Could carbon financing boost green wastewater treatment?

Researchers from Colorado State University have explored the potential of using carbon financing to fund green wastewater-treatment approaches that go beyond existing greywater treatment practices.

Carbon financing is the mechanism by which companies will voluntarily buy ‘carbon credits’ on an open market in order to offset their own emissions. These credits represent a reduction or removal of carbon from the atmosphere that can be accomplished in a variety of ways (eg, tree planting, renewable energy projects, carbon sequestration).

Based on data collected at over 22,000 facilities, the report from Colorado’s Walter Scott, Jr. College of Engineering explored the relationship between emissions, costs and treatment capabilities for utility operators and decision-makers. It found that if carbon financing were to subsidise green infrastructure and technology solutions, this could save US$15.6 billion and just under 30 million tonnes of CO₂-equivalent emissions over 40 years. The findings have been published in Nature Communications Earth and Environment.

The work examined both point-source water treatment and non-point sources of water pollution.

Traditional point-source water treatment facilities — or ‘grey-infrastructure’ systems — such as sewage plants remove problem nutrients like nitrogen and phosphorus before releasing water back into circulation. Existing facilities already account for 2% of all energy use in the US and 45 million tonnes of CO₂ emissions, according to Braden Limb, first author on the paper and a PhD student in the Department of Systems Engineering.

A significant source of freshwater contamination in the US comes from non-point source activity such as fertiliser runoff from agriculture entering rivers. Other non-point sources of pollution can come from wildfires — aided by climate change — or urban development, for example.

Limb said that rather than building more grey-infrastructure treatment facilities to address these growing issues, the paper explores green approaches financed through carbon markets that can tackle both types simultaneously.

“There could be a switch to nature-based solutions such as constructing wetlands or reforestation instead of building yet another treatment facility,” he said. “Those options could sequester over 4.2 million carbon dioxide emissions per year over a 40-year time horizon and have other complementary benefits we should be aiming for, such as cheaper overall costs.”

While there are financing markets for water that operate in a similar way to carbon financing, water has the challenge of being more localised than air quality and carbon — something that has limited the value of water market trades in the past. The paper suggests that these existing markets could be improved, and that carbon markets could also be leveraged to change some of the financial incentives farmers have around water treatment and impacts from their activity.

The researchers found that using the markets could generate $679 million annually in revenue, representing an opportunity to further motivate green infrastructure solutions within water quality trading programs to meet regulated standards.

“These findings draw a line in the sand that shows what the potential for adopting green approaches in this space is — both in terms of money saved and total emissions reduced,” said Braden Limb, first author on the paper and a PhD student in the Department of Systems Engineering.

“It is a starting point to understand what routes are available to us now and how financing strategies can elevate water treatment from a somewhat local issue into something that is addressed globally through market incentives.”

Mechanical Engineering Professor Jason Quinn, a co-author on the study, said the findings had some limitations, but were an important first step in modelling both the problem and opportunity available now. He said the results in the paper have supported new research at CSU with the National Science Foundation to further develop the needed carbon credit methodology with stakeholders.

“This is the first time we are considering air and water quality simultaneously — water is local and carbon is global,” he said. “But by bringing these market mechanisms together we can capitalise on a window of opportunity to accelerate the improvement of America’s rivers as we transition to a renewable energy and restored watershed future.”

Image caption: The Big Thompson River in Rocky Mountain National Park. Image credit: Colorado State University.