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© 2009 David W Kukuk

Member of Eco Green Group-www.ecogreengroup.org

Email - Davidw-kukuk_EGG@usa.net

Solar

Photovoltaic Solar shows great promise, and is beginning to come into its own.

Pro – Clean, no emissions whatever.

Pro – To create power in the range needed to power electric vehicles will mean covering huge areas with solar panels, BUT we have a lot of rooftops and open parking lots that could be used.

Con – Cost per kW is still high, but has been coming down steadily.

Con – Current Photovoltaic panels have a relatively short life and will need replacement once in a while, but lifetimes seem to be increasing. However, disposal will not create poisons and disposal should be relatively clean. Materials may be recyclable.

Con – Covering large areas of open land may affect the environment. My own thought - If it reduces growth of vegetation in areas where vegetation has a problem growing, it may increase erosion.

Con – In some localities, readily accessible locations, such as covers over parking lots may be attractive targets for vandals, thus be expensive to maintain.

Con – Solar power is only available during sunlit hours, and is affected by the length of the day and weather. At the current time, the best locations for large amounts of sunlight, are where electricity is least needed. Areas where more power for winter heating is needed are those with less sunlight during the winter.

Many utility companies have announced major solar power projects, ranging from 10MW, to more than 1GW within their territories. [1],[2]

Thermovoltaic Solar

Thermovoltaic Solar shows great promise, and is beginning to come into its own.

Thermovoltaic solar shows a lot of promise. Rather than turning solar radiation directly into electricity, the light heats water or some other material to provide a working fluid to spin turbines which turn generators. Solar heating of the liquid or gas to turn a turbine is much more efficient, though it takes a large mirrored area to provide useful amounts of heating. The largest such plant in early 2009 can produce up to 354 MW.

A system in Israel provides the electricity for some 70 homes near Eilat. The system uses a number of mirrors which track the sun and reflect it onto a ‘flower’ on a tall support, superheating the already compressed air in it to 950ºC/1750ºF before funneling it through a part time combustor, followed by a turbo-generator. It produces 100 kW of electricity and 170kW of ‘waste heat. The waste heat can be used to heat water or for industrial processes. The combustor is used to provide added power on cloudy days, and to create power at night. The combustor uses alternative fuels including biogases. [3]

© 2009 David W Kukuk

Member of Eco Green Group-www.ecogreengroup.org

Email - Davidw-kukuk_EGG@usa.net

This is part four in a series of articles looking at some of the overlooked or glossed over factors affecting conversion of the US to a greener, more sustainable future, as far as automobiles are concerned

Hydroelectricity

Hydroelectricity is one of the cleanest sources of power, but has problems. It requires water to drop from a higher elevation to a lower one, and this usually requires a dam all the way across the source, to proved the fall and storage for times when less power is needed or less flow is available.

Dammed Rivers

Pro – It’s clean

Con – The majority of sources in the US are already in use, at least as far as high flow rivers are concerned.

Con – Hydropower dams block rivers. The Law of Unintended Consequences applies, as dams prevent fish from reaching their natural spawning grounds, and change the natural flow patterns from the top of their lakes to the sea. Dams also affect the amount of sand reaching the ocean for natural rebuilding of beaches. As a result, many environmentalists are attempting to have some dams removed. [4], [5]

Con – Dams also store water that many downstream feel they need, and even have legal water rights to. If the changed flow of building more hydro dams will not meet those needs when they are needed, it may not be possible to build a dam for future hydropower.

Con – Dam failures are among the causes of the largest numbers of loss of life. Failures have occurred because of poor design, earthquakes from unknown faults, ( which may have been triggered by the enormous weight of the water behind the dam ), and poor maintenance.[4]

Con – In warm and cold climates, especially where trees may not have been logged before being covered by lakes, lakes may become generators of methane as trees decay. Thus, they might be responsible to creation of greenhouse gases. [4] However there is a lot of debate on this, and no solid numbers. [6]

Con – Creation of lakes often displaces large numbers of people and may take large areas of producing farmland out of production. [4]

Con – Dams, or at least the lakes behind them may have relatively short lives. Sediment collects as the flow behind the dam slows, and can build up relatively quickly. [4], [5], [6]

“Professor K. Mahmood of George Washington University in Washington, DC, "roughly estimated" for a 1987 World Bank study that around 50 cubic kilometres of sediment – nearly one per cent of global reservoir storage capacity – is trapped behind the world’s dams every year. In total, calculated Mahmood, by 1986 around 1,100 cubic kilometres of sediment had accumulated in the world’s reservoirs, consuming almost one–fifth of global storage capacity.” [4] Note that these numbers are 23 years old already and from a 13 year old book!