What’s in your “renewable” energy?

We’re all used to seeing slogans about renewable energy, from product labels (“made in a facility powered by renewable energy!”) to electricity suppliers touting their green credentials (“we sell renewable power!”) – most of these have pictures of neat and tidy wind turbines or sleek photovoltaic arrays on a pretty green background. Clean, green, high-tech, modern: that’s what we tend to think of when we hear “renewable”…so it may come as a surprise that some of the renewable power out there comes from trash and poop!

Renewable defined

Something is renewable if it can’t be depleted and/or is constantly replaced. That’s why sun, rain, heat under the earth’s crust, and wind are all considered renewable energy sources - they happen continuously and cannot be used up, whereas it takes thousands of years for geologic processes to create fossil fuels like coal and oil. It’s a no-brainer that solar, hydro, geothermal, and wind energy are renewable – and that coal, oil and natural gas are not renewable because they get burned up.

But there are other energy sources where things are less intuitive… 

Let’s start with the down and dirty: animal excrement is not something we associate with “clean and green,” but electricity derived from it is mostly considered renewable – if fecal matter decomposes without air it produces methane, which is natural gas that can be burned as a fuel to run a power plant. Since animal waste is hardly an exhaustible resource, poop-power is renewable power.Canstockphoto3550826

Another source we’re not running out of anytime time soon is trash. Due to chemical reactions that happen in a landfill, methane accumulates in the depths of a dump and can be siphoned off and burned to produce electricity. Since trash is abundant and we keep getting more of it, so-called landfill gas is considered a renewable energy source as well.

Then there’s biomass: power stations are burning wood, brush, and other plant matter to generate electricity – this fuel is also not finite, since trees and bushes grow back. A biomass plant with a big pile of wood chips and sawdust is pictured at the right.

Renewable on your power bill?

So if you buy “renewable energy,” where does it come from? It’s generally hard to tell. Currently hydro and wind are by far the biggest sources of renewable power in the US (see pie chart)  but lots of little biomass-burning plants and landfills or farms feedingRenewable Generation2010 renewable methane into the system add up. When you look at your power bill, however, it does not list individual farms and landfills that may have accounted for some of the electrons in your region’s power pool…Although some retail power providers do make an effort to distinguish between types and sources of renewable power. 

Some examples? A mid-Atlantic area power provider offers rates for “Neighborhood Wind” electricity: your power bill supports not just wind energy, but specifically wind farms in the mid-Atlantic region to spur wind energy development in that area. A New England supplier uses your electricity payments to foster wind energy and small hydro projects in the region, as well as what it calls “cow power” projects.
Very soon, you will be able to use ClearlyEnergy’s search engine to see what kind of renewable power providers offer in your area – so you can make this choice for yourself!

By Norma Jean Autry

You can find Norma Jean Autry on Google+


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