Cindy Haigh, of Auburn, CA, writes:
How hard and green would it be to replace current coal or natural gas plants with waste-to-energy plants that run on renewable sources like trash and livestock manure?
I read that Hawaii generates energy from ocean trash (fish nets, etc). My idea is to stop digging and importing energy and use the "problems" we have as the solution. Solar and wind may not be cost justifiable everywhere but all communities have many forms of waste. Let’s not just bury or flush it away.
Joe Fargione, lead scientist with the Conservancy’s North America Region, replies:
Waste-to-energy is a good idea, with a major advantage being that it avoids the land use impacts associated with most other form of energy production.The United States already converts a significant amount of waste to energy. For example, of the municipal waste that is not recycled or composted, about 18% is combusted for energy production.
If you add all of this up, it would take a meaningful bite out of our increasing demand for energy, on the order of 10-15% of our current coal usage.
There is no silver bullet for solving the problem of producing renewable energy, but waste-to-energy can be an important part of the solution. Waste from energy is not only renewable, it avoids putting the waste into landfills that produce methane gas, a greenhouse gas 23 times more potent than carbon dioxide. Therefore, waste-to-energy provides significant greenhouse gas emission reduction benefits.
Using more waste for energy is not without challenges. There are some air quality issues. However, the EPA has stringent rules for mercury and other toxic air emissions from waste-to-energy plants, rules which are not yet in place for coal plants, so waste energy compares very favorably to coal energy in this regard.
Additionally, after combustion, approximately 10% of the waste remains as ash that must be disposed of in landfills, representing a significant reduction, but not elimination, of the use of landfills.
And because these wastes have lower energy density than traditional forms of fossil fuel, it is not practical to truck them long distances. Fortunately, cities generate waste in a relatively small area, making it practical to collect enough waste in one place to fuel a power plant. Also, some of these waste streams are seasonally variable, while power plants require a constant supply year-round. Finally, local groups often oppose incinerators in and around cities, even though this continues our reliance on dirtier non-renewable energy sources that are produced outside cities.
With increased knowledge and political will, communities are increasingly overcoming these challenges. Check out the Database of State Incentives for Renewable Energy to see if your state has a Renewable Portfolio Standard that includes municipal solid waste.