Water scarcity: Another good reason to shift to renewables

CNA Corporation, a US-based not-for-profit think tank, has released a report detailing the enormous water usage reduction potential that greater global reliance on renewable energy sources like solar PV and wind would enable.

The report is highly relevant in dry, sunny Australia, as well as for Australia’s large-scale solar project developers like Solar Choice, which has several utility-scale solar plants planned for Queensland, NSW and Victoria.

The report notes that between 4–168 tonnes of water are required for the generation of 1MWh of electricity with nuclear, 1–43 tonnes with natural gas, and 2–86 tonnes with coal plants—Australia’s main source of electricity.

The variation in these figures depends mainly on the type of technology in question, and whether it uses ‘once-through’ cooling during operation instead of recirculating cooling water.

For once-through systems, the water is eventually sent back into the surrounding environment, but as long as it is in use at the power plant it cannot be allocated for other purposes such as agriculture or manufacturing.”

While these numbers come from case studies in the USA, they are nevertheless still useful when examining the Australian context because they are broken down by generation technology.

To give some perspective: The ‘average’ Sydney household that uses around 20kWh per day. If this electricity comes from a coal-fired plant (using ‘once-through’ cooling), the equivalent of more than 2,800 bottles of water would be used in just one day.

Sourced from ‘A Clash of Competing Necessities: Water Adequacy and Electric Reliability in China, India, France and Texas’.

Although commonly overlooked as a selling point, solar PV’s rate of water use per megawatt‑hour (MWh) of generated electricity is tiny when compared to those of coal, gas and nuclear plants. Wind turbines require no water at all to operate efficiently.

CNA determined that solar PV requires only 0.1 tonnes per MWh—used for occasional cleaning. What this shows is that, at their best, non‑renewable generators still require easily up to ten times more water usage than solar PV. On the other end of the spectrum, the most water-inefficient nuclear power plants can use over 1,500 times as much fresh water as solar!

Looking at it this way, it is little surprise that China and India—the world’s two most populous nations—are making substantial investments in renewables. By fostering the development of a huge number of PV and wind projects, these countries will meet the needs of their combined 2.6 billion citizens without further endangering their own water security.

For Australia, a country just coming out of an extended drought, water security and conservation should be a top priority. Politicians from both sides of the renewables debate must acknowledge that there is common ground on the importance of preserving our water resources in the face of a growing population.

The idea that adopting renewable energy technologies such as solar PV is beneficial to the environment is no revelation. For years, the majority of climate scientists have warned of the havoc that climate change could wreak globally. But CNA’s report also highlights the immediate threat that water shortages pose on electricity security, exacerbated by the continued use of thermal generators such as coal, gas and nuclear to meet our electricity needs.

It seems obvious that the deployment of more renewable energy technologies will be better for us as a society, not just in the long term but also in ways that will have immediate, positive impacts that will be felt by our current generation. My hope is that we don’t have to wait until the swimming pools of policy makers run dry before we tackle this issue.

John Rodriguez is a PhD candidate in solar PV engineering at the University of New South Wales and a technology blogger for Solar Choice