- "The sunlight ... that strikes Earth’s land surface in two hours is equivalent to total human energy use in a year. While much of that sunlight becomes heat, solar energy is also responsible for the energy embodied in wind, hydro, wave, and biomass, each with the potential to be harnessed for human use. Only a small portion of that enormous daily, renewable flux of energy will ever be needed by humanity."
- "Improved energy productivity and renewable energy are both available in abundance—and new policies and technologies are rapidly making them more economically competitive with fossil fuels. In combination, these energy options represent the most robust alternative to the current energy system, capable of providing the diverse array of energy services that a modern economy requires. Given the urgency of the climate problem, that is indeed convenient."
– Christopher Flavin in Worldwatch Institute (2008). Building a Low-Carbon Economy in State of the World 2008, p. 80.