Oil and coal, which have brought about modern industry, are limited resources and destined to be exhausted someday. Moreover, combustion of oil or coal causes various kind of pollution. That’s why the advanced nations are groping for the clean alternative energy sources since the oil crisis. There are many candidates for it, such as nuclear power, photovoltaic power, wind power, waterpower generation, but it is my considered opinion that methane is the best alternative energy sources. I’ll tell you the reason for it.
1. Nuclear Power Generation
Everyone knows how dangerous the accidents of nuclear power generation are, but besides this safety problem, there are many difficulties with this generation of electricity. Promoters of nuclear power generation propagandize that the nuclear power generation is inexpensive or that it is clean because it emits no carbon dioxide and so on. Don’t be deceived by such propaganda.
First, nuclear power generation indirectly emits much carbon dioxide; because lots of oil must be burned to construct the plants, refine uranium fuel etc. The nuclear power generation discharges two thirds of the thermal energy produced by nuclear fission as hot water into the sea, thus heightening the temperature of seawater. The warmer the seawater becomes, the more carbon dioxide spouts out from seawater. Operating a one million kilowatt nuclear power plant only for one day gives off no less than 1000t carbon dioxide into the atmosphere. Carbon dioxide in the seawater is used for photosynthesis of phytoplankton and the fixed carbon sinks to the seabed when the plankton dies. Therefore, the decrease in carbon dioxide in seawater weakens marine carbon dioxide absorbency.
Second, nuclear power generation is expensive. It cannot be operated without an annual subsidy and this shows that nuclear power generation cannot take profit by itself. Electric power is to be liberalized also in Japan and this liberalization is likely to reduce the unit price in the wholesale market to 5-6 yen per kilowatt-hour. Despite a large amount of subsidy, nuclear power generation costs 11-12 yen per kilowatt-hour. But since the back end expense, such as the processing expense of radioactive waste and decommissioning expense, is not fully internalized into the price, 11-12 yen per kilowatt-hour is still less expensive than it should be. The liberalization should weed the inefficient nuclear power out from electricity market.
2. Photovoltaic Power Generation
Photovoltaic power generation cannot be the main energy resources. It works only in the daytime, and it cannot fully operate in the daytime because, if it hardly rains, dust will pile up on the panel and generation efficiency will soon drop. Because of this inefficiency, it takes about ten years for photovoltaic power generation to redeem all the energy required to make the set of photovoltaic apparatus. It takes further more to redeem the energy to dispose of the set. Considering that combustion of oil necessary to make and dispose of the set pollutes the environment, it is hard to say photovoltaic power generation is clean energy. As the performance of photovoltaic apparatus exposed to wind and rain deteriorates gradually, it may get useless or broken when it redeems all the energy debt. That is to say, photovoltaic power generation might turn out not a producer but a consumer of energy.
It is more difficult for the economic income to cover the expenses of photovoltaic power generation than for the energy income. Japanese government bears a third of expenses and finances the rest at low interest, which is, however, higher than earning rate of electricity generation. It is deplorable that photovoltaic apparatus, which is neither friendly to the environment nor economically reasonable, should sell well promoted by public subsidy and the so-called ecological movement.
3. Wind Power Generation
As wind power generation as well as photovoltaic is at the mercy of changeable nature, both need backup generators and adjusting equipment, which raises the amount of initial investment. Since generators will break if the wind gains in force, the wind power must be constant, but there are few areas that fulfill this condition. Appropriate places, if any, are usually far from electricity consuming area. In that case, long transmission lines are necessary, which lowers energy efficiency and heightens economic costs. The unit price of wind power generation is 15 yen per kilowatt-hour, not so expensive as that of photovoltaic power generation (25 yen per kilowatt-hour), still higher than the standard unit price.
You might think that wind power generator, once set up, generates electricity almost forever, therefore turn out to be efficient in the long run. But actually the maintenance expense is required and its performance deteriorates gradually owing to friction between an axis and axis bearing etc., so it is doubtful whether the income meets the expenses.
Wind power generator has another problem. It is reported many birds involved in a propeller die. As explained at the next section, birds play an important role to keep the ecosystem.
4. Waterpower Generation
Some regard waterpower as clean natural energy. But damming up the flow of river cuts off the circulation of nutrition that flows from mountains via rivers to seas to enrich fishery resources, which are in turn eaten by birds and animals, which reduce their excrement and dead bodies as nutrition to the mountains. So, dams destroy not only sunken areas but also extended areas including mountains and seas. Chinese government, which is building the world biggest dam, does not understand this harmful effect.
5. Methane Power Generation
I have examined four major candidates of clean energy sources and concluded that all of them are not qualified. The most desirable alternative energy sources are methane, the chief constituent of natural gas, for the following reasons.
Combustion of natural gas discharges no sulfur dioxide and far less nitrogen oxide and carbon dioxide than that of oil or coal does. Burning pure methane emits only water and carbon dioxide. Methane can also be used as material of the fuel cell known as a clean power generator.
5.2. Abundant in deposit
The recognized amount of natural gas deposits is 148,875 billion cubic meters, but the potential amount reaches 300 trillion cubic meters, so it will take more than 100 years to consume it. Besides this old type natural gas, the new type deposits, methane hydrates, are found almost everywhere in the world. Although oil can be mined only from special areas, methane is widely distributed, which lowers the transportation costs.
A methane hydrate is a cage-like lattice of ice, inside of which molecules of methane are trapped in a certain pressure and temperature conditions. Methane hydrates are found on land in permafrost regions, where cold temperatures persist in shallow sediments, and beneath the ocean floor at water depths greater than about 500 meters, where high pressures dominate. Recent global warming is melting methane hydrates and emits a large quantity of methane gas into the atmosphere. Methane is on the one hand an important fuel and on the other hand greenhouse effect gas twenty-one times as effective as carbon dioxide per molecule. Giving off methane into the atmosphere is as wasteful as to discharge useful oil into sea to pollute it. Global warming heightens methane density in the atmosphere, which in turn promotes further global warming.
In order to prevent this vicious circle, we should make use of methane hydrates as resources before they evaporate. Combusting methane can reduce its greenhouse effect to a twentieth. The amount of minable methane hydrates is 250 trillion cubic meters. The total amount of minable methane is more than two times as large as that of oil.
5.3. Reproducible in natural circulation
The organic wastes such as excrement or dead bodies of animals, kitchen garbage, wood, when put into the sealed container, generates various gases such as methane, carbon dioxide, ammonia, of which methane occupies 50-60%, as a result of the anaerobic fermentation of bacteria. You can use this methane as resources and the decomposed organic wastes as manure for agriculture. Many farmers have succeeded in this methane fermentation power generation.
The energy efficiency of methane power generation is high. While thermal power generation or nuclear power generation can utilize only 35% of potential energy, gas combined cycle can utilize 50% and in the case of the cogeneration system the energy efficiency reaches no less than 80%.
The unit price of methane power generation is lower than that of oil, when methane is transported by pipeline. You might think we should bear high expenses to protect the environment, but low price is important, because the new desirable fuel sources must spread also among developing countries, which are likely to be major players of destroying the environment in the future.
To sum up, methane power generation is clean, inexhaustible and economically reasonable, the best alternative energy sources. I am sorry that Japan, where I live, plans to invest as much as one trillion yen in constructing an experiment furnace for nuclear fusion reactor.