Exploring the Forgotten Water Footprint

Exploring the Forgotten Water Footprint

Image CC licensed by Flickr user Jaypeg21

It is becoming increasingly common for companies to measure and report the water they consume within their four walls. Yet they rarely track all the water used to make the electricity powering their operations.

It's called the forgotten water footprint and it's about to get a lot more attention. The World Business Council for Sustainable Development (WBCSD) is working on a new module for energy to be added to the Global Water Tool, the groundbreaking resource introduced in 2007 that helps companies assess water risks in their businesses and supply chains.

"Why are we building this?" Jan Dell, vice president of engineering firm CH2M Hill, asked during a business conference Thursday. "Because the world has been so focused on counting carbon emissions, we're concerned that in our race to low carbon energy, have we forgotten about water along the way?"

The water intensity of electric power generation varies wildly, Dell explained at the Corporate Water Scarcity Risks and Footprints conference being held through Friday in San Francisco. CH2M Hill led the development of the Global Water Tool in partnership with the WBCSD.
"Not all electricity," Dell said, "is water equal,"

For example, it takes 520 gallons of water to produce 1 megawatt hour of electricity in a coal-fired power plant. Add carbon capture and storage -- which some hail as a low-carbon solution that's needed so we can continue burning plentiful but dirty coal -- and water use nearly doubles to 990 gallons per megawatt hour of electricity.

On the other end of the spectrum is photovoltaic solar energy, which takes roughly 30 gallons of water to produce one megawatt hour of electricity. The least water intensive energy source is wind, which consumes just 1 gallon of water per megawatt hour.

Obscuring the problem is the fact that carbon and water are not accounted for in the same way. Under the Greenhouse Gas Protocol, companies typically report their so-called Scope 1 and Scope 2 greenhouse gas emissions, which are direct emissions and indirect emissions from the electricity they consume, respectively. Water reporting, in contrast, usually only covers direct use, not what is used in the electricity they buy.

"This is the so-called energy water nexus that needs to be balanced," Dell said.

A survey of more than 100 of the world's largest utilities found 90 percent tracked their greenhouse gas emissions, but just 40 percent reported water use. Meanwhile, 56 percent of the top oil and gas companies reported emissions, but only 40 percent did the same for water.

The potential impact from giving water use short shrift compared to carbon is significant, Dell said, particularly as a variety of factors combine to put more pressure on the world's water sources, such as population growth and climate change.

"This is a problem because the forgotten footprint of water consumed in energy production could lead us astray and have us put in coal carbon capture and storage," Dell said, "driving zero to the hero of carbon but having huge impacts on water use."

Image CC licensed by Flickr user Jaypeg21.