Wind power holds tremendous potential as a renewable energy source, but until recently we have only been able to tap into a small fraction of what’s available. Recent technological breakthroughs in ultracapacitors, however, have revolutionized wind power, making turbines considerably more efficient and less costly to maintain.
The strength and intensity of wind fluctuates dramatically throughout the day. Strong gusts can last just a few seconds before being reduced to a mild breeze. When winds are too strong for the turbine to handle safely, the pitch of the turbine blades must be adjusted to a neutral position to act as an emergency brake. Until recently, only bulky batteries could provide the power necessary to shift the pitch and stop the blades. Now, ultracapacitors enable the turbine to adjust the pitch of each blade continuously, significantly boosting efficiency.
We encounter capacitors every day. They are found in televisions, computers, and cell phones. Ultracapacitors, also known as electronic double-layer capacitors, have an energy-density capacity hundreds of times greater than the capacitors found in home electronics. Companies such as New York’s Ioxus manufacture ultracapacitor modules, which group six capacitors together in a series. These modules are the ones primarily used in wind power, and it takes 30-60 modules to power each of a wind turbine’s three blades.
Ultracapacitors themselves are more efficient than traditional battery technology, even though they both function by charging and discharging energy. Batteries use chemical energy storage and lose about 30% of their energy during each cycle of charging and discharging. Ultracapacitors, on the other hand, rely on static electricity to store energy on the surface, resulting in a longer, more efficient life cycle. While ultracapacitors can complete over a million cycles of charging and discharging, batteries are capable of only 10,000-50,000 cycles. This means that ultracapacitors need only be replaced once every 10 years, instead of every 3-5 years for batteries.
Batteries also present several logistical and physical challenges. For example: The best location within a turbine to house power storage is in the rotating assembly. But batteries large enough to cope with the highest of winds are heavy, requiring extensive structural supports. They also need to be insulated from the cold, and vented to release hydrogen gas during cycling. Ultracapacitors, by comparison, are lighter (1/5 the weight), can cope with lower temperatures, and do not require venting.
Because cost is often cited as a prohibitive factor in wind-power generation, ultracapacitors may well be the answer to this challenge. Turbines are frequently located in difficult-to-reach locations, particularly if that location is offshore. By reducing the number of power supply changes, savings are realized in the cost of sending expensive technicians out to the rigs. Finally, the cost of ultracapacitors themselves has been dropping at a faster rate than the cost of batteries.
Since their first use in wind turbines in 2006, over 1,000,000 ultracapacitors have been installed in wind turbines. Existing turbines are now being retrofitted to eliminate the need to replace and maintain batteries, and turbine manufacturers are turning more often to ultracapacitors for their pitch-control potential. Ultracapacitor applications may soon expand to include controlling the yaw, or the orientation of the entire turbine. We’ll keep you posted!
