Energy Minister Jack Keir is launching an aggressive wind energy strategy that could drive New Brunswick to double its entire power supply by 2025 simply with wind power,” wrote Daniel McHardie on May 16.
“Keir told a Saint John conference this week that the province could add as much as 4,500 megawatts of wind power onto the provincial grid by 2025. Keir’s pronouncement is a staggering figure considering NB Power’s total load is now just shy of 4,000 megawatts.”
Wonderful! Wind is free!
Well, let’s take a longer look.
Mr. McHardie’s story continued: “if the government added 4,500 megawatts to the grid by 2025, that means it could technically replace all existing generators that power the province.”
Even better! What are we waiting for?
But perhaps we are seeing a hint of backtracking when Minister Keir elaborates. “Even if they are half right, even if it is 1,250 to 2,000 (megawatts), the opportunities there are wonderful,” Keir said.
“Not only for ratepayers of electricity but the environment, and a new industry could be built in New Brunswick on this opportunity.”
What is the reality behind the press releases?
Let’s be kind and take that low value (1,250 MW) as a working figure.
A typical wind turbine these days can develop 1.5 MW when the conditions are ideal. That would theoretically call for about 835 turbines. And what are those “ideal” conditions? Typically, a wind of 50 km/h. In much of New Brunswick, that is quite a strong wind.
A slight complication is that the power available from a turbine varies with the cube of the wind speed. If the speed is 25 km/h, half the optimum speed, the power output drops by a factor of 8, to only an eighth as much. And below the “cut-in” wind speed (typically around 15 km/h), a turbine produces no power at all. There is also an upper limit. Turbines are usually locked down when the wind reaches 100 km/h, otherwise they might be damaged.
The best wind locations around New Brunswick have been identified by Dr. Yves Gagnon of the Université de Moncton. However, even at those sites there will be many times when the wind isn’t blowing very strongly.
Denmark is the poster child of wind generation. It has long stretches of coast that receive strong winds. If any place should be suited to generating wind power, Denmark is it. However, there have been periods when the wind was so weak that the system was producing almost zero power.
Conversely, there have been other times when it produced far more electricity than Denmark could use. What did they do with it? They had to sell it, at a very low price (or a loss), to neighboring Germany. In 2003, such exports actually cost Danish electricity consumers the equivalent of 100 million British pounds. It would be naive to believe that the New England Power pool would pay more than a pittance for irregular slugs of our surplus power.
As for our 1.5 MW turbines, that number is only the “rating plate” output under ideal conditions. But nature seldom co-operates, and actual output typically averages only about 20 per cent of the rating. So, to obtain the full 1,250 MW under all conditions, we would have to install five times as much rating plate (7,250 MW), which would equal five times as many turbines (4,175 windmills). Denmark has over 5,000 wind turbines, though most are smaller than 1.5 MW.
Wind turbines are huge. The diameter of the rotor of a GE 1.5 MW unit is 70.5 metres and the height reaches to 100 m. It is recommended that turbines be spaced at least five to 10 times the rotor diameter apart. Our 4,175 turbines at, say, 6X spacing, would stretch out about 1,766 kilometers. This must approximate the perimeter of the province.
For some perspective on numbers, GE (a major manufacturer) has a total of 3,300 1.5 MW units in operation worldwide. For further perspective, turbine manufacturers’ PR announcements trumpet orders for only 50 turbines.
Delivery times for 4,175 turbines would run into years.
Then there is the vital question of how our existing power grid would react to 1,250 MW of wind power being added to its present 4,000 MW. If the wind and 1,250 MW were constant, it could be done. But the wind does vary, even in minutes, and the turbine contribution could drop abruptly, while electricity customers expect a constant supply, 24/7. The only way to guarantee this power is to keep conventional generating plants on standby, to produce power if required, which means that they are running and consuming fuel whether they are producing power or not. Denmark has not been able to shut down any of its conventional generating stations.
Kaare Sandholt, a partner with EA Energianalyse, is quoted as saying that it is viable for New Brunswick to switch to wind generators and turn off traditional thermal stations. Mr. Sandholt is dreaming. But he is a salesman, after all.
Experience shows that adding even as little as 15 per cent wind electricity to a grid causes many problems and requires continual monitoring and adjustment to prevent power fluctuations and grid instability. German experts say that the number should be more like 4 per cent. This would change the recommendation for N.B. down from 1,250 MW to 160 “continuous wind” MW, and a realistic 800 “rating plate” MW installed capacity. This would require “only” about 535 turbines. Obtaining 1,250 MW from wind is unrealistic, and 4,500 MW is an “impossible dream.”
But wind is still cheaper, isn’t it?
Well, reliable sources actually put the cost of wind power at two to four times as much as power from conventional sources.
Minister Keir should be sure that he is getting sound engineering advice about wind power and not just promoters’ hype.
He should not plan to spend gigabucks on wind power simply because the “greens” mindlessly demand it.
Ian McQueen
URL to article: https://www.wind-watch.org/news/2008/06/20/sing-a-song-of-turbines/