Protecting the environment and renewable energy don't always mix.

Just look at California's Mojave Desert, where several large-scale solar and wind power projects have been stymied under threat of a national monument designation proposed by Sen. Dianne Feinstein.

Feinstein officially introduced legislation this week to protect about 1 million acres of the desert. But she's been threatening to do so since this spring - and the results have been the cancellation of many megawatts of proposed solar and wind farms.

One example is BrightSource Energy, the Oakland, Calif.-based solar-thermal startup, which canceled a 500-megawatt project it had been planning for the region (see BrightSource Energy Ditches Project in Eastern Mojave).

Tessera Solar, which has canceled a project known as "Solar Six," and Cogentrix Energy, a Goldman Sachs-owned solar developer that has backed off of plans for the region, are other casualties of the looming national monument designation, the New York Times reports.

The conflict over wildland protection and renewable energy has set some would-be allies against one another.

Noted environmental activist Robert F. Kennedy Jr., who also is a partner in BrightSource investor VantagePoint Venture Partners, has criticized Feinstein's proposal, saying that renewable energy and protecting endangered species in the area can coexist (see Robert Kennedy on Being Subversive).

Feinstein's proposed legislation does make some concessions from previous versions, including shrinking the acreage meant for protection from 2.5 million acres to just over 1 million acres, the New York Times reports.

Part of the land proposed for monument status includes about 266,000 acres owned by the Wildlands Conservancy, which raised $40 million to buy land in the region, owned by the Catellus Corp. and donate it to the U.S. Department of Interior for protection between 2000 and 2004.

Interestingly enough, one of the backers of the Wildlands Conservancy is former hedge fund manager and philanthropist David Gelbaum, who is also the key investor in the secretive - and more recently, struggling - green technology investment firm Quercus Trust (see Where the Quercus Trust Went Wrong).