One year ago, when the price of crude oil sat comfortably above $100 a barrel, the energy space was a feeding frenzy as investors tripped over each other looking for companies that were exploring new, sometimes zany sources of fuel.
Royal Dutch Shell (RDS.A) spending billions of dollars to extract oil from tar-sand pit mines in Canada?
Refining biofuel from blades of grass, or even the from the gizzards left over from your Thanksgiving dinner?All of those ideas and more were deemed economically viable when crude oil was above three digits. Today, oil is trading for about $40 a barrel, and the world that once offered infinite possibilities is now uncomfortably cluttered with limits, restrictions and caveats. Some energy sources that were considered cash cows a year ago now yield only marginal rates of return. Other efforts to find energy sources have been shelved, and some investors and companies promoting them have gone bankrupt. The Des Moines Register reported that 16 of the country's 182 ethanol plants have filed for bankruptcy and cited a source that that number would likely surpass 40 in early 2009. Here are some of the most newsworthy energy ideas that emerged in the commodity bubble, along with their current status as a viable source of fuel in the future: