The title of the HN article matches that of the article linked to, but that title is wrong. It’s 711 Wh/kg. Still impressive, but 711kWh/kg would be almost 60 times that of oil (at about 12kWh/kg. <a href="https://www.forestresearch.gov.uk/tools-and-resources/fthr/biomass-energy-resources/reference-biomass/facts-figures/typical-calorific-values-of-fuels/" rel="nofollow">https://www.forestresearch.gov.uk/tools-and-resources/fthr/b...</a>)