Sign In or Create an Account.

By continuing, you agree to the Terms of Service and acknowledge our Privacy Policy

Climate

The Eclipse Was a 3-Hour Boon for Gas, Batteries, and Hydro

What happens to the grid when the sun goes away?

An eclipse and solar panels.
Heatmap Illustration/Getty Images

Early April is typically a kind of goldilocks moment for solar power. Days are getting longer but the weather is still mild, meaning that higher solar power generation isn’t entirely eaten up by increased demand due to air conditioning.

But that all depends on the sun actually shining.

Monday’s solar eclipse took a big chunk of power off the grid. Since 2017’s eclipse, solar power generation has increased substantially, both locally (think rooftops) and at utility scale (think massive fields of solar panels). In 2017, the U.S. had around 35 gigawatts of utility-scale solar capacity, a figure that had increased to an estimated 95 gigawatts by the end of 2023.

While total solar eclipses are rare (the next one to hit the lower 48 isn’t expected until 2044), the challenges they present to grid operators may be part of the new normal. With vastly expanded renewable energy generation comes a greater degree of unpredictability, as a growing a portion of the generation fleet can drop off the grid due to weather and climate conditions — like, say, clouds of smoke from a wildfire — that cannot be precisely predicted by 17th century science.

Grid operators were confident they’d be able to manage through the eclipse without any reliability issues, and what actually transpired mostly confirmed their forecasts. In Texas, solar power production shrunk from around 13.5 gigawatts at noon, making up 27% of the grid’s electricity supply, to a mere 0.8 gigawatts at 1:30 p.m. Things did not go as well for the Midcontinent Independent System Operator, however, which includes a swath of the middle of the country from Minnesota to Indiana to Louisiana. Solar output was estimated to drop from around 4 gigawatts at 1 p.m. Central time to 2 gigawatts an hour later, according to Grid Status. Instead, output dropped to around 300 megawatts, causing real-time prices for power on the grid to spike.

ERCOT energy mix chart.ERCOT’s fuel mix from Monday, April 8, including during the solar eclipse.ERCOT

Overall, the U.S. Energy Information Administration estimated that some 6,500 megawatts of solar generation capacity would be fully obscured during the eclipse, which would “partially block sunlight to facilities with a combined 84.8 GW of capacity in an even larger swath of the United States around peak solar generating time.” Some 40 gigawatts may have come off the grid, enough power for about 28 million homes, according to a release from Solcast, a solar forecasting company.

By comparison, during the 2017 eclipse, solar power loss at its peak was between 4 and 6.5 gigawatts and the total loss of power was around 11 gigawatts, according to the National Renewable Energy Laboratory.

In states like Texas, the main effect was on utility-scale production of solar, but in the Northeast and parts of the mid-Atlantic and Midwest, there was also a related problem: Behind-the-meter solar fell off, too, thus requiring the homes and businesses that generate power for themselves in the middle of the day to get more power from the grid, increasing demand on the grid at a time of low supply.

New England has seen immense growth in rooftop solar, and solar production was expected to fall by “thousands” of megawatts, according to ISO New England, while the New York Independent System Operators expected to lose 700 megawatts of behind the meter solar.

During the 2017 eclipse, the National Renewable Energy Laboratory found that “the burden of compensating for the lost energy from solar generators fell to the thermal fleet,” i.e. natural gas, along with some increases in coal and hydropower production.

Since then, the coal fleet has shrunk, thus putting more of the burden of responding to Monday’s eclipse onto gas and hydro, but the basic logic still applies. “Grid operators are expected to rely on natural gas to ensure stability and meet the household demand spike across national grids, as was done during the previous eclipse in 2023 in California and Texas,” according to Solcast. As the sun was dimming in Texas, natural gas generation rose from 18.7 gigawatts to 27.5 gigawatts.

Something else that’s changed since 2017: batteries. By the end of 2023, Texas had installed 5.6 gigawatts of grid storage, most of it providing so-called “ancillary services,” power sources that can respond quickly to immediate needs. ERCOT, the electricity market that covers most of Texas, said in a presentation back in February that it would rely on these ancillary tools to get through the eclipse, and once again, it was right. Power from batteries on the grid got up 1.4 gigawatts during the eclipse.

Editor’s note: This story has been updated to reflect the actual effects of the eclipse on U.S. power generation.

Blue

You’re out of free articles.

Subscribe today to experience Heatmap’s expert analysis 
of climate change, clean energy, and sustainability.
To continue reading
Create a free account or sign in to unlock more free articles.
or
Please enter an email address
By continuing, you agree to the Terms of Service and acknowledge our Privacy Policy
Climate Tech

Climate Tech Pivots to Europe

With policy chaos and disappearing subsidies in the U.S., suddenly the continent is looking like a great place to build.

A suitcase full of clean energy.
Heatmap Illustration/Getty Images

Europe has long outpaced the U.S. in setting ambitious climate targets. Since the late 2000s, EU member states have enacted both a continent-wide carbon pricing scheme as well as legally binding renewable energy goals — measures that have grown increasingly ambitious over time and now extend across most sectors of the economy.

So of course domestic climate tech companies facing funding and regulatory struggles are now looking to the EU to deploy some of their first projects. “This is about money,” Po Bronson, a managing director at the deep tech venture firm SOSV told me. “This is about lifelines. It’s about where you can build.” Last year, Bronson launched a new Ireland-based fund to support advanced biomanufacturing and decarbonization startups open to co-locating in the country as they scale into the European market. Thus far, the fund has invested in companies working to make emissions-free fertilizers, sustainable aviation fuel, and biofuel for heavy industry.

Keep reading...Show less
Green
AM Briefing

Belém Begins

On New York’s gas, Southwest power lines, and a solar bankruptcy

COP30.
Heatmap Illustration/Getty Images

Current conditions: The Philippines is facing yet another deadly cyclone as Super Typhoon Fung-wong makes landfall just days after Typhoon Kalmaegi • Northern Great Lakes states are preparing for as much as six inches of snow • Heavy rainfall is triggering flash floods in Uganda.


THE TOP FIVE

1. UN climate talks officially kick off

The United Nations’ annual climate conference officially started in Belém, Brazil, just a few hours ago. The 30th Conference of the Parties to the UN Framework Convention on Climate Change comes days after the close of the Leaders Summit, which I reported on last week, and takes place against the backdrop of the United States’ withdrawal from the Paris Agreement and a general pullback of worldwide ambitions for decarbonization. It will be the first COP in years to take place without a significant American presence, although more than 100 U.S. officials — including the governor of Wisconsin and the mayor of Phoenix — are traveling to Brazil for the event. But the Trump administration opted against sending a high-level official delegation.

Keep reading...Show less
Blue
Climate Tech

Quino Raises $10 Million to Build Flow Batteries in India

The company is betting its unique vanadium-free electrolyte will make it cost-competitive with lithium-ion.

An Indian flag and a battery.
Heatmap Illustration/Getty Images

In a year marked by the rise and fall of battery companies in the U.S., one Bay Area startup thinks it can break through with a twist on a well-established technology: flow batteries. Unlike lithium-ion cells, flow batteries store liquid electrolytes in external tanks. While the system is bulkier and traditionally costlier than lithium-ion, it also offers significantly longer cycle life, the ability for long-duration energy storage, and a virtually impeccable safety profile.

Now this startup, Quino Energy, says it’s developed an electrolyte chemistry that will allow it to compete with lithium-ion on cost while retaining all the typical benefits of flow batteries. While flow batteries have already achieved relatively widespread adoption in the Chinese market, Quino is looking to India for its initial deployments. Today, the company announced that it’s raised $10 million from the Hyderabad-based sustainable energy company Atri Energy Transitions to demonstrate and scale its tech in the country.

Keep reading...Show less
Green