Biomass

Capture and Utilisation of

Landfill Gas

What is the potential for additional utilisation of

landfill gas in the USA and around the world?

By Nickolas Themelis and Priscilla Ulloa,

Columbia University.

In his 2003 review of energy

recovery from landfill gas,

Willumsen1 reported that as of

2001, there were about 955 landfills that

recovered biogas. The largest number of

such landfills were in the USA, followed

by Germany and the UK (see Table 1).

Willumsen also provided2 detailed information on 21 landfills in Denmark that in

total captured 5,800Nm3 of biogas per

hour, equivalent to 276.4MW of contained

thermal energy, or 20,000 tonnes of

methane (CH4) per year.

LANDFILLING OF MUNICIPAL SOLID

WASTE IN THE USA

The USA is the biggest operator of

regulated landfills in the world. There are

about 2000 operating in the USA. In 2003,

the Earth Engineering Center (EEC) of

Columbia University conducted a nationwide survey of waste management in the

USA in collaboration with BioCycle

Journal. The landfill data in this survey

were supplied by the waste management

department of each state, and the results

are shown in Table 23

. An interesting

finding of the survey was that the amount

of municipal solid waste (MSW) landfilled

annually was 211 million tonnes, nearly

100 million tonnes higher than that

reported by the US Environmental Protection Agency (EPA).

PRODUCTS OF BIOCHEMICAL

REACTION OF BIOMASS IN MSW

It has been estimated6 that biomass

materials such as paper, food and wood,

constitute about 70% of the MSW, and

petrochemicals constitute another 15%.

The rest is made up of inorganic materials

such as metals, glass, gypsum and other

minerals. The biomass fraction of MSW

can be approximated8 by the molecular

formula C6H10O4. The gaseous product

of the predominant anaerobic bioreaction

of MSW in landfills consists of about 54%

methane and 46% CO2. Theoretically,

complete bioreaction of one tonne of dry

biomass will generate nearly 210

standard cubic metres (Nm3

) of

methane7

. Experimental tests by Barlaz et

al10 on the complete bioreaction of

biomass contained in MSW are in good

agreement with this projection.

The dry biomass concentration in MSW

may be only 40-60% of its weight. Therefore, the corresponding generation of

methane would range from 80-120Nm3

per tonne of MSW. Also, some of the

biomass within the landfill may not be

subjected to biodegradation for lack of

moisture that is required to sustain bacterial growth; this would reduce the amount

of methane generated per ton of MSW.

USA 325

Canada 25

Germany 150

France 10

Holland 60

UK 135

Spain 10

Italy 40

Austria 15

Switzerland 10

Norway 20

Denmark 21

Sweden 70

Finland 10

Poland 10

Czech Republic 5

Hungary 5

China 3

Australia 25

Brazil 6

Total 955

Country Approx. number of Plants

Table 1: Energy recovering landfills

(Willumsen2

) 

14th SOG survey4 USEPA 2001 survey6

million % Million %

tonnes/year tonnes/year

Amount generated 336 100 211 100

Amount recycled and 90 26.7 65 30.8

composted

Amount to waste-to-energy 26 7.7 27 12.8

Amount landfilled 220 65.6 119 56.4

Table 2: Generation and fate of MSW in the USA3
Biomass

US DATA ON GENERATION OF

BIOGAS AT LANDFILLS

Eileen Berenyi, a Research Associate

of EEC, compiles the Methane Recovery

from Landfills Yearbook9

. The data

presented in Table 3 is from the 1999

Yearbook. This data included tonnages of

MSW landfilled since the opening of each

landfill, but not the annual rate of

landfilling. This last is important because

it has been shown experimentally7 (Figure

1) that most of the bioreaction of the

biomass in MSW may occur in the first

year of landfilling.

The 42 states reported in Table 3

captured a total of 6.8 billion Nm3 of

biogas and represent 89% of the US

population. However, it should be noted

that the MSW tonnages in this table represent the total amount landfilled in each

state while the biogas generation is for

the 327 landfills that collect biogas.

Therefore, it is not possible to correlate

the gas generation to MSW landfilled from

the above data.

As an alternative, 25 California landfills

were examined where the amounts

landfilled annually were reported by the

California Integrated Waste Management

Board12 and the captured gas by Berenyi9

.

Their combined annual deposition rate

was 16.6 million tonnes of MSW. On a

yearly basis, the total methane captured

in these 25 landfills corresponded to an

average of 32Nm3 of methane per tonne

of MSW landfilled.

LANDFILL METHANE OUTREACH

PROGRAMME

The US Environmental Protection

Agency (USEPA) operates a Landfill

Methane Outreach Programme that

encourages landfill owners to develop

gas recovery projects wherever it is

feasible to do so13. Through this

programme, USEPA works with MSW

landfill owners and operators, states, utilities, industry and other federal agencies

to lower the barriers to economic landfill

gas energy recovery. Table 4 compares

the electricity generated by landfill gas to

energy plants in each state, as reported

by Berenyi in 19999 and by USEPA in

200513. The difference represents the

growth in landfill gas collection projects

from 231 in 1999. Electricity generation

from biogas has increased by 18% since

1999 to 1.07MWe.

Figure 1. Generation methane in

experimental apparatus simulating

landfill bioreactions (M1 and M2

denote two different tests; reference 9)

State MSW Landfilled Landfill Gas Landfill Gas LFGHeating Value

(Solid Wastes generated used Processed Untreated

Digest) (Berenyi) (Berenyi) Gas

tonnes/y Nm3/y Nm3/y % KJ

Alabama 5,110,224 446,559 446,559 100% 580

Arizona 6,460,129 8,186,916 531

California 35,188,243 1,952,168,440 1,408,295,409 72% 500

Colorado 6,269,618 3,096,143 3,096,143 100% 514

Connecticut 257,643 55,819,881 20,497,060 37% 543

Delaware 1,587,590 38,538,046 20,675,684 54% 501

Florida 16,248,753 245,796,024 189,780,153 77% 550

Georgia 10,827,361 33,581,240 33,581,240 100% 563

Hawaii 595,119 21,702,770 21,702,770 100% 528

Illinois 17,972,421 635,117,780 486,899,870 77% 547

Indiana 6,097,251 66,983,857 21,137,128 32% 522

Iowa 1,835,254 20,675,684 20,675,684 100% 554

Kansas 2,835,889 36,179,553 36,179,553 100% 528

Kentucky 4,486,075 21,434,834

Maryland 2,849,497 53,333,829 31,005,877 58% 543

Massachusetts 1,406,151 203,407,647 111,848,156 55% 535

Michigan 16,686,020 455,795,378 417,920,820 92% 559

Minnesota 1,978,590 135,977,230 131,065,081 96% 513

Missouri 4,066,951 56,564,146 37,213,254 66% 580

New Hampshire 1,629,321 72,238,369 72,238,369 100% 574

New Jersey 3,594,303 350,548,853 223,279,524 64% 534

New York 6,647,011 445,472,421 336,958,573 76% 543

North Carolina 6,630,681 113,296,992 85,221,081 75% 552

Ohio 12,572,802 182,970,127 124,566,158 68% 563

Oregon 4,870,725 16,954,359 16,954,359 100% 520

Pennsylvania 22,458,496 556,625,930 363,379,983 65% 545

Rhode Island 1,375,306 86,334,749 86,334,749 100% 570

South Carolina 5,271,705 14,260,119 11,163,976 78% 563

Tennessee 5,877,710 79,963,840 35,665,183 45% 591

Texas 21,501,406 312,839,422 278,768,621 89% 547

Vermont 410,052 6,981,206 6,981,206 100% 475

Virginia 12,157,307 104,078,029 77,403,568 74% 563

Washington 4,692,008 253,050,127 13,099,065 5% 464

Wisconsin 6,263,268 199,492,812 184,160,952 92% 540

Total

reporting 253,814,753 6,811,497,272 4,901,214,602

Table 3: Landfill gas capture by state (based on references 9, 11)
Biomass

State Electricity Produced Electricity Produced

kW State kW

Berenyi USEPA Berenyi USEPA

1999 2005 1999 2005

Alabama 4,000 n/a Missouri 800 n/a

Arizona 18,425 10,350 Nebraska n/a 3,200 

California 237,570 255,935 New Hampshire 15,700 13,800 

Colorado 800 n/a New Jersey 48,900 45,700 

Connecticut 9,840 5,000 New York 46,047 48,300 

Delaware 1,500 n/a North Carolina 10,350 11,600 

Florida 19,800 39,830 Ohio 8,500 36,200 

Georgia 5,400 7,400 Oregon 5,660 5,600 

Hawaii 3,000 n/a Pennsylvania 46,350 68,400 

Illinois 177,766 153,934 Rhode Island 12,000 17,000 

Indiana 7,525 21,585 South Carolina n/a 8,400 

Iowa 8,500 6,400 Tennessee 7,000 7,200 

Kansas 3,000 n/a Texas 15,600 57,656 

Kentucky n/a 10,400 Vermont 1,500 1,200 

Maryland 7,250 8,050 Virginia 14,600 31,800 

Massachusetts 27,650 37,744 Washington 15,700 15,200 

Michigan 79,900 72,300 Wisconsin 29,000 47,375 

Minnesota 25,800 24,200 Total 911,433 1,071,759

Table 4: Electricity Generation by using LFG

Direct Heating Applications • Use for industrial boilers

• Space heating and cooling

(e.g.greenhouses)

• Industrial heating/cofiring

Electricity Generation Applications • Processing and use in reciprocating

internal combustion (RIC) engines

(stoichoimetric or lean combustion)

• Processing and use in microturbines,

gas, and steam turbines

• Processing and use in fuel cells

Feedstock in Chemical • Conversion to methanol (industrial

Manufacturing Processes or vehicular use)

• Conversion to diesel fuel

(vehicular fuel)

Purification to Pipeline Quality Gas • Utilization as vehicular fuel

• Incorporation into local natural

gas network

Soil remediation • Leachate evaporation system.

Heat Recovery from Landfill Flares • Using organic Rankine cycle

• Using Stirling cycle engines

Table 5: Utilisation of Landfill Gas

Electricity

72%

Snyfuel/Other

3%

Pipeline Quality

4%

Direct Heating

21%

Uses of LFG-to-Energy

Plants in US

Figure 2: Distribution of uses of

landfill gas in the USA
Biomass

Table 5 shows how landfill gas is

utilised in the USA, and Figure 2 shows

the distribution of uses in graphical form.

California, with 65 plants, has the

largest number of landfill gas facilities,

because of state and local requirements

that require collection and control of

biogas8

. Other states with a significant

number of landfill gas plants include

Illinois (43), Michigan (22), New York (20)

and Pennsylvania (19).

Table 6 lists some of the characteristics

of landfill gas projects in each state. The

total active area of landfills collecting gas

is about 21,000 hectares; about 57% of

the active area is equipped for methane

recovery. The states of California, Illinois,

Michigan, New York and Pennsylvania

represent approximately 50% of the total

landfill area devoted to methane recovery.

On the other hand, 60% of the total MSW

buried in landfills equipped for gas collection is located in the states of California,

New York, Illinois, Texas and Michigan.

The average landfill depth in the gascollecting landfills range from 14 to 53m;

the national US average depth is 28m.

The density of the MSW buried in these

landfills ranges from 594-832kg/m3

, while

the national average is estimated at

732kg/m3

.

CAPITAL COSTS FOR UTILISING

LANDFILL GAS

The California Energy Commission13

has studied the capital costs for installing

facilities for electricity generation from

landfill gas, as shown in Figure 3. Reciprocating engines appear to be the best

option for facilities up to 10MWe in size.

For facilities in the range 10-18MWe, the

use of gas turbines is more practical.

Above 18MWe, steam cycles are mostly

used, although combined cycles offer

lower investment per kW generated.

CONCLUSIONS

On the basis of the theoretical and

experimental evidence presented above,

it can be assumed that under the right

conditions, at least 50% of the ‘latent’

methane in MSW can be generated within

one year of residence time in a landfill.

This would correspond to about 50Nm3 of

methane per tonne of a typical MSW.

However, on average, the 25 California

landfills that were examined in detail

captured only 32Nm3 of methane per

State Number of Active Devoted Refuse Average Average

LFG Area Area Buried Depth Density

Projects CH4 Refuse

Recovery

hectares hectares tonnes m kg/m3

Alabama 2 236 16 1,306,359 14 653

Arizona 5 285 254 17,418,126 29 693

Arkansas 1 57 57 4,717,409 18 772

California 65 5,746 3,570 546,179,234 36 730

Colorado 1 36 36 27,215,821 26

Connecticut 5 147 109 12,655,357 32 733

Delaware 2 146 53 8,527,624 23 653

Florida 12 697 530 69,971,877 25 731

Georgia 4 160 68 15,694,457 24 698

Hawaii 1 17 17 1,195,500 23 594

Illinois 43 1,743 1,087 117,968,430 26 814

Indiana 4 163 93 10,886,329 22 832

Iowa 3 210 62 11,974,961 23 761

Kansas 3 482 77 19,958,269 18 713

Kentucky 1 304 122 n/a 46 891

Louisiana 2 209 122 n/a 53

Maryland 4 233 128 14,424,385 21 624

Massachusetts 16 345 267 20,638,665 25 752

Michigan 22 1,038 697 67,676,676 24 744

Minnesota 5 190 158 20,303,003 25 743

Missouri 2 100 37 12,185,430 46 594

New Hampshire 6 158 151 10,646,829 28 713

New Jersey 11 770 492 62,367,776 23 790

New York 20 1,050 619 152,041,187 38 812

North Carolina 15 723 435 31,942,937 24 695

Ohio 6 383 245 47,718,407 23 792

Oregon 5 531 139 14,116,847 29 812

Pennsylvania 19 1,496 572 64,773,655 32 736

Rhode Island 1 62 47 10,886,329 46 653

South Carolina 4 84 37 5,663,612 18 653

Tennessee 3 181 116 12,428,558 35 793

Texas 8 865 475 117,730,352 22 730

Vermont 2 24 13 1,327,225 25 653

Virginia 7 347 190 29,393,087 26 754

Washington 5 663 364 35,017,690 34 817

Wisconsin 12 546 289 39,335,934 25 759

Total 327 20,426 11,742 1,636,288,340

Table 6: Characteristics of LFG projects in the USA by state
tonne landfilled. Of course, conventional

landfills are far from perfect bioreactors.

In addition, there is no information

regarding the effectiveness of the gas

collection at the landfills.

There are nearly 330 landfills in the

USA, capturing a total of 3.7 billion Nm3 of

methane, of which 70% is used to

generate thermal or electric energy. The

rest is flared, because it is not considered

to be of economic use. There are nearly

1300 landfills that do not capture any

biogas.

If it were possible to build and operate

bioreactor landfills where water is added

and nearly all the generated methane is

captured, the methane collected in the

USA, at an assumed average rate of

50Nm3 of methane per tonne of MSW,

would be 11 billion Nm3 of methane, ie,

three times the amount that is presently

captured.

With regard to the global picture, on

ongoing EEC study7 has estimated the

global disposition of MSW in landfills to

be 1.4 billion tons of MSW. The corresponding generation of methane is close

to 50 million tons, of which only 5 million

tons are currently being captured. Therefore, methane emissions to the

atmosphere are about 45 million tons.

Since methane has 23 times the global

warming potential of carbon dioxide,

global landfill emissions correspond to

about one billion tons of CO2.

If landfilling of organic materials is to be

continued in some countries, future

landfills must be fully controlled bioreactors where most of the methane

generated is captured and used to

produce energy. Landfill biogas is one of

the very few sources of renewable

methane. ■

REFERENCES

1. H.Willumsen (2003), Experience

with landfill gas recovery plants, in

Renewable Energy 2003, www.sovereign-publications.com/renewable-ene

rgy2003-art.htm

2. H Willumsen., Energy recovery

from landfill gas, www.lei.lt/

Opet/pdf/Willumsen.pdf

3. N.J. Themelis, N.J. and Scott M.

Kaufman (2004), Waste in a land of

plenty, Waste Management World,

Sept-Oct 2004, p 23-28 

4. S.M. Kaufman, N. Goldstein, K.

Millrath, and N.J. Themelis (2004),

The State of Garbage in America,

BioCycle, January, p. 31-41.

5. N.J. Themelis, N.J. and S.M.

Kaufman (2004), State of Garbage in

America-Data and Methodology

Assessment, BioCycle, April, p. 22-26.

6. USEPA (2003), Municipal Solid

Waste in the United States: 2001 Facts

and Figures, Executive Summary,

Office of Solid Waste and Emergency

Response, EPA530-S-03-011

(http://www.epa.gov/)

7. Earth Engineering Center, Landfill

gas generation, capture, and utilization, study in progress (2005)

8. N.J. Themelis and Shefali Verma

(2004), Anaerobic Digestion of

Organic Waste in MSW, Waste

Management World, Jan.-Feb, p. 20-

24. (see also S. Verma, M.S. Thesis,

Earth and Environmental

Engineering, Columbia University

2003, www.columbia.edu/cu/wtert ,

Publications).

9. Eileen Bernyi, Methane Recovery

from Landfills Yearbook (1999),

Methane Recovery from Landfill

Yearbook, 5th Edition, Governmental

Advisory Associates, Westport, CT .

10. M.A. Barlaz, S. Cowie, B. Staley

and G. Hater, 2004, Production of

NMOCs and Trace Organics During

the Decomposition of Refuse and

Waste Components under Anaerobic

and Aerobic Conditions, 3rd Intercontinental Landfill Research

Symposium Nov . 2004.

11. Solid Waste Digest (2004),

“Special Report: Landfill Capacity”,

vol. 14 No. 9 (htttp://www.wasteinfo.com)

12. California Integrated Waste

Managament Board (http://www.ciw

mb.ca.gov/landfills/Tonnage/2003/La

ndfill.htm)

13. USEPA (2005), Landfill Gas

Outreach Program (http://www.epa

.gov/lmop/proj/index.htm)

AUTHOR NOTE:

Nickolas Themelis and Priscilla

Ulloa, Earth Engineering Center and

Department of Earth and Environmental Engineering, Columbia

University, New York, NY 10027, USA.

Biomass

Figure 3: Capital cost vs. facility size, for landfill gas utilisation