Energy–renewable sources and thermodynamics

Sunlight and wind are provided by nature. Sunlight and wind are widely considered at present to be renewable and sustainable sources of energy. Sunlight and wind can be harnessed by converting them to energy that is used to do work, but not without cost.

Note: The focus of this essay is access to energy via wind power and solar power. The laws of nature dealing with energy apply to all human undertakings to achieve access to energy, including mining, petroleum exploration and production, and the operation of power plants that use energy from fossil fuels to generate electricity.

In physics, energy is defined as the capacity to do work. The first and second laws of thermodynamics inform us that access to renewable and alternative energy sources entails costs (first law) and is not reliably available without continuing inputs of energy (second law).

The First Law of Thermodynamics, known as the principle of conservation of energy, states that energy cannot be created or destroyed.

The Second Law of Thermodynamics, known as the law of entropy, states that order in a closed system deteriorates into a disorderly state unless more energy is input to maintain order.

The two laws have been epitomized in simple terms as follows.

First law: you can’t get something for nothing.

Second law: You can’t even break even.

Firewood as a source of energy illustrates the operation of the first two laws of thermodynamics. Burning wood releases heat energy for warming and for cooking. As a wood log is burned it turns to ash which is not a further source of energy in the form of heat. That is entropy.

In every step of the processes of accessing energy via sunlight and wind, there is consumption and processing of resources and energy. Large amounts of energy are needed to extract raw materials from the crust of the earth  by mining, to build wind turbines and solar collectors, and to build a power plant installation. That is the first law of thermodynamics in operation. One cannot access energy without spending energy.

Solar and wind generating facilities must be maintained to prevent degradation and loss of efficiency. This is the Second Law of Thermodynamics in operation.

Fossil fuels provide the energy to build and maintain wind and solar power generation facilities.

All things considered, generation of electricity by wind and solar power may cause as much emission of carbon dioxide as is saved by the consumers of electricity.

According to Richard A. Muller, professor of physics at the University of California at Berkeley, wind turbines will produce far more usable energy than solar collectors. Wind could provide about 15% of world energy use, although that is a projected outcome that has not yet been attained.

The U.S. Department of Energy concluded that solar electric systems could not meet the energy demands of an urban community or industry because of their cost, and the variability of sunlight—less in winter except in the tropics, less on cloudy days, and none at night.

Wind power 

Wind power is accessed by towers holding three propeller-like blades. The wind turns the blades around a rotor, which spins a generator that creates electricity.

A typical wind turbine has a base, a tower, a nacelle and three blades. Its foundation is made of concrete, the tower of steel or concrete, the nacelle from steel and copper and the blades from composite materials.

Wind towers are tall, ranging from 400 to over 600 feet. Wind turbine blades span 300 feet and sometimes more. Their operation kills birds and bats.

Wind turbines are anchored in steel and rebar platforms that typically exceed a thousand tons in weight. They are buried 6 to 30 feet in the ground. Turbines are fitted with lights so they can be visible.

The Altamont Pass wind facility in California covers approximately 234 square miles. 7,000 wind turbines have been installed there of which about 5,000 are operating at present.

Construction of a wind turbine facility requires preparation of the land for installation of concrete bases for each turbine. Fossil fuels are required to quarry the raw materials for a turbine’s concrete base and to transport them to a construction site.

Wind turbines are situated in rural and forest areas. The turbines require land clearing for the facility and new access roads. Plants and animals lose their habitats when a wind turbine facility is built.

Wind industrial complexes emit large amounts of carbon dioxide in their construction and maintenance.

At times there is no wind. For those times it is necessary to have a backup power source that is usually fired by fossil fuels.

When the turbine is not spinning it still requires energy for controls, lights, communications, sensor, metering, data collection, oil heating, pumps, coolers and gearbox filtering systems. This energy comes from the grid.

Wind turbine blades can last 15 to 20 years. Wind turbine blades are very large. They wear out or break. They are not suitable for recycling. When discarded they are deposited in landfill where they emit toxins. Incinerating the blades produces toxic gases and soot.

Solar power 

Industrial-scale solar power plants use hundreds of large mirrors, The mirrors are placed on the ground to concentrate sunlight and reflect it onto water-filled boilers that sit hundreds of feet above ground on top of towers well over 300  feet in height, taller than the Statute of Liberty. When the sunlight hits the boilers, the water inside is heated and creates high temperature steam. The steam is then piped to conventional steam turbines, which generate electricity.

The largest industrial-scale solar facility is located at Ivanpah, in the Mojave Desert of southeastern California.

According to a source on the internet, the construction cost of the Ivanpah facility was $2.2 billion dollars, which is $18 per watt of capacity. In comparison, a similar capacity nuclear power plant “. . . had an inflation-adjusted construction cost that worked out to $0.50 per watt of capacity, making Ivanpah 36 times more expensive.” Ivanpah is not producing enough revenue from sale of electricity to pay its operating costs.

The other method of accessing electricity from sunlight is via photovoltaic (PV) cells made of silicon. A silicon solar cell converts one wavelength of the spectrum of solar energy into electrical energy. A serious problem with solar power from PV cells is inefficiency. Only 15% of the sun’s energy is converted into electricity with the best PV technology.

At present there are no cost-effective batteries to store solar energy for use at night.

PV cells are cost effective for generating electricity in small-scale applications. According to Australian geology professor Ian Plimer, “in remote areas with small power needs and where regular maintenance is prohibitively expensive, solar power is sensibly used for lighting, telecommunications, navigation beacons, recording equipment, marine buoys, electric fences, pumps at bores and satellites.”

To produce the highest efficiency PV cells requires use of rare-earth elements such as germanium, gallium, indium and cadmium. These metals are byproducts of the zinc, aluminum and tin smelting and refining industries, all energy intensive users of fossil fuels.

There are numerous poisonous, flammable and hazardous chemicals used in the manufacture of a silicon solar panel. To manufacture PV cells requires fossil fuel power and large amounts of water. The useful life of solar power station ranges between five and twenty years.

Solar power, like wind power, requires infrastructure construction that produces emissions of carbon dioxide.

To maintain efficiency of the PV cells they must be cleaned regularly to remove dust and plant spores from the glass surface covering the PV cells.

A typical solar power station would be designed for a generating capacity of 1,000 megawatts (MW). That is about the capacity of typical fossil fuel or nuclear fired power stations. A 1,000 MW solar power facility requires far more space than fossil fuel or nuclear power facilities because, to prevent shading that blocks the sun, the space between solar panels plus the area needed for maintenance roads requires a total land area of fifty square miles.

Rooftop solar facilities are very expensive in comparison to the electricity they produce. According to California attorney Dennis Beaver, consumers have not been served well by rooftop solar PV installations. Although they reduce the cost of electricity from a utility company, often they malfunction, the seller may not be available to service them, and they end up with liability to a bank secured by a lien on their home.

A rooftop PV solar appliance, while not effective to generate adequate electricity for a home, could be used as an adequate source of heating water for home use.

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