Proceeding With Caution: Let’s Avoid The Negative Impacts Of Conventional Ocean Desalination
Sierra Martinez (he/him)
Senior Program Officer, Climate at Clif Family Foundation
The California Legislature holds a committee hearing tomorrow on a bill that asks the question: Should the state set mandatory conventional desalination goals? Answer: No. We can do better. Much better.
Conventional ocean desalination plants convert seawater into potable water through a very energy-intensive filtration process. Pressurizing the water, pumping it through the reverse osmosis filters, and re-filtering the water, altogether makes energy costs about 40% of the total cost of running a conventional ocean desalination plant. The result? Conventional desalination plants are the most expensive water source around.
We have better options
There are several water options to meet our water needs that cost less money and cause less environmental damage. Whether it’s damage to our oceans or water systems (as my colleague Kala pinpoints), or it’s the burden on our electric grid and associated global warming pollution, we should pursue first those water options that avoid the total environmental consequences of conventional ocean desalination, starting with water efficiency and working our way down the list.
We can make desalination less harmful
If and when we reach the need for desalination, after implementing the cheaper and better water options above, there are several changes that should be made to mitigate the energy and climate burdens of a desal plant.
First, desalination plants should minimize the amount of energy they use to filter water. Using brackish groundwater supplies (slightly saline bodies of water underground) instead of ocean water significantly decreases the amount of energy that a desalination plant uses. Brackish groundwater desalination plants use less energy because the water is less saline than ocean water (which takes a lot of energy to purify) and closer to potable levels of dissolved particles. On the other hand, if ocean desalination is built, it should implement all cost-effective energy efficiency to reduce its energy consumption, like devices that capture and reuse some of the pressure from the water and higher tech filters.
Second, desalination plants should reduce their impact on the electric grid by operating flexibly. Many locations where desalination plants are proposed—nearly all of the coastal locations in Southern California—are in electrically constrained areas. We are building energy resources just to meet the energy needs in those areas without any new desalination plants. If ocean desalination plants are built, they should minimize their burden on the local electric grids by not drawing electricity during times of peak need (which is what drives the need for new resources to be built).
Desalination plants should eliminate their associated global warming pollution by powering themselves with renewable energy. For example, this brackish water desalination plant plans to run exclusively on solar energy. On the other hand, if a desalination plant is running on electricity form the grid (backed by a lot of fossil fuels) then it should minimize its global warming pollution by operating the plant flexibly: matching its cycle to the production of renewable energy on the electric grid. And in the very least, all desal plants must mitigate their greenhouse gas emissions with compliance-grade instruments.
Making the right choices
The state is thirsty for water. But we should not let it affect our judgment in finding new water sources. There are plenty of good options that meet our water needs and save people money that we should pursue before turning to desalination. And even then, we can do better than what we’ve done before.
Environmental, Water/Wastewater, Solid/Hazwaste, Drainage/Flooding Advisor - 50+ years experience
8yAS, here in Arizona, we have the Central Arizona Project and significant artificial groundwater recharge ponds which have been very helpful in our water supply for cities, tribes, agriculture, commerce and industry. We have some insignificant desalination - solar for remote Navajo villages and for households where groundwater is too hard. Likely in a few decades, desal will be a big source from mineralized groundwater and springs, and a seawater pipeline from the Sea of Cortex (Gulf of California). Some of our cities are reforming streets to capture urban runoff. Many of us have rooftop rainwater harvesting systems for landscaping and gardening. Cheers from Tucson.
Great job Sierra Martinez. You are a Great American!
Educator, Trainer & Team Builder - Seeking high-impact opportunity to help with the growth of a great company or startup; while enhancing the level of value created for the benefit of its customers.
8yThanks for posting Sierra. One thing seldom discussed is the fact that we have not expanded our reservoir capacity in since Jerry Brown was governor the last time, and our state population has doubled. Adding more capacity seems to be the lowest hanging fruit. We are blessed this year with El Ninio rain and lack the capacity to keep all of it.
Staff Archaeologist at Pat Paramoure Archaeology Consultant
8yWhy pay for desalination when there is abundant natural fresh water sources throughout the state of California that are less expensive. California's problem is a water storage problem with most storm water going into the ocean and streams is lost because of improper planning and development of surface storage capacity in the context of managing underground storage capacity. There's plenty of reasonably priced water [say free] in California. The problem is the inept gross mismanagement of the state's water resources by incompetent politicians and bureaucrats, or private water purveyors who put their ROI first.