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 lthough the world's oil reserves are substantial and new discoveries doubtless remain to be found, there is no doubt that oil, coal, natural gas and other hydrocarbons are a finite resource and will eventually be exhausted. What to do then? Will Western Civilization disappear like the Easter Islanders after they cut down their last tree? Or, will we find new energy sources to replace them. If so, what might they be?
Although the point of oil depletion may be relatively far off, there are political reasons to begin now to reduce our dependence on oil which finances repressive Middle Eastern regimes intent on spreading their brand of thought by violent means.
To understand what might replace coal and oil as a viable fuel for the future, it is first necessary to understand what fuels actually are … and are not. First understand that energy is heat and heat is energy. What we call fuels are simply storage mechanisms for the heat and light energy from our sun. Life on earth, particularly plant life, has evolved mechanisms to store solar energy for use by other species as either foods or as fuels. Solar energy is frequently touted as the eventual replacement for fossil fuels. When the sun is directly overhead, some 1400 watts of energy are radiated to each square meter of the earth. It seems probable, therefore, that it should be possible to harness that energy for industrial purposes, and is some places it is. But there is not nearly enough direct, real-time, solar energy for modern society's needs. The efficiency of photovoltaic conversion allows us to harness less than a tenth of the incident energy and, of course, the sun is only overhead a small patch of earth at a time. Then there is the problem of cloud cover and the fact that energy stored as electricity for use at night is limited by the problems of storage - primarily chemical storage in batteries. Incidental solar energy can also be concentrated by mirrors to produce electricity while the sun shines.
What we call fossil fuel is solar energy stored by the action of chlorophyll in plants for use later. It is solar energy accumulated for a long time in the wood of trees. That is the key to the use of otherwise diffuse solar energy by modern societies for industrial processes, lighting and locomotion. A tree accumulates radiant solar energy for 20-50 years and is consumed in a day or two in a fireplace/cook stove or boiler. An accumulation of trees and other vegetative material over centuries becomes coal and oil and natural gas. What took hundreds or thousands of years to accumulate is burned in minutes to allow a jetliner to take off and fly, or the family car to go to the mall. It is the accumulation over time that makes solar energy useful as a fuel. Solar energy is a poor real-time resource. It needs time.
Solar energy is also available in other ways too. The evaporation of seas and the resulting upland rainfall can in certain locales be harnessed as hydroelectric power. The harnessing of the Niagara River was one of the first ways that electric power generation was accomplished on a practical scale in this country, just a bit more than a century ago. The wind, driven by differential heating from the sun, can be harnessed, as it has for generations, by windmills. These are good and useful ways to extract energy from the sun. But the amount of energy that can be so collected falls far short of the need when the advantage of accumulation over time is unavailable.
There are other sources of potentially useable energy. Gravity, manifest in the moon's effect on the seas as tidal movement, is one such source. And of course there is the potential of nuclear energy. Nuclear energy will probably never become the major resource it was once thought to be because of fears - rational or not - for the safety of reactors, and the potential for terrorist mischief. Also, it is dependent on the finding and refining of a finite resource, uranium. It, too, will eventually be depleted.
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So what is the long-term solution? Where will mankind find a virtually inexhaustible source of heat energy to fuel a future hydrogen economy (in which hydrogen is used as the storage mechanism)? We will find it directly under our feet, in the molten core of the earth. As earthquakes and volcanoes remind us, the solid surface of the earth is a thin crust (comparable in thickness to an eggshell) floating on a very hot, molten interior. Remember: energy is heat and heat is energy. Coal and oil are not themselves sources of energy. Their energy was provided over millennia by the heat of the sun, the oil is merely the storage mechanism as that energy was accumulated and stored by living plants whose decomposition produced today's fossil fuels. The solution to the coming "energy shortage" is to utilize the heat from the earth's hot interior to drive generators which can produce hydrogen as a new storage mechanism to fuel vehicles. This is not a radically new idea. Geothermal plants presently produce some hundreds of thousands of kilowatts in places where the earth's crust is particularly thin and the hot magma can be easily tapped. There are geothermal plants in Hawaii, Iceland, New Zealand and in California at the Geysers. These are places where geology has allowed the core heat to reach the surface or be close to the surface. In other such places, the earth's core heat is used for medicinal purposes.
Given that the average thickness of the crust is but 4.5 miles (under the sea) to 20 miles thick beneath the continents, and that boring through the earth is one of mankind's oldest and most notable accomplishments, it is evident where the solution lies to the question of "what do we do when the oil runs out?" We drill a hole or a series of holes until we reach sufficiently hot rock and we use the heat to turn generators. There are a number of technologies already in place to do this and more development effort can surely provide the solution to having earth's core heat-fueled electric generation capability be available in a broad range of places on the earth's surface … not just places where core heat lies close to the surface.
Burning oil to produce electricity to make hydrogen is a losing proposition. Using core heat to make electricity to produce hydrogen is the beginning of a fossil fuel-free hydrogen-based economy that promises to be the long-term solution to the looming fuel shortage. Car companies are beginning to talk about hydrogen-burning vehicles, BMW is showing off Hydrogen-fueled models, but that really requires that the other side of the equation also be addressed, how to produce the hydrogen without burning our dwindling fossil fuel reserves.
With the political instability in many of the oil-producing countries, there is considerable reason to begin now to fund a long-term energy independence based on the use of geothermal resources. If a small fraction of what is presently spent to defend the oil pipelines and infrastructure was devoted in a modern day "Manhattan Project" or the challenge of landing of men on the moon, to develop the already-known technologies for harnessing the heat of the earth's core, we could realize energy independence in a relatively short while. It is a project worthy of America.
References:
http://www.livescience.com/environment/070122_geothermal.html
http://geothermal.marin.org/pwrheat.html
http://www.os.is/iddp/
http://www.worldbank.org/html/fpd/energy/geothermal/
http://rglsun1.geol.vt.edu/CrisfieldDeepGeothermalTest.html
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