Cost of Solar Power: Water

The effect of this on the Colorado River therefore needs to be determined before construction commences.


29/09/2010 Ámbito: América (Noticia leida 300 veces)

EWP.-Californian officials have recently approved the world's largest solar power project. The 1,000-megawatt solar plant will utilise groundwater in its auxiliary wet cooling system during the summer; the effect of this on the Colorado River therefore needs to be determined before construction commences.

Planned for a site eight miles west of the town of Blythe in the Mojave Desert, the power complex will comprise four individual 250 MW units generating electricity using parabolic mirrors. Solar Millennium, the project's owner, has signed a contract with Southern California Edison for the entire output of the complex which will begin operating in 2013.

The Blythe facility will not only be the world's largest solar power operation, but will also double the installed commercial solar capacity in the US. Governor Arnold Schwarzenegger has fast-tracked solar energy projects as California strives to meet its goal of obtaining 33% of its energy from renewable sources by 2020. The California Energy Commission (CEC) approved two solar projects earlier this summer and will rule on three more by the end of the month, according to a press release from the governor's office.

The plants in the Blythe project will be dry-cooled, a technology that uses ambient air to dissipate heat. While it will increase the cost of the plant and reduce its efficiency, dry cooling decreases water consumption by more than 90%. Solar Millennium has decided to use dry cooling in all of its plants, according to company representative Bill Keegan. "Obviously there's a trade off because of a loss of efficiency and power capacity, but we feel it's worth it with the water savings," Keegan said.

However, the Blythe plants will have an auxiliary wet cooling system for the summer months to keep critical equipment functioning at its designed capacity. The company will drill wells onsite for its water needs: 4,100 acre-feet during construction and 600 acre-feet annually to operate the plant. The CEC's environmental review found that the extraction rate will exceed recharge, but the plant will not significantly affect the groundwater basin because of the large amount (five million acre-feet) of water already stored.

The groundwater recharge is however believed to be connected to surface flows from the nearby Colorado River, which cannot add new users to its appropriation. As part of its decision, the CEC is requiring Solar Millennium to study the relationship between the groundwater and the river, as well as submit a plan to offset any effects its water use would have on the river. This plan will need approval before the company withdraws any water.

The CEC's suggested options include conservation programs; funding irrigation improvements elsewhere; purchasing water rights; or participating in the Bureau of Land Management's program to remove tamarisks, a water-intensive invasive plant. Keegan said Solar Millennium is still looking into how best to offset its water use.