Environmental Engineering Reference
In-Depth Information
Biomass energy is derived from plant or animal matter, whether wood, crops, crop waste, grass, or even
manure. Biomass includes biofuels, which are liquid fuels, usually alcohol, derived from these sources
and used for mobile power. Other forms of biomass are used for fixed electrical power or directly for heat
(such as wood or animal dung burned to stay warm).
In practice, biomass has, like solar and wind, produced a small amount of energy worldwide—although
considerably more than solar and wind.
Why?
Biomass is renewable and natural, because the energy comes from the sun—but not all the inputs in the
process can scale. It resembles hazelnut energy; in fact, hazelnut energy is a form of biomass energy.
To its credit, biomass has a storage system, unlike solar and wind—plants store energy from the sun
through photosynthesis. The problem is, it takes a lot of resources to grow them—namely the resources in-
volved in farming, including large amounts of energy, land, machinery, water, fertilizer—just like it takes
a lot of water to build solar and wind installations. But while solar and wind installations can be built in
many places (though part of their problem is that northern and southern latitudes don't give them good
sunlight for many hours), biofuels need to be grown on relatively scarce farmland, which starts to bring us
into hazelnut energy territory. It means that biomass scales badly—often, the more of it we try to produce,
the more scarce and expensive the inputs become, and the more expensive our energy becomes.
Biofuels like ethanol from corn or sugarcane, or biomass from wood, compete with cropland or forest
land, driving prices up for both fuel and food.
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Scalability has been the problem for every biofuel that
works (the Bush administration tried to force us to use cellulosic ethanol, a form of ethanol from nonfood
sources that has been promoted since the 1920s but still doesn't work) at a smaller scale. But even if non-
food biomass worked better than it does, it would still be extremely resource intensive to regrow over and
over.
A thought: Throughout history it has been a challenge for human beings to produce enough crops to
feed us, because agriculture requires a lot of resources just to produce our meager number of calories. We
need many dozens of times as many calories for our machines as we do from our food! If we could eat oil
or electricity, we would, because it's much cheaper per unit of energy. Why should we feed human food to
machines with hundreds of times our appetites?
Already, the increased use of biomass energy has strongly correlated with a rise in food prices—see
Figure 2.5. The idea of scaling it ten times or more, to even make a dent in fossil fuels' energy production,
is unthinkable, given all of the evidence we have.
According to a recent report from the United Nations,
The State of Food Insecurity in the World,
High and volatile food prices are likely to continue. Demand from consumers in rapidly growing eco-
nomies will increase, population continues to grow, and any further growth in biofuels will place addi-
tional demands on the food system.
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Figure 2.5: Comparison of Food Price Index to Biofuel Production
