Cutting Landfills Methane Emissions Should be Key Goal for Abating Climate Change

Cutting Landfills Methane Emissions Should be Key Goal for Abating Climate Change

tri·age noun \tre-'äzh

: the sorting of and allocation of treatment to patients and especially battle and disaster victims according to a system of priorities designed to maximize the number of survivors

Like in the searing images from the movie, M*A*S*H, “triage” is what doctors and nurses in hospital emergency rooms do when disaster hits. They are flooded with the sick and injured. They must determine who are the most hurt and for whom something can be done. And then they must help them before others who are left to wait.

Amidst the coming challenges that America confronts today, triage means something else. It describes a world careening into the climate abyss, while a growing political class hides behind “I’m not a scientist” in order to pander to their science-addled base. As George Bernard Shaw once famously said, “The Earth is some wiser planet’s insane asylum.”

Fortunately, in the waning days of the current administration, some folks in President Barack Obama’s policy shop are doing triage on a global scale. President Obama is working on overdrive to issue new rules that build a legacy of bold climate action to preserve a livable world for our grandchildren by doing everything he can through executive orders.

Admirably, his climate team has used triage to focus on achieving the most with their limited political capital. In that vein, they have astutely seen that the biggest, and quickest, bang for the buck can come from methane cutbacks. That’s because methane is a greenhouse gas on steroids with 86 times the short-term warming potential of carbon dioxide whose gains are seen right away.

To that end, last year, the Environmental Protection Agency (EPA) laid the groundwork for a coherent climate policy, first with reductions in carbon dioxide emissions from new power plants and then from existing facilities. However, because most of those cutbacks are expected to come via fuel switching from coal to natural gas, the measure’s value turns on one’s view of how badly fracked gas wells leak methane. If more than 3 percent escapes, as most field observations have found, gas is thought to be worse for the climate than coal.

The EPA segued into proposed rules for methane leaks from gas and oil wells, as if it had anticipated concerns with the after-effects of power plant fuel-switching.

To date, the only concerns with those rules are limiting their application to new wells and their thrust to voluntary efforts. The tangible gains will be far less than is needed commensurate with the climate threat.

That only scratches the surface of what is wrong with the well rules. For there is a gaping hole in the logic of their triage that has led them to miss a huge beat.

Landfills, which are among the largest sources of anthropogenic methane, have been largely ignored because the sector’s total methane generation is estimated to be only 2.8 percent of what comes from natural gas, and landfill gas capture has been assumed, based on industry claims, to be as high as 95 percent.

But, sector size turns out to be the wrong metric to triage its importance to climate action plans, and unsupported industry representations of efficient abatement are often suspect. Instead, it is the potential magnitude of greenhouse gas (GHG) reductions that constitutes the value of any plan to lessen emissions and the risks of a warming climate, not the totality of GHG generation, except when there is either only incidental trace leakage or unavoidable emissions. It is that mistake that has led climate leaders to ignore landfills’ enormous responsibility for greenhouse emissions and to leave recycling on the cutting room floor.

Landfills are man-made tombs of trash that are so enormous, just one could dwarf 30 of the Pharaoh’s Great Pyramid at Giza. Stacked hundreds of feet high and sprawling over hundreds of acres, eventually half of that mass will rot. In an oxygen-starved environment, food scraps, grass and other organics decompose anaerobically, creating methane as a byproduct of decay.

Each year, approximately 137 million tons of solid waste are landfilled in the U.S. The accumulating annual gaseous output from all that trash generates something in the order of 8 million metric tons of methane over the disposal site’s extended life, which, because of its potency, is equivalent to 839 million metric tons of carbon dioxide.

Because landfills do not have “smokestacks,” they are a non-point source, and emission rates are elusive to estimate. One of the key unsettled points has been how much of these gases generated in landfills are not controlled by the gas collection systems that are installed at the very large sites.

Unfortunately, as it had done with natural gas where field measurements are also absent, the EPA acted in lock step with industry’s unsupported claims. It has blindly adopted assumptions of collection efficiency reaching 95 percent, instead of undertaking a realistic assessment on how much methane escapes from landfills.

On the other hand, based upon a real-world understanding of how gas collection systems actually work, the Intergovernmental Panel on Climate Change (IPCC) concluded in its 2007 Fourth Assessment that “estimates of ‘lifetime’ recovery efficiencies may be as low as 20 percent.”

The IPCC found that gas capture in landfills was less than a quarter of what industry claimed, and what the EPA repeated, because in these mountains of society’s detritus, gas collection is not functional during the very time when most of landfill gas is generated. Rather, they only work properly, which may conceivably approach 95 percent, when little of the landfill’s lifetime gas is produced.

The reason for this seeming anomaly is that these are vacuum-based systems that, to work, rely upon a seal on top of the landfill to prevent oxygen infiltration. Also, if oxygen from above mixes with the methane below, an explosion could result and the systems must be short- circuited.

But that same seal, which is needed to keep oxygen out for collection to work, also prevents infiltrating rainfall from entering the waste mass. And moisture—lots of it—is a prerequisite for decomposition. It is in that time before the cover is installed, and decades later after it deteriorates, that rainfall enters, putrefaction accelerates, and methane is generated.

In the years that followed the IPCC’s assessment, cutting-edge field research confirmed the organization’s conclusions, and in the process completely discredited the EPA’s blithe rose-colored glasses. Optically scanning the entire surface with either near infrared or lasers at landfills with and without seals provided a reasonable comparison of how much methane is escaping from each.

Scanning has shown that the methane flux over open landfills without a cover seal—which is when most of the gas is generated—averages 280 times greater than in closed landfills after the covers have been installed—which is when gas production tapers off.

These same results also showed that, instead of reducing greenhouse gases, recovering energy from landfill gas turns out to make a bad situation worse instead of better. For generating enough energy rich gas to be commercially exploited requires leaving the top of the landfill uncovered for years in order to let in more rain to accelerate decomposition and methane-laden gas generation. As in the case of natural gas, the resulting increase in upstream leaks of methane overwhelm carbon dioxide reductions in power generation due to methane’s outsized warming effects.

Fortunately, there is an elegant solution that works around these fatal flaws in landfill gas collection. That is to divert our food scraps and yard trimmings from landfills to be composted so uncontained methane is not generated in the first place. Hundreds of cities are, right now, engaged in that building upon their existing recycling infrastructure to reach that new plateau. Millions of households are physically involved in helping to address climate change and are empowered by that.

Here is what all this means on the bottom line. The natural gas industry may extract 35 times more methane than is thought by the EPA to be generated in landfills. However, the critical fact is that 30 percent more of the methane escaping from landfills can be avoided compared with from gas wells.

This does not mean that efforts to reduce leaky gas wells should not continue to be pursued. But, it does mean that long-neglected landfills should be given the same if not more attention in any balanced climate strategy, especially one strategically focused on methane.

It would be a very bad mistake if, out of ignorance, the White House left recycling and composting in the waiting room. 

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.