BPA trials acquifer recharge system

UNITED STATES: The Bonneville Power Administration (BPA), grid operator for the majority of the Pacific Northwest region of the US, is one of a group of trialling a new system to help avoid the need to curtail wind power generation in the event of electricity over-supply.

In June 2011, the BPA confirmed it has curtailed wind farm output in the Pacific Northwest region by almost 7%. The body’s policy of cutting wind supply during times of low demand – typically night time and weekends – was drawn up to counter unusually high levels of hydroelectric generation.

In response, the BPA is trialling what it describes as a "small-scale" 1.8MW acquifer recharge project in Idaho, involving pumping water into permeable rock during periods of light electricity use.

The trial, which is located in Cassia County, Idaho, is being carried out with the United Electrcic Co-op and the Southwest Irrigation District (SWID). The aim is to allow SWID to pump water in March and November, instead of between mid-April and mid-October, when electricity demand is higher, thus reducing deep-well-pumping costs.

The BPA said that increasing irrigational pumping in times of low electricity demand or decreasing pumping during times of high demand lowers operational costs for SWID. It believes there is 50MW to 100MW of pumping load in the region that can be stored.

Lee Hall, BPA smart grid programme manager said: "This test could provide benefits to utilities and irrigation districts across the Northwest. This practice could save utilities and irrigation districts money, and use pumps that recharge aquifers as a repository for excess electricity created at times by high wind and high river flows."