Wednesday, 7 April 2010

In BOB We Trust

One of the most common criticisms of renewable energy sources is that their electricity is intermittent.  Solar photovoltaic (PV) panels only produce electricity when the sun is shining, and wind turbines will only generate power when the wind is blowing at the right speeds - not too gently, and not too hard. This intermittency makes it more difficult for households, companies or electric utilities to precisely match supply and demand when using most renewable energy sources.

If we want to use electricity from renewables at other times, we need storage.  I've written in the past about different storage technologies, including "virtual storage on the electric grid".  It seems a town in Texas has taken things more literally.

Electric Transmission Texas recently announced completion of a 4 MW sodium-sulfur battery in Presidio, Texas.  The battery has been nicknamed "BOB" - short for "Big Old Battery" - by local residents.  And big it is.  BOB is the largest battery of its kind in the United States and the first in Texas.  It is designed to reinforce the local electricity supply while a replacement for the existing 60-year old long-distance transmission line is constructed between now and 2012.  In the event of a power outage, BOB can supply the city with continuous power for up to eight hours, until grid power is restored.

At a capital cost of around $25 million, BOB certainly isn't cheap, but neither is the $44 million cost of connecting Presidio to the regional electricity grid 60 miles away.  For that cost, the city could build around 10 MW of solar power generation, or around 20-30 MW of wind power - assuming local wind conditions were favourable.

ETT and the city of Presidio are clearly planning for the future.  BOB has a planned opertaional lifetime of 15 years, but ETT expects the upgraded transmission line to be complete by 2012.  After that date, BOB will be available as a facility for other utilities that need to store electricity (presumably from intermittent renewables) to match consumer demand.  Depending on the rates they charge for this service, BOB's owners could generate handsome profits from their giant battery system.

BOB is an example of the technological innovation that is making low-carbon renewable energy a realistic option for providing reliable power around the world.  At Carbon Clear, we're working to support innovations in the supply of sustainable energy.  We're eager for you to join us.

(Carbon Clear website)