Screens a preliminary CHP (combined heat and power) system electrical capacity from a facility's continuous electrical and thermal baseload demand, and the candidate CHP technology's heat-to-power ratio (HPR — thermal output per unit of electrical output). The system is sized to the more limiting of the electrical-baseload-derived size and the thermal-baseload-derived size, since oversizing against either wastes the corresponding output and undermines the project economics.
Standards followed
Baseload-matching CHP sizing practice: size = min(electrical baseload, thermal baseload / HPR)
What it can do
- Electrical-baseload-derived and thermal-baseload-derived candidate sizes.
- Recommended size as the smaller (more limiting) of the two, with the governing baseload identified.
- SMALL to VERY LARGE size classification for preliminary screening.
Example problem
500kW continuous electrical baseload, 800kW continuous usable thermal baseload, HPR=1.3 (typical reciprocating-engine CHP).
- Electrical-baseload size = 500kW
- Thermal-baseload size = 800/1.3 ≈ 615.4kW
- Recommended = min(500, 615.4) = 500kW, governed by the electrical baseload
500kW recommended CHP electrical capacity (STANDARD class) — electrical baseload governs.
This is a preliminary screening estimate based on steady baseload demand — real CHP sizing also needs a full 8760-hour load-duration analysis (electrical and thermal load profiles rarely track each other hour-by-hour), local utility interconnection/export rules, and the specific prime mover's actual HPR at partial load, which differs from its rated HPR.