green electricity

[farm]

i have been offered 100 % green electricity

surely this is not possible as it all shares the same cable on pylons

am i being ignorant if so please enlighten me

thanks very much

[Loosehead]

There are several sources of green electicity but I would say it's virtually impossible to say whether what is comming down the cable is green. It's not even as simple as that, without going into detail the electrons you are using are not generated so you'd have to go back to the source, so on balance I can't see how anyone can claim their electricity is 100% green. If you exclude nuclear power for a moment only about 5-10% comes from non fossil fuel sources anyway so I'd say the salesman is talking ^%$�"cks!

[Octavius]

Green energy must be renewable and non-polluting and is generally considered to include:

Geothermal power
Wind power
Small-scale hydropower
Solar power
Biomass power
Tidal power
Wave power
Some versions may also include power derived from waste incineration.

For green energy to be truly "ecological electricity" it must not include medium or large-scale hydroelectric power (which could produce waste water) or sources of air pollution such as burning biomatter or petroleum.

Current electricity retailing arrangements make it possible for consumers to buy green electricity, either by purchasing their electricity from a generating company that uses only renewable technologies, or by buying from a general supplier who undertakes to buy at least as much power from renewable sources as their "green" customers purchase. Generally green electricity commands a price premium compared with standard supplies. Obviously this option is only available where common carrier arrangements have been put in place to allow competitive supply of power. Renewable energy certificates, or green tags, are currently the most convenient way for consumers and businesses to support "green power". Over 35 million homes in Europe, and 1 million in the United States, are purchasing green tags.

No power source is impact-free so therefore cannot possibly be 100% green. For instance, concerns are raised over bird kills and in some cases noise pollution by windmills and over heavy metal use and associated mining damage by solar cells.

[tomd]

To answer the question that's being asked:

Regardless of whether there are an environmental impacts of 'green' energy, the idea isn't that the actual energy to your home is produced totally by renewable sources, but, as all homes are fed from the same reserves, that the company supplying your electricity will put into the National Grid the same amount of energy from renewable sources as your house is taking out.

When you change energy suppliers, they don't change the actual cable or pipe to your house, or even direct the power from particular power stations to your house. You take energy from a communal pool, (to put it crudely), and the energy companies supply your energy into the communal pool. Each company puts in as much as their customers are taking out.

So, in this case, they put in all green energy. It does the same amount of good for the environment, but you may or may not get that energy itself.

[KARL]

I suspect Octavius is incorrect regarding hydro-power, none of which discharges wastewater in the common sense (i.e. sewage of sorts) - it is spent, so far as the generation cycle is concerned but it is no worse than the stored surface water used. Additionally, the flood regulating qualities of hydro schemes are often highly valued. In general, non-fossil fuel and non-nuclear (a contentious source) are considered non-polluting and "green". Waste incineration is considered green when compared to the alternative of using fossil fuels - this is especially true for woodburning systems which are described as "CO2 neutral" because it is renewable fuel cycle.

[Octavius]

Hydroelectric dams produce significant amounts of carbon dioxide and methane, and in some cases produce more of these greenhouse gases than power plants running on fossil fuels.

This is because large amounts of carbon tied up in trees and other plants are released when the reservoir is initially flooded and the plants rot. Then after this first pulse of decay, plant matter settling on the reservoir's bottom decomposes without oxygen, resulting in a build-up of dissolved methane. This is released into the atmosphere when water passes through the dam's turbines.

In effect man-made reservoirs convert carbon dioxide in the atmosphere into methane. This is significant because methane's effect on global warming is 21 times stronger than carbon dioxide's.