (net) of ethanol by fermentation. While the corn ethanol
production process emits a lot of CO2 into the atmosphere, the biochar produced
as a byproduct of pyrolysis can be buried for carbon credits and crop
enhancement. Every ton of biomass produces about 400 lbs of biochar by weight
which is equivalent to about ˝ ton of CO2. (CO2 is only 27% carbon)
Because biomass has low energy density, it is expensive
to ship, pyrolysis units should therefore be close to the biomass source. Since biooil occupies about one tenth as
much volume as the biomass that produced it, it can be easily shipped by tanker
truck or used locally. Pyrolysis
units are available that fit in a standard shipping container and can handle
the needs of a small village. Using catalysts, central plants can convert the
biooil and syngas to ethanol
and other chemicals usually made from petroleum.
Carbon-inefficient slash and burn agriculture is
practiced by 300-500 million people today. If we could convert these people to
slash and char methods, we could stop the growth of greenhouse gasses in its
tracks. The International
Biochar Initiative and the Biochar
Fund are dedicated to making that happen. This is a win-win proposition
because crop yields are significantly improved while global warming is brought
under control and the biooil produced provides a local source of fuel for
electricity, cooking or heating. More crops, free fuel plus a revenue stream
from selling carbon credits could transform these subsistence cultures while
saving the planet.
As a direct result
of global warming, large tracts of forests in Canada and the United States have
been decimated
by bark beetles. Though fast growing
trees initially take in a lot of CO2 and sequester it temporarily in their
wood, dead wood absorbs nothing. If we
burn the trees all of the carbon they took in will be returned to the
atmosphere. If termites
consume the trees they will produce methane and CO2 with even worse effects.
Methane is forty times worse for global warming than CO2. Pyrolysis could pay
for itself by producing biooil and biochar while disposing of the dead trees to
make room for healthy new ones.
The 2008 farm bill
(passed over Bush’s veto!) included amazingly strong provisions for encouraging
development of Biochar. The farm lobby finally got it right! Agriculture has
been a big contributor to global warming and now they can be a major part of
the solution. To quote James
Lovelock, creator of the Ghia theory: “The biosphere pumps out 550 gigatonnes of carbon yearly;
we put in only 30 gigatonnes. Ninety-nine per cent of the carbon that is fixed
by plants is released back into the atmosphere within a year or so by consumers
like bacteria, nematodes and worms. What we can do is cheat those consumers by
getting farmers to burn their crop waste at very low oxygen levels to turn it
into charcoal, which the farmer then ploughs into the field”
Farming practices turn out to be an extremely sensitive
pressure point for fighting greenhouse gas. Fertilization emits oxides of
nitrogen which are 140
times worse than CO2. Tilling
of the soil lets carbon escape as CO2. Since agriculture began, about 140
billion tons of CO2 have been lost to the atmosphere. Carbon trading provides a financial incentive for improved
agricultural practices. By growing our fuel using no till, no fertilizer crops
such as elephant grass, the farmer can help save the planet, improve yields and
make good money too.
(Click here for an excellent 49-minute BBC movie about
Treea Preta)