Desalination use growing despite energy, environmental issues

Carlsbad desalination plant. San Diego
Carlsbad desalination plant. San Diego

Desalination seems a perfect solution to water shortages. Take the salt out of ocean water and turn it into drinking water. 300 million people today rely on desal water. However, there are serious issues. First off, desalination requires a lot of electricity and in too many areas today, like the Middle East, that power comes from fossil fuels, which contribute to global warming. Second, bringing ocean water into the plant can kill fish, larvae, and plankton plus dumping the salty brine back into the ocean will have deleterious effects. Third, it’s expensive. The Carlsbad desal plant near San Diego treats 50 millions gallons a day. However the cost is double that of their primary source of water, the Colorado River.

One promising approach is to use brackish water, which is much easier to clean because it has much less solids in it and doesn’t require being near an ocean, so it’s cheaper than ocean water desalination.

De-sal proponents acknowledge the industry must confront and solve some serious environmental issues if it is to continue to grow. Desalination requires vast amounts of energy, which in some places is currently provided by fossil fuels. Kiparsky warns of a feedback loop where more de-sal is needed as the planet warms, which leads to more greenhouse gas emissions. In addition, there are serious concerns about the damage to marine life from the plant’s intake systems and extra-salty wastewater.

A study by the UN Institute for Water, Environment and Health published earlier this year contends that the problem of brine waste has been underestimated by 50 percent and that, when mixed with the chemicals meant to keep systems from fouling, the brine is toxic and causes serious pollution.

FYI: Las Vegas has had toilet-to-tap for years and traps as much storm water as possible. One big advantage is Vegas can store the cleaned-up water in Lake Mead and it doesn’t count against their allotment of water from the lake.

The Pacific Institute’s Cooley argues that before building de-sal plants, municipalities should fully implement conservation programs, promote potable re-use – the re-use of wastewater, also known as toilet-to-tap recycling – or treat storm water runoff. “It makes sense to do the cheaper options first and leave the more expensive options down the road to be developed when you need them,” she said.