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By Sherry Listgarten

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About this blog: Climate change, despite its outsized impact on the planet, is still an abstract concept to many of us. That needs to change. My hope is that readers of this blog will develop a better understanding of how our climate is evolving a...  (More)

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Burping Landfills?

Uploaded: Mar 10, 2019
People love to weigh in on whether it’s burping cows or farting cows that puff more methane into the air. But landfills don’t burp, or moo, or do anything even remotely cute. A landfill is more like a barnacle-crusted Jabba the Hutt with an acute case of acid reflux. Not something we're eager to talk about. But given they generate a whopping 70% of the anthropogenic methane emissions from our two counties (San Mateo and Santa Clara) (1), it’s time to talk landfill.

In the United States, landfills are #3 on the methane list, behind those cute cows and our natural gas systems. (2)

But our relatively urban area has few cattle, little natural gas production, and lots of people (and their trash), so landfills are an easy #1 for us.

Why so much methane from landfills? They are oxygen-free environments packed with organic material like paper, yard waste, and food. As you may remember from an earlier blog post, that is a perfect recipe for methane! 16% of the anthropogenic methane emissions in the US come from landfills. Incredibly, that is down 40%(!) since 1990. Partly that is because we are recycling and composting more, taking organics out of the landfill. (3) And partly it is because (fewer, larger) landfills are doing a better job of capturing methane gas. But our improvements are tapering off. With only 9% of food waste being composted nationally (see the EPA’s chart below), we need to continue to find ways to keep organics out of our landfills. (4)

Are we faring better locally, in our cities? Yes! Palo Alto and Mountain View are diverting an impressive 80% or so of waste from landfills, compared to the national average of 52%. (5) But despite that, so much of what heads to the landfill is compostable. Here is what is found in Palo Alto’s “single family residence” trash bins:

We are great at composting our yard waste and compostable plastics. But food? Paper? Not so much.

Of the top items found in our trash bins, most should be in the green bin:

Fortunately for us, the SMART station in Sunnyvale sorts through the trash from Palo Alto and Mountain View. They do a good job pulling out food scraps, but even so, nearly 40% of what remains after sorting (all of which goes to landfill) is compostable. These are the top items sent to landfill after sorting, from a mix of residential and commercial trash:

It’s true in Menlo Park and Mountain View as well -- around half of the trash from single family residences is compostable material. (5)

You may be thinking -- but won’t the landfills capture the gas for us? At best, just some of it. A perfectly operating landfill will emit methane from the portions that are unsealed or only temporarily sealed. (6) And inoperative landfills need to handle methane emissions for decades after they are closed. If the gas collection system is overdrawn, gas can leak out or, worse, subsurface fires can start and be very difficult to put out. Mistakes happen. For example, shortly after Shoreline Amphitheater opened in the mid-80’s atop Mountain View’s closed landfill, concert-goers lighting up on the grass ignited “great balls of fire”, due to methane leaks from the underlying landfill. Yikes. (7) Landfills can be pretty dangerous places. Composting makes them safer, not only by reducing methane, but also by stabilizing landfill loads and killing pathogens in our waste.

Palo Alto continues to monitor and manage methane at the old landfill at Byxbee Park nearly a decade after the final portion was closed. (8) Back in the 80’s, when the landfill was still open, a cogeneration facility produced electricity from the methane and sold it back to the grid. More recently, with a smaller methane supply making that financially infeasible, the methane was piped over to the water treatment facility where it was used to process sewage, saving an estimated $250,000 annually versus using natural gas. (9) Below you can see the blowers that draw the methane in from the landfill (pipe to the left), and the pipe in back that sent gas over to the water treatment facility.

Now that Palo Alto no longer incinerates its sewage (yay!), the methane is simply flared (burned) on site, turning it into carbon dioxide, which is a much less potent greenhouse gas. You can see the chimney where it is burned in the picture below.

Many thanks to Elise Sbarbori, of Palo Alto’s Public Works Department, for showing me around these facilities, and for her work helping to maintain our safe and environmentally-friendly landfill.

In the next blog, we’ll see what happens to the food and yard waste you are putting into the green bins…

Notes and References

1. You can find out more about Bay Area methane emissions here (60-page pdf).

2. The EPA’s inventory of greenhouse gases through 2017 (executive summary) is here (29-page pdf). The entire inventory, consisting of multiple chapter pdf’s, is here.

3. Much of our progress with recycling and composting can be traced back to California’s AB 939, sponsored by Palo Alto’s own Byron Sher. PBS has an interesting discussion of things other states are trying to reduce food waste and bypass the landfill, and some of the challenges they face.

4. The EPA’s 2017 inventory of greenhouse gases coming from waste is here (39-page pdf).

5. Palo Alto’s thorough and interesting waste characterization from early 2018 can be found here (92-page pdf), along with some zero waste plans at the end of this 2018 Earth Day report. Menlo Park’s 2017 zero waste plan (and current status) can be found here (65-page pdf). Mountain View has some information available here, with a new waste composition analysis coming soon.

6. A 2011 EPA document reviews where and when methane is emitted from landfills, and outlines ways to reduce methane emissions.

7. An interesting but brief overview of methane leaks at Shoreline Amphitheater can be found in the fourth case study listed at the bottom of this CalRecycle page.

8. A timeline of waste management in Palo Alto can be found here. Interesting fact: In the early 1900’s, Palo Alto used to incinerate its garbage, right near where the fire station is today at Embarcadero and Newell. Ironically, the incinerator burned down after about 20 years, and trash disposal was moved to the Baylands.

9. The EPA maintains a registry of projects that produce energy from landfill methane. This is a brief writeup on Palo Alto’s usage of landfill methane for water treatment.

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Comments

 +   2 people like this
Posted by a renewable energy source?, a resident of Duveneck/St. Francis,
on Mar 11, 2019 at 7:59 am

the key is to turn garbage into a renewable energy source. in 'back to the future' dr. brown phased-out plutonium & used garbage to power his DeLorean time machine.

this is the key...that & the development of an efficient flux capacitor for generating massive amounts of power.

methane gas is highly volatile. in high school, some guys used to ignite flatulence with a bic lighter & an intense blue flame would emerge from another kid's rectum. there was an incident where one of the students suffered 2nd-3rd degreeburns when his rectal hairs ignited in the process. he was immediately sent to the er at standford hospital for burn treatment.


 +   1 person likes this
Posted by Sherry Listgarten, a Almanac Online blogger,
on Mar 11, 2019 at 10:24 am

Sherry Listgarten is a registered user.

OMG. I did not know that fart lighting is a thing. There's some interesting info in that link, but as you say, methane (or hydrogen) is no joke, don't try this at home...

Re renewable energy, we are at least making good use of our compost, though not quite to the tune of Dr. Brown's 1.21 gigawatts. Stay tuned for the next blog...


 +  Like this comment
Posted by JLN, a resident of Charleston Meadows,
on Mar 11, 2019 at 11:37 am

JLN is a registered user.

Thanks for bringing these figures to our attention! As you know, numbers speak better than words.


 +  Like this comment
Posted by Curmudgeon, a resident of Downtown North,
on Mar 11, 2019 at 5:01 pm

Do you know why they flare (waste) methane instead of burning it in an engine hooked to an electric generator connected to the grid? Building that smokestack thingy must have cost at least as much as a motor-generator, and it produces zero return on that outlay.


 +  Like this comment
Posted by Sherry Listgarten, a Almanac Online blogger,
on Mar 11, 2019 at 9:47 pm

Sherry Listgarten is a registered user.

@Curmudgeon -- Great question. Apparently there is not enough methane to power anything but a so-called microturbine, and they are struggling to find a cost-effective way to do that. However, they are still exploring options, because they don't like flaring either. I'll ask if they want to weigh in here with more details. FWIW, I'm also guessing they may have needed the flaring option anyway, as a redundancy. But let's see what they say!


 +  Like this comment
Posted by EN, a resident of Leland Manor/Garland Drive,
on Mar 12, 2019 at 12:44 pm

California must make use of ‘renewable' natural gas. Here's how . Web Link .


 +   1 person likes this
Posted by Curmudgeon, a resident of Downtown North,
on Mar 12, 2019 at 6:11 pm

"Apparently there is not enough methane to power anything but a so-called microturbine, and they are struggling to find a cost-effective way to do that."

Strange, because Menlo's old dump, now Bedwell Bayfront Park, generates griddable power from its collected methane*, and its area is apparently smaller than Byxbee's. Maybe their methane collection system is more effective than ours?

* Take Marsh Road to its end, then hike toward what sounds like a convoy of 18-wheelers.


 +  Like this comment
Posted by Sherry Listgarten, a Almanac Online blogger,
on Mar 12, 2019 at 9:34 pm

Sherry Listgarten is a registered user.

@Curmudgeon -- Elise said she will respond, so best to hear from her. She's just pretty busy this week, so hang in there... I can imagine, just as one thought, that Palo Alto has less organics in the landfill than Menlo Park, due to composting yard waste since the 70's. But it's just a guess.


 +  Like this comment
Posted by eileen , a resident of another community,
on Mar 13, 2019 at 8:47 am

Guess my post didn't post but I'll enlarge my question. Recycling "paper" often trips me up--tissues (AKA Kleenex)?wax paper? parchment paper? paper with a sticky back? clear paper that isn't quite plastic? used paper napkins--compost or recycle? Anyone else have these questions?


 +   2 people like this
Posted by Elise, a resident of Another Palo Alto neighborhood,
on Mar 13, 2019 at 9:40 am

@ Curmudgeon, thanks for your question -- the City of Palo Alto generated power from its landfill gas at a cogeneration station from 1987-2004, when the % methane became too low to continue to operate cost-effectively. From 2005 to the present the City plumbed the landfill gas to the Regional Water Quality Control Plant to be used as a fuel source in the plant's sludge incinerator afterburners, which displaced the use of natural gas. In landfills, methane generation decreases over time as the organic material breaks down, and now in 2019 the % methane has been determined too low to power even a small microturbine.


 +  Like this comment
Posted by Sherry Listgarten, a Almanac Online blogger,
on Mar 13, 2019 at 9:07 pm

Sherry Listgarten is a registered user.

@eileen -- My understanding is that if paper isn't clean and dry, it should go in compost. I expect that applies generally. That is true for waxed paper and parchment paper as well. Tissues are fine in compost, since it is heated to remove pathogens. A friend of mine who is a recycling expert told me that small bits of paper also don't recycle well, so she puts those in compost. But iirc gum wrappers, which have a foil liner, are not okay. The detailed guide for Palo Alto is here. But there are some city differences. For example, Mountain View does not like "compostable utensils" composted, because they take too long to break down. But they are okay for Palo Alto. So the safest bet is to ask your city.


 +  Like this comment
Posted by Sherry Listgarten, a Almanac Online blogger,
on Mar 14, 2019 at 6:03 pm

Sherry Listgarten is a registered user.

@curmudgeon -- I hope Elise's response was helpful. It is only very recently that we started flaring instead of sending the gas to the water treatment facility. Since the amount is low, my worry is more about Kirby Canyon in Morgan Hill, which is where Palo Alto and Mountain View send their trash these days. AFAICT, they flare everything, and that is a new/operating landfill. And as you can see from the post, we are certainly sending plenty of organic material there...


 +  Like this comment
Posted by Curmudgeon, a resident of Downtown North,
on Mar 15, 2019 at 9:51 pm

"and now in 2019 the % methane has been determined too low to power even a small microturbine."

But it does burn. How about a generator run with a piston engine?



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