[originally published in RealClear Energy]

Rail travel is back on track. With Amtrak reporting an 18% annual increase in passengers, trains are once again gaining steam as a reliable option for commuters. As bus stations are shuttering nationwide and car traffic surges past pre-pandemic levels, trains are emerging as a dependable transportation option for many commuters. As we look for sustainable ways to meet this growing demand for transportation, there’s an opportunity right before us: harnessing advanced biofuels to reduce emissions from our rail systems.

Despite trains’ reputation as an eco-friendly alternative to cars and planes, the reality can be quite different. Long-distance train rides can be more harmful to the environment than air travel. For example, a single passenger traveling from New York to San Francisco by train generates between 950 to 1,133 pounds of CO2, compared to 840 pounds from an equivalent plane trip. The root of the problem? Most American trains still burn diesel.

Some have argued that full electrification of America’s rail system, like in the Northeast corridor, would solve this problem. But, achieving that in the near term is unrealistic. Electrification requires significant infrastructure investments, including installing overhead catenary wires across vast distances. Even if this were achieved, much of the electricity feeding the grid is still generated by fossil fuels, reducing the potential environmental benefits.

To reduce the carbon footprint of train travel, we need immediate solutions that reduce emissions now – and advanced biofuels offer exactly that.

Advanced biofuels are a category of low-carbon liquid fuels derived from sources like lignocellulosic biomass, non-food crop feedstocks, and recycled industrial waste. These fuels are not just theoretical – they are already mandated by Congress to reduce carbon emissions by at least 50% compared to traditional fossil fuels. Among them, renewable diesel is particularly promising. Made from recycled fats and oils, it’s chemically identical to petroleum diesel, meaning it can power existing train engines without any modifications.

With domestic production of advanced biofuels, including renewable diesel, ramping up, the U.S. has a growing supply of sustainable fuels that could power our trains today.

This isn’t a pie-in-the-sky idea. Rail companies are already proving the viability of advanced biofuels. In 2022, Union Pacific, in collaboration with Chevron Renewable Energy Group, launched a pilot program to test whether engines could run on 100% renewable fuels—and they could. Last year alone, Amtrak used two million gallons of renewable diesel, and in June 2024, the Catskill Mountain Railroad became the first heritage railway to operate entirely on biodiesel.

These success stories show that advanced biofuels aren’t just a future solution; they are already reducing emissions in rail today.

To accelerate this progress, policymakers must act. One critical step is amending renewable volume obligations (RVOs), which dictate the amount of low-carbon fuel that must replace fossil fuels under the Renewable Fuel Standard (RFS). Currently, RVOs underestimate the potential of renewable diesel, slowing its adoption. As these standards come up for revision next year, it’s essential that advanced biofuels and renewable diesel are prioritized.

With the right policy framework, we can scale the production and use of advanced biofuels, allowing rail to meet growing demand while significantly cutting emissions.

While all technologies should be leveraged to reduce transportation emissions, advanced biofuels offer a practical, immediate solution to the environmental challenges facing rail travel. They are available now, they work with our current infrastructure, and they significantly reduce greenhouse gas emissions.

Sometimes, the best solutions are the ones already within reach. It’s time to make advanced biofuels a bigger part of the future of American rail travel. Let’s seize this moment to invest in a cleaner, greener rail system – one powered by sustainable fuels.

Michael McAdams is the president of the Advanced Biofuels Association (ABFA). For more information on ABFA click here.