Overcoming the challenges of combining combustion fuels with low-carbon fuels
https://www.iea.org/articles/overcoming-the-challenges-of-combining-combustion-fuels-with-low-carbon-fuels
https://www.iea.org/articles/optimising-fuels-and-engines-to-boost-efficiency-and-performance
Running combustion engines on non-carbon fuels
https://www.iea.org/articles/running-combustion-engines-on-non-carbon-fuels