Capturing the Wind
Better Batteries Dramatically Boost Wind Energy
David Room April 14th 2008
The giant wind turbines on the west coast of Ireland stand not only on the geographical limits of Europe, but also on the cutting edge of a revolutionary technology that makes wind power more reliable and valuable. The 32 megawatt (MW) Sorne Hill wind park will be Europe’s first to integrate a large scale battery back-up system that ensures a reliable supply of electricity regardless of how the wind blows.
“The battery enables large amounts of energy from wind or solar power to be stored, managed, controlled and sent into the electricity grid when it is needed. It doesn’t matter whether the wind is blowing or not; the battery makes the electricity output predictable and reliable,” said Tim Hennessy, CEO of VRB Power Systems, the battery manufacturer based in Vancouver, Canada.
Analysts say the potential market is huge for technology that can improve the reliability of large amounts of energy from wind and solar power. Wind power is not generally considered dispatchable or “firm” because wind is intermittent and fluctuates greatly on all scales (e.g., minute by minute, day, season). Furthermore, the wind does not always blow when electricity is most needed and therefore valuable.
Battery storage is particularly useful when wind power feeds a grid belonging to a so-called “island” such as in the UK and Ireland. Spain, on the Iberian Peninsula, is also effectively an electrical island because it has limited interconnections with France in the north and Morocco in North Africa.
By contrast, the electricity grids of Germany and Denmark are interconnected with those of their neighbors. Their excess wind power goes all over Europe; the extensive and varied demands of the grid negate the need for a huge storage system. In addition, Germany uses hydropower and biomass to back up wind and compresses air into salt mines to store excess energy.
With few dams for hydropower and few salt mines, the “electrical islands” of Ireland and Great Britain have fewer options. As a result, they will probably need large amounts of battery storage as they expand their use of wind power.
Both the UK and Ireland are planning wind parks on a massive scale. The UK plans for 33 GW of capacity of offshore wind power by 2020. Ireland already has 1,000 MW of wind power and plans to install 2,400 MW more by 2016 and 4,300 MW by 2020 to reduce their dependence on imported fossil fuels and cut greenhouse gas emissions.
Thus, the 2 MW battery in Sorne Hill, slated to begin operation in 2009, could be the start of something big. Hugh Sharman, a contractor with VRB, estimates that Ireland may need as much as 1,000 MW of battery storage capacity by 2016.
As oil and gas prices continue to rise, battery storage systems become even more cost effective. A MW of wind electricity generated in Ireland costs 70€ ($106), which Sharman says is much cheaper than generating the equivalent electricity using natural gas. The lower cost of wind generation helps offsets the high initial investment costs of the battery, and the battery would enable wind power to be delivered when it is most valuable: electricity could be stored during off-peak hours when the price is low and fed into the grid in peak hours when the price is higher.
If the UK proceeds with its plan to install 33 GW of wind capacity by 2020, it could use as much as 12,000 MW of battery storage to balance out the system, Sharman said. Under the plan, nuclear and clean coal will supply a base load of 20 GW augmented by 33 GW of wind power. Without batteries, the base load would be difficult to supply with a fluctuating wind power supply.
The flow battery was developed in the early 1980s at the University of New South Wales in Australia, and further refined and brought to market by VRB Power Systems. It generates current by moving oppositely charged electrolytes in a vanadium sulphate solution between positively and negatively charged half-cells.
The battery charges when the wind turbines produce more power than is needed. When the wind speed drops, the battery almost instantaneously feeds the electricity into the system. In this manner, it can make wind power up to 95 percent constant.
VRB’s battery can be charged and discharged more than 10,000 times without significant deterioration, compared to only 2000 times for conventional lead-acid batteries. It also emits less key environmental pollutants such as CO2 and Nitrogen Oxide through its life cycle and is made without toxic metals (lead, cadmium, zinc, and nickel).
In places like Europe and California, which have relatively aggressive CO2 reduction laws, wind power augmented with battery storage is likely to become a key electricity source over the next several decades. Further, as cities and counties take control of their energy procurement through California’s Community Choice Energy law to boost the renewable content of their power mix, large scale battery systems are one of few viable options for realizing the ultimate goal of a reliable and stable, 100% renewable electricity grid.
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