Two charitable groups will spend $48 million over the next three years to help states figure out how to reduce emissions from electricity production, an effort to seize the possibilities that are opening up as the cost of clean power falls.

The plan is to be announced Wednesday morning in New York. Half the money will come from Bloomberg Philanthropies, the charitable organization set up by Michael R. Bloomberg, former mayor of New York City, and half will come from Mark Heising and Elizabeth Simons, a California couple who have taken a strong interest in reducing the risks of climate change.

In interviews, people involved in the project said the goal was to provide technical assistance, including economic forecasting and legal analysis, for a dozen or so states that are willing to consider ambitious clean-energy plans.

One motive for the grant is that the Obama administration is expected this summer to make final its emissions-cutting targets for the power industry. If that plan survives expected political and legal challenges, it may require extensive revamping of electricity markets that are largely regulated by the states.