Consumption of Electricity

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Consumption of Electricity Elise L. Chapman

Many aspects of life in developed nations demand electricity. It is produced by a variety of methods but in the United States is primarily generated through the burning of fossil fuels. Coal combustion accounted for 51% of the fossil fuels consumed in the generation of electricity in 2003 and coal has the highest carbon emissions per unit burned of all fossil fuels 1. This production of electricity resulted in an estimated 3.8 trillion kilowatt-hours of power. Consumption is split almost evenly among commercial, industrial and residential contingents. As our lives become more automated, with appliances and transportation private demand for electricity increases. The average household uses 8,900 kilowatt hours per year, or about 24.38 kilowatt hours per day 2.

All power used for our propulsion, living and research needs while on the Gato Verde is supplied by batteries charged from a bio-diesel generator or from plugging in to shore power while docked. Shore power is provided through hydroelectric power plants, which avoid depleting fossil fuel resources and carbon emissions but do have large impacts on the river systems in which they are located. Specifically in this area, salmon migrations to spawning grounds are impeded. Since we use electricity in propulsion, it is difficult to compare our usage with American households as most homes do not move using electric motors. At this time, it is difficult to separate the consumption of electricity by the propulsion system from that of the “house battery” used in the living needs (computing, water pumping, lighting) of those on the Gato Verde. It is currently possible only to estimate our kilowatt hour consumption for computing needs.

During the Beam Reach program, we challenge ourselves to think about sustainability at many levels and make sacrifices to leave less of an impact. When striving to conduct research, it is difficult, at times to the point of being prohibitive, to limit computer use, which demands high levels of electricity. Over the course of one hour of computing, we consume power at a average of 0.07 kilowatts.

Another aspect of the Gato Verde that impacted people’s well being was the lack of exercise options. With these two thoughts in mind, a possible supplement to the supply of electricity on the Gato Verde could be the use of pedal power. A pedal power generator from Windstream Power can produce 30 watt hours with 3-4 hours of pedaling 3. There are numerous personal computers being used simultaneously on the Gato Verde contributing to power consumption. It seems more realistic to offset individual personal computing power consumption by pedaling than to successfully offset the whole groups computing by an individual pedaling. Installing a pedal power generator would provide exercise opportunities for those on board, which releases endorphins combating stress and burning calories while contributing to the battery charge. An average 155 lb person will demand 533 calories per hour to pedal at moderate effort on a stationary bike 4. For a notable increase in offsetting power consumption for house use on the Gato Verde, additional sources should be considered. (See Anne Harmann’s sustainability posting for use of solar power.)

Wind power is currently used to charge the batteries while sailing. The flow created while moving forward in the water turns the propellers and this rotation can charge the batteries. In order for this system to work, the Gato Verde must maintain a critical sailing speed of about 7 knots because there is drag created from friction in the charging system. Wind could also be harnessed as a source of alternative charge for the batteries if a wind turbine were installed.

A wind turbine can produce 38 kilowatt hours per month at wind speeds of 10 knots 5. Average wind speed for Friday Harbor Washington during the 2007 Beam Reach course was about 3 knots 6. The annual average wind speed for Seattle Washington is about 7.7 knots7. The winds in the Haro Strait are often higher because it is more exposed than Friday Harbor and Seattle. Even with wind speeds as low as 5 knots a wind turbine on the Gato Verde would average about 20 kilowatt hours per month. If numerous personal computers are used for about 5 hours a day for a month they would demand about 10.5 kilowatt hours, making a wind turbine a viable option for offsetting the computing consumption of electricity with a surplus to aid in other house uses of electricity.

Finding sources that are more sustainable is an appropriate measure to reduce the environmental impacts of fulfilling our valid electricity needs. Some of our demands on power could be eliminated, decreased, or made more efficient. Many of these suggestions would be best applied to our lives at home as we were quite aware of our consumption while aboard the Gato Verde. The following are possible changes and the influence they would have on a household’s environmental impact (mostly in terms of a reduction in CO2 emissions) 8, 9, 10.

Suggestion Reduction in CO2 emissions Insulation of wall and ceilings 140 to 2100 pounds per year Weatherizing (caulking, weather stripping, etc.) 1100 pounds per year Alter thermostat setting (2o ↓ in winter and 2o ↑ in summer) 420 pounds per year Replace incandescent bulbs with compact fluorescents bulbs 260 pounds per year per bulb Install insulation jacket on water heater 1100 lbs./year electric;220 gas