Environmental Engineering Reference
In-Depth Information
14 A Biobased Economy
INTRODUCTION
As was previously discussed, one of the weakness of the economic system, which includes
food production and distribution, is the reliance on fossil feedstocks for the production of
fuels, polymers, and chemicals. The long-term sustainability of the way we do business is
compromised by persistent predictions of “peak oil,” which eventually will come but no one
knows exactly when it will happen.
According to original predictions by King Hubbert (1971), global peak oil was reached in
the year 2000; other predictions indicate that may take place during this decade or the next
(see Chapter 15). Once peak oil is reached, a progressive decline in production will make oil
scarcer, driving prices up. In the long run, total depletion is unlikely, but at some point the
energy needed to convert oil into fuels (including exploration, development of the oil fields,
and distillation) will exceed the energy contained in the oil—a situation known as energy
return on the investment (EROI) being equal or less than one (see Chapter 11).
Dr. Hubbert said “So long as oil is used as a source of energy, when the energy cost of recov-
ering a barrel of oil becomes greater than the energy content of the oil, production will cease
no matter what the monetary price may be” (1982, pp. 140-41).
As a short-term solution, petroleum-based feedstocks could be replaced with natural gas,
but eventually natural gas will peak too, in the future. The third alternative is coal, which is
abundant, could be transformed into liquid fuels and into bulk chemicals by gasification
followed by other processes (Tullo and Tremblay, 2008). However, the constant use of fossil
feedstocks will lead to a deeper alteration of the long-term carbon cycle (Chapter 2) with
possible consequences in the near future.
The alternative to fossil-based feedstocks for the production of liquid fuels, polymers, and
chemicals is the use of plant materials, which certainly is not a new idea. Plant materials had
been used for centuries before the advent of petroleum and gas to provide fuel, fiber, and an
array of chemical compounds, and even today, many materials are produced from plant
tissues.
Currently, there is a renewed interest in the use of plant material for a more ambitious
enterprise: the substitution, or strong complementation, of fossil-based with biobased
feedstocks. The idea is to cultivate dedicated crops and use agricultural by-products as feed-
stocks to transform them into fuels and chemicals. In this type of system, the sun is the ulti-
mate source of energy that is captured by plants and transformed into carbohydrates via
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