Storage Boosts the Power of Wind

The Achilles heel about renewable power sources like wind and solor is its intermittency.

When the wind doesn't blow, no electricity can be created. And when breezes come, say in the middle of the night, demand is typically very low, so some of energy is effectively “spilled” or lost. And it’s pretty easy to imagine the amount of electricity that can be generated when the sun doesn’t shine.

The current electric power system is built around a central tenet: electricity must be produced when it is needed and used once it is produced.

Or as Alan Greenspan testified before Congress shortly after the August 2003 blackouts "utilities are an industry without inventory."

Wind power generation is considered a non-firm resource for system planning purposes. The consequence of which is that the price paid for capacity from wind generation is severely discounted.

However wind + storage completely changes the game. Storage smooths out wind and enables it to be a "firm" power.

Storage also can enable wind to have "baseload capabilities. While its true that integrating wind into the grid at levels of around 10% or less, yes, you can use several factors such as reserve, frequency control and the grid infrastructure to support wind's volatility.

All without storage.

However, once wind penetration levels reach 15% to 20%, wind's volatility becomes a real problem. Storage is needed if wind energy is to become "firm."

There’s been some good quantitative work done by independent Sustainable Energy Ireland (SEI) comparing wind-generated power with and without storage.

For Tapbury’s upcoming Sorne Park Wind farm in Ireland, SEI studied 17 storage installations. SEI concluded that with wind + storage gave a better than 98% firmness -- equivalent to good base load generating assets (and better than such assets as gas-fired turbines).

The most important conclusion within the SEI report is the level of return generated with storage. When the proposed 2 MW/12 MWh VRB-ESS batteries were internally financed by Tapbury, the project would have a 11.7% internal rate of return. Generally acceptable given the hurdle rates in the wind industry are typically 8-9% range.

However, if appropriate gearing is applied, the IRR jumps to 17.5 – an unheard of figure for any component of a windfarm.

However there’s a lot more to the storage story than just the boost it gives wind.

Storage protects against mistakes in forecasting, removes barriers in connecting renewable sources to a variety of grids, shifts demand peaks by storing off-peak energy to sell back to the grid during peak times, provides frequency regulation and deters expensive grid upgrades.

In short, storage provides the basis for a complete change in the thinking surrounding renewable power generation and use.

This story (http://www.renewableenergyworld.com/rea/news/story?id=52716) provides a good introduction.

And for the Irish feasibility study, go here: http://www.vrbpower.com/publications/energy-storage-news.html.