Are there cost benefits to conservation? It may appear to be an obvious answer, but researchers at the University of California Davis wanted to quantify this answer. Spang and his co-authors investigated how much the state of California saved on electricity and greenhouse emission reductions after the Governor of California mandated a 25% reduction and water consumption statewide in 2015. On April 1, 2015, Governor Brown passed Executive Order B-29-15 in response to the four-year drought that impacted 48% of the state’s surface water resources. Consequently, the drought impaired 542,000 acres of land, $2.74 billion of the state’s revenue, and approximately 21,000 jobs according to the researchers. This was the first bill that regulated urban water consumption in their state history.
Water and energy are interdependent. Water is needed to produce energy for fuels and electricity generation. In California, energy is needed to transport water resources across the state. Additionally, energy is needed to treat water and waste water. This is way the authors decided to calculate the savings for energy. By conserving energy, they can reduce greenhouse gas emitted into the air.
For their study, they observed energy use from June 2015 to May 2016. During this time, California saved 524,000 million gallons (MG) in water, which is a 24.5% decreased from their 2013 baseline. From this, California saved $230 MG-1 on water conservation. In energy, they saved 1830 gigawatts statewide (GWh). Because of these energy savings, they avoided approximately 521,000 metric ton (MT) CO2e in greenhouse gas emission. This is equivalent to taking 111,000 average cars off the road annually.
The hydrologic region that saved the most was the South Coast region (237, 200 MG), which has populous cities like Los Angeles and San Diego. The North Lahontan region (1,400 MG) had the lowest savings, which has sparsely populated cities like Susanville and Truckee, California.
After comparing the general cost benefits, the researchers compared the cost benefits from the statewide mandate and the energy programs of investor-owned utilities. They found that they saved 11% more on energy than investor-owned electricity utilities’ efficiency programs.
These findings could be useful in other advertisements for conservation efforts. If people knew the savings and environmental benefit from this mandate, this could encourage people to reduce consumption.
Spang, E.S., Holguin, A.J., Loge, F.J. 2018. The estimated impacts of California’s urban water conservation mandate on electricity consumption and greenhouse gas emissions. Environmental Research Letters 13:1.