Machines generate waste heat when they do work for us. And this year, seven billion of us will use twenty‐five trillion kilowatt hours of electricity. An awful lot of that will end up as waste heat. So, we treat waste heat as a problem. We see it as a challenge to design how we can manage it. We don’t think of it as a resource. If we thought of it as a resource, that would be results we are just throwing away.