SAN FRANCISCO – A group of companies and nonprofit agencies that includes energy giants Royal Dutch Shell and BHP Billiton said global greenhouse gas emissions could be cut in half by 2040 without impeding economic development, in part by converting grids to use mostly renewable power.

The declining costs of wind, solar and batteries will make it possible within 15 years to build power networks that get as much as 90% of their power from renewable sources while providing electricity at a cost that’s competitive with fossil fuels, according to a report released Tuesday by the Energy Transitions Commission, a group of energy companies, investors and non-profit organisations including the Rocky Mountain Institute.

The study’s details will be outlined Tuesday at the Bloomberg New Energy Finance Future of Energy Summit in New York and presents a road map toward meeting the Paris climate agreement aimed at keeping global warming well below 2 °C. It comes as US President Donald Trump is weighing whether to meet a campaign promise of pulling out of the Paris accord.

“The really good news is the potential on renewable electricity,” Adair Turner, chairman of the Energy Transitions Commission, said in an interview. “It is really credible to say we can decarbonise electricity.”

Converting grids to green power and running cars and heating buildings on electricity would account for half of the emission cuts outlined in the report, which details how to slash carbon from 36 gigatonnes a year to 20 gigatonnes by 2040. The group said governments and companies must boost investments in hydrogen, bioenergy, waste heat and carbon-capture technologies, which would reduce emissions in aviation, shipping and heavy industries.

Fossil fuel use will also need to fall by 30% by 2040 as energy-efficiency measures accelerate to meet international climate goals, according to the report.

The group said policies including putting a price on carbon, phasing out fossil fuel subsidies, and encouraging more research into low-carbon technologies will be needed to hit the targets, along with more public investment in transport and city infrastructure.

Investments will also need to shift, including a $3.7-trillion reduction in spending on fossil fuels, a $6-trillion increase for low-carbon technologies and a $9-trillion boost for energy-efficient equipment and buildings.