First, a press release from the Major Electricity Users' Group (MEUG) of New Zealand describes how the unreliability of wind energy is costing utilities more on the spot market and requiring more diesel backup.
"[T]he underlying driver of current high spot prices is that water is relatively short because of low seasonal inflows and wind generation has been unreliable. These are the types of renewables the government puts much faith in to achieve its 90% renewables by 2025 target, assisted by a ban on new thermal power stations.Second, a Mar. 27 news story from the Colorodoan describes the Platte River Power Authority (PRPA)'s maintenance problems with their 10-year-old Vestas turbines. It also shows the sham of renewable energy credits, or "green tags", as a substitute for actual energy, since they cost the PRPA one-fifth what operating their own turbines costs.
"Yesterday the Te Apiti wind farm had peak generation of approximately 30 MW. Installed wind turbine capacity at Te Apiti is 90 MW. Average wind generation for the whole day from Te Apiti was approximately 12 MW. Just when we need as much supply as possible to cover known outages and hence put pressure on spot prices, wind has been missing.
"Once again the expensive to run government owned Whirinaki power station burning diesel entered the market yesterday. Whirinaki has been used partly for 13 days over the last 5 weeks. If government dictates more wind generation should be built by banning new cheaper gas fired base load power stations, we will need a lot more Whirinaki type plants around New Zealand. The operating costs of Whirinaki are estimated to be in excess of 30 c/kWh so using diesel plants in the future to cover dry years or windless periods will penalise all consumers of electricity.
"The evidence that relying on more renewables rather than a mix of generation types will lead to extreme spot prices and the need for inefficient peaking thermal plant is happening almost everyday with the current prolonged summer weather. Government needs to heed the signs and urgently rethink the proposed ban on thermal generation," concluded Ralph Matthes, Executive Director of the MEUG.
Some components on Vestas Wind Systems-manufactured wind turbines at Platte River Power Authority's Medicine Bow Wind Project are failing more than 15 years earlier than expected, according to PRPA.wind power, wind energy, wind turbines, wind farms
Since the Medicine Bow, which is in southern Wyoming, went online in 1998, 30 major outages have occurred on the wind farm's nine turbines due to component failure, said John Bleem, PRPA division manager.
Although outages vary, Bleem said repairs have led to turbines being down for as long as three months and costing as much as $100,000 -- paid for by Vestas under its manufacturer warranty set to expire in 2011. ...
"When that warranty expires, then it's treated just like a warranty on a car where we will be responsible for the cost of repairs," Bleem said. "We are negotiating service contracts; and those costs have gone up for repairs and maintenance on the machines, and it will continue to go up with labor rates and parts costs." ...
Historically, PRPA has bolstered its renewable portfolio through the purchase of renewable energy credits, or RECs, that allow it to invest in wind farms owned by others who pay for maintenance and repairs. ...
Although PRPA receives a majority of its renewable energy through RECs, its homegrown Medicine Bow project has been far more costly despite producing less energy.
"We spend two-thirds of our renewable budget on energy and one-third on purchasing RECs," Bleem said. "About 80 percent of our portfolio supply comes from RECs, and 20 percent is coming from energy. So what that tells you is that renewable energy is much more expensive than purchasing RECs."
Nearly five to six times more expensive.
"We pay about 1 cent (per kilowatt-hour) for RECs, and we pay about 5 to 6 cents (per kilowatt-hour) for the wind energy we produce ourselves," Bleem said. ...
PRPA has been negotiating with Vestas to extend its Medicine Bow warranty beyond 2011 with some success, but the final result will likely leave the power authority paying a higher premium and more for repairs to its nine turbines. ...
"There is regular scheduled maintenance," Bleem said. "Lubrication is the major thing as well as some minor components that need replacement like filters, but the biggest concern is unscheduled outages. The unscheduled repairs are what have us concerned the most."
