Ten fundamentals about bioenergy: Part 1
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Fundamental #1: Basically all energy used by humans originates from the sun.
Over the next several weeks we will be publishing a series of brief
articles regarding ten fundamental concepts of bioenergy. The purpose is
to provide accurate, basic information on the subject of bioenergy
which will arguably be one of the most important agricultural and
societal issues of this new century.
The first installment regards the origin of bioenergy. The answer to the
question of where bioenergy originates from is quite simple – the sun.
In fact, virtually all of the energy we use today comes from the sun –
even fossil fuels. Petroleum and other fossil fuels were made from the
process of photosynthesis performed by plants and oceanic
micro-organisms that lived 300 million years ago. Photosynthesis is the
process used by plants to convert atmospheric carbon dioxide to longer
chain carbon molecules such as glucose. This process is sometimes
referred to as “autotrophically derived” energy since it is created from
organisms using inorganic CO2 and sunlight (more on that in an upcoming
issue). Yesterday’s biofuels, including the hay that grandpa fed to his
horses, and the logs he fed to his furnace, were autotrophically
derived.
Today’s biofuels including ethanol and biodiesel are autotrophically
derived, but unlike fossil fuels, they are made from CO2 taken from
today’s atmosphere which offers society a huge benefit (sometimes called
an “ecosystem service” in the environmental vernacular). Conversely,
gasoline, diesel, and other fossil fuels such as coal and natural gas
emit CO2 into the atmosphere every time we use them – CO2 that was
safely sequestered below the surface of the earth for hundreds of
millions of years. This release of CO2 to the atmosphere is the basis
for the global warming issue we currently hear so much about, but more
about that in an upcoming issue.
Nonautotrophic forms of sun-derived energy are generated from the
radiative forcing, or heat, produced by the sun. The uneven heating and
cooling cycles over the surface of the earth provide wind energy and
wave energy which can be converted to electricity or other forms of
mechanical energy. Similarly, these heating and cooling cycles drive
precipitation events which we ultimately use for hydroelectric power.
Geothermal heat, solar panels, and to some extent photovoltaic energy is
derived more directly from the energy of the sun. One could argue that
nuclear energy is perhaps one form of energy that we do not derive from
the sun. It may be more comparable to bringing a little bit of the sun
down to the earth, since the sun is basically one large nuclear reactor.
Nevertheless, the elements we use in nuclear energy would not be
available to us had the earth not crystallized around the sun when the
solar system was created.
The good news is that the sun has enough hydrogen fuel to burn for
several billion more years; and, directs 10,000 times the energy used by
man to the earth every day. Our challenge for the future will be in
creating the technology to harness that energy.
Read part 2, part 3, part 4, part 5, part 6, part 7, part 8, part 9, part 10 of this series.