The US government is putting a hold on new solar energy projects on public land for two years so it can study the environmental impact of sun-driven plants.
The Bureau of Land Management says the moratorium on solar proposals is needed to determine how a new generation of large-scale projects could affect plants and wildlife on the land it manages.
The move has angered some solar energy proponents who argue it could hold up the industry at a vital juncture, given the pressing need to secure alternative energy sources at a time of soaring oil prices. "This technology has been around for nearly three decades.
If there is an environmental concern, that can be addressed without putting a halt to this technology and helping to impact our greenhouse gas emissions and the environmental degradation from coal-fired and natural gas plants," said Brad Collins, executive director of the American Solar Energy Society.
He said the review appeared to be an arbitrary "road block" that contradicted "the stated goals of both presidential candidates, the stated goals of Congress and the American public." The Bureau of Land Management, which looks after 258 million acres of federal land, much of it flat, sun-baked terrain in the western US considered ideal for solar energy development, says the study is required by law and backed by environmental groups.
"Obviously the footprint from solar development is significant," said Celia Boddington, a BLM spokeswoman.
"(The solar plants) cover thousands of acres potentially, and we need to determine what the environmental consequences are of that, look at what it means when you spray the land with herbicides or remove vegetation." She said the BLM's solar programme was "completely new" and required a framework to be established.
The environmental assessment was being "fast-tracked". During the study, the BLM will not accept any new applications to lease public land for solar developments. But it insists it is "not holding industry up" and will continue to process 150 existing applications for roughly one million acres of federal land considered to have the best potential for solar development.
Together the proposed projects could produce as much as 70 billion watts of electricity, enough energy to power 20 million homes. Most of the applications were received during the past year and a half, Ms Boddington said.
"So it's still very, very new. The potential is there but we want to make sure we do it properly because the environmental impacts are potentially significant. This is exciting, it's a great opportunity but solar development has not yet been established commercially on a large scale."
Mr Collins argued the analysis could halt recent momentum in the domestic solar industry that has seen "a large number of international, large-scale players move their operations and headquarters" to the US and impact the growing field of "green collar jobs".
"It would be an example of taking a new industry and arbitrarily placing road blocks in the way to a transition to the safe, sustainable energy economy that everybody says they want."