January 8, 2013 § 2 Comments

The title brings immediately to mind energy from biomass.  While that is a perfectly reasonable thought we ought to consider the other angle, that of energy use in agriculture.  Water intensity of agriculture is one of its hallmarks.  In the US roughly 31% of water withdrawals are for this purpose.  The vast majority of withdrawals require the use of pumps.  This is because Artesian wells, which are naturally pressured, are in a minority.

canola field

According to a World Bank study, the economic status of the farmer determines the type of energy used in farming operations.  Human effort is progressively replaced by animals such as bullocks.  The next step up the economic ladder causes the use of pumps powered by fossil fuel, usually diesel or kerosene.  The use of wind, which goes back centuries, is still nascent.

The ever increasing economic status in the developing world would therefore point to greater use of fossil fuel for lifting water and for tilling and harvesting.  In response to this virtual certainty, two options are available.  One is a shift to wind or solar.  In the consideration of these alternatives, the economic parity required may be with very expensive fossil fuel.  In India much of the diesel for this purpose is heavily subsidized and so the apparent cost may not be high.  But the real cost to society is high in the tax burden of subsidies and cost of transportation in trucks over long distances.  Furthermore, hybrid systems could be considered where the wind power produces electricity when not pumping.

The other solution is to produce diesel substitutes locally.  At RTEC and RTI this year we will be making a major push on the concept of small footprint production of fuels and chemicals from natural gas and biomass.  The scale would be about a hundred times smaller than conventional refineries and chemical plants and the targeted economics of production would be comparable or lower than with large plants.  This flies in the face of current dogma on economies of scale but is feasible with exceptional innovation.  Each farming community would be supplied locally, using the raw material of convenience.  This would be natural gas, methane from refuse and waste, or biomass in the form of waste cellulose (stalks of plants and so forth) or woody biomass.  The fuel produced could be diesel, methanol or di-methyl ether, all of which would function in pumps, tractors and cook stoves.

Chemical fertilizers are also energy intensive and farming increasingly relies on these.  The dominant feed stock for these is natural gas.  Potash, a source of the nutrient potassium, is mined and processed, also using much energy.  Reduced reliance on fertilizer is a tough but worthy target.  These chemicals are also amenable to smaller footprint production, but likely not as dramatic as for transport fuel.

Increasing per capita GDP is also strongly correlated with more meat in the diet.  It appears that this is a sociological response similar to the escalation in ownership from scooters and motorcycle to cars.  Meat is decidedly less energy efficient than a vegetarian alternative.  This is especially so as practiced in the west, where corn and soy beans are used as feed in place of forage.  But the bigger environmental factor may be the inefficiency of the rumen in animals such as cattle.  That results in the production of methane, which in many countries such as the US is one of the top contributors to greenhouse gases.  The solution likely lies in two areas.  One would be selection of the more efficient breeds, but on a large  scale this could be tough.  The other is additions to diet to improve conversion.  Researchers in Canada and France have already reported some success with enriching feed with certain lipids.  Some believe that addressing the meat eating increase could rapidly become the highest priority element of the imperative to feed a burgeoning world population.

Finally, there is the whole issue of producing energy from plant matter.  Congress appears to be on track to retain subsidies of about $1 a gallon on cellulosic ethanol. This is a tough techno-economic nut to crack so deserves an assist till it gets going.  But as we have discussed before, methanol could be produced economically from biomass with no subsidies for the fuel.  That is the reasonable course especially this year when cliff avoidance compromises have left the country with a greater burden on deficits.

Vikram Rao



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