Based on its energy requirements for lighting alone, vertical farming would be incapable of substituting for a substantial share of our soil-based agricultural production. But the lighting problem is only the first among many obstacles facing high-rise agriculture. Climate control to achieve suitable growing conditions would add huge energy requirements. And light fixtures would release more energy as heat than as light, which in summer would put huge loads on air-conditioning systems. To maintain the good health of plants grown indoors, humidity and air circulation must be very precisely controlled, often at a high energy cost. And before any of those needs would come the gargantuan resource requirements for construction of the towers themselves.