Renewable energy sources have received significant amounts of investment in recent years as combating climate change becomes a higher priority. Sunlight, the movement of water, and the natural movement of wind all have been harnessed to generate energy. Most of these systems work by harnessing the heat or kinetic energy to either charge lithium-ion batteries or turn a turbine to generate electricity. Renewables overall have little or no emissions and are relatively safe, but lack of energy storage and intermittency have limited their widespread usage.

Solar energy involves the harnessing of heat energy from sunlight and either directly using that energy to turn a turbine or by converting it into electricity using photovoltaic cells (PV) in solar panels. Concentrated solar power (CSP) focuses all sunlight using mirrors onto a single point to generate energy, while PV cells convert sunlight directly into electrical power. PV cells can be placed on rooftops and other surfaces and connected to a building’s energy grid to provide heat and electricity.  Depending on whether CSP or PV cells are being utilized, energy can be captured at 70 percent and 25 percent efficiency. Solar energy works at even less efficient rates when there is not adequate sunlight and energy storage for solar energy is currently lacking.

Hydropower has been used for hundreds of years, but never on an industrial scale. Hydroelectric dams push water through channels where it collides with turbines to generate electricity. Hydropower is highly efficient with up to 90 percent of the kinetic energy from water captured in hydroelectric facilities. Facilities must be scaled to a certain size in order to be constructed economically, while fast-flowing bodies of water make the best sources of hydropower. Location is the single largest limiting factor for hydropower, as regions with few changes in elevation will mean rivers will not have meaningful kinetic energy to harness. Innovations in hydropower technology have raised the possibility of facilities being able to harness the power from changing tides and waves, but that technology is still in development.

Wind power is another type of renewable energy that has existed for centuries. Wind turbines turn energy from the wind into mechanical energy using rotor blades. Wind turbines can be connected directly to a generator that can send power to the electrical grid. Different types of wind turbines can capture between 30 and 50 percent of the wind’s energy. Similar to hydropower, wind power is limited by location and energy storage. Potential solutions to alleviating wind power’s intermittency are to harness wind power on the open ocean, with offshore wind possessing 8.086 trillion potential kWh of energy in 2018.

Renewable energy holds massive potential to reduce carbon emissions and generate even more energy for the American economy. However, intermittency issues and the challenge of storing captured renewable energy without it atrophying beyond usage remain the two key barriers to widespread reliability. Each region of the U.S. stands to benefit from different types of renewable energy. Innovations and investments into renewable energy stand to continue to overcome barriers and renewables stand to be a strong boon to the U.S. energy grid.

Written by Roy Mathews, Former Public Policy Associate


The Alliance for Innovation and Infrastructure (Aii) is an independent, national research and educational organization. An innovative think tank, Aii explores the intersection of economics, law, and public policy in the areas of climate, damage prevention, energy, infrastructure, innovation, technology, and transportation.