Clean Electricity - July's Sustainable Living Tip

Instead of gas, oil, pellets or wood, choose clean electricity for your household energy needs.

The Path to Sustainability

We believe that in terms of sustainability, "green" electricity is the best option today and in the foreseeable future for all household energy needs. Efficient products are on the market now for space and water heating, refrigeration, lighting and all other household activities; it is relatively easy for consumers to go "all electric". Of all the possible energy options (including biofuels, pellets, wood, and hydrogen), electricity has the clearest path to sustainability. Maine's electricity grid is already powered in part by clean energy sources such as rivers and wind. Many more clean options are in our future -- much sooner than many people realize.

Energy Facts

1. Electricity is a sustainable option for home heating and other household energy needs because it can be cleanly generated from many inexhaustible sources, including the sun, wind, rivers, and tides.
2. Mainers can sign up for green electricity. Paying a little extra on your monthly power bill ensures that the grid is supplied by clean and renewable energy sources, and provides capital for new clean power plants.
   
3. Solar is available throughout Maine, with little variation in solar intensity among sites.
4. Wind is available in Maine along the coast, mountain ridges, and offshore, with huge variations in energy intensity among sites and height above ground level.
5. More than one hundred large-scale hydroelectric facilities are operating in Maine, producing more than 12 million gigajoules (GJ) of electricity per year.
   
6. Since 2006, more than a dozen tidal power projects have been proposed in Maine.
   
7. One acre of Maine woods managed for sustainable harvest could yield 25 GJ (one cord) of hardwood per year.
8. The roof of an average-sized house in Maine (1,400 square feet) in full sun receives about 625 GJ of solar energy per year. This is the energy equivalent of a 25 acre wood lot.
9. Each year the average home in Maine uses about 136 GJ of energy: 22 GJ (6,000 kilowatt hours) for electricity, and 114 GJ (108 million British thermal units) for space and water heating.
10. If you have an average-sized home in full sun, every year you could meet all your home's energy needs (heat, hot water, lighting and appliances) by collecting, storing and using just 21.76% of the solar energy that reaches your roof.
11. The efficiency of solar photovoltaic (PV) cells that produce electricity are between 6% and 40%; the types most commonly available today are about 16% efficient.
12. The efficiency of photosynthesis (the natural process plants use to build wood and other tissues) is about 5%.
    
13. Maine has a net metering law which allows you to get credit for sending electricity to the grid. This means that you can install solar PV cells without needing batteries to store the electricity they produce.
    
14. Completely covering an average-sized home's roof in Maine with today's 16% efficient solar PV cells would generate about 100 GJ (27,777 kWh) of electricity every year, of which approximately 70 GJ (after balance of system efficiency losses) could be fed into the grid to "spin your meter backward."
    
15. In 2007, the Maine Solar House near Wells, Maine, fed into the grid almost 17 GJ (4,707 kWh) of electricity using 384 square feet of 13-year-old solar PV cells (enough to cover about 27% of an average sized roof).
16. Solar PV cells have no moving parts, emit no noise or pollution when generating electricity, require no fluids and little maintenance, continue to operate reliably in extreme cold and hot weather conditions, and have an expected lifetime of more than 30 years.
17. Every year, a typical home on the Maine coast (wind profile area equivalent to a 6.4 m diameter rotor), assuming an average wind speed of 4 meters per second (m/s), deflects about 41 GJ of wind energy. Assuming a higher average wind speed of 6 m/s, the same home deflects about 139 GJ of wind energy.
18. The theoretical maximum efficiency of a wind turbine is 59%, because it must allow some wind to flow through it (i.e. if a turbine attempts to use all of the wind's kinetic energy at any given moment, it stops airflow and thus loses the ability to capture energy at future moments).
    
19. A small 400 watt turbine (rotor diameter 1.17 m) at a 4 m/s wind site will generate about 0.65 GJ of energy per year. At a 6 m/s site, it will generate 2.1 GJ per year.
20. Microhydro run-of-river turbines in streams and tidal flows can be smaller than wind turbines for the same energy output because water is about 800 times denser than air.
21. No data exists for the energy production of tidal turbines in Maine. In April 2008 a 1.2 MW turbine was installed in Strangford Lough in Ireland, the world's first commercial tidal power station.