Emissions (tons CO2e) = (V x M x (1-OX) x GWP)/2000 where:
V = Volume of CH4 collected (ft3);
M = Mass of CH4 per cubic foot (0.04246 lbs/ft3 default value at 1 atmosphere and 20°C);
OX = Oxidation factor (0.10), representing estimated portion of collected CH4 that would have eventually oxidized to CO2 if not collected; and
GWP = CO2e global warming potential of CH4 (28)
Emissions Reductions (tons CO2e) = (V x M x (1 - OX) x Cef x GWP)/2000 where:
V = Volume of CH4 collected (ft3);
M = Mass of CH4 per cubic foot (0.04246 lbs/ft3 default value at 1 atmosphere and 20°C);
OX = Oxidation factor (0.10), representing estimated portion of collected CH4 that would have eventually oxidized to CO2 if not collected;
Cef = Combustion efficiency of CH4control technology (0.98); and
GWP = CO2e global warming potential of CH4 (28)
For such projects, the number of CO2 offset allowances to be awarded will be calculated pursuant to the requirements of subsection 9(D)(2) of this Chapter without regard to quantity of credits that were awarded to the project under the voluntary program.
MP (%) = MGAD / MGSTATE where:
MGAD = Average annual manure generation for the number of dairy cows and swine serving all anaerobic digester projects in the applicable state at the time of submission of a consistency application pursuant to subsection 9(C) of this Chapter.
MGSTATE = average annual manure production of all dairy cows and swine in the state at the time of submission of a consistency application pursuant to subsection 9(C) of this Chapter.
Eb(tons) = (Vm x M)/2000 x GWP where:
Eb= Potential CO2e emissions due to calculated CH4 production under site-specific anaerobic storage and weather conditions(tons);
Vm = Volume of CH4 produced each month from decomposition of volatile solids in a baseline uncontrolled anaerobic storage scenario under site-specific storage and GWP(ft3); and M = Mass of CH4 per cubic foot (0.04246 lb/ft³ default value at one atmosphere and 20°C) GWP = Global warming potential of CH4 (28)
VSdec= VSavail * f
where:
VSdec = volatile solids decomposed monthly (kg)
VSavail = volatile solids available for decomposition in manure storage each month as determined from the equation:
VSavail = (Mp + 1/2 Min - Mout) x TS% x VS%
where:
Mp = manure or organic food waste storage present at the beginning of a month (left over from the previous month) (kg);
Min = manure or organic food waste added to storage during the course of the month (kg). This number is multiplied by a factor of 1/2 to represent the average mass of manure or organic food waste available for decomposition for the duration of the entire month; and
Mout = manure or organic food waste removed from storage for land application or export (assumed value based on standard farm practice)
TS% = concentration (percent) of total solids in manure as determined through EPA 160.3 testing method (U.S. EPA Method Number 160.3, Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020)); and VS% = concentration (percent) of volatile solids in total solids as determined through EPA 160.4 testing method (U.S. EPA Method Number 160.4, Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020))
and
f = van't Hoff-Arrhenius factor for the specific month as determined using the equation below if the reported temperature used to determine T2 below is above 5°C; if the reported temperature is below 5°C, then f = 0.104. Using a base temperature of 30°C, the equation is as follows:
f = exp[E * (T2 - T1)/(GC * T1 * T2)]
where:
f = conversion efficiency of VS to CH4 per month
E = activation energy constant (15,175 cal/mol)
T2 = average monthly ambient temperature for the facility where manure or organic waste is generated (converted from ° Celsius to° Kelvin) as determined from the nearest National Weather Service certified weather station;
T1 = 303.15 (30° C converted to ° K)
GC = ideal gas constant (1.987 cal/K mol)
Vm = (VSdecx Bo) x 35.3147
where:
Vm = volume of CH4 (ft3);
VSdeg = volatile solids decomposed (kg); and Bo = manure type-specific maximum methane (CH4) generation constant (m3) CH4/kg VS decomposed). For dairy cow manure, Bo = 0.24 m3 CH4/kg VS decomposed. The methane generation constant for other types of manure shall be those cited in U.S. EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010, Annex 3 Table A180 (U.S. EPA, February, 2017), unless the project sponsor proposes an alternate methane generation constant and that alternate is approved by the Department. If the project sponsor proposes to use a methane generation constant other than the one found in the above-cited reference, the project sponsor must provide justification and documentation to the Department.
ERt = Eb - Ep
where:
ERt = CO2e emissions reductions due to project activities (tons);
Eb = Potential CO2e emissions due to calculated CH4 production under site-specific anaerobic storage and weather conditions (tons); and Ep = CO2e emissions due to project activities additional to baseline (tons), including, but not limited to, manure transportation, flaring, venting, and effluent management.
Emissions reductions may not exceed the potential emissions of the anaerobic digester, as represented by the annual volume of CH4 produced by the anaerobic digester, as monitored pursuant to subsection 9(D)(3)(e) of this Chapter. CO2 emissions due to transportation of manure and organic food wastes from the sites where the manure and organic food wastes were generated to the anaerobic digester shall be subtracted from the emissions reduction calculated pursuant to subsections 9(D)(3)(c)(i) through (iii) of this Chapter. Transport CO2 emissions shall be determined through one of the following methods:
Table 1
Monitoring Requirements
Parameter | Measurement Unit | Frequency of Sampling | Sampling Method(s) |
Influent flow (mass) into the digester | Kilograms (kg) per month (wet mass) | Monthly total into the digester | Average herd population and application of American Society of Agricultural and Biological Engineers (ASABE) standard (ASAE D384.2, March 2005) Digester influent pump flow Recorded mass |
Influent total solids concentration (TS) | Percent (of sample) | Monthly, depending upon recorded variations | U.S. EPA Method Number 160.3, Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020) |
Influent volatile solids (VS) content of manure | Percent (of TS) | Monthly, depending upon recorded variations | USEPA Method Number 160.4, Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020) |
Average monthly ambient temperature | Temperature oC | Monthly (based on farm averages) | Closest National Weather Service-certified weather station |
Volume of biogas produced by digester | Standard cubic feet (scf) | Continuous, totalized monthly | Flow meter |
Methane (CH4) composition of biogas produced by digester | Percent (of sample) | Quarterly | Bag sampling and third party laboratory analysis using applicable U.S. EPA test methods |
06-096 C.M.R. ch. 156, § 9