Reusing water while capturing carbon
September 12, 2023
September 12, 2023
So, how can the water industry capture carbon and reduce energy consumption? Let’s explore.
Water is essential to life. But the management of it can impact the environment significantly. The water sector, which is responsible for the supply, treatment, and disposal of water, accounts for about 4% of global energy consumption.
Water utilities are tasked with providing water and wastewater management services to the masses. At the same time, they are encouraged to reduce their carbon footprint. According to the latest Intergovernmental Panel on Climate Change (IPCC) report, carbon sequestration—or the capturing, removal, and storage of carbon dioxide (CO2) from the earth’s atmosphere—must be deployed quicky and to scale.
Can the water industry reduce their energy consumption and capture carbon? Let’s find out below.
One of the most pressing issues facing inland communities is water scarcity. Advanced water treatment (AWT) offers a drought proof, local water supply and less reliance on imported water. The process produces potable water—or water that is considered safe to drink—from treated wastewater and is becoming increasingly common to address water scarcity.
However, the AWT process consumes more energy than conventional drinking water treatment. It produces carbon emissions which must be offset if utilities plan to meet their environmental, social, and governance (ESG) goals. Additionally, the AWT process creates reverse osmosis (RO) brine, which has a high salt concentration and must be disposed of responsibly. Because inland utilities do not have access to an ocean outfall for their brine disposal, they instead use evaporation ponds, which take up a lot of land and can cost up to three times as much as the RO process itself.
The combination of changing weather patterns due to climate change and a lack of access to seawater that can be desalinated for drinking water has inland utilities exploring a component of AWT: potable reuse. The process uses treated wastewater for drinking water and could augment utilities water supply.
To make potable reuse more viable, inland utilities have been exploring more economical brine disposal solutions compared to evaporation ponds. Ideally, they are seeking a solution that enhances water security and reduces the carbon footprint. Also, if the brine disposal can somehow help offset carbon emissions from the AWT processes, that makes it even more attractive.
A new approach known as direct air capture has been developed recently to achieve both objectives. Instead of creating evaporation ponds for brine disposal, direct air capture uses a chemical produced from brine to extract carbon dioxide from the atmosphere and produce clean water and chemicals, both of which can be reused.
In California, our teams are partnering with the Palmdale Water District (PWD) and carbon removal startup Capture6 to put this new technology to the test. PWD’s Pure Water Antelope Valley program will produce approximately five million gallons per day (MGD) of potable water. However, it will also produce a significant amount of RO brine, approximately 700,000 gallons per day.
Leveraging the synergies between potable reuse and carbon sequestration could increase water supply while offsetting the industry’s greenhouse gas footprint.
As an inland utility with no access to an ocean outfall, the disposal of brine through the use of evaporation ponds could cost PWD millions of dollars per year. Instead, the proposed Capture6 treatment process could eliminate the need for brine disposal and produce byproduct chemicals that can be reused in AWT facilities or sold to industrial users. Better yet, the cost for additional water recovery and carbon removal by Capture6’s technology could be partially offset by federal incentives for carbon removal and funding from private corporations for their carbon footprint reduction.
If the pilot phase is successful and can be scaled, Capture6 could be a groundbreaking, cost-effective solution for inland water utilities who want to lower their brine disposal cost and offset carbon emissions from AWT for potable reuse. Leveraging the synergies between potable reuse and carbon sequestration could increase water supply while offsetting the industry’s greenhouse gas footprint.