Convert power plant heat rate to thermal efficiency and vice-versa
Heat Rate to Efficiency (%)
Efficiency (%) to Heat Rate
BTU/kWh
kJ/kWh
kcal/kWh
Results:
Understanding Heat Rate and Efficiency
In power generation, the Heat Rate is a measure of the energy efficiency of a power plant. It represents the amount of fuel energy required to generate one unit of electricity (typically 1 kilowatt-hour). The lower the heat rate, the more efficient the facility.
The Conversion Formulas
To convert from Heat Rate (BTU/kWh) to Efficiency (%):
Efficiency (%) = (3,412.14 / Heat Rate) × 100
To convert from Efficiency (%) to Heat Rate (BTU/kWh):
Heat Rate = 3,412.14 / (Efficiency / 100)
Unit Conversion Constants
1 kWh = 3,412.14 BTU (British Thermal Units)
1 kWh = 3,600 kJ (Kilojoules)
1 kWh = 859.85 kcal (Kilocalories)
Real-World Examples
Technology
Typical Heat Rate (BTU/kWh)
Efficiency (%)
Combined Cycle Gas Turbine
6,400
~53.3%
Supercritical Coal Plant
8,500
~40.1%
Simple Cycle Gas Turbine
9,800
~34.8%
function toggleInputs() {
var mode = document.getElementById("calcMode").value;
var hrSection = document.getElementById("heatRateInputSection");
var effSection = document.getElementById("efficiencyInputSection");
var resultBox = document.getElementById("hrResultBox");
resultBox.style.display = "none";
if (mode === "hrToEff") {
hrSection.style.display = "block";
effSection.style.display = "none";
} else {
hrSection.style.display = "none";
effSection.style.display = "block";
}
}
function calculateHeatRate() {
var mode = document.getElementById("calcMode").value;
var resultDiv = document.getElementById("hrOutput");
var resultBox = document.getElementById("hrResultBox");
var btuConstant = 3412.142;
var kjConstant = 3600;
var kcalConstant = 859.845;
if (mode === "hrToEff") {
var val = parseFloat(document.getElementById("heatRateValue").value);
var unit = document.getElementById("heatRateUnit").value;
if (isNaN(val) || val <= 0) {
alert("Please enter a valid positive heat rate value.");
return;
}
var btuEquivalent;
if (unit === "btu") {
btuEquivalent = val;
} else if (unit === "kj") {
btuEquivalent = val * (btuConstant / kjConstant);
} else if (unit === "kcal") {
btuEquivalent = val * (btuConstant / kcalConstant);
}
var efficiency = (btuConstant / btuEquivalent) * 100;
resultDiv.innerHTML = "Thermal Efficiency: " + efficiency.toFixed(2) + "%" +
"Based on a heat rate of " + val.toLocaleString() + " " + unit.toUpperCase() + "/kWh";
} else {
var eff = parseFloat(document.getElementById("efficiencyValue").value);
if (isNaN(eff) || eff 100) {
alert("Please enter a valid efficiency percentage between 0 and 100.");
return;
}
var btuHr = btuConstant / (eff / 100);
var kjHr = kjConstant / (eff / 100);
var kcalHr = kcalConstant / (eff / 100);
resultDiv.innerHTML = "Heat Rate results for " + eff + "% efficiency:" +
"• " + btuHr.toLocaleString(undefined, {maximumFractionDigits: 2}) + " BTU/kWh" +
"• " + kjHr.toLocaleString(undefined, {maximumFractionDigits: 2}) + " kJ/kWh" +
"• " + kcalHr.toLocaleString(undefined, {maximumFractionDigits: 2}) + " kcal/kWh";
}
resultBox.style.display = "block";
}