Dare To Be Green: The Pros and Cons of Alternative Energy Sources
By Sofia Gearty ’09
News Senior Staff Reporter
We know we should turn off our lights when we leave a room to save electricity. But what does this really save, and how does it connect to global warming? Electricity generation is the key. We do not think about it much, but some kind of energy is necessary to produce electricity—energy from fossil fuels like coal or from renewable sources. According to the journal Nature, this process produces more than 10 gigatons of carbon dioxide emissions each year, the single biggest contribution to global warming of any industry. This also represents 40% of US carbon dioxide emissions each year.
Coal produces more carbon dioxide than any other fossil fuel when burned. It is used in 50% of US electricity generation and is responsible for 80% of the emissions from the entire industry. This kind of pollution is unacceptable, no matter how cheap coal is.
The alternatives to fossil fuels such as coal and petroleum are renewable energy sources, like hydro and solar power. These industries are growing rapidly, as more people realize the necessity of developing new ways to power the nation. What follows is a quick overview of several renewable energy sources, drawing on a recent Nature journal article, “Electricity Without Carbon.”
Hydropower uses the force of water through systems like dams to create electricity. It is a mature technology, already implemented on a large scale across the globe. There are approximately 45,000 large dams already in use, which supply about 20% of the electricity consumed worldwide. Hydropower does not use fuel, has a relatively stable production rate, and is efficient and powerful—dams can generate more power than geothermal, solar, and wind power combined. There are, however, some serious environmental costs to hydropower, because blocking rivers and creating reservoirs can disrupt the local wildlife like migrating fish and force people to relocate to other areas.
Nuclear power is another renewable source that is already used worldwide. There are currently about 500 plants in operation that produce about 15% of the electricity generated globally. The nuclear plants in the US deliver about 90% of their capacity, making nuclear power a particularly clean and efficient energy source. There are serious costs, however, to using nuclear power. One is the dilemma over how to store the radioactive waste that is generated. There is also a connection between nuclear energy sources and nuclear weapons, which creates political tension over this technology. The danger seen in disasters such as the nuclear disaster at Chernobyl is still a deterrent to many.
Electricity generation using biomass, or plant matter, can supplement coal or natural gas in conventional plants. Biomass such as wood is more commonly used for heating but could theoretically be used to generate electricity on a larger scale. Although plants release carbon dioxide when burned, technology is developing to capture the released carbon and reuse it. This energy source, however, is constrained by the space and resources to grow the crops, and the mass production of “energy crops” could cause a rise in food prices. The environmental impact of growing, fertilizing, and transporting the crops could also offset the carbon dioxide gains. This system of electricity generation could be effective on a small scale, but it is unlikely to gain popularity as a major solution to the energy crisis.
Wind power is growing faster than any other renewable industry, and currently represents 35% of the US’s electrical generation capacity. With recent subsidies and technological improvements, wind generates electricity more cheaply than coal. Wind power also does not require fuel, so it is only upfront costs are from building, installing, and transporting turbines. A major limitation remains the wind’s intermittency, as well as the lack of infrastructure to set up turbines in the windiest areas, which are frequently remote. Wind power also requires cheap land for the space sufficient to produce a significant amount of electricity. These problems can be solved as the industry grows, and wind power is likely to become a major source of clean energy.
Geothermal power uses pumps to exploit the earth’s stable core temperature. This system does not require fuel except for the water in the pumps and is guaranteed a steady supply of heat. Because of its dependability, it also has the highest capacity of all renewables, 75%. The earth’s core heat, however, is only accessible in certain areas, like hot springs. This is a severe limitation to the growth of geothermal power as a major electricity source. Geothermal pumps can also be used on the small scale to heat and cool buildings: the new dorms here at Choate use this system. Although it may start to supplement oil or gas heating in buildings and houses, geothermal power is unlikely to overtake wind and hydro power in magnitude.
Solar power is one of the most popular renewables today, and the industry has seen tremendous growth over the past several years. Standard photovoltaic panels convert about 12 to 18% of the sun’s energy into electricity—not too bad when one considers that plants only use 1% of the energy they receive from the sun for photosynthesis. New models, however, exhibit as much as 20% efficiency. There are fewer objections to this technology than to nuclear, wind and hydro power, but improvements are necessary to lower costs for the public to purchase private panels, to deal with fluctuations in generation in cloud cover or darkness, and also to distribute the electricity generated from desert areas to cities.
Solar is definitely one of the most promising technologies available, but it cannot be used everywhere—at Choate, the energy payback for setting up panels is 60 years. Connecticut simply does not receive enough energy from the sun to make solar panels an efficient and cost-saving method. With improvements in storage and planning for inclement weather that decreases generation, solar power can become one of the major clean energy sources.
Choate cannot change how electricity is generated, but it has the ultimate power of controlling the other end, how much electricity is consumed. Turn off your lights and computer when you leave your room, and do not keep chargers plugged when they are not being used—these simple actions can drastically reduce the amount of electricity we waste.
