Renewable Energy Integration
NREL is developing the technologies and tools to enable the integration of high levels of renewable energy resources on electric power systems.
Renewable energy is being interconnected with electric power systems at increasing rates and now makes up more than 20% of the annual electricity produced in the United States. Some technologies—such as hydropower, geothermal, and concentrating solar power—use standard synchronous generators to produce power. Other technologies—such as wind and solar—have power electronics-based inverters that converter DC electricity to grid-compatible AC power.
Hydropower uses the flow of rivers to spin turbines to produce electricity. These can be several gigawatts in size, like the Hoover Dam, or only a few kilowatts, such as small run-of-river generators. Large hydropower plants connect to the grid through synchronous generators.
Geothermal plants use the natural heat of the earth to produce steam to turn turbines and spin electric generators. Geothermal plants interconnect with the grid through synchronous generators.
Wind power captures the energy of the wind through large spinning blades that turn generators, including induction machines and direct-drive generators. Modern wind turbines often include inverters to convert DC electricity to grid-compatible AC power.
Solar technologies include photovoltaics (PV) and concentrating solar power (CSP). CSP plants heat liquids that are used to produce steam to spin turbines and generators. CSP plants use synchronous generators to connect to the power grid. PV, on the other hand, produces DC electricity and needs an inverter to create grid-compatible AC power.
The share of variable renewable energy such as wind and solar is increasing on electric power systems. Because these sources of electricity are dependent on weather conditions, a variety of technical challenges must be overcome to safely connect them to the grid while maintaining stability and reliability. To address these challenges, NREL is developing a range of solutions.
|Energy balancing of generation and load over timescales of less than 1 hour|
|Energy balancing of generation and load over timescales of more than 1 hour|
|Response to transient and dynamic grid conditions to maintain stability|
|Real-time grid operation tools|