Chemistry professor Mike Norris

3 Questions: Turning CO2 into fuel

September 8, 2020

Chemistry professor Mike Norris researches ways carbon dioxide can be captured and converted into fuel. Here he explains how a cleaner burning fuel with a smaller carbon footprint can be produced from CO2, and how renewable energy might fit into the process.

Why is it important to study fossil fuels?

Fossil fuels power most of what we do around the world, despite the rise in renewable and alternative energy sources. Although it’s important to move away from fossil fuels due to the fact that burning them releases CO2, renewable sources still make up a relatively small percentage of world-wide energy generation. Mostly, this is because it is difficult, expensive, and time consuming to convert from fossil fuels to renewables as an energy source. Some of the biggest roadblocks include energy generation on demand (peak power) — a powerplant throws away lots of power so that when everyone gets home from work and turns down the AC, there aren’t any brownouts; transportation — combustion engines are pretty popular and while it may be easier to convert to electric engines in cars, this is more difficult for planes; storage — liquid fuels are very easy to store and are ready when you need them, while batteries lack some of the energy density and portability; and infrastructure — we have lots of pipelines for transporting fuels quickly and easily across the country to where they are needed, but we cannot easily transport solar electricity generated in a desert in California to the Midwest. Since it will not be easy to completely stop using fossil fuels, it’s important to understand how we can lessen their impact on climate change and devise solutions that work in concert with renewable energy to overcome some of the limitations of renewable sources.

How might we capture CO2 and turn it into fuel?

Since CO2 is an acid, it reacts with bases. We actually already use this idea to capture CO2 from powerplants where the concentration of CO2 is relatively high. Capturing CO2 at the point of generation is really the best option since the concentration of CO2 in the atmosphere is relatively low — it’s still high in terms of its effect as a greenhouse gas, but difficult to capture and separate from the other gases in the atmosphere. Current mitigation strategies mostly stop after capturing the CO2 and then storing it somewhere indefinitely. In order to convert CO2 back into fuel, we basically have to run the combustion reaction in reverse. This requires an input of energy — with the goal being to get this energy from solar power — as well as a catalyst to speed up the reaction. We work on making the catalysts that allow us to run the combustion reaction in reverse. It is especially appealing to design catalysts that have basic sites — specific areas of the molecule that can act as bases to neutralize the acid (CO2) — so they can act to both capture the CO2 and then convert it to something like methane or methanol.

Essentially, we are trying to store solar energy by using it to manufacture methane or methanol out of CO2, and then getting that energy back when needed by burning the fuel.

Ideally, the capture and conversion of CO2 would mean that no new CO2 would be produced. You could burn a fuel, capture the CO2 that comes from that process, then “recycle” the CO2 back into fuel using solar energy and our catalyst. Additionally, the fuels will be much “cleaner” burning due to the fact that we are synthesizing the fuels from a basic building block, which means the fuel will not have contaminants that are typically found in naturally formed deposits of things like coal and oil.

What might surprise people about this area of research?

One of the surprising things is how reliant we are on poor infrastructure for transporting energy across the country. Our electric grid is a bit of a hodgepodge mess and we have a lot of crisscrossing pipelines carrying various gaseous and liquid fuels. Without a complete overhaul of this system, we can’t just put a bunch of solar cells in the desert and generate power for the entire country. This is one of the big challenges in finding a way to meet energy demands across a large geographical area. Hopefully, being creative about what we do with solar energy will allow us to transition to a greater percentage of renewables while also capturing CO2 and not making the situation worse.