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, 20°C).
OX = Oxidation factor (0.10), representing estimated portion of collected CH4 that would have eventually oxidized to CO2 if not collected.
GWP = CO2e global warming potential of CH4 (28).
Emissions (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 methane control technology (0.98).
GWP = CO2e global warming potential of CH4 (28).
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 under § 145.394.
MGSTATE = Average annual manure production of all dairy cows and swine in the participating state at the time of submission of a consistency application under § 145.394.
Eb = (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 weather conditions for the facility at which the manure or organic food waste is generated (ft3).
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 x f
Where:
VS = Volatile solids as determined from the equation:
VS = Mm x TS% x VS%
Where:
Mm = Mass of manure or organic food waste produced per month (kg).
TS% = Concentration (%) of total solids in manure or organic food waste as determined through EPA 160.3 testing method (EPA Method Number 160.3, Methods for the Chemical Analysis of Water and Wastes (EPA/600/4-79/020)).
VS% = Concentration (%) of volatile solids in total solids as determined through EPA 160.4 testing method (EPA Method Number 160.4, Methods for the Chemical Analysis of Water and Wastes (EPA/600/4-79/020)).
VSavail = Volatile solids available for decomposition in manure or organic food waste storage each month as determined from the equation:
VSavail = VSp + 1/2 VSin - VSout
Where:
VSp = Volatile solids present in manure or organic food waste storage at beginning of month (left over from previous month) (kg).
VSin = Volatile solids added to manure or organic food waste storage during the course of the month (kg). The factor of 1/2 is multiplied by this number to represent the average mass of volatile solids available for decomposition for the entire duration of the month.
VSout = Volatile solids removed from the manure or organic food waste storage for land application or export (assumed value based on standard farm practice).
f = van't Hoff-Arrhenius factor for the specific month as determined using the equation below. Using a base temperature of 30°C, the equation is as follows:
f = exp {[E(T2 - T1)]/[(GC x T1 x 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 facility where manure or organic food waste is generated (converted from degrees Celsius to degrees Kelvin) as determined from the nearest National Weather Service certified weather station (if reported temperature °C > 5 °C; if reported temperature °C < 5 °C, then f = 0.104).
T1 = 303.15 (30°C converted to °K).
GC = Ideal gas constant (1.987 cal/K mol).
Vm = (VSdec x Bo) x 35.3147
Where:
Vm = Volume of CH4 (ft3).
VSdec = Volatile solids decomposed (kg).
Bo = Manure or organic food waste type-specific maximum methane 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 at the EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010, Annex 3, Table A 180 (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 ones found in the previously-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).
Ep = CO2e emissions due to project activities additional to baseline (tons), including manure transportation, flaring, venting and effluent management.
Table 3. Monitoring requirements
Parameter | Measurement Unit | Frequency of Sampling | Sampling Methods |
Influent flow (mass) into the digester | Kilograms (kg) per month (wet mass) | Monthly total into the digester | In descending order of preference: 1) Recorded mass 2) Digester influent pump flow 3) Livestock population and application of American Society of Agricultural and Biological Engineers (ASABE) standard (ASAE D384.2, March 2005) |
Influent total solids concentration (TS) | Percent (of sample) | Monthly, depending upon recorded variations | EPA Method Number 160.3, Methods for the Chemical Analysis of Water and Wastes (EPA/600/4-79/020) |
Influent volatile solids (VS) concentration | Percent (of TS) | Monthly, depending upon recorded variations | EPA Method Number 160.4, Methods for the Chemical Analysis of Water and Wastes (EPA/600/4-79/020) |
Average monthly ambient temperature | Temperature °C | 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 composition of biogas produced by digester | Percent (of sample) | Quarterly | Bag sampling and third party laboratory analysis using applicable EPA test methods |
25 Pa. Code § 145.395
This section cited in 25 Pa. Code § 145.302 (relating to definitions); 25 Pa. Code § 145.391 (relating to purpose); 25 Pa. Code § 145.392 (relating to definitions); 25 Pa. Code § 145.393 (relating to general requirements); 25 Pa. Code § 145.394 (relating to application process); 25 Pa. Code § 145.396 (relating to accreditation of independent verifiers); and 25 Pa. Code § 145.397 (relating to award and recordation of CO2 offset allowances).