SUMTER FIELD DESK
Backup or power plant?
What if it generates power on site?
Short answer
Occasional emergency backup is different from regular generation. If engines or turbines run for months because grid service is delayed or inadequate, the campus is functioning as an on-site power plant regardless of labels such as “temporary” or “mobile.”
Three numbers officials need
- Normal facility demand - how much power the campus normally uses.
- Installed generating capacity - often larger because of redundancy.
- Allowed operating hours - the difference between rare backup and routine pollution.
Diesel scale scenario
A representative Caterpillar 3516B has a 1.64 MW continuous rating and uses about 119 gallons of diesel per hour at that rating. Scaling comparable engines to 100 MW of continuous output gives approximately:
| Measure | Approximate amount |
|---|---|
| Diesel per hour | 7,300 gallons |
| Diesel per day | 175,000 gallons |
| Diesel per year | 63.6 million gallons |
| Direct CO₂ per year | 650,000 metric tons |
| Passenger-car CO₂ equivalent | 140,000 typical cars |
This is an around-the-clock scale illustration, not an Americus project forecast.
Natural-gas turbine scale scenario
A representative 16.53 MW turbine with a 9,630 Btu/kWh heat rate scales to approximately:
| Measure at 100 MW continuous output | Approximate amount |
|---|---|
| Gas per hour | 963,000 cubic feet |
| Gas per day | 23.1 million cubic feet |
| Gas per year | 8.44 billion cubic feet |
| Direct CO₂ per year | 450,000 metric tons |
| Passenger-car CO₂ equivalent | 98,000 typical cars |
Natural gas usually emits less direct CO₂, particulate matter, and sulfur pollution than diesel per unit of electricity, but it still emits NOx, CO, VOCs, hazardous pollutants, and CO₂. Upstream methane is outside the stack calculation.
Local health cannot be reduced to “cars”
The car comparison describes annual CO₂ scale only. Cars spread emissions over many roads; a generator plant concentrates emissions at one property. Local health analysis requires unit-specific emission rates, stack heights, operating hours, weather, and dispersion modeling for NO₂, particulate matter, CO, VOCs, and hazardous pollutants.
Questions that close the loopholes
- List every engine and turbine by model, rating, fuel, controls, and location.
- Separate hours for testing, outages, demand response, peak shaving, and delayed grid connection.
- Define “emergency” narrowly.
- Model simultaneous testing and credible outage operation.
- Aggregate temporary, mobile, phased, and commonly controlled equipment.
- Require public hour-meter, fuel, and emissions records.
- Do not allow occupancy before firm grid service without separate approval as a power plant.
The equipment schedule and any air-permit application are records held by the county and Georgia EPD. See how to obtain the records and reach the officials.
Relevant precedent
An official Irish filing illustrates why residents should ask whether generation is truly for emergencies. It describes temporary gas engines followed by nine permanent dual-fuel engines, with seven serving normal load, selective catalytic reduction, and continuous emissions monitoring. This is an example from South Dublin Routing 4 No. 2 Limited, not evidence about the Sumter County proposal.