For decades, landfills have presented numerous problems when it comes to dealing with issues such as groundwater contamination, adverse effects on wildlife, urban sprawl, and more recently, climate change. Although increased efforts and improved technologies in areas such as recycling and hazardous chemical sequestration have alleviated some of these effects, landfills will still be with us for some time to come. The good news is that landfills also present solutions to several environmental problems currently confronting society.
An emerging trend is the collection and combustion of landfill gas (LFG) to generate electricity. This is a process where the gas released as landfill waste decomposes is collected from the ground, treated and purified, and then burned to generate electricity, which can be provided to the local power grid.
This practice provides several benefits, both environmental and economic. First, burning methane breaks it down into carbon dioxide (CO2) and water. Although CO2 is the most prevalent greenhouse gas (GHG) in the atmosphere, hence the term carbon footprint, methane (CH4) is 25 times more potent (Value from 2007 IPCC report. GWP over a 100-year period). Landfill gas is 50% methane, so burning it will yield a significant reduction in global warming potential, compared to just allowing its release.
Secondly, when any renewable source provides energy to the grid, it reduces the demand for electricity from traditional sources, which tend to pollute more, and contribute to global warming. These include the combustion of fossil fuels, such as coal, which release large quantities of CO2, as well as particulate matter that can negatively impact human health. Nuclear energy doesn’t have the same airborne problems associated with fossil fuel consumption, but the disposal of waste remains an issue.
Thirdly, unlike wind and solar power, gas generation at an active landfill rarely comes to a full stop. Therefore, landfill gas combustion can act as buffer during periods of cloud cover or low wind velocity.
Furthermore, there are some economic incentives to using LFG power. The foremost of these is the fact that, in spite of our best efforts, garbage will be with us for some time to come. In fact, it will be many years before the garbage we have now is fully decomposed. Hence, we won’t have to worry about a supply problem for quite some time. In addition, unlike more conventional fuels, such as coal and uranium, the transportation footprint of landfill waste is relatively low. At the least, garbage will not be hauled much further away than it’s being taken now.
The garbage also has no additional extraction cost. As extraction of fossil fuels even at proven reserve sites becomes more difficult, the methods required to obtain these fuels will become more costly. Moreover, the methods used to extract these fuels often have measurable repercussions on the environment. Garbage, by contrast, is essentially free fuel.
In addition, unlike wind and solar power, the amount of methane gas a landfill will produce is usually highly predictable over a long period, and even if factors such as moisture change over time, the process doesn’t halt entirely. This makes LFG combustion a relatively stable investment.
Lastly, although nation-wide, all-encompassing carbon taxes are still unlikely to take effect in the near future, industry-sector and regional carbon taxes are already starting to appear. If a carbon tax on waste disposal companies and landfills appears on the horizon, landfills with LFG combustion facilities will be better positioned to mitigate this added financial burden, since their GHG footprint due to methane release would effectively be reduced by a factor of 25.
An Ongoing Trend
The benefits of LFG combustion should in no way dissuade us from current waste diversion efforts, nor from eliminating landfill waste altogether, if possible. The “Reduce, Reuse, Recycle” strategy should still remain a principle component of our approach to waste. However, the landfills we have now will be with us for some time to come, and garbage will not disappear from our curbs and dumpsters tomorrow. Therefore, it makes sense to not only mitigate the adverse effects of landfills, but also to make them work for us.
JP Brown is a sustainability analyst with e3 Solutions.