Sure, energy density can be looked up pretty much everywhere but here is a paper mentioning it, which might be otherwise interesting to you as well: https://afd

Sure, energy density can be looked up pretty much everywhere but here is a paper mentioning it, which might be otherwise interesting to you as well: https://afdc.energy.gov/files/pdfs/hyd_economy_bossel_eliasson.pdf#page=6 https://afdc.energy.gov/files/pdfs/hyd_economy_bossel_eliass... (middle of the page) To show that its really by volume they usually talk about, here just 1 example: https://www.energy.gov/sites/prod/files/2014/03/f11/blending_h2_nat_gas_pipeline.pdf#page=6 https://www.energy.gov/sites/prod/files/2014/03/f11/blending... ( first paragraph). Using volume percent is not directly a dishonest way to talk about it as that is pretty common way to look at things when it comes to gas and gas distribution networks, however it conveniently gives the wrong impression to a lot of people about potential emission savings - originally myself included ;). A 50% hydrogen - 50% methane/natural gas (by volume) mix just reduces the carbon footprint by ~22% (while requiring lots of investments, for example into gas turbines which work well with such a gas mix, lots of other end users also would have trouble with that mix)