250 R.I. Code R. 250-RICR-120-05-43.10

Current through November 7, 2024

Section 250-RICR-120-05-43.10 - Credit for Concurrent Emissions Reductions

43.10.1Flared Fuels

A. If a distributed generator uses fuel that would otherwise be flared, the emissions that were or would have been produced through the flaring can be deducted from the actual emissions of the distributed generator for the purposes of calculating compliance with the emission standards in this rule. If the actual emissions from flaring can be documented, they may be used as the basis for calculating the credit, subject to the approval of the Office of Air Resources. If the actual emissions from flaring cannot be documented, then the following default values shall be used:

Emissions	Waste, Landfill, Digester Gases
nitrogen oxides	0.1 lbs/MMBtu
carbon monoxide	0.7 lb/MMBtu
carbon dioxide	117 lb/MMBtu

43.10.2Combined Heat and Power

A. CHP installations must meet the following requirements to be eligible for emissions credits related to thermal output:

a. The power-to-heat ratio must be between 4.0 and 0.15.

b. The design system efficiency must be at least 55 percent (55%).

B. A CHP system that meets these requirements can receive a compliance credit against its actual emissions based on the emissions that would have been created by a conventional separate system used to generate the same thermal output. The credit will be subtracted from the actual generator emissions for purposes of calculating compliance with the emission standards in § 43.8.2 of this Part. The credit will be calculated according to the following assumptions and procedures:

1. The emission rates for the displaced thermal system (e.g. boiler) will be:

a. For CHP installed in new facilities, the emissions limits applicable to new natural gas-fired boilers in 40 C.F.R. § 60 Subparts Da, Db, Dc, incorporated in § 43.4(A) of this Part, as applicable, in lb/MMBtu.

b. For CHP facilities that replace existing thermal systems for which historic emission rates can be documented, the historic emission rates in lbs/MMBtu but not more than:

Emissions	Maximum Rate
nitrogen oxides	0.3 lbs/MMBtu
carbon monoxide	0.08 lb/MMBtu
carbon dioxide	117 lb/MMBtu

2. The emissions rate of the thermal system in lbs/MMBtu will be converted to an output-based rate by dividing by the thermal system efficiency. For new systems the efficiency of the avoided thermal system will be assumed to be eighty percent (80%) for boilers or the design efficiency of other process heat systems. If the design efficiency of the other process heat system cannot be documented, an efficiency of eighty percent (80%) will be assumed. For retrofit systems, the historic efficiency of the displaced thermal system can be used if that efficiency can be documented and if the displaced thermal system is either enforceably shut down and replaced by the CHP system, or if its operation is measurably and enforceably reduced by the operation of the CHP system.

3. The emissions per MMBtu of thermal energy output will be converted to emissions per MWh of thermal energy by multiplying by 3.412 MMBtu/MWh_thermal.

4. The emissions credits in lbs/MWh_thermal, as calculated in §43.10.2(B)(3) of this Part, will be converted to emissions in lbs/MWh_emissions by dividing by the CHP system power-to-heat ratio.

5. The credit, as calculated above in §43.10.2(B)(4) of this Part, will be subtracted from the actual emission rate of the CHP unit to produce the emission rate used for compliance purposes.

6. The mathematical calculations set out in §§43.10.2(B)(1) through (4) of this Part are expressed in the following formula:

Credit lbs/MWh_emissions = [(boiler limit lbs/MMBtu)/(boiler efficiency)] x [3.412/(power to heat ratio)]

43.10.3End-Use Efficiency and Non-Emitting Resources

When end-use energy efficiency and conservation measures or electricity generation that does not produce any of the emissions regulated herein are installed and operated contemporaneously at the facility where the generator is installed and operated, then the electricity savings credited to the efficiency and conservation measures or supplied by the non-emitting electricity source shall be added to the electricity supplied by the generator for the purposes of calculating compliance with the emission standards of this rule, subject to the approval of the Office of Air Resources and in accordance with any guidelines established by the Office of Air Resources for determining such savings.

250 R.I. Code R. 250-RICR-120-05-43.10

Amended effective 1/13/2019