In the race to combat climate change, scientists are developing technologies to turn carbon dioxide (CO₂) into valuable fuels and chemicals. These innovations help curb greenhouse gases while providing a low-carbon fuel to power our future. As the U.S. shifts to a low-carbon economy, we need environmentally friendly fuels to power vehicles that are hard to electrify, like planes, ships and trains. Scientists are developing technology to convert CO₂ to fuel. However, this conversion requires a lot of energy and water.

To address this challenge, scientists at the U.S. Department of Energy's (DOE) Argonne National Laboratory are exploring ways to convert CO₂ into valuable fuels and chemicals while preserving water resources. They recently released a new tool called WATER, for CO₂Rue WATER module, which can assess and help reduce the local water impacts of different carbon conversion technologies.

This tool is part of a much larger effort by the national laboratories to ensure that we move toward a low-carbon future sustainably. It is a product of DOE's CO₂ Reduction and Upgrading for e-Fuels Consortium (CO₂Rue), which focuses on advancing technologies to convert CO₂ into e-fuels and chemicals and assessing their environmental, economic and social impacts.

As part of this effort, Argonne researchers leveraged their water modeling expertise to develop the CO₂Rue module, which is now part of the WATER (Water Analysis Tool for Energy Resources) model. This decision-support tool measures the water footprint of biofuels in the U.S.

"Water is an increasingly valuable natural resource. With climate change fueling more frequent droughts, our freshwater supply is at greater risk than ever," said May Wu, who leads the WATER model at Argonne. "Our work focuses on ensuring water is available to all sectors while advancing technologies that support a sustainable, low-carbon economy."

The CO₂Rue WATER module assesses the potential benefits of using reclaimed water instead of freshwater in technologies that convert CO₂ into sustainable aviation fuel (SAF). The module uses two primary indices—the Water Availability Index (WAI) and the Water Stress Footprint (WSFP)—to measure localized water impacts. The first version of the model works in four pilot states: California, Texas, Louisiana and Iowa. Future versions of the model will expand the tool's coverage to 28 states, reflecting the diverse water conditions across the United States.

Using the CO₂Rue WATER module, Argonne researchers were able to assess the impact of producing SAF on regional freshwater resources. Their three-year study, published in a recent report, identified key drivers, challenges and opportunities for improving water sustainability in CO₂ reduction and utilization technologies. The report also explored the potential of using non-traditional water resources, such as reclaimed municipal wastewater, to ease water stress. With the U.S. leading these innovations, this type of analysis provides the opportunity to help meet our energy demands of tomorrow while protecting the nation's vital freshwater resources today.

The study found that the freshwater impacts of refining SAF varied greatly depending on the region and production method. For example, SAF production had minimal effects on local water resources in Iowa and Louisiana, but posed a much greater strain on water supplies in West Texas and parts of California. Generally, eastern and corn-belt states were better suited for SAF production based on water resource availability.

Researchers also found that using reclaimed water to produce SAF or hydrogen fuel could significantly reduce freshwater demand, relieve local water stress and increase freshwater availability. These findings aim to guide industry stakeholders in making informed decisions and developing strategies to mitigate risks while enhancing the sustainability of CO₂ utilization technologies.

"By leveraging reclaimed water, we can make these technologies more sustainable, reducing their freshwater footprint as they are scaled up to meet our nation's climate goals," said Ling Tao, an engineer at DOE's National Renewable Energy Laboratory (NREL) and member of the consortium. Tao provided simulation results of the carbon conversion technologies as inputs to the module.

The release of the CO₂Rue WATER module is just the beginning. Argonne and NREL continue to work together, combining their expertise in modeling and economic analysis to enhance the sustainability of emerging energy technologies. Their ongoing work with the CO₂Rue Consortium will help to ensure that CO₂-to-fuel technologies are both environmentally and economically sustainable.

"The consortium's goal is to help the U.S. achieve deep decarbonization by advancing technology to create energy-dense, low-carbon and economically viable fuels and products," said Michael Resch, who leads CO₂Rue and is a leading researcher at NREL.

Resch emphasized the impact the project can have on the future of fuel: "Insights from the CO₂Rue WATER module will drive critical strategic decisions, accelerate feasibility studies and boost the economic and environmental performance of CO₂-to-fuel technologies."

This collaborative effort underscores Argonne's commitment to pioneering innovative solutions that address critical energy challenges. As CO₂Rue continues its work, tools like the CO₂Rue WATER module will be essential in guiding the responsible development and deployment of CO₂-to-fuel technologies, ensuring these technologies can scale up without overburdening our water resources.

More information: May Wu et al, Assessing the Impacts of CO₂ Reduction and Utilization Technologies on Regional Freshwater Resources, (2024). DOI: 10.2172/2396748