US Power Systems Can Operate on 100% Renewables. Here’s How.

Arguments against renewable energy tend to revolve around the lack of flexibility that power systems have to support the variability of wind and solar power. However, multiple jurisdictions in the United States (US) demonstrate the opposite, explains Doug Arent of the National Renewable Energy Laboratory (NREL): “System operators are increasing confidence how to operate systems with high shares of renewables”.

While the Trump administration continues to push coal, renewable energy is making its way in the US energy system. As Arent details, the most remarkable event in 2019 in the US was the continued economic competitiveness of renewables.

“Progress of renewables is continuing to advance at a rapid pace and there is increasing enthusiasm as well as engineering innovation to address the challenges that high penetrations of renewables pose in grid systems, small and large”, the expert explains.

Cost-competitiveness and ability to provide critical system services

In the last 5 years in particular the economics of renewables, in particular wind and solar, even in combination with batteries, have proven to be robustly cost-competitive and with the ability to deliver critical services that the utilities and the system operators depend on to operate their grids reliably.

“This cost-competitiveness of renewables is here to stay, not only in the US, but – as well known through REN21 – around the world. This will be a substantial driver going forward for many, many decades,” concludes Arent.

According to the Renewables 2020 Global Status Report (GSR), Solar PV markets saw in 2019 more capacity installed than ever before, with the strong demand in the US as well as Europe and other emerging markets making up for a substantial decline in China.

The report details that the demand for solar PV is expanding as it becomes the most competitive option for electricity generation in a growing number of locations – for residential and commercial applications and increasingly for utility-scale projects – even without accounting for the external costs of fossil fuels.


FIGURE28 - GSR2020


As for wind, the GSR records rapidly falling costs per kilowatt-hour (both onshore and offshore). Consequently, it made wind energy ever more competitive allowing onshore wind power to compete head-to-head with fossil fuel generation in a large and growing number of markets around the world, often without financial support.

The sun isn’t always shining in California. But the system copes.

Arent also offers an example of what happens in California, where he sees an increase as well as annual penetrations of renewables. “There is the famous duck curve analysis which has been done for California showing many GW of morning and evening ramps, if it’s a sunny day and all of the solar technologies come online. And within that, as instantaneous penetrations exceed 70-75%, the Californian system operator has very successfully managed those ramps and the transitions.”  California now has put out plans to achieve their 100% clean energy goal.

However, California is not the only state where these engineering solutions are emerging rapidly. Arent explains: “we are seeing across the East as well as across the West and in Texas multiple jurisdictions in the United States that instantaneous penetration of renewables can exceed 70 or even 80% and grids are reliable, services are reliable and affordable.”

Focusing on local initiatives: 100% Renewables in the city of Los Angeles

According to Arent, both the Mayor as well as the constituents of Los Angeles have committed to a 100% renewable energy goal. The NREL also works very closely with the Los Angeles Department of Water and Power. This is a municipal utility that serves tens of millions of people in the Los Angeles basin.

“Through our detailed analytics which include all the buildings, all electrification of appliances, other services, all electrification of mobility, installation of distributed energy resources as well as grid resources, they are seeing the possibility of achieving 100% renewable energy – slightly different in California where it is a 100% clean energy goal”, says Arent. “They are confident that they are achieving this in their goal timeframe which is in the 2030 to 2045 timeframe.”