How might renewable energy technologies fit in the food-water-energy nexus?

Feeding the growing population in the U.S. will require additional land for crop and livestock production. Similarly, a growing population will require additional sources of energy. Renewable energy is likely to play an increased role in meeting the new demands of electricity consumers. Renewable energy technologies can differ from conventional technologies in their operation and their siting locations. Many renewable energy technologies have a lower energy density than conventional technologies and can also have large land use requirements. Much of the prime area suitable for renewable energy development in the U.S. has historically been used for agricultural production, and there is some concern that renewable energy installations could displace land currently producing food crops. In addition to requiring vast expanses of land, both agriculture and renewable energy can require water. The agriculture and energy sectors are responsible for the majority of water withdrawals in the U.S. Increases in both agricultural and energy demand can lead to increases in water demands, depending on crop management and energy technologies employed. Water is utilized in the energy industry primarily for power plant cooling, but it is also required for steam cycle processes and cleaning. Recent characterizations of water use by different energy and cooling system technologies demonstrate the choice of fuel and cooling system technologies can greatly impact the withdrawals and the consumptive use of water in the energy industry. While some renewable and conventional technology configurations can utilize more water per unit of land than irrigation-grown crops, other renewable technology configurations utilize no water during operations and could lead to reduced stress on water resources. Additionally, co-locating agriculture and renewable energy production is also possible with many renewable technologies, avoiding many concerns about reductions in domestic food production. Various metrics exist for defining land use impacts of energy technologies, with little consensus on how much total land is impacted or is necessary. Here we characterize the land use requirements of energy technologies by comparing various metrics from different studies, providing ranges of the potential land impact from alternative energy scenarios. Land use requirements for energy needs under these scenarios are compared with projected land use requirements for agriculture to support a growing population. The water implications of various energy and food scenarios are analyzed to provide insights into potential regional impacts or conflicts between sectors.