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Worth the extra cents
You might think your electricity is clean and green, because your local utility claims to generate mostly from renewable sources. But electrical grids in places like North America and Europe are so interconnected, that your electricity at any given moment could be coming from the wind turbine farm a few miles down the road, or the coal-fired plant a thousand miles away, depending on the flux of supply and demand.
It can be an environmentally friendly and renewable source of electrical generation, such as wind, small scale hydro, geothermal, or solar electricity
It can be an arrangement between an electricity user and a supplier who generates or delivers clean electricity.
The point of this distinction is that, in most cases, you can't choose where the power racing through your electrical wires comes from. So in a mixed electrical grid like the North American grid, no household can claim to be using electricity that is 100% green in the first sense above, even if they are buying 100% of their electricity from a green supplier.
For more on solar power and how free solar energy can be turned into household electricity, see How solar power works at SolarPowerAtHome.com.
Is hydroelectric power green electricity?
Many people in countries such as Canada, which gets a lot of its electric power from hydroelectric projects, think that their energy is clean because it only takes falling water to generate it.
In fact, large scale hydroelectric projects are far from green energy. Among the negative impacts of large scale hydro generation are :
As the reservoir upstream of a new dam fills, flooded habitat is destroyed, including forests and species-rich wetlands.
Flooded vegetation decomposes, releasing CO2 and methane. Methane is a greenhouse gas about 30 times more powerful than CO2 in terms of its greenhouse effect, and because the bottom of a reservoir tends to be so oxygen-poor, reservoir decomposition tends to be anaerobic (without oxygen), in which methane, not CO2, is the main byproduct.
A reservoir increases the river surface area, increasing evaporation, which in turn increases the salinity of the water.
A reservoir alters the temperature downstream, making the river downstream warmer in winter and cooler in summer. This can wipe out species that are sensitive to temperature changes.
A reservoir can hold back floodwaters that would normally flow out onto a flood plain, which depends upon the nutrients and seasonal water flow provided by seasonal flooding.
A dam fragments the waterway upon which it is built. Fish ladders are added to most dams to allow spawning fish to swim upstream, but the dams can still prevent fish from traveling downstream, which reduces downstream populations.
Sediments, which before a dam help replenish riverbanks, river deltas, and other formations downstream, are trapped behind a dam, slowly filling its reservoir and reducing the reservoir's capacity. Meanwhile, the downstream formations are eroded because of the reduced sediment flows.
Given these problems with large dams, many renewable energy experts don't include large-scale hydro projects in their definition of green electricity. Instead, they favor a small-scale hydroelectric generation sometimes referred to as microhydro.
My family and I stayed for a month at the Durika Biological Reserve in the Talamanca mountain range in sourthern Costa Rica. This intentional community of 30-odd inhabitants and up to 25 visitors at a time, is entirely powered by one microhydro installation. The installation does not disrupt the flow of the mountain river from which it draws its power.
The Durika microhydro project consists of a small dammed area on a mountain river; most of the water flows over the top of the dam, much as it does over waterfalls both upstream and downstream. A small portion of the water flows to one side of the dam and down a 6" pipe. This pipe falls several hundred feet to a high-pressure microturbine. When you see the water coming out of this turbine it's astonishing how little there is and how slowly it travels - the energy comes from the high pressure that is built up by the substantial drop in height between the water intake and the turbine. This small system causes minimal disruption to local ecosystems, yet generates 20 kilowatt hours of electricity 24 hours a day year-round.
Many green electricity suppliers insist on providing only microhydro, not large-scale hydro, in their mix of green electricity products. While the Durika installation is an example particularly suited to mountain rivers, other types of microhydro projects are used in less hilly areas, but always with the same objective: only take a portion of the river's water, and avoid disrupting the waterflow or creating a reservoir.
Green electricity and the electric car
Electric cars, and plug-in hybrids, seem to be gaining ever more attention these days - Toyota has announced plans to produce a new plug-in version of the Prius by the 2010 model year, as well as an all-electric car based on one if its domestic sub-compacts, while the Smart Car will be coming out with an all-electric version soon. While it's still better to power an electric car with coal-fired power, than to run regular cars on gas, better still is to run these electric cars on green energy.
See the Green energy page on MyCoolElectroCar.com for a discussion of the merits of using green electricity to power electric cars, compared to running them on non-renewable electricity, and running regular cars on fossil fuels.
Ways of buying green electricity
You can buy non-polluting electricity either by paying to have a green supplier generate all your electricity for you, or by a program sometimes known as a Green Tags program, where you buy blocks of green power in advance, in order to allow a green supplier to put that much electricity on the grid over a specified period.
When you sign up with a green supplier, they bill you each billing cycle for the amount of electricity you used, and they are responsible for putting that much electricity on the grid as a result of your using it.
When you sign up with a green tags program through your local utility, you typically purchase a block of electricity, perhaps 100 or 250 or 500 kwh. Usually you are paying only for the premium (the price difference between the green and the dirty electricity you'd otherwise get), and by adding this premium to your bill you obligate your utility to buy that much electricity from a green supplier.
When you sign up directly with a green tags program, you are simply paying that program money to reflect the fact that it costs more to supply clean electricity than dirty electricity, because the dirty electricity sources are artificially subsidized. By buying green tags you make it more affordable for a green supplier to generate their electricity, and therefore, in theory at least, you increase the amount of green electricity on the grid.
When looking for a green supplier, you should find answers to the following questions:
How green is their electricity? Do they only exclude coal and nuclear? Do they include large-scale hydro, which many don't consider environmentally friendly?
Are they putting new green sources of electricity on line, or just remarketing a supply that was already being put on the grid for general consumption? Are they legally or contractually obligated to contribute to the grid an amount of green electricity equal to what you
