Sustainable Energy Without the Hot Air

David MacKay's 2009 energy primer, written while he was a Cambridge physics professor (and later a UK Department of Energy adviser). It replaces political rhetoric with arithmetic: how much energy do cars, planes, heating, and industry actually consume, and how much can solar, wind, nuclear, and other sources realistically supply? MacKay works entirely in kilowatt-hours per person per day, making every claim checkable with back-of-envelope calculations.

Gates called it "a primer on how we make energy and its impact on the climate" and has cited its numbers throughout his own climate writing. For founders building in energy, climate, or hardware, the book's method is the real lesson: quantify everything, ignore nobody's numbers, and refuse to let advocacy substitute for arithmetic.

MacKay's discipline — treating all energy sources with the same honest unit — is directly applicable to any resource-constrained system a founder manages. The question 'can this work at scale?' is answered before the technology debate begins. Gates has said he waits for MacKay's books the way others wait for movies, and This is the one he recommends most often to non-specialists who want the real numbers behind the climate discussion.