Is biomass energy really green energy?

A few days ago, in one of the early posts about the potential of Fibrowatt coming to the Shenandoah Valley, I wrote that it would be exciting to have those “green energy” jobs here. It got me thinking about whether biomass energy is really a sustainable form. This question may be the basis of some of the community resistance to Fibrowatt in North Carolina (I am gathering info for a future post on this), so I thought I would it would be a good idea to look into it further.


First quote here is from the Energy Information Agency (EIA), which is part of the Department of Energy. There is a reference URL at the end of this post.

“Biomass is organic material made from plants and animals. Biomass contains stored energy from the sun. Plants absorb the sun's energy in a process called photosynthesis. The chemical energy in plants gets passed on to animals and people that eat them.

“Biomass is a renewable energy source because we can always grow more trees and crops, and waste will always exist. Some examples of biomass fuels are wood, crops, manure, and some garbage.

“When burned, the chemical energy in biomass is released as heat. If you have a fireplace, the wood you burn in it is a biomass fuel. Wood waste or garbage can be burned to produce steam for making electricity, or to provide heat to industries and homes.”

So the federal government considers biomass to be green energy because it is a renewable source. The process involved at Fibrowatt (graphic to the left), burning the biomass, is one of several methods that can be used to produce energy from biomass – in their case, poultry litter sometimes supplemented with other materials. For example (sourced from the second reference URL at the end of the post):

Alcohol Fermentation – conversion of organic starches into sugar by heating, the fermenting with yeast, for the production of ethyl or grain alcohol – “ethanol.” After distillation, ethanol is usually blended with another fuel, as with “gasohol.” This process uses fossil fuels in production of the alternative fuels, so it’s inefficient and is not exactly sustainable.

Anaerobic Digestion – converting biomass, especially human, animal, and agricultural waste, into methane and carbon dioxide. The biomass is mixed with water and stored in an airtight tank, where a natural process does its work – this is considered a costly but efficient process for biomass energy production.

Pyrolysis – this process heats biomass in sealed containers without oxygen, producing gas and charcoal from the decomposition of the materials. While the process reduces carbon dioxide output, which is one of the side effects of the other processes, it requires the biomass to be heated to 1,000 degrees Fahrenheit – a process that requires significant amounts of energy in its own right.

So, while there are pros and cons related to the material – chicken litter, and the process – combustion, this review doesn’t indicate why the environmental reaction in NC is so strong. So, I went in a bit further, this time to Wikipedia, about the combustion process to see if I could find the reasons for the resistance. As with the others, there is a reference link at the end of the post.


It turns out that all of the resources I reviewed for today’s post mention the potential for gas and particulate emissions from the biomass combustion process – greenhouse gases that contribute to climate change, and particulates and hydrocarbons that contribute to effects such as acid rain. Modern combustion technologies are designed to improve management of these byproducts, so that the effects are reduced or even eliminated. In any case, the biomass process is much cleaner than fossil fuel combustion, including coal-fired electrical generation. As noted in the Wikipedia article:

“A problem with the combustion of raw biomass is that it emits considerable amounts of pollutants…even modern pellet boilers generate much more pollutants than oil or natural gas boilers. Pellets made from agricultural residues are usually worse than wood pellets…” However, “…numerous studies have shown that biomass fuels have significantly less impact on the environment than fossil based fuels.”

The article goes on to summarize the findings of a Department of Energy study on the matter, which discusses the effects of sequestering the green house gases output during the process. While this creates inefficiencies and costs in the firing process, over the life-cycle of the plant there is a significant positive impact on what’s called GWP or Global Warming Potential.

Let’s summarize the pros and cons based on this review of the biomass combustion process.

Pros – offers an alternative method for disposing of poultry waste, instead of spreading it or landfilling it. It has a reduced environmental impact when compared to the combustion of other fuels. Poultry litter, as an industrial-agricultural by-product, is readily available.

Cons – there is the potential for particulate pollution and greenhouse gas emissions from the combustion process. Due to transport and other requirements, it is not the most efficient energy production methodology, and therefore, it is likely to be more expensive energy than other processes.

Going back to the “Thinkquest” article cited below, biomass provides about four percent of the energy used in the US. Fibrowatt’s technology is one of quite a few that explore, and implement, the use of this fuel, with the expected impact that there may be an overall reduction in particulate pollution and greenhouse gas emission.

I still have a few posts to get through on the potential of a Fibrowatt plant in Page County. But I want to take a moment here to say thanks to loyal readers who have made it through this long and technical post on the biomass combustion process. I’ll look forward to gathering data for the next one – and your comments and questions are welcome!

http://tonto.eia.doe.gov/kids/energy.cfm?page=biomass_home-basics
http://library.thinkquest.org/20331/types/biomass/advant.html
http://en.wikipedia.org/wiki/Biomass_energy