Additional Resources Save and Share How to Build a Retrofit Project Step 1: Determine Target Emissions Step 2: Identify Candidate Equipment and Technology Options Step 3: Assess Cost Effectiveness Step 4: Emission Credits Step 5: Consider Implementation Issues

 

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Step 4: Emission Credits

Each air quality nonattainment or maintenance area has a plan that demonstrates to the U.S. EPA that it can meet and maintain the Federal National Ambient Air Quality Standards (NAAQS). These plans are called State Implementation Plans (SIPs). The SIPs must show the amount of emission reductions each polluting sector (stationary, area, off-road mobile and on-road mobile) will reduce.

EPA requires that each state achieve the reductions called for in the SIP. Diesel retrofit programs have proved to be very cost effective, and demonstration of these reductions is critical to the State. If CMAQ funds, which are from the Highway Trust Fund, are used for diesel retrofit programs, it is especially helpful to transportation agencies to be able to take "credit" for the emission reductions.

A general overview for claiming credit for on-road reductions and off-road is provided below. For more detailed guidance, download EPA's report - Diesel Retrofit: Quantifying and Using Their Benefits in SIPs and Conformity.

Emissions Credit for On-Road Mobile Source Diesel Retrofit Programs

If the diesel retrofit program is for buses, trucks, or other on-road vehicles, the Metropolitan Planning Organization (MPO) should be sure to take credit for the reductions in its transportation conformity analysis, which is required in order for the area to receive federal transportation funding. In fact, the MPO may likely need the credit to pass the required transportation conformity tests, pursuant to U.S. EPA's transportation conformity rule.

What makes diesel retrofit programs especially attractive to MPOs and State DOTs is that the emission reductions are immediate and cost-effective, and can help them meet the transportation conformity requirements. This is very important in the near term, from now through the next five or so years. Diesel retrofits are more cost effective than most projects and programs that CMAQ has funded in the past ten year and transportation agencies are challenged to find cost-effective reductions from on-road mobile sources.

There are a number of methods to calculate the emission reductions for such projects. The following resources provide guidance on calculation methodologies for emissions credits:

• Carl Moyer Program
• Sacramento Emergency Clean Air Transportation (SECAT)
• Texas Emission Reduction Program
  

Emissions Credit for Off-Road Mobile Source Diesel Retrofit Programs

For off-road retrofit projects (e.g., construction equipment, port equipment) transportation agencies may need to be able to take emission reduction credits if CMAQ funds are used. This is because transportation agencies can have a difficult time meeting transportation conformity requirements and need all the emission reducing projects they can possibly identify.  

So, if CMAQ funds are used, the transportation agencies may need a mechanism to take credit for those reductions as a part of their efforts to improve air quality. Procedures for addressing this are under discussion in a number of states, and EPA is aware that this is a potential obstacle to using transportation funding for other than on-road retrofit projects.

However, there are numerous examples of states developing methodologies for estimating the emission reductions from both on and off-road diesel retrofit programs in order to meet SIP commitments. These approaches could easily be used for on-road mobile source reductions. The resources listed above all address how to determine cost effectiveness and emission reductions for projects and in each of the three cases listed (Carl Moyer, SECAT, and TERP) SIP credits are taken for these retrofit projects.