I worked in a team to develop and analyze a business plan to replace the primarily coal-fired boilers at the Anheuser-Busch brewery in St. Louis, which provides electricity and steam for the brewery’s operations. Note that this was a class project for CEVE 307: Energy and the Environment, which we completed using publicly available data and was no way affiliated with the brewery.

Our goal was to generate 100,000 MWh of electricity per year (thus restoring the plant to it’s peak capacity from historical EIA data) and reduce pollutant emissions while saving the company money long-term. To achieve this objective, we considered three options:

  1. Replacing the coal coilers with a combined heat and power natural gas boiler system.
  2. Updating the current plant with proper control technologies to reduce emissions, including limestone forced oxidation (LSFO), selective catalytic reduction (SCR), activated carbon injection (ACI), and carbon capture (CC).
  3. Shutting down the onsite utility plant and purchasing all electricity from the local utility company.

After evaluating the proposals via energy, environmental, and financial metrics, we ultimately recommended implementing the natural gas combined heat and power plant.

In this analysis, I focused on energy and environmental calculations. First, I calculated and compared the efficiencies of the current plant, an updated plant with and without carbon capture technology, and natural gas CHP with and without SCR technology. The comparison accounted for the capacity penalty associated with additional control technology, and the results are shown in the graph below.

efficiencies graph

To evaluate the environmental impact of the proposals, I considered NOx, SO2, CO2, CH4, and N2O emissions for six different scenarios. The analysis accounts for capacity pentalties and the effectiveness of each control technology. Also, the environmental impacts of purchasing all electricity from the grid were quantified using Electric Power Annual 2012 data on the resource mix and source emissions for electricity generation in Missouri to derive emission rates for the utility sector.

Emission Emission rate (lb/MWh)
Current Plant Current + LSFO, SCR, ACI Current + LSFO, SCR, ACI, CC Buy electricity Natural Gas CHP Natural Gas CHP + SCR
NOx 2.637 0.2682 0.3353 1.6332 0.7638 0.0768
SO2 24.2225 0.4928 0.6160 3.3699 0.0213 0.0214
CO2 1275.84 1297.7606 214.0265 1854.7317 735.3512 738.9847
CH4 0.0155 0.0158 0.0197 na 0.0146 0.0147
N2O 0.0216 0.0220 0.0275 na 0.0015 0.0015
Note: na = not available

To complete the analysis, my teammates compared the economics of each proposal, created an approval plan, and developed a tentative implementation schedule for the natural gas comvined heat and power plant.