The Green Paradox: A Supply-Side Approach to Global Warming

3. Table or Tank?

3 Table or Tank? Capturing the sun Civilization developed with the help of bioenergy. When our ancestors enjoyed the heat of a fire, or when they used animal muscle power for transportation, the source of energy was plants. In many regions of the world, plants still are the dominant source of energy today. Bioenergy is nothing more than stored sunlight. In photosynthesis, plants use sunlight to transform carbon dioxide and water into carbohydrates , stripping the oxygen from the carbon and latching hydrogen to it instead. These carbohydrates contain what chemists call reduced carbon. Out of them a plant makes the complex biological compounds, such as sugars, starch, and cellulose, that constitute both the plant’s structure and its fruit. Reduced carbon can be burned in order to retrieve the energy it contains. This can be accomplished, for example, by burning wood to make a bonfire, or by eating plants and burning in the body the carbon compounds, fats, proteins, and carbohydrates they contain. When burned, carbon oxidizes, that is, binds again with oxygen. Oxidation and burning are one and the same; whether a flame occurs is immaterial . Photosynthesis uses energy to break down carbon dioxide into carbon and oxygen. Burning releases this energy once again, as carbon and oxygen bind to each other.1 When storing energy, the same amount of CO2 will be captured as will be released through combustion. For this reason, using biomass as a fuel source is, under ideal conditions, CO2 neutral.2 In nature, photosynthesis and plant decay are in equilibrium. Plants grow, die, and decay. When they decay in the presence of oxygen, the carbon contained in them burns, and carbon dioxide is released. If this to the US Farmers’ Association, with a suggestion that they join OPEC 86 Chapter 3 occurs in the absence of oxygen, methane will be released. But, as was explained in chapter 1, methane oxidizes to carbon dioxide over an average of 15 years when it comes into contact with the oxygen in the atmosphere. Photosynthesis then again strips the oxygen from carbon dioxide, generating reduced carbon and thus creating biomass. This closes the circle. Carbon dioxide is also absorbed by the oceans, loosely binding itself with the water in the upper layers to form carbonic acid; then it is eventually released back into the atmosphere through the action of waves. The saturation of the upper layers of the world’s oceans with CO2 is closely related, at a given temperature, with the CO2 saturation of the atmosphere. In a closed cycle involving the air, biomass, and the upper layers of the oceans, a nearly fixed amount of CO2 circulates over very long periods. At any given time, the carbon is bound in certain proportion in the oceans’ upper layers, in the atmosphere, and in the biomass. Mankind lived as part of the biological carbon cycle until about the middle of the eighteenth century, when industrialization began around the coal mines of Sheffield in England. With the invention of the steam engine and all the other combustion engines that followed, the wheels of industrialization began to spin, leading to rapid economic growth that gave rise to the standard of living that Western civilization enjoys and to which Asian societies now aspire. However, mankind is beginning to realize that the carbon exhaust that industrialization has released into the atmosphere is a serious debt left to future generations. A substantial fraction of the fossil carbon that is added to the cycle, about a quarter in the long-run, accumulates in the atmosphere and warms the planet, as CO2 hinders the incoming visible short-wave radiation from the sun being reflected back to space as invisible long-wave thermal radiation. This is the rationale for returning to biological energy sources. If biomass is used as an energy carrier, no additional CO2 will be added to the carbon cycle, and hence the saturation of the atmosphere with CO2 will not increase. Of course this benefit is also offered by wind, solar, hydro, and nuclear power, to name the most important technological options. However, bioenergy may possess the greatest beneficial potential, as plants are a natural and cheap device for capturing thinly dispersed energy. As was explained previously, renewable energy, though abundant, is thinly dispersed across the planet’s surface and therefore can be used as a replacement for fossil fuels only if techniques are found to concentrate it in Table or...