Germans Are Paid to Use Excess Power Generated from Wind Turbines
May 3rd, 2010Wind is an intermittent power source, so feast or famine situations are possible. There are several options for capturing excess energy for later release into the grid, but high-energy flywheels probably make the most sense:
Flywheel energy storage works by accelerating a cylindrical assembly called a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. The energy is converted back by slowing down the flywheel. The flywheel system itself is a kinetic, or mechanical battery, spinning at very high speeds to store energy that is instantly available when needed.Flywheel
At the core of Beacon’s flywheel is a carbon-fiber composite rim, supported by a metal hub and shaft and with a motor/generator mounted on the shaft. Together the rim, hub, shaft and motor/generator assembly form the rotor. When charging (or absorbing) energy, the flywheel’s motor acts like a load and draws power from the grid to accelerate the rotor to a higher speed. When discharging, the motor is switched into generator mode, and the inertial energy of the rotor drives the generator which, in turn, creates electricity that is then injected back into the grid. Multiple flywheels may be connected together to provide various megawatt-level power capacities. Performance is measured in energy units – kilowatt-hours (kWh) or megawatt-hours (MwH), indicating the amount of power available over a given period of time.
Beacon’s Smart Energy 25 flywheel has a high-performance rotor assembly that is sealed in a vacuum chamber and spins between 8,000 and 16,000 rpm. At 16,000 rpm the flywheel can store and deliver 25 kWh of extractable energy. At 16,000 rpm, the surface speed of the rim would be approximately Mach 2 – or about 1500 mph – if it were operated in normal atmosphere. At that speed the rim must be enclosed in a high vacuum to reduce friction and energy losses. To reduce losses even further, the rotor is levitated with a combination of permanent magnets and an electromagnetic bearing.
Via: Bloomberg:
On windy nights in northern Germany, consumers are paid to keep the lights on.
Twice this year, the nation’s 21,000 wind turbines pumped out so much power that utilities reduced customer bills for using the surplus electricity. Since the first rebate came with little fanfare at 5 a.m. one October day in 2008, payments have risen as high as 500.02 euros ($665) a megawatt-hour, about as much as a small factory or 1,000 homes use in 60 minutes.
The wind-energy boom in Europe and parts of Texas has begun to reduce bills for consumers. Electricity-network managers have even ordered windmills offline at times to trim supplies. That hurts profit for wind-farm operators, said Christian Kjaer, head of the European Wind Energy Association, which represents RWE AG of Germany, Spain’s Iberdrola SA and Dong Energy A/S of Denmark.
“We’re seeing that wind energy lowers prices, which is great for the consumers,” Kjaer said at his group’s conference in Warsaw this week. “We as producers have to acknowledge that this means operating the existing plant fewer hours a year, and this has an effect on investors” and profit.
After years of getting government incentives to install windmills, operators in Europe may have become their own worst enemy, reducing the total price paid for electricity in Germany, Europe’s biggest power market, by as much as 5 billion euros some years, according to a study this week by Poeyry, a Helsinki-based industry consultant.
