"... People tire of being taken advantage of. Some commit their lives to reforming city politics, and others work on technological solutions that benefit both humankind and . The latter efforts have led to (1) the development of efficient, affordable renewable-energy strategies; (2) carbon-capturing, recyclable construction materials with low s; (3) cost-effective atmospheric water-harvesting methods; and (4) productive vertical farms situated within the city. issues are now front and center on many city council agendas. I call these four applications of technology the four pillars of sustainability."