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.

PV panels and a wind turbine near mountain foothills.

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 icon

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 plant icon

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 icon

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 icon

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.

Challenges and Solutions to Integrating Variable Renewable Energy
Challenge Solutions

Geographic diversity of resources

Ramping capability of existing generation

Increased power-sharing among balancing areas

Coordination of flexible loads and demand response


Improved resource forecasting

Improved load forecasting

Modeling and simulation of high-renewable grids

Energy balancing of generation and load over timescales of less than 1 hour

Grid services from inverter-based resources

Lithium-ion batteries

Pumped hydro storage

Energy balancing of generation and load over timescales of more than 1 hour

Energy storage

Hydrogen generation and storage

Demand response and controllable loads

Response to transient and dynamic grid conditions to maintain stability

Advanced inverter functionality

Protection coordination

Protection coordination of inverter-based resources

Black start

Black start of grid based on inverters

Real-time grid operation tools

Advanced distribution management systems

Bulk-system operations


Ben Kroposki

Center Director, Power Systems Engineering