Saving the Salton Sea with Solar Arrays

2GreenEnergy super-supporter Gary Tulie, one of the brightest and most energetic people I’ve ever met, is constantly “thinking outside the box” when it comes to the use of large-scale engineering solutions to our environmental problems.  Here’s a set of suggestions he makes regarding the eco-issues pertaining to the Salton Sea (pictured), a large man-made lake in California, visible to anyone who flies from Los Angeles to the East Coast of the U.S. – ed 

The Salton Sea is a man-made lake made up mostly of runoff water from agricultural irrigation. It is the largest lake in California, and is currently under threat from reduced inflows and climate change.

From 2017, the amount of water agreed to flow into the lake is due to be reduced by 10% as a result of changes to agricultural water allocation, so risking a substantial reduction in both the lake’s area and volume as well as a huge rise in the salinity of the water.

Why is this a problem?

You might think that with the Salton Sea being an artificial lake which would currently be dry in the absence of human intervention that there would be few problems associated with it drying out. If you thought this, you would be wrong.

Already lake levels are reduced, exposing areas of lake bed made up of fine highly saline silt contaminated with persistent agricultural chemicals like DDT. With this exposure comes a large increase in particulate matter in the air resulting in very poor air quality. For the moment, this is mostly a local problem, but with exposure of a substantially greater area, there is a potential threat to air quality in cities like San Diego and Los Angeles as well as across the border in Tijuana and Mexicali.

Has this happened elsewhere?

The most obvious example is the Aral Sea on the borders of Kazakhstan and Uzbekistan – which has massively shrunk due to over abstraction from its sources. This has resulted in huge economic loss and substantial health impacts for the local population.

A solar solution?

In the Far East, floating solar arrays are becoming increasingly common – with suitable land being scarce in India, Japan, and Malaysia to name just a few.

http://www.malaysiandigest.com/frontpage/29-4-tile/556551-huge-potential-for-floating-photovoltaic-systems-in-malaysia-tnb.html

There are significant advantages to floating solar arrays, albeit with a somewhat higher engineering and O & M cost.

1. In India, each MW of solar array built over a canal is estimated to save 9 million litres of evaporation per year. Results in Salton or over the irrigation canals feeding it are likely to be broadly similar.
2. Solar arrays built over water achieve higher yields by around 7% than similar arrays built on land.
3. Low cost single axis tracking is possible by rotating the whole array to track the sun – very little energy is required to move an object floating on water, and the technology is simple.
4. With a large amount of energy taken out by arrays, the water will tend to be cooler increasing its oxygen carrying capacity – it would also be relatively easy to add aeration equipment to floating solar rafts to improve lake aeration.
5. There are few if any environmental concerns likely to apply to solar arrays floating on the Salton Sea, potentially allowing for tens of GW of floating PV on the lake to be developed with relatively low environmental impact assessment costs.

For Salton to fully offset the expected 10% reduction in its inflow using floating solar arrays would according to my preliminary and admittedly rather crude calculations probably require of the order of 10 to 20 GW of floating solar capacity, which would involve a very substantial level of investment, however with other mitigation strategies such as piping in sea water from the Pacific estimated to cost as much as $9 billion, the approach might just prove attractive.