There is a Congressional caucus for just about every issue imaginable these days, so we're not embarrassed to admit that we had never heard of the Senate Renewable Energy and Energy Efficiency Caucus before today, even though it's been around for more than a decade.

But hey, we're glad it exists, and it's in the news today because a group of more than 170 businesses and organizations have sent a letter to the 64 senators who are not caucus members, urging them to join. That list has some surprising names on it, including Senate Majority Leader Harry Reid (D-Nev.) and Environment & Public Works Committee Chairman Barbara Boxer (D-Cal.). Other omissions include presidential contenders Barack Obama and John McCain. Hillary Clinton, however, is a member.

The letter notes that renewable energy technologies now contribute almost 8 percent of the nation's energy supply while energy efficiency investments made during the past three decades now save more than any single energy source. "These technologies help to curb reliance on energy imports and lessen energy costs thereby enhancing both national and homeland security," they wrote.

The letter was delivered by the Sustainable Energy Network, an informal group of more than 500 organizations and individuals aimed at promoting increased use of renewable energy and energy efficient technologies.