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.