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October 28, 2009

Wind-generated electricity

Greg Felton

Wind powerTo get a sense of the giddy optimism surrounding wind-generated electricity, pick up a copy of the Canadian Wind Energy Association report WindVision 2005-Powering Canada’s Future.

The introduction page is a marketer’s fantasy. Set on a solid deep-blue page, “Introduction” is set green type, and the six paragraphs of text below are in white. Anchoring the page at the bottom is a pretty blond girl about 10 years old, arms outstretched, hair blowing in the wind, eyes closed, and face pointing blissfully skyward.

The message is unmistakable: wind energy stands for clean air, sustainability and wholesome optimism. Also unmistakable is CanWEA’s determination to ensure Canada’s place in this energy revolution:

“At the end of 2007, worldwide wind generating capacity stood at 94,000 MW. By 2020, close to $1 trillion in global investment is projected to bring global installed capacity to more than 500,000 MW. Will Canada be a major player in this green energy revolution?

CanWEA wants Canadians to start thinking big about wind energy, to power a greener future and to capture our fair share of the opportunities flowing from the explosive worldwide growth in this industry. To join the global leaders in wind energy we believe Canada should set a goal of producing 20 percent or more of our electricity from wind by 2025. This exciting vision is not only practical from a technical perspective, [but] there are also very strong business and environmental cases for making wind energy a priority in our country.”

What CanWEA does not say, though, is that Canada’s wind-generated energy at the end of 2007 constituted a mere 0.5 percent of all energy generated.

In other words, CanWEA believes that increasing wind-generated energy by 4,000 percent over 18 years, and decreasing greenhouse gas emissions in the bargain, is technically practical. Here are the numbers behind the optimism:

In 2007, Canada generated a total of 7,968 petajoules of energy. A petajoule (1 million billion joules) is a standard unit of measure and is equivalent to 277,777.78 Megawatt-hours (MWh) of electricity.

Twenty percent of this figure amounts to 442,666,670.21 MWh.

Now, a 10,000-acre wind farm containing 87 1.5 MW wind turbines will have an annual output density of 13 KW per acre. If we assume a 30 percent capacity - the ratio of a turbine’s actual annual output divided by its theoretical round-the clock maximum annual output - that gives us 3.9 kW per acre or 34.164 MWh per acre.

When divided into CanWEA’s 20 percent target, that translates into a total required area of 12,957,108.95 acres or 51,828.44 square kilometers— a space almost the size of Nova Scotia. Is this doable? Guy Dauncey has no doubts.

Dauncey is perhaps B.C.’s most enthusiastic and active advocate for renewable energy. In addition to being an award-winning author on climate change, disease prevention and other subjects, he is president of the BC Sustainable Energy Association, executive director of The Solutions Project, board member of Prevent Cancer Now, and publisher of the monthly newsletter EcoNews.

“Every year, Greenpeace’s estimates for wind energy are met faster than predicted,” he said. “However, there is a lag in manufacturing capacity for wind turbine blades. We need to learn from World War II, when factories re-tooled within six months.”

B.C. is currently only one of two provinces without installed wind-turbine generation. (The term “wind power” is a misnomer since wind does not provide power but rather is used to generate electricity.)

Now there are several projects underway, including the huge Nai Kun Wind Development Project in Hecate Strait. Up to 110 turbines in a 550 square kilometer area between Prince Rupert and the Queen Charlotte Islands (Haida Gwai’i) will generate 396 MW in the first phase of a project to deliver a total of 1,750 MW.

Even though the vast majority of B.C.’s energy comes from renewable, clean hydropower, Dauncey says that wind-turbines are needed to replace the 10-15 percent of fossil-fuel-generated electricity that B.C. still has to import from Alberta and the U.S.

As such, wind would be a valuable complement to existing renewable hydropower and a good way to reduce greenhouse emissions. If B.C. were to replace all of its fossil-fuel generated electricity-25.46 PJ or 7,072,778 MWh (2003 data)-it would need 828 square kilometres of turbines.

While the use of wind turbines as an adjunct to conventional generation is a realistic goal, the same cannot be said for their ability to replace conventional energy generation or reduce greenhouse gas emissions to any significant degree.

First, because of the inconsistency of wind speeds, wind-turbines have to rely on existing hydropower, fossil fuels or nuclear power to provide the base load during peak demand times.

Blades start up at around eight kilometres per hour (the “cut-in speed”) and a large commercial turbine generates power if the average wind speed is between 16 and 19 kilometres per hour over the course of a year. Maximum generation occurs between 32 and 48 kilometres per hour.

Second, much wind-turbine generation occurs during off-peak hours when it is not needed to reduce conventional power generation. The example of Denmark provides an excellent example of the qualified promise of wind power that can apply to Canada.

Denmark has 6,000 turbines that generate about 17 percent of its total energy, but the country only benefits from a fraction of it because it is linked to a larger Scandinavian power grid.

Because most of Denmark’s wind-turbine energy is generated at night, most of it is sent to hydroelectric power stations in Norway, which Dauncey says acts like a huge storage battery for Denmark.

The problem with this scenario for wind power advocates is that Denmark benefits very little from its own wind-turbine energy. In 2003, Eltra, a company in West Denmark (Jutland), exported 84 per cent of its wind-produced electricity to Norway. According to a 2004 energy supply report from the Danish Energy Association, the reason was a lack of water in the Nordic hydropower system:

The Danish electricity system is physically an open area having large exchanges with the neighbouring countries. The net exportation is mainly determined by changes in precipitation in Norway and Sweden, but also bottlenecks in the transmission systems have a certain influence.

Because of the interconnectedness of the Danish power system, and the fact that wind power is unpredictable and cannot give a steady flow of energy by itself, Denmark has not closed a single fossil-fuel power plant.

These plants, taken together, provide 75 percent of Denmark’s energy. Also, since power systems in Norway and Sweden are nuclear- or hydro-based, which are low polluters, the Danish turbine energy that these countries import does not go toward reducing carbon emissions.

CanWEA’s goal of having 20 percent wind-turbine energy by 2025 is an ambitious goal that will, if successful, reduce greenhouse gas emissions somewhat.

Fossil-fuel power plants generate 25 percent of Canada’s energy, as well as 17 percent of CO2, 25 percent of SO2, and 36 percent of mercury emissions.

Nevertheless, the idea that wind turbines could be anything more than a complement to fossil fuels, nuclear or hydroelectric generation blows their benefits out of proportion.

Greg Felton is a freelance writer based in Westminster B.C.

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