Landfill Gas-to-Energy: Toxic and Bad for the Climate… Not Green or Renewable

Land­fill Gas-to-Ener­gy Projects May Release More Green­house Gas­es Than Flaring

Land­fill Gas Fact­sheet

Land­fill Gas Pow­er­point Presentation

Stud­ies on Mer­cury in Land­fill Gas

Zero Waste Hier­ar­chy
(includes keep­ing organ­ics out of land­fills, digest­ing organ­ics before land­fill­ing, and how best to man­age land­fill gas at end of hierarchy)

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“Land­fill gas” is not the same thing as “nat­ur­al gas” or “methane.” They are three sep­a­rate terms which mean dif­fer­ent things. They should not be used inter­change­ably. The term “land­fill methane” is deceiv­ing as it’s usu­al­ly used to imply that land­fill gas is sim­ply methane.

Methane is a hydro­car­bon gas (CH₄). It is a green­house gas and it is explo­sive. It is gen­er­at­ed by decom­po­si­tion (in land­fills, from swamps, in the stom­achs of cows, etc.).

Nat­ur­al gas is approx­i­mate­ly 80–99% methane, with the remain­der being most­ly oth­er hydro­car­bons (ethane, propane, butane, etc.) as well as some nitro­gen, oxy­gen, water, CO₂, sul­fur and var­i­ous con­t­a­m­i­nants.¹

Land­fill gas is about 40–60% methane, with the remain­der being most­ly car­bon diox­ide (CO2). Land­fill gas also con­tains vary­ing amounts of nitro­gen, oxy­gen, water vapor, sul­fur and a hun­dreds of oth­er con­t­a­m­i­nants — most of which are known as “non-methane organ­ic com­pounds” or NMOCs. Inor­gan­ic con­t­a­m­i­nants like mer­cury are also known to be present in land­fill gas. Some­times, even radioac­tive con­t­a­m­i­nants such as tri­tium (radioac­tive hydro­gen) have been found in land­fill gas.

NMOCs usu­al­ly make up less than 1% of land­fill gas. EPA iden­ti­fies 94 NMOCs in their 1991 report, “Air Emis­sions from Munic­i­pal Sol­id Waste Land­fills — Back­ground Infor­ma­tion for Pro­posed Stan­dards and Guide­lines.” Many of these are tox­ic chem­i­cals like ben­zene, toluene, chlo­ro­form, vinyl chlo­ride, car­bon tetra­chlo­ride, and 1,1,1 trichloroethane. At least 41 of these are halo­genat­ed com­pounds. Many oth­ers are non-halo­genat­ed tox­ic chem­i­cals. ^{2, 3} More exhaus­tive test for con­t­a­m­i­nants in land­fill gas have found hun­dreds of dif­fer­ent NMOC contaminants. 

When halo­genat­ed chem­i­cals (chem­i­cals con­tain­ing halo­gens — typ­i­cal­ly chlo­rine, flu­o­rine, or bromine) are com­bust­ed in the pres­ence of hydro­car­bons, they can recom­bine into high­ly tox­ic com­pounds such as diox­ins and furans, the most tox­ic chem­i­cals ever stud­ied. Burn­ing at high tem­per­a­tures does­n’t solve the prob­lem as diox­ins are formed at low tem­per­a­tures and can be formed as the gas­es are cool­ing down after the com­bus­tion process.⁴

Mat­ter can­not be cre­at­ed or destroyed — it is one of the first lessons of high school physics. Through­out EPA’s reports on land­fill gas uti­liza­tion, they refer to the destruc­tion effi­cien­cy of var­i­ous land­fill gas com­bus­tion tech­nolo­gies. They usu­al­ly assume it’s about 98% or more. In oth­er words, they pre­tend that these halo­genat­ed non-methane organ­ic com­pounds sim­ply go away. There is almost no talk about what hap­pens to the chlo­rine, flu­o­rine and bromine atoms that go into the burner.

Mer­cury and tri­tium can­not be destroyed through com­bus­tion and no efforts have been made to pre­vent their release into the envi­ron­ment when land­fill gas is col­lect­ed and burned. Land­fills Make Mer­cury More Toxic

Isn’t it cleaner to burn landfill gas to make energy than to just flare it?

There is lim­it­ed data com­par­ing emis­sions from land­fill gas flares to ener­gy pro­duc­ing com­bus­tion devices (which includes boil­ers, tur­bines and inter­nal com­bus­tion engines).

Accord­ing to very lim­it­ed data in a 1995 EPA report, car­bon monox­ide and NO_x emis­sions are high­est from inter­nal com­bus­tion engines and low­est from boil­ers. Flares and gas tur­bines are in the mid­dle.⁵

Diox­in emis­sions data is also very sparse. EPA, in their 1998 diox­in inven­to­ry, looks at only a few tests and shows that, for the most part, flares pro­duce more diox­in than inter­nal com­bus­tion engines or boil­er muf­flers.⁶ How­ev­er, a more com­pre­hen­sive review (by the Coun­ty San­i­ta­tion Dis­tricts of Los Ange­les Coun­ty in 1998) of about 20 stud­ies involv­ing 76 tests at 27 facil­i­ties shows that inter­nal com­bus­tion engines on aver­age pro­duce 44% more diox­in than shroud­ed flares. Since there is high vari­abil­i­ty in diox­in emis­sions from land­fill gas burn­ers (based on com­po­si­tion of waste dumped and also on the com­bus­tion tech­nol­o­gy — inter­nal com­bus­tion engines are much more vari­able), these fig­ures should not be applied to site-spe­cif­ic sit­u­a­tions.⁷

Burn­ing land­fill gas is dirt­i­er than burn­ing nat­ur­al gas. Whether using an inter­nal com­bus­tion engine or a gas tur­bine, burn­ing land­fill gas to pro­duce ener­gy emits more pol­lu­tion per kilo­watt hour than nat­ur­al gas does.⁸

Why is it that nat­ur­al gas (a non-renew­able resource which is not con­sid­ered “green ener­gy”) burns clean­er than land­fill gas, yet ener­gy from land­fill gas gets away with being con­sid­ered renew­able green power?

But the landfill gas is there anyway (usually being flared), so why not use it to make energy?

This is a clas­sic case of ask­ing the wrong question.

It’s a very dif­fer­ent thing to ask “what is the best way to man­age land­fill gas?” than to ask “how should we pro­duce green, renew­able energy?”

Green ener­gy mar­keters aren’t in the busi­ness of man­ag­ing land­fill gas. If they want to be in the waste man­age­ment busi­ness, then that’s a dif­fer­ent story.

In brief, if you ask what the best way to man­age land­fill gas is, the answer is along the lines of “before you do any­thing with it, fil­ter out the tox­ic con­t­a­m­i­nants and treat them with a non-burn tech­nol­o­gy.” If the ques­tion is how to pro­duce green, renew­able ener­gy, the answer is “use tech­nolo­gies such as wind and solar that don’t cre­ate pol­lu­tion in the process of mak­ing energy.”

Noth­ing that emits diox­ins should be con­sid­ered “green” or “renew­able” energy.

“Green” or “renew­able” resources should­n’t pro­duce pol­lu­tion in the process of mak­ing ener­gy. Any­thing that has envi­ron­men­tal­ly-dam­ag­ing emis­sions you can mea­sure per kilo­watt is not deserv­ing of sub­si­dies or pref­er­en­tial pric­ing afford­ed to “green power.”

So what should be done with landfill gas?

Well, let’s exam­ine the options:

The default option is to do noth­ing. Doing noth­ing leads to gas migra­tion off-site and can cause explo­sions. The release of the methane cre­ates some glob­al warm­ing prob­lems and the release of the tox­ic con­t­a­m­i­nants can cause can­cer and oth­er health prob­lems in local com­mu­ni­ties. A New York study of 38 land­fills found that women liv­ing near sol­id waste land­fills where gas is escap­ing have a four-fold increased chance of blad­der can­cer or leukemia.^{9, 10}

Land­fills should install gas col­lec­tion sys­tems to pre­vent the prob­lems with gas migra­tion. Once col­lect­ed, land­fills can do any of the oth­er options. These options are focused around han­dling the methane (usu­al­ly by burn­ing it) and are not focused around address­ing the tox­i­cs issues. Regard­less of what is ulti­mate­ly done with the gas, the gas should be fil­tered so that the halo­genat­ed com­pounds are seg­re­gat­ed. Once fil­tered out, these com­pounds should not be com­bust­ed (as that does­n’t tend to improve the sit­u­a­tion, but may make it worse). They should be han­dled as haz­ardous waste and iso­lat­ed from the envi­ron­ment as best as is pos­si­ble until there is a proven tech­nol­o­gy which can neu­tral­ize the tox­i­cs by con­vert­ing the halo­gens to rel­a­tive­ly harm­less chem­i­cals like salts.

The gen­er­al options for deal­ing with land­fill gas (once col­lect­ed) are as follows:

1. flare it
2. boil­er — makes heat
3. inter­nal com­bus­tion engine — makes electricity
4. gas tur­bine — makes electricity
5. fuel cell — makes electricity
6. con­vert the methane to methyl alcohol
7. clean it up enough to pipe it to oth­er indus­tries or into the nat­ur­al gas lines

Note: a more com­pre­hen­sive list of options is online at http://www.eia.doe.gov/cneaf/solar.renewables/renewable.energy.annual/chap10.html

Flares

Flar­ing of land­fill gas is either done in a can­dle flare or a shroud­ed flare. A can­dle flare is an open air flame. With such, there is no reli­able means to mon­i­tor for diox­ins or oth­er tox­ic emis­sions. Shroud­ed flares involve enclos­ing the flame in an insu­lat­ed cylin­dri­cal shroud which can be any­where from 16 to 60 feet tall.¹¹ While diox­ins can be test­ed for in such flares, it is pos­si­ble that enclos­ing the flare will keep the post-com­bus­tion tem­per­a­ture in diox­in-for­ma­tion range, result­ing in increased diox­in emis­sions. Essen­tial­ly, this is a lose-lose sit­u­a­tion. It should be not­ed that some (per­haps most or all) shroud­ed land­fill gas flares have exit tem­per­a­tures of around 1400^oF — well above the diox­in for­ma­tion range (which end around 752^oF). In such cas­es, diox­ins will be formed in mid-air as the exhaust hits the cool­er back­ground air after leav­ing the stack.

Boil­ers

Boil­ers are among the cheap­est options. They pro­duce heat, not elec­tric­i­ty. Boil­ers are gen­er­al­ly less sen­si­tive to land­fill gas con­t­a­m­i­nants and there­fore require less cleanup than oth­er alter­na­tives. Boil­ers have the low­est NO_x and car­bon monox­ide emis­sions of the com­bus­tion tech­nolo­gies.¹²

Land­fill gas use in boil­ers bring in the issue of pip­ing the gas to local indus­tries. While boil­ers them­selves may not require much cleanup of the gas, the pipelines do require some cleanup, since cor­ro­sive com­pounds in the gas (par­tic­u­lar­ly the acids and hydro­gen sul­fide — H₂S) can dam­age the pipelines. There have been many con­cerns asso­ci­at­ed with land­fill gas pipelines brought out by envi­ron­men­tal­ists liv­ing near land­fills con­sid­er­ing this use. Among the con­cerns are the integri­ty of the pipeline (at least one pro­pos­al involves lat­er­al seams), lia­bil­i­ty issues, and the eco­nom­ic sup­port of neigh­bor­ing pol­lut­ing indus­tries which might use the gas.¹³ In addi­tion, such projects have been used as excus­es to devel­op addi­tion­al pol­lut­ing indus­try that would uti­lize the gas in their processes.

Inter­nal Com­bus­tion Engines

IC engines are the dirt­i­est tech­nol­o­gy for burn­ing land­fill gas. They emit the most car­bon monox­ide and NO_x and they may be the largest diox­in source of the avail­able tech­nolo­gies.¹⁴

Gas Tur­bines

Gas tur­bines are some­where in the mid­dle in terms of car­bon monox­ide and NO_x emis­sions. There isn’t enough data on diox­in emis­sions from land­fill gas tur­bines to pro­vide any sort of comparison.

Fuel Cells

Fuel cells are the most expen­sive tech­nol­o­gy, as they are still large­ly exper­i­men­tal. EPA describes fuel cells as “poten­tial­ly one of the clean­est ener­gy con­ver­sion tech­nolo­gies avail­able.” In order not to “poi­son” the fuel cells, halo­genat­ed con­t­a­m­i­nants must be fil­tered out. This is a won­der­ful thing, since it demon­strates that such fil­ter­ing tech­nolo­gies are real­is­tic and may even­tu­al­ly be put into prac­tice. How­ev­er, in EPA’s twist­ed log­ic, they state that the fil­tered con­t­a­m­i­nants would be incin­er­at­ed.¹⁵ This would defeat the point of fil­ter­ing them in the first place, unless all we care about is the health of fuel cells.

Con­ver­sion to Methanol and/or Dry Ice

At least one com­pa­ny is involved with con­vert­ing methane from land­fills into methyl alco­hol or methanol. How­ev­er, the halo­genat­ed organ­ics they fil­ter out are sent to a flare (again defeat­ing the point).¹⁶ Oth­er com­pa­nies have expressed inter­est in con­vert­ing the car­bon diox­ide in land­fill gas to dry ice for sale to indus­try. They have claimed that the car­bon diox­ide in land­fill gas is actu­al­ly more prof­itable to recov­er than the methane.

Clean­ing up the Gas to Pipeline Quality

Since nat­ur­al gas prices are so low, this is not expect­ed to be eco­nom­i­cal any­time soon. It also requires a high degree of clean­ing and fil­ter­ing the gas. To the extent that the gas is not ade­quate­ly fil­tered, then the land­fill gas will be degrad­ing the qual­i­ty of the nat­ur­al gas by adding more con­t­a­m­i­nants to the sys­tem.¹⁷

What about source reduction? How can we cut down on landfill gas?

As with any waste issue, the proac­tive solu­tion is to look upstream and see what can be done to stop cre­at­ing waste prod­ucts. With land­fill gas, it’s no dif­fer­ent. Land­fills are the end-point of much of the excess­es of our waste­ful econ­o­my. At the very begin­ning of the sys­tem, we must look at such things as phas­ing out of halo­gens in indus­tri­al use. This is the only way that we can stop chlo­rine, flu­o­rine and bromine pol­lu­tion and the organohalo­gens (diox­ins, furans, etc.) that come with them. We also must con­sid­er the tech­nol­o­gy of land­fills. There are com­mu­ni­ties in the Unit­ed States which are recy­cling 80–90% of their waste (some even high­er). It is the act of mix­ing mate­ri­als togeth­er that makes waste. Source sep­a­ra­tion and recy­cling pre­vents this.

In land­fills them­selves, it makes sense to seg­re­gate organ­ic wastes from oth­er wastes by plac­ing them in dif­fer­ent cells of a land­fill. This would con­cen­trate the methane gen­er­a­tion in an area where many of the tox­ic com­pounds won’t be present (which is not to imply that yard waste and such does­n’t come laden with pes­ti­cides and tox­ic sludge “fer­til­iz­er” appli­ca­tions).¹⁸ In con­sid­er­a­tion of land­fill gas man­age­ment, EPA dis­missed com­ments which would favor waste seg­re­ga­tion.¹⁹

The Global Warming Politics of Landfill Gas

Pro­mot­ers of land­fill gas com­bus­tion con­sis­tent­ly point to the fact that methane is a potent green­house gas. This gets used as a rea­son to burn land­fill gas to pro­duce ener­gy and also to have that ener­gy con­sid­ered “green.” Often ignored is the fact that most land­fills which have gas col­lec­tion sys­tems are burn­ing that gas in one form or anoth­er any­way. “Green ener­gy” should not be used as an excuse to move from flares to inter­nal com­bus­tion engines or gas tur­bines, as there is not a sol­id envi­ron­men­tal argu­ment for doing so. The incen­tives involved in green ener­gy mar­ket­ing are not enough that land­fills with­out gas col­lec­tion sys­tems are going to install them to pro­duce “renew­able” ener­gy from land­fill gas. Land­fill gas man­age­ment should be based on iso­la­tion of tox­ic con­t­a­m­i­nants and not on the pol­i­tics of glob­al warming.

Pro­po­nents of land­fill gas pipelines to boil­ers of local indus­tries often argue that there would be dis­place­ment of oth­er green­house-gas emit­ting fuels in the boil­ers of the pre-exist­ing indus­tries by the land­fill gas that would be used in its place. While this can be a legit­i­mate argu­ment, it does not neces­si­tate pip­ing gas that is not cleaned up to nat­ur­al gas pipeline standards.

EPA has a mis­named “Land­fill Methane Out­reach Pro­gram” which pro­motes burn­ing land­fill gas to pro­duce ener­gy. This pro­gram is part of EPA’s Methane Out­reach Pro­grams which are a part of their Atmos­pher­ic Pol­lu­tion Pre­ven­tion Divi­sion.²⁰ It is appar­ent that EPA’s agen­da on land­fill gas man­age­ment is being dri­ven by glob­al warm­ing pol­i­tics and not sound man­age­ment of tox­ic air pollutants.

As green­house gas­es go, methane is very potent. Accord­ing to the lat­est sci­ence, methane is 86 times more effi­cient at trap­ping heat than car­bon diox­ide (CO₂) over a 20-year time frame. Nitrous oxide (N₂O) is 310 times more effi­cient than CO₂. Per­flu­o­ro­car­bons (PFCs) and hydro­flu­o­ro­car­bons (HFCs) are any­where from around 1,000 to 10,000 times more effec­tive than CO₂. Anoth­er flu­o­ri­dat­ed com­pound, sul­fur hexa­flu­o­ride (SF₆), traps 23,900 times as much heat as CO₂.²¹ Methane is respon­si­ble for 10.6% of glob­al warm­ing dam­age from human-sources in the U.S. Of this, 35.8% is from land­fill gas. Thus, 3.8% of U.S. glob­al warm­ing dam­age is from methane in land­fill gas.²² This is hard­ly a rea­son to advo­cate burn­ing it one way vs. anoth­er, or even burn­ing it at all. Since methane in cap­tured land­fill gas can be con­vert­ed to methyl alco­hol with­out requir­ing com­bus­tion, there is no need to have to sub­ject the oth­er chem­i­cal con­t­a­m­i­nants in land­fill gas to incineration.

Why is there such a push for landfill gas to be considered “renewable” energy?

Land­fill gas and oth­er “bio­mass” (incin­er­a­tion) tech­nolo­gies are cheap­er to devel­op than wind (which is the next cheap­est “renew­able” tech­nol­o­gy). Ener­gy from land­fill gas projects also pro­vides the eas­i­est-to-obtain new renew­able (built since the incep­tion of green ener­gy mar­ket­ing) for the Green‑e cer­ti­fi­ca­tion process.

It is because of this that we don’t expect to see as much devel­op­ment of tru­ly clean renew­ables from green ener­gy mar­ket­ing as we expect to see devel­op­ment of pol­lut­ing land­fill gas and bio­mass tech­nolo­gies. While not a renew­able ener­gy source, cheap nat­ur­al gas is also like­ly to under­cut renew­ables. Until we suc­ceed at knock­ing out pol­lut­ing tech­nolo­gies like “bio­mass” from the def­i­n­i­tion of renew­ables, we won’t see the true poten­tial for long over­due wind development.

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FOOTNOTES:

1. “Tech­ni­cal Data for Nat­ur­al Gas,” Ely Ener­gy http://www.elyenergy.com/tdngtypchemcomp.htm Con­t­a­m­i­nants in nat­ur­al gas include organometal­lic com­pounds such as those con­tain­ing lead and mer­cury, as well as many oth­er com­pounds which lead to the for­ma­tion of haz­ardous air pol­lu­tants, includ­ing some halo­genat­ed com­pounds. Nat­ur­al gas lines have also been known to be con­t­a­m­i­nat­ed with PCBs. Doc­u­men­ta­tion on this can be found on the web at https://energyjusticenetwork.org/naturalgas/
2. “Air Emis­sions from Munic­i­pal Sol­id Waste Land­fills — Back­ground Infor­ma­tion for Pro­posed Stan­dards and Guide­lines” Doc­u­ment # is EPA/450/3–90/011A. March 1991, 544 pages. http://www.epa.gov/ttn/atw/landfill/landflpg.html#TECH
3. “Growth of the Land­fill Gas Indus­try,” Chap­ter 10 of the “Renew­able Ener­gy Annu­al 1996” report by the U.S. Depart­ment of Ener­gy’s Ener­gy Infor­ma­tion Admin­is­tra­tion. Avail­able online at http://www.eia.doe.gov/cneaf/solar.renewables/renewable.energy.annual/chap10.html
4. The 1994 EPA Diox­in Reassess­ment, Esti­mat­ing Expo­sure to Diox­in-Like Com­pounds, Vol­ume 2, Chap­ter 3 http://www.cqs.com/epa/exposure/ Diox­ins are formed from around 200^oC (392^oF) to 400^oC (752^oF).
5. “Method­olo­gies for Quan­ti­fy­ing Pol­lu­tion Pre­ven­tion Ben­e­fits from Land­fill Gas Con­trol and Uti­liza­tion,” EPA doc­u­ment #600SR95089, July 1995. 
6. “The Inven­to­ry of Sources of Diox­in in the Unit­ed States,” EPA/600/P‑98/002Aa, April 1998. 
7. Caponi, Frank R., Ed Whe­less & David Fre­di­ani, “Diox­in and Furan Emis­sions From Land­fill Gas-Fired Com­bus­tion Units,” Coun­ty San­i­ta­tion Dis­tricts of Los Ange­les Coun­ty, 98-RP105A.03, 1955 Work­man Mill Rd. Whit­ti­er, CA 90607. 
8. Note 5 supra.
9. “Inves­ti­ga­tion of Can­cer Inci­dence and Res­i­dence Near 38 Land­fills With Soil Gas Migra­tion Con­di­tions, New York State, 1980–1989,” State of New York Depart­ment of Health, (Atlanta, Ga: Agency for Tox­ic Sub­stances and Dis­ease Reg­istry, June, 1998). 
10. “Land­fills are Dan­ger­ous,” RACHEL’s Envi­ron­ment & Health Week­ly #617, Sep­tem­ber 24, 1998. http://www.rachel.org/bulletin/index.cfm?issue_ID=1149
11. Note 7 supra.
12. Note 5 supra.
13. All of these issues have been raised by the Alliance for a Clean Envi­ron­ment (ACE). ACE worked for sev­er­al years to suc­cess­ful­ly stop plans for build­ing a 5 mile pipeline to pipe the tox­ic land­fill gas from Waste Man­age­ment Inc.‘s Pottstown, PA land­fill to an Occi­den­tal Petro­le­um vinyl chlo­ride facil­i­ty on the oth­er side of town. 
14. Note 5 supra.
15. “Demon­stra­tion of Fuel Cells to Recov­er Ener­gy from Land­fill Gas: Phase I Final Report: Con­cep­tu­al Study,” EPA #600SR92007, Jan­u­ary 1992. 
16. Con­ver­sa­tion with Bill Wis­brock of Alco­hol Solu­tions, Jan­u­ary 12, 1999. 
17. Note 3 supra.
18. Even the Nat­ur­al Lawn com­pa­ny, which mar­kets envi­ron­men­tal­ly-benign lawn care, uses sewage sludges in their prod­ucts which they spray on their cus­tomer’s lawns. Sewage sludges con­tain a stew of tox­ic chem­i­cals which aren’t fil­tered out before being sold as fer­til­iz­er. For back­ground on sewage sludge, vis­it http://www.ejnet.org/sludge/
19. “Air Emis­sions from Munic­i­pal Sol­id Waste Land­fills. Back­ground Infor­ma­tion for Final Stan­dards and Guide­lines.” Doc­u­ment # is EPA-453/R‑94–021. Decem­ber 1995, 311 pages. http://www.epa.gov/ttn/atw/landfill/landflpg.html#TECH
20. See their web­site at: http://www.epa.gov/methane/
21. See EPA’s Green­house Gas Inventory 
22. Ibid.