Everyone's heard of solar, wind, and hydro power, but that hasn't stopped alternative energy researchers from thinking (way) outside the box for more ways to produce heat and electricity.

Even though the world is still trying to wrap its head around the fact we don't need oil, coal, or gas to stay warm, light up cities, and power our vehicles, many are looking beyond known sources of renewable energy in their search for a cleaner future.

Here are 3 of the most unlikely sources of energy to watch for in the coming decade.

MuckBuster Anaerobic Digester Generates Energy from Poop

Built inside a re-purposed shipping container, the MuckBuster uses animal poop, grass clippings and other stuff bound for the septic tank to generate renewable energy.

Using bacteria to break down the organic materials, the digester produces methane, a gas which can later be burned to produce electricity. SEaB Energy claims that the MuckBuster can generate 2KWh of power from 100 gallons of organic waste, which is about half of what a typical home consumes.

Mushrooms and Lichen Turn Plant Waste into Biofuel

A Danish company called Novozymes A/S has scientists in China, Brazil, Denmark and the U.S. working to find an affordable alternative to gasoline made from corn cobs and sugarcane stalks. If successful, they could put an end to concerns that global hunger for energy is driving up food prices worldwide.

Fungi like mushrooms and lichen make enzymes to eat rotting logs and decaying leaves. Biofuel producers use the proteins to break down the complex carbohydrates in plant cells into a soup- like mixture of simple sugars that yeast can eat. In a process much like making beer, yeast ferments the mixture, producing ethanol. Enzymes now on the market can't break down the tougher parts of plants effectively enough to be affordable (Bloomberg.com).

Harnessing the Power of Lightning

You only have to see lightning crack across the sky once to know that this is an awesome display of natural energy. Researchers in Brazil now say they have come a step closer to harnessing the power of the ambient electricity responsible for lightning and believe that it has the potential to become a source of clean energy.

Early research has indicated it may be possible to develop devices that can capture ambient electricity, much as solar panels capture sunlight, while also preventing lightning before it can discharge, researchers said at a recent National Meeting of the American Chemical Society.

Know of another weird source of renewable energy? Share it in a comment!

Image Credit: Flickr - stevoarnold | takomabibelot