Hi Jeanne, these are all somewhat complex questions; however 1) mostly, yes hydrogen will replace oil in over 80% of the market, although gas will be replaced much later (the EU gas grid is switching to hydrogen entirely) - and also coal for 30% of EU steel by 2030 2) hydrogen will cost about €2/kg by 2030. So easily less than oil ($7-12/kg-equivalent today in most geographies), less than coal ($2/kg-equivalent, even in China) and eventually less than LNG $1.50/kg-equivalent. 3) timeline for price parity is 2030 in the EU and most geographies globally as electrolysis scales 4) There are no environmental tradeoffs with green hydrogen - only water is produced. I'd also say that burning hydrogen in conventional engines (trucks, cars etc) is likely to be very popular as either petrol or hydrogen can be used.

My first book looks at all these factors in a lot of depth, however my new book will look at some other factors slowing down progress that may be very useful to know as barriers are not obvious, and a more nuanced understanding my be helpful.