If you’ve ever driven past a landfill, you’ve probably seen pipes emerging from the ground, venting off the naturally-produce “biogas” or “biomethane”. “Renewable natural gas” means using those natural emissions to produce a product very similar to natural gas by refining the gasses emitted by agricultural resources, wastewater management facilities, and landfills. Much more here (PDF).
In a piece at RealClearEnergy David Cox and Tom Russo tout the virtues of RNG:
When it comes to energy solutions to invigorate our economy and slow the pace of climate change, some have asserted that electrification alone, is the most viable solution. But this is a false proposition. It would be a mistake to romanticize a “one-size fits all†approach that proposes that electrification is the only viable route to a successful energy transition. If we are serious about lowering greenhouse gas (GHG) emissions and getting our economy back on track, renewable natural gas (RNG) must be a part of the solution.
The technology is largely proven but its distribution is still in its infancy. Its really only been in use for a couple of decades. RNG can clearly be a useful part of our energy future but it faces economic and even psychological hurdles. The psychological hurdles come in the form of distrust of the product but also identity. When was the last time you saw a sign advertising something like “Abner’s Dairy Farm, Power, and Light”? We need to start thinking in those terms.
I can already see hardcare environmentalists’ heads exploding over this thought but IMO it’s only prudent to use resources efficiently. There will always be methane emissions even if we were to stop eating meat and dairy and we should stop venting them into the environment and start using them.
Actually, the use of biogas used to be more widespread. Biogas from municipal septic tanks was used to fuel street lights in the 1890’s in one English city. And between the world wars many sewage treatment plants used gas from their sludge digesters to generate electricity for plant use. Some sewage treatment plants supplied biogas to automobiles. Columbus, Ohio, still had gas electric generators (mothballed) as late as the 1970’s.
All of this ended in the 40’s and 50’s when the gas pipelines from Texas brought natural gas nationally. The basic reason was that biogas is dirty and requires cleanup. The gas from sewage sludge digesters is about 60% methane, 30% carbon dioxide, 10% nitrogen, a few % hydrogen sulfide, and with an aerosol of grease and grit. The grease, grit, and H2S have to be removed, and if the biogas is to be put into the natural gas pipelines, the CO2 has to be removed too. The upshot is that it is cheaper for a sewage treatment plant to buy pipeline gas than to use what it makes onsite. Today most treatment plant merely remove the H2S, grit, and grease and use the gas for heating.
Landfill gas has much the same composition, except for the grease and grit.
Besides cleanup costs, the small volumes of gas and its widely distributed sources makes collection and distribution a problem. Economies of scale it a killer. Generally, biogas is flared (to avoid explosion hazards), and that is its best “use.â€
Bob you must read a lot.
Made me think of , back in aught seven when fuel prices got high a feller around here converted his pickup to wood gas. Apparently if you heat the wood in absence of oxygen it emits a flammable gas that he piped to the intake manifold. Whole thing fit in the pickup truck box with room to spare for plenty of firewood. Don’t know how many miles he got to the cord.
California has legislation proposed for RNG to be used for electricity generation. The counterargument from the environmental people is that the actual amount available is small enough they should bypass it and got straight to renewable electricity. Kind of supports bob’s story.
https://energynews.us/2019/02/14/west/analysis-why-utilities-arent-doing-more-with-renewable-natural-gas/
Steve
Around here I think most of the closed landfills sell methane to businesses that specialize in it, not utilities. Federal regulations require landfills that accept household waste to monitor methane and respond to exceedances in methane levels. AFAIK they are not required to capture methane for energy use, but it makes a lot of sense if there is a business partner because methane is a cost item and particularly if they are closed, they have no income.
The situation I’m most familiar with involved a closed landfill that contracted with an energy company (not a utility) that built a pipeline under an interstate to a grain elevator about a mile or two away (for drying grain?). The arrangement involved a post-expenses sharing of profits, but for the landfill there was a benefit from methane reduction even if there were no profits.
Added: Landfills are required to provide post-closure financial assurance to guarantee they can address post-closure operating costs and contingencies, so something that can reduce those post-closure obligations essentially earns money. That’s the context in which a landfill might say, take my methane please.
RNGs are common on German farms, I believe they are subsidized. They are becoming more common on farms in British Columbia. The drawback is the large amount of manure required for efficacious power production but a small set up will pay for itself over time, like roof top solar.
I did my MS thesis and PhD dissertation on the production of methane by anaerobic sewage sludge digesters. Cows and other ruminants do pretty much the same thing, although they absorb the fatty acids made before they are converted to methane.
I timed out on a long edit.
Any use of landfill gas that is local and that requires little or no cleanup makes good economic sense. So landfills selling raw gas to neighboring businesses for space heating is a good idea.
Some time ago PG&E tried to capture the gas from a huge LA landfill. But they wanted to put it into their pipelines, and the clean up costs put the kibosh on the project. That CA might want to revive the idea merely shows how confused and self-contradictory is everything that they do.
As long as natural gas from gas wells remains cheap, all these projects to capture waste are doomed to economic failure. And if you count gas hydrates on the ocean floor (which would be much more expensive than current sources), the supply of natural gas is good for hundreds if not thousands of years.
And if you’re Russia or Canada or Scandinavia, and you believe in AGW, then you go for it and get several million square miles of habitable, arable land.