MadSci Network: Engineering

Re: Are there any safe, non-polluting power sources that last (almost) forever?

Area: Engineering
Posted By: Dennis Verhaagh, ,Wisconsin Department of Natural Resources
Date: Fri Feb 21 18:27:25 1997
Message ID: 856325519.Eg

For stationary uses, such as factories and residences, high wattage users of electrical power such as refrigerator motors and electrical heating applications cannot be met (with current technology) by solar powered generators which are essentially non-polluting. The most common non-polluting generator of high wattage electrical power is an electrical generator powered by a water turbine. Canada produces much of its electricity with them. The U.S.'s Hoover Dam was constructed during the Depression and is in part responsible for the development of the Southwest. Here in Wisconsin, you can drive through the countryside and you see small old mill dams constructed in the last century and abandoned for years that are now being reconstructed by small rural cooperatives to produce power and sell it to the grid. I've heard of coastal countries harnessing the power of the tides and wave action to power water turbines.

However, for mobile sources such as vehicles or during times of drought and low water or in countries that do not have either water energy or the money available to capture it available to them, there is nothing like the availability of energy on demand from the internal combustion engine. The nearest thing to a non-polluting source that can produce the power to pull heavy loads is the modern gas turbine. However, though it is very low in emissions of particulate, sulfur dioxide and hydrocarbons, it does produce high CO and NOx emissions. Oxides of nitrogen (NOx) are precursors of ozone. There are low NOx applications and the industry is working to produce better and better low NOx gas-fired turbines. Carbon monoxide (CO) comes from the incomplete combustion of any hydrocarbon. It is said to contribute to global warming. There are long range plans afoot to produce natural gas from coal, oil and other heavier hydrocarbons. If the CO and NOx emissions can be reduced significantly, the natural gas fired turbine should replace all other fuel-fired internal combustion engines in the next century. You will only see liquid fuels used in emergency backup.

As for the low powered applications (calculators, clocks, some computers), solar power is presently able to power many of those. With a battery storage, it could power some intermittent motorized applications such as printers and copiers. Lighting, heating and refrigeration are heavy energy users which cannot yet be met economically with solar power. However, one has to only pick up a recreational vehicle (RV) catalog to see the many low powered lighting, heaters and refrigerators being developed. If that trend continues, the economics of completely solar powered residences may be met in the next 20 years. Experimentation is going on right now to power small vehicles with batteries charged with solar power for short runs and a natural gas fired internal combustion engine for touring.

One more thing, the natural gas fired IC engine was not really responsive to your question since it is not a "non-polluting power source" as you asked. Therefore, I'd bring to your attention the pending test trials sponsored by Chrysler Corporation of a hydrogen-fired IC engine powered vehicle. Of course, the ignition of hydrogen in the presence of oxygen merely produces water which is ordinarily not considered a pollutant. The problems with hydrogen are how to produce it economically in a non-polluting way and how to store it. It is the smallest atom and it takes a lot of it to produce enough power to move a car. It is generally produced by bubbling electricity in water to produce bubbles hydrogen. But if the electricity is produced by a polluting generator, we don't gain much.

Part II.

Power involves the release of energy that is either stored in a body such as coal or uranium or derived from the body's position (water behind a dam) or motion (as the energy from the wind). In some instances, there are very few consequences from releasing that energy except for the cost of capturing it in the first place (how clean is the factory that produces the windmills?) but for every dam built, someone downstream goes with less water and for every windmill constructed, someone's view of the ocean becomes more cluttered. In other instances, the consequences are more dire. In most electrical applications, fossil-fueled or nuclear, heat is generated to power steam turbines. At some point, the steam condenses and is no longer able to power the turbines. That hot water is released and is discharged raising the temperature of the water into which it is discharged thus changing the ecology of the water surrounding the power plant. Air pollutants are released from combustion of fossil fuels--hopefully none are from the nuclear plant. But at some point, the stored energy in the nuclear fuel loses its potential to meet the specifications of the turbine and it is stored as "low level nuclear waste" a very serious pollutant.

What this all comes down to is the concept of entropy. Order costs--disorder is free. Mother nature works that way. She is constantly at work wearing down mountains, eroding the land, aging our bodies, carrying out the Darwinian scheme, etc. She goes about this in a pitiless and determined fashion. If you seek to stop or slow her by building a dam, going to the doctor or curbing male aggressiveness, you must pay a price. Sometimes it is only money. Othertimes, the price is not apparent at first. However, damming the Colorado resulted in increased salt content of water downstream. The medicines the doctor gives you may have unknown side effects and laws are very expensive to enforce. But, in general, the most polluting energy sources are those that require the most order or seek to restrain nature rather than just slow her up and take a little nip. Explosions produce a great amount of pollution. Dams are very simple. Nuclear and fossil fueled plants are very complex and expensive. So following that reasoning, the least polluting sources are those that work with nature rather than those that work against her.

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