The proprietary Greenmont Energy Model (GEM) optimizes and forecasts the steam coal and electricity supply/demand/price balances as they are likely to operate in a free market in the United States over the next few decades. GEM contains fairly sophisticated methods of dealing with air emission limitations under various future scenarios and models the markets of the emission allowances for the various pollutants considered.

GEM includes all power plants in the U.S. in detail, but when it comes to coal-fired power plants, the model level of detail is unique. The coal-fired plants are modeled on a unit-by-unit basis, providing the most specificity of any U.S. domestic steam coal markets model.

GEM minimizes total system cost of U.S. electricity production and distribution. The demand zones or areas, together with load curves, are given and connected via a transmission network. Power plants supply energy into this network. A power plant is assigned to a particular demand area, based on its location. For power plants not fired by coal or gas, a simplified generation cost and emission rate is applied. For gas-fired plants, the generation cost is taken off a complex gas supply curve based on some elasticity assumptions.

In the model, coal-fired power plants can invest or use already installed abatement technology capacity to reduce the emission rates for all major pollutants. In addition, they can buy emission allowances from other emitters. The coal-fired power plants also have complete freedom of choice in the quality of coal to use. All coals are available to every coal-fired units based on realistic coal use assumptions.
The delivered cost of coal is determined for each plant by a tranportation cost estimate and a mining cost which is drawn from a set of detailed supply curves.

The cost modules of GEM are:

- Cost of wheeling power
- Cost of new plant construction
- Generation cost which for coal units consist of:

1- FOB Mine Price
2- Clean-up technology cost
3- Penalty cost of usage
4- O&M cost
5- Transport cost