HOUSTON (Reuters) -The U.S. government needs to streamline permitting for renewable energy projects, including development of power transmission infrastructure and grid connectivity, to support needed growth, executives said on Thursday at a conference in Houston.

"It's a tremendous issue," said NRG interim CEO Larry Coben, pointing to difficulties around interconnection, the rules that new electricity generators must follow to connect to the grid.

It can take up to four years to move a project through the interconnection process, according to the American Clean Power Association.

Coben lamented that it is much harder to move through permitting processes in places like California than Texas.

States with fewer regulatory restrictions are going to be the big winners in attracting renewable investment and growth, said Andrés Gluski, CEO of utility firm AES Corporation.

Hurdles around permitting have been discussed frequently among executives attending the annual CERAWeek energy conference in Houston Texas. Earlier in the week, U.S. Senator Joe Manchin told participants that permitting reform "will get done."

The call for faster permitting comes as renewable deployment is forecast to grow by as much as 17% to 42 gigawatts this year, representing about a quarter of electricity generation, consultancy Deloitte said in a report, citing U.S. government figures.

"We've got to get infrastructure built, transmission lines built. We've got to work through these kind of political forums that are being used to stonewall and stop progress," said Chris Womack, chief executive at utility firm Southern Company.