LITTLETON, Colorado, July 11 (Reuters) - Combined electricity generation from solar and wind farms in the United States surpassed output from nuclear plants for the first time during the opening half of 2024, cementing renewable energy assets as the primary source of clean power in the country.

Electricity generation from utility-scale solar and wind assets during the first half of 2024 was a record 401.4 terawatt hours (TWh), compared to 390.5 TWh from nuclear reactors, data from energy think tank Ember shows.

That marked the first time over a half-year period that renewables electricity supplies exceeded nuclear-powered electricity output, and is a significant milestone in U.S. energy transition efforts.

With utilities building out solar and wind capacity at a faster pace than any other generation source, 2024 looks set to be the first full year when more U.S. electricity will come from renewables than from any other form of clean power.

MOUNTING SHARE

From 2015 through the end of 2023, combined monthly electricity generation from utility-run solar and wind farms only surpassed output from U.S. nuclear plants on three occasions: in April and May of 2022, and in April 2023, according to Ember data.

This year, solar plus wind output has surpassed nuclear output for the past four months running, and resulted in solar plus wind output exceeding nuclear output by nearly 3% during the opening half of the year.

During the same half-year period a year ago, nuclear-powered electricity output was more than 9% greater than electricity output from solar and wind sources, which underscores how rapid the growth has been in renewable energy output.

FAST PACE

During the first half of 2024, electricity generation from solar assets was 149.6 TWh and 251.7 TWh from wind farms.

Those totals are up 30% and 10% respectively from the same period in 2023, and were both records for the first half of the year.

Nuclear electricity generation during the first half was 3.4% above the same period in 2023, but down slightly from the latter half of 2023 and suggests U.S. nuclear generation may have limited scope for any substantial further gains over the near to medium term.

CAPACITY TRENDS

Installed capacity is the key driver of electricity generation potential across the U.S., and over the past five years renewables capacity has vastly outpaced capacity growth from all other power sources.

From 2018 to 2023, utility solar generation capacity leaped 168% to 139 gigawatts (GW) while wind capacity grew 56% to 148 GW, according to Ember.

That compares to a nearly 4% reduction in national nuclear generation capacity over that period, and a 40% rise in overall clean electricity generation capacity to roughly 483 GW.

Total fossil fuel generation capacity declined by 3.7% from 2018 to 2023 to around 775 GW, including a 23% drop in coal-fired generation capacity.

In 2024, developers plan to add a further 34 GW of solar capacity, while wind generation capacity is expected to remain largely flat, according to the U.S. Energy Information Administration (EIA).

If those plans are completed, that would mean solar capacity could surpass wind capacity for the first time, and would result in a further large rise in solar electricity generation.

And given U.S. nuclear generation is likely to remain flat for the near to medium term, that means combined solar and wind generation potential looks set to make further gains relative to other forms of clean power and to establish renewables as the primary source of clean electricity in the U.S.

(Reporting by Gavin Maguire; Editing by Jamie Freed)