Air dispersion modeling is a critical path element of all capital projects and is expected to remain so for the foreseeable future. Large gains have been made over the years in model accuracy, driven by ever lower standards that must be complied with for projects to move forward. But how will models develop in the future? AERMOD has now been the preferred short-range model for permitting for 15 years but has known limitations as a steady-state model. CALPUFF, once EPA’s preferred long-range model, was removed from the recommended model list with the revisions to 40 CFR Part 51, the “Guideline on Air Quality Models” in 2017, with no identified replacement. Will that remain the case in years to come?
While there are no changes in the preferred modeling systems on the immediate horizon, improvements are continuously being made to improve the accuracy of the existing models. Future versions of AERMOD are expected to include additional NOX-NO2 conversion options, better handling of low wind conditions, and consideration for off-shore conditions amongst other new features.
In the long term, what might the next generation of models look like? Would the next generation after AERMOD be a one-size fits all model, likely Lagrangian, that tracks parcels of air pollutants on an hour to hour basis, has the capability to address atmospheric chemistry, and be sufficiently accurate not only at the fence line but also hundreds of kilometers from the source? What other features might the next preferred modeling system have, and how would we get there?
This presentation will focus on these questions and speculate on what the future of air dispersion modeling holds and what the drivers will be that get us there, as well as what conditions might stifle future development. It will start with a look at the improvements and progress being made with the current preferred modeling systems, and then move on to what the future might hold.
