Attainment / Nonattainment:

An area is said to be in attainment or nonattainment depending on whether it meets EPA's ambient air standards for concentrations of the 6 criteria pollutants. If concentrations of a pollutant exceed EPA's standards the area is said to be in nonattainment for the given pollutant.

Best Available Control Technology (BACT):

This level of control is required when a source triggers Prevention of Significant Deterioration (PSD). It requires a top-down cost analysis of possible control technologies. States make a case-by-case determination of what controls will be required for a new unit based on consideration of both cost and effectiveness.

Combined Heat and Power (CHP) / Cogeneration:

Combined heat and power, also called cogeneration, is the use of a heat engine or a power station to simultaneously generate both electricity and heat.

Criteria Pollutants:

• sulfur dioxide (SO2)
• particulate matter (PM)
  • PM 2.5 – particulate matter less than 2.5 micrometers in diameter
• carbon monoxide (CO)
• ozone
  • Measured by precursor pollutants - nitrogen oxides (NOx) and volatile organic compounds (VOCs)
• nitrogen dioxide (NO2)
• lead

The criteria pollutants are six pollutants that EPA monitors to determine if a region is meeting National Ambient Air Quality Standards (NAAQS). Ambient concentrations of these pollutants that exceed EPA allowable limits result in the area being designated as "nonattainment."

Distributed Generation (DG):

Small, modular, decentralized, grid-connected or off-grid energy systems located in or near the place where energy is used. Also called on-site generation, dispersed generation, embedded generation, decentralized generation, decentralized energy or distributed energy.

Federal New Source Review:

This is the program that requires preconstruction permitting, either NSR or PSD, and requires application of either BACT or LAER for major sources.

Hazardous Air Pollutant (HAP):

The Clean Air Act Directs the EPA to regulated emissions of 189 HAPs. These pollutants are known or suspected carcinogens.

Interconnection:

A distributed generation unit interconnects to the utility electricity grid for back or standby power, or for net-metering. Customers that are interconnected are subject to paying standby rates .

kW - Kilowatt:

A kilowatt is equal to one thousand watts.

Lowest Achievable Emission Rate (LAER):

This level of control is required when a source triggers NSR. It requires application of the most stringent control equipment that has been demonstrated for a similar technology regardless of cost.

Major:

A source that triggers PSD/NSR is considered major.

Maximum Achievable Control Technology (MACT):

The national emission standards for hazardous air pollutants (NESHAPs) established by the U.S. Environmental Protection Agency (EPA) are commonly called maximum achievable control technology (MACT) standards. MACT standards are designed to reduce HAP emissions within a source category, with consideration of cost and available control technology.

Minor:

A minor source has lower emissions than the major threshold. A minor source does not require PSD/NSR.

New Source Review (NSR) / Prevention of Significant Deterioration (PSD):

NSR stands for New Source Review, but actually represents a certain course of action within the federal New Source Review program for permitting of sources in a nonattainment area. Sources that trigger NSR must apply Lowest Achievable Emissions Reduction (LAER). In attainment areas the course of action used is PSD, which stands for Prevention of Significant Deterioration. PSD requires Best Available Control Technology (BACT).

Potential to Emit (PTE):

A unit's potential to emit is the maximum possible emissions that could be generated by that unit if it were to operate 8,760 hour per year at maximum capacity.

Significant:

A source that triggers Title V is considered to emit at a significant level.

Standby Rates:

Standby rates are utility rates that a customer pays to receive power from the grid at times when its own DG is unavailable either unexpectedly or for maintenance reasons.

Title V:

Title V is a section of the Clean Air Act, in part 70, that requires states to issue a separate federal operating permit for sources that exceed certain air pollutant emission thresholds. This is also a federal program typically administered by individual states. The operating permit does not set new control requirements, but rather consolidates all the air requirements applicable to a facility under one regulatory document and establishes the monitoring and reporting requirements necessary to demonstrate compliance with the permit.

If a source emits 100 tons of criteria pollutants, or if the source emits 10 tons of one hazardous air pollutant (HAP) or 25 combined of all HAPs the source may be subject to MACT and must get a Title V permit.

MW - Megawatt:

A megawatt equals one million watts