To become sustainable, Samsø turned to one of its most plentiful natural resources.
In an ambitious plan, Samsø’s leaders wanted to do more than merely transition to renewable energy sources. Their goal was for the island to become energy neutral (produce as much energy as its residents consume) or even energy positive (produce more energy than consumed). A major part of Samsø’s transformation was the installation of 11 onshore and 10 offshore wind turbines designed to harness the power of wind energy, or energy contained in the motion of air across Earth’s surface. There is no shortage of wind on Samsø, and the powerful breezes turn huge blades (up to 40 meters [130 feet] in length) that are connected to a generator, which converts mechanical energy into electricity.
wind energy
Energy contained in the motion of air across Earth’s surface.
Nine of the onshore turbines on Samsø were purchased collectively by groups of farmers who bought shares in their construction. “People on the island are personally invested in this,” says Bernd Garbers, a German engineer who lives on the island and is a consultant for the firm that won the energy contest, Samsø Energy Academy. By 2013 the windmills were producing enough power to supply 100% of the electricity used by the islanders— sometimes more. In just 10 years, Samsø had become an energy-positive island.
Samsø uses about 500 billion kilojoules (kJ) of energy each year. A barrel of oil produces 6.15 million kJ, so Samsø uses 81,300 barrels of oil equivalents (BOE) annually. (That’s 500 billion divided by 6.15 million.) In 2013, the entire human population used an estimated 90 billion BOE, and only about 9% of that energy came from renewable resources. The United States ranks far below that average, fulfilling only about 5% of our energy needs through renewable energy in 2013. INFOGRAPHIC 23.1
RENEWABLE ENERGY USE
According to the U.S. Energy Information Administration, as of 2010, renewable sources of energy contributed 4.18 trillion kilowatt-hours (kWh) of total electricity energy production worldwide (about 21% of the total). By 2040, electricity generation by renewable energy sources is projected to increase by more than 40% but will account for only about 25% of the total because total usage is expected to double over that time. Of renewable sources, biomass (mostly fuels like wood, charcoal, and animal waste) makes up the largest proportion, followed by energy produced by hydroelectric dams.
To address climate change and other pollution issues associated with fossil fuels, we should begin to phase out fossil fuels and increase our use of renewables. Are we on track? Summarize the change in total energy use and the usage of renewables and fossil fuels from 2010 to the projected values for 2040.
Between 2010 and 2040 energy usage is predicted to more than double with increases in each sector except liquid fuels such that in 2040 we will have increased fossil fuel use, not decreased it.
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In addition to wind power, Samsø also generates heat that is piped to homes by burning locally grown straw, a biomass energy source. Biomass fuels, or biofuels, have the advantage of being carbon neutral; they do release CO2 into the air, but this is CO2 that the growing plants recently removed from the air. They also can be locally sourced, reducing transportation costs (monetary and environmental). On the other hand, they release air pollutants (particulates), and raising biofuel crops can displace food crops, reducing overall food supplies. (For much more on biofuels, see LaunchPad Chapter 32.)
biomass energy
Energy from biological material such as plants (wood, charcoal, crops) and animal waste.
The straw used in the power plants is the only energy source that is burned on the island other than the gasoline and diesel fuel used in vehicles. Ideally, Samsø residents would have swapped their vehicles for cars that run on hydrogen or electricity, but those technologies were too expensive and not efficient enough to use on the island. Since Samsø would continue to rely on conventional fuels for transportation, engineers decided to install large offshore wind turbines to produce an equivalent amount of clean energy, offsetting uses by motor vehicles and boats. Islanders are working toward a gradual transition to electric vehicles and those powered by biofuels. The island’s small size helps make all this feasible since daily “commutes” are short and miles traveled per person per day are lower than in most industrialized nations.
KEY CONCEPT 23.2
Fossil fuels are the leading fuel for electricity production. The use of both renewables and fossil fuels is rising, due to increased energy demand.
Far off the coast, the offshore turbines are especially efficient at generating energy because wind conditions are better at sea. In some especially windy locations, people have built strategically placed wind farms, which can contain dozens of turbines. In 2014, the world’s largest was located in California, with a generation capacity of 1,548 megawatts (MW), but Texas is the leading producer of wind energy in the United States. It has 7,772 wind turbines that generate enough electricity—12,355 megawatts (MW)—to power 3.3 million homes per year. INFOGRAPHIC 23.2
HOW IT WORKS: WIND TURBINES
Some people feel that windmills and wind farms are eyesores, but one must also consider the alternatives. Would you rather live near a wind farm or a mountaintop removal coal mine? Explain.
Answers will vary but this question helps put the disadvantages of living near a windmill or wind farm in perspective. Perhaps windmills are an eyesore but the alternative could be much worse. Even if we don't live near a coal mining site, if we continue to use coal, then someone lives near one. This means our use of electricity harms those people and communities. Perhaps having wind farms in our own community is more just than coal mining sites in the communities of others.
KEY CONCEPT 23.3
Wind power is pollution free but is an intermittent energy source. In addition, turbines are dangerous to wildlife, and some consider them eyesores.
But wind energy isn’t perfect. First, even for a blustery location like Samsø, wind is intermittent—it stops and starts irregularly, not producing a steady stream of power. And large wind turbines are not cheap. Each onshore turbine cost the Samsø islanders the equivalent of $1 million; offshore turbines rang up at $5 million apiece. (Less expensive, smaller wind turbines can be purchased by homeowners for personal use.) Beyond cost, wind turbines can create noise, and some people see them as eyesores. They can also have an impact on the local environment, threatening birds and bats, who are unable to nest near turbines or are killed by rotating turbine blades. More than 1 million birds and bats are killed by wind turbines annually in the United States. While that may seem like a large number, it is far less than the number of birds killed by flying into communication towers (40 million) or those killed by domestic cats (hundreds of millions). Still, to decrease the risk from windmills, engineers now avoid placing them in known migratory flight paths or close to areas frequented by birds of prey such as eagles.
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