Energy feeds our bodies and our industry. Most of our livelihoods rely upon it. We will eventually exhaust the non-renewable energy sources such as fossil fuels. Naturally we will look to replace the energy. The obvious renewable energy source is biomass. Biomass is the vegetation that surrounds us, is the base of all our food and also was the impetus for starting us up the technological ladder.
Though biomass gave us the start we needed, its ability to replace our current energy needs is limited. Canada, a country that thrives from the exploitation of its natural resources, is a good example. Within its borders are 9.98×108 hectares of land. Of this, 42% is forested while 25% is considered timber productive forest [1]. In a typical year Canadians harvest 286 million tonnes of biomass; trees and crops. This equates to about 5.1 exajoules (x1015) of energy.
There is approximately 47 exajoules of net primary productivity added in Canada every year [2]. This is a lot! However, the biomass, according to the definition of net primary production, includes leaves, twigs and roots along with branches. Not only would it be inefficient to try to capture the energy in the small detritus, it would also be incredibly detrimental to other life forms that rely upon it. Such action would shatter the ‘circle-of-life’ and thus prevent further vegetation growth.
Last, and just as important is the realization that Canadians are already, in total using 20 exajoules[3] as seen in the figure below. If Canadians were to use biomass to replace the energy after they exhaust the fossil fuels, precious little will remain for vegetation and other life forms.
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