Nathan S. Lewis and William J. Royea in Project Syndicate:
In the United States and other industrialized countries, many applications that rely on fossil fuels (such as air transport or aluminum production) cannot be reconfigured to use electrical power. Moreover, fossil fuels are required to produce electricity as well, both to meet demand and to compensate for the intermittency of renewable energy systems such as wind or solar power. Is there really a scalable, low-carbon alternative?
One promising approach is artificial photosynthesis, which uses non-biological materials to produce fuels directly from sunlight. The sun is a nearly inexhaustible energy source, while energy stored in the form of chemical bonds – like those found in fossil fuels – is accessible, efficient, and convenient. Artificial photosynthesis combines these features in a viable technology that promises energy security, environmental sustainability, and economic stability.
While natural photosynthesis provides a complex, elegant blueprint for the production of chemical fuels from sunlight, it has significant performance limitations. Only about one-tenth of the sun’s peak energy is used; annualized net energy-conversion efficiencies are less than 1%; significant amounts of energy are expended internally to regenerate and maintain the exquisite molecular machinery of photosynthesis; and the energy is stored in chemical fuels that are incompatible with existing energy systems.