Environmentally-friendly executions, that's the way to go: wind/solar generated leccy for the chair, rope from sustainable sources for hangings; bullets retrieved afterwards and recycled to make new ones - or just use a bolt-gun and get loads of reuses from it; drown in a vat of harvested rainwater, pass through a solar-powered UV filter and use to flush the prison toilets or as untreated drinking water for the condemned, on the basis that it's not a problem if it kills them, but rather saves the state going to the bother. Then use the meat off the corpse to feed the prsion guard dogs and have the bones ground down to make bone-meal for the prison vegetable plot. Gold teeth and mercury fillings, plates and screws all salvaged for high rates of return atm from recycling; spectacle glass ground down and re-used in road paint. Drop the pointless last meal request, as it serves no useful purpose - instead save the food/drink for a lucky vagrant outside the prison gate.
Win-win as they say.