Worldwide oil and natural gas investments fell for the second consecutive year in 2015 by 8%, lifted by efficiencies, pummeled by weaker finances and squeezed by robust outlays in renewables, the International Energy Agency (IEA) reported Wednesday.

The energy industry is set to reduce capital spend for the third straight year as more efficiencies kick in and finances continue to slip on low commodity prices, Paris-based researchers said.

Upstream investments could drop by almost one-quarter to $450 billion this year, more than the 17% decline estimated in February. Investments fell in 2014 and 2015, the first two-year consecutive decline in 40 years.

Spend has never fallen for three consecutive years.

“There are no signs that companies plan to increase their upstream capital spending in 2017,” IEA researchers said. “Many operators have revised downwards their 2016 capital spending guidance throughout the year and, as of September 2016, they plan to maintain 2017 investment at 2016 levels” or even more.

In the first-ever such analysis, the IEA’s World Energy Investment (WEI) 2016 said total oil and gas spend reached $1.8 trillion in 2015, versus $2.0 trillion in 2014. The WEI provides a comprehensive picture of the current investment landscape across fuels, technologies and countries, showing the energy system is undergoing a broad reorientation toward low-carbon energy and efficiency.

“We see a broad shift of spending toward cleaner energy, often as a result of government policies,” said IEA Executive Director Fatih Birol. “Our report clearly shows that such government measures can work, and are key to a successful energy transition. But while some progress has been achieved, investors need clarity and certainty from policymakers. Governments must not only maintain but heighten their commitment to achieve energy security and climate goals.”

Investment in the U.S. energy supply declined to about $280 billion in 2015, falling nearly $75 billion year/year, because of low oil prices and cost deflation, representing half of the total decline in global energy spending.

With energy supply spending of $315 billion, China once again was the world’s largest energy investor as it continued to work on low-carbon generation and electricity networks, as well as implementing energy efficiency policies. The Middle East and Russia emerged as the “most resilient regions to spending cuts, thanks respectively to lower production costs and currency movements.”

National oil companies accounted for 44% of overall upstream investments, an all-time high.

Global natural gas-fired power generation investment declined by nearly 40% year/year, as Asian markets continued to favor investment in coal power. Investment activity in European gas power “remained muted despite large retirements anticipated in the next decade,” WEI said.

With investments up by 6% from 2014, energy efficiency spending was robust last year, in part on government policies requiring minimum standards to cover a rising share of new buildings, appliances and motor vehicles.

In some countries, most notable in the United States, lower oil and gas prices slowed the trend toward more fuel-efficient vehicles. The rate of improvement in U.S. efficiency was two-thirds lower than that in recent years.

Renewable energy investments of $313 billion accounted for nearly 20% of total energy spending last year, establishing renewables as the largest source of power investment. Spending on renewable power capacity was flat between 2011 and 2015, but electricity generation from the new capacity rose by one-third, reflecting a steep cost decline in wind turbines and solar photovoltaic.

Investments in renewable power capacity in 2015 generated more than enough to cover global electricity demand growth, WEI noted.

Technology innovations increased investment in smart grids and storage, and they are expected to play a crucial role in integrating large shares of wind and solar. Grid-scale battery storage investment expanded tenfold since 2010, however, their value predominantly is to complement the grid, which continues to absorb much larger investment.