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Industrial waste-heat ORC unit: efficiency by source temperature, auxiliaries and LCOE

ORC unit on industrial waste heat (thermal-oil loop): conversion efficiency from the source temperature as a fraction of Carnot, 7 % auxiliaries, installed CAPEX on a sourced 0.867 scale law and the LCOE in EUR/MWh.

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Open Jack

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  • CurrencyEUR 2013
  • Battery limitinstalled
  • 65 documented assumptions
  • Updated2 Nov 2026

Mass and energy balance

What the asset draws and delivers for the case and load you choose.

Reference case

capacity factor: 85.6 %

Equivalent hours per year at gross output. IFC 2014 gives 7,200-7,800 h/year as typical for cement kiln heat recovery and assumes 7,500 h.

Flows

  • In: Industrial waste heat (thermal oil loop)—

Asset

Industrial waste-heat ORC unit

  • Out: Net electricity—

Annual quantities at the current usage.

Gross electric power of the ORC at the generator terminals, before auxiliaries. 0.1-20 MW covers industrial waste-heat ORC units, including the catalogue products Exergy CementiRossi Pederobba (3.5 MW, the default) and Sisecam Targovishte (4.8 MW). The cost anchor is a 0.375 MW kiln ORC (Lemmens 2016); larger sizes follow its 0.867 scale law.

Heat absorbed from the source
— MW
Net electric output
— MW
Auxiliary load
— MW
Heat rejected at the condenser
— MW

CAPEX

Specific cost at this size, what backs it, and how it behaves with scale.

Specific CAPEX at this size

—

Reference size 0.375 MW

Lemmens 2016 §4.2

Model value: the Lemmens 2016 installed cost scaled to the size. Customized: your own installed figure, used as is at every size and no longer sourced.

Specific installed CAPEX by gross electrical output

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  1. Ex-factory
  2. Installed· this figure
  3. Fully financed
CAPEX at the battery limit—
Working capital, contingencyproject level

Included

  • Equipment
  • Installation, civil works and engineering

Not included

  • Working capital
  • Contingency

Added at project level

  • Working capital layer, from the project settings
  • Contingency, from the project settings

Project figures

Values passed to project mode when this asset is added to a project.

Concept sketch, not to scale · drag to rotate

Industrial waste heat (thermal oil loop) in
—
Net electricity outMain product
—
CAPEX to the battery limit
—
Fixed O&M
—
Variable O&M, excluding feedstocks
0 EUR/year
Asset lifetime
25 years

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Levelised cost of electricity

A standalone indicator for a quick read. Project mode recomputes it for the whole system.

—

  • LCOE - capital—
  • LCOE - fixed O&M—

Linked to the balance above

capacity factor: 85.6 %

Equivalent hours per year at gross output. IFC 2014 gives 7,200-7,800 h/year as typical for cement kiln heat recovery and assumes 7,500 h.

Temperature of the thermal oil (or hot gas) entering the ORC evaporator. 150 °C is the IFC floor for ORC; 300 °C is the Exergy Targovishte oil inlet. Pederobba runs at 280 °C.

Thermal power the source can deliver to the oil loop (site measurement or m·cp·ΔT). It is compared with the heat the ORC must absorb; a shortfall raises a flag but does not resize the unit.

Price of the grid electricity the plant no longer buys. 180 EUR/MWh is the Eurostat EU non-household average, H1 2026, including non-recoverable taxes. Used only for the avoided cost; it does not enter the LCOE.

Real weighted average cost of capital. IRENA uses 5 % real (OECD and China, 2020) and 7.5 % in 2010.

Annuity period. IRENA uses 25 years for geothermal plants and 20 for biomass power; Quoilin gives an ORC turbine 30 years.

Levelised cost of electricity by operating hours

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Benchmarks

This model's figures against published references and reference cases.

Gross cycle efficiency, %

22.8 Exergy CementiRossi

24 Quoilin 2013 §4

Fraction of Carnot applied, %

30 ORNL/ICF 2015 §3.1

50 ORNL/ICF 2015 §3.1

Reference cases at this size and usage

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All results

Every model output at the current settings, grouped, with the sensitivity charts.

46 outputs · 4 groups · 13 also shown above, dimmed

Levelised cost of electricity

7
Levelised cost of electricity
ComputingEUR/MWh
LCOE - capital
ComputingEUR/MWh
LCOE - fixed O&M
ComputingEUR/MWh
Capital share of the LCOE
Computing%
LCOE at 7.5 % real WACC
ComputingEUR/MWh
LCOE with the six-tenths rule
ComputingEUR/MWh
Avoided electricity purchases
ComputingEUR/year

Conversion efficiency

8
Net conversion efficiency
Computing%
Gross cycle efficiency
Computing%
Carnot efficiency
Computing%
Fraction of Carnot applied
Computing%
Carnot fraction of the Pederobba anchor
Computing%
Net efficiency at Targovishte conditions
Computing%
Efficiency capped at 24 %
Computingbool
Auxiliary load penalty
Computingratio

Heat and power balance

15
Heat absorbed from the source
ComputingMW
Net electric output
ComputingMW
Auxiliary load
ComputingMW
Heat rejected at the condenser
ComputingMW
Source heat coverage
Computing%
Heat shortfall
Computingbool
Gross output the source can carry
ComputingMW
Operating hours
Computingh/year
Capacity factor
Computing%
Gross electricity
ComputingMWh/yr
Auxiliary electricity
ComputingMWh/yr
Net electricity
ComputingMWh/yr
Waste heat absorbed
ComputingMWh/yr
Heat rejected and losses
ComputingMWh/yr
Specific heat consumption
ComputingMWh/MWh

Capital and O&M

16
Installed CAPEX
ComputingEUR
Installed CAPEX (MEUR)
ComputingMEUR
Specific installed CAPEX
ComputingEUR/kW
Specific CAPEX, model value
ComputingEUR/kW
Specific CAPEX per net kW
ComputingEUR/kW
Specific CAPEX with the six-tenths rule
ComputingEUR/kW
ORNL installed cost bracket
ComputingUSD/kW
Thermal-oil loop CAPEX
ComputingEUR
ORC unit and integration CAPEX
ComputingEUR
Implied module price (low)
ComputingEUR
Implied module price (high)
ComputingEUR
Capital recovery factor
Computing1/year
Capital recovery factor at 7.5 %
Computing1/year
Annualised CAPEX
ComputingEUR/year
Fixed O&M
ComputingEUR/year
Total annual cost
ComputingEUR/year

Sensitivities

5 charts
LCOE components vs operating hours

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Efficiency and heat absorbed vs source temperature

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Specific CAPEX and LCOE vs gross output

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LCOE vs real WACC

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Heat balance vs source temperature

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Sources

65 documented assumptions · 8 sources

About

Calculator context

This calculator targets industrial waste heat: an organic Rankine cycle (ORC) unit that turns the heat of cement-kiln or glass-furnace flue gas, engines or compressors, usually carried by a thermal-oil loop, into electricity. It is filed under the geothermal sector only to attach to the catalogue sheet of ORC power units; there is no well, no brine and the heat is free.

Efficiency follows the ORNL/ICF 2015 method: the cycle reaches a fraction of the Carnot efficiency between the source inlet temperature and a 15.6 °C sink. The default fraction, 47.7 %, is calibrated on one plant, Exergy's CementiRossi Pederobba ORC (3.5 MWe, 22.8 % gross at 280 °C oil, with reheat), so reproducing 22.8 % there is the calibration, not a validation. A non-reheat case removes Exergy's 10 % reheat gain (derived), and two cases span ORNL's 30-50 % range; the gross efficiency is capped at the 24 % Quoilin ceiling. Auxiliaries take 7 % of gross output (IFC 2014, cement WHR, transposed to ORC). At 4.8 MW and 300 °C (Exergy Targovishte) the model predicts about 22 % net; Exergy prints no efficiency for that plant.

The installed CAPEX scales from the actual cost of a 375 kW kiln ORC in Flanders, 4,216 EUR2013/kW gross including the oil circuit, piping, installation and project management (Lemmens 2016), with the 0.867 ORC capacity exponent reported by Lemmens; it is declared installed, never a module price (Quoilin: total cost 2-3x the module). Published gaps: ORNL's 2015 installed brackets (4,500 to 2,500 USD2015/kW) sit close to the model, IFC's 7,000 USD/kW for a 2 MW cement ORC sits well above it, and ORNL's O&M per kWh is about twice the 1.25 % of CAPEX derived from IFC. The CAPEX depends on electric output only, so it does not grow with the larger heat exchangers a low-temperature source needs: below about 200 °C the cost is likely understated.

At the nominal case (3.5 MW, 280 °C, 7,500 h, 5 % real WACC, 25 years) the unit absorbs 15.35 MW of heat, nets 21.2 % and 24,413 MWh/yr for 10.96 MEUR2013 installed (3,132 EUR/kW), an LCOE of about 37.5 EUR2013/MWh. Costs are in EUR 2013, not escalated; the avoided electricity price (Eurostat, H1 2026) is in EUR 2026 and is not compared with the LCOE without indexation.

Model

125 variables — inputs, calculations and outputs, with their dependencies.

125 variables shown of 125
VariableValueUnitDepends on
3.5MW—
7500h/year—
280°C—
1——
16MW—
0——
3100EUR/kW—
180EUR/MWh—
0.05ratio—
25years—
VariableFormulaUnitDepends on
if((<=)+(<=)+(>)+(<)+(>)+(!=)*(!=)*(!=)*(!=)+(<)+(<)+(>)+(>=)*(<=)+(<)+(<)+(>=)+(<)+(>)>,,)bool
+K
+K
(-/(+))*%
/(+*)%
**%
/ratio
if(>=,,)—
*ratio
VariableFormulaUnitDepends on
(-/max(,))*%
/max(,)*%
if(==,,if(==,,if(==,,)))%
min(,)%
if(>,,)bool
*ratio
*(-)%
min(**(-/(+))*,)*(-)%
/max(*,)MW
*MW
-MW
-MW
/max(,)*%
if(<,,)bool
**MW
min(,)h/year
/*%
*MWh/yr
*MWh/yr
*MWh/yr
*MWh/yr
-MWh/yr
/max(,)MWh/MWh
clamp(*^(-),,)EUR/kW
if(>=,,clamp(*^(-),,))EUR/kW
**EUR
/MEUR
/max(*,)EUR/kW
**EUR
-EUR
/EUR
/EUR
*^(-)EUR/kW
if(<,,if(<,,if(<,,if(<=,,))))USD/kW
if(<,/max(,),(*(+)^)/max((+)^-,))1/year
*EUR/year
**EUR/year
+EUR/year
/max(,)EUR/MWh
/max(,)EUR/MWh
+EUR/MWh
/max(,)*%
(*(+)^)/max((+)^-,)1/year
(*+)/max(,)EUR/MWh
***(+*)/max(,)EUR/MWh
*EUR/year

Assumptions

65 assumptions used in the calculations

  • Prevents division by zero.

    Market range Not applicable.

    0.000001
    Numerical guard

  • Named zero for guards (no inline literal).

    Market range Not applicable.

    0
    Numerical constant

  • Named one for guards, switches and the annuity formula.

    Market range Not applicable.

    1
    Numerical constant

  • Converts a fraction to percent.

    Market range Not applicable.

    100%
    Unit convention

  • Converts a percent to a fraction.

    Market range Not applicable.

    0.01
    Unit convention

  • Upper limit of operating hours and capacity-factor base.

    Market range 8760 (8784 in a leap year).

    8760h/year
    Time convention

  • MW to kW for the specific CAPEX.

    Market range Not applicable.

    1000kW/MW
    Unit convention

  • EUR to million EUR for display.

    Market range Not applicable.

    1000000EUR/MEUR
    Unit convention

  • Carnot efficiency needs absolute temperatures.

    Market range Not applicable.

    273.15K
    Unit convention

  • Keeps the scale law positive if the size input is ever pushed to an absurd value.

    Market range Not applicable.

    1EUR/kW
    Numerical guard

  • Upper numerical guard; it does not cap any value inside the declared domain.

    Market range Not applicable.

    1000000EUR/kW
    Numerical guard

  • Numeric id of the reference case: reheat cycle, Exergy Pederobba calibration. The DSL has no strings.

    Market range Not applicable.

    1
    Numeric selector encoding.

  • Numeric id of the reference case: non-reheat cycle. The DSL has no strings.

    Market range Not applicable.

    2
    Numeric selector encoding.

  • Numeric id of the reference case: ORNL low end of the Carnot-fraction range. The DSL has no strings.

    Market range Not applicable.

    3
    Numeric selector encoding.

  • Numeric id of the reference case: ORNL high end of the Carnot-fraction range. The DSL has no strings.

    Market range Not applicable.

    4
    Numeric selector encoding.

  • Fraction of the Carnot efficiency reached by the reference case 'Reheat cycle'.

    Market range ORNL: 30-50 % of Carnot for Rankine cycles.

    47.7%
    Calibration on Exergy Pederobba (one plant).

  • Low end of the ORNL range, used by the reference case 'ORNL low end'.

    30%
    ORNL/ICF 2015 §3.1

  • High end of the ORNL range, used by the reference case 'ORNL high end'.

    50%
    ORNL/ICF 2015 §3.1

  • Cold-side temperature of the Carnot efficiency. Kept fixed: no sourced air-cooled versus water-cooled split was found.

    Market range No independent range cited.

    15.6°C
    ORNL Fig. 5 convention

  • Removes the reheat gain from the Pederobba calibration to build the 'Non-reheat cycle' case: 47.7 / 1.10 = 43.4 % of Carnot (derived, not printed).

    Market range No independent range cited.

    10%
    Exergy CementiRossi

  • Caps the gross cycle efficiency. It binds only in the 'ORNL high end' case above about 292 °C; the flag efficiency_capped_flag then shows 1.

    Market range Current high-temperature ORC: up to 24 %.

    24%
    Quoilin 2013 §4

  • Calibration anchor of the default Carnot fraction; shown as a benchmark next to the gross efficiency.

    Market range Quoilin 2013: current high-temperature ORC does not exceed 24 %.

    22.8%
    Exergy CementiRossi

  • Size of the calibration plant and default size of the calculator.

    Market range Not applicable.

    3.5MW
    Exergy CementiRossi

  • Hot-side temperature of the calibration; the Carnot efficiency of the anchor is recomputed from it.

    Market range Not applicable.

    280°C
    Exergy CementiRossi

  • Oil return temperature of the calibration plant; not used by the efficiency method.

    Market range Not applicable.

    100°C
    Exergy CementiRossi

  • Second catalogue product inside the size slider.

    Market range Not applicable.

    4.8MW
    Exergy Targovishte

  • Upper limit of the source temperature and the condition of the output net_efficiency_at_targovishte_pct (a model prediction: Exergy prints no efficiency for this plant).

    Market range Not applicable.

    300°C
    Exergy Targovishte

  • Oil return temperature of the Targovishte plant.

    Market range Not applicable.

    150°C
    Exergy Targovishte

  • Lower limit of the source temperature; below it the input is invalid.

    Market range Not applicable.

    150°C
    IFC 2014

  • Share of the gross output used by the unit's own auxiliaries.

    Market range No independent range cited.

    7%
    IFC 2014 Fig. 11 / 12

  • Default of the operating-hours slider.

    Market range IFC: 7,200-7,800 h/year.

    7500h/year
    IFC 2014

  • Lower end of the operating-hours slider.

    7200h/year
    IFC 2014

  • Upper end of the operating-hours slider.

    7800h/year
    IFC 2014

  • Installed specific cost of the cost anchor, in EUR 2013, per kW gross.

    Market range ORNL Table 5: 4,500-2,100 USD2015/kW (50 kW to >20 MW); IFC 2014: up to 7,000 USD/kW at 2 MW.

    4216EUR/kW
    Lemmens 2016 §4.1

  • Reference size of the scale law.

    Market range Not applicable.

    0.375MW
    Lemmens 2016 §4.1

  • Capacity exponent of the installed cost on gross electric output.

    Market range Generic six-tenths rule 0.6 (Lemmens §2), rejected over 0.1-20 MW.

    0.867
    Lemmens 2016 §4.2

  • Exponent of the comparison output specific_capex_six_tenths_eur_per_kw.

    Market range Not applicable.

    0.6
    Lemmens 2016 §2

  • Currency year of every cost in this calculator.

    Market range Not applicable.

    2013year
    Lemmens 2016

  • Splits the CAPEX into the thermal-oil loop and the ORC unit with its integration.

    Market range No independent range cited.

    11%
    Lemmens 2016 §4.1

  • Lower ratio: gives the highest module price implied by the installed CAPEX.

    2
    Quoilin 2013 §3

  • Higher ratio: gives the lowest module price implied by the installed CAPEX.

    3
    Quoilin 2013 §3

  • ORNL bracket shown next to the model's specific CAPEX.

    4500USD/kW
    ORNL/ICF 2015 Table 5

  • ORNL bracket shown next to the model's specific CAPEX.

    4000USD/kW
    ORNL/ICF 2015 Table 5

  • ORNL bracket shown next to the model's specific CAPEX.

    3000USD/kW
    ORNL/ICF 2015 Table 5

  • ORNL bracket shown next to the model's specific CAPEX.

    2500USD/kW
    ORNL/ICF 2015 Table 5

  • Largest ORNL bracket.

    2100USD/kW
    ORNL/ICF 2015 Table 5

  • Bracket edge of the ORNL comparison.

    Market range Not applicable.

    0.5MW
    ORNL/ICF 2015 Table 5

  • Bracket edge of the ORNL comparison.

    Market range Not applicable.

    1MW
    ORNL/ICF 2015 Table 5

  • Bracket edge of the ORNL comparison.

    Market range Not applicable.

    5MW
    ORNL/ICF 2015 Table 5

  • Bracket edge of the ORNL comparison.

    Market range Not applicable.

    20MW
    ORNL/ICF 2015 Table 5

  • Upper reference for a small cement ORC; sets the top of the Customized CAPEX slider.

    Market range Not applicable.

    7000USD/kW
    IFC 2014

  • Fixed O&M as a share of the installed CAPEX per year.

    Market range ORNL: 10-20 USD2015/MWh.

    1.25%/year
    IFC 2014

  • Base of the derived ORC O&M share.

    Market range Not applicable.

    2.5%/year
    IFC 2014

  • Cross-check of the O&M assumption.

    0.013USD/kWh
    ORNL/ICF 2015 Table 5

  • Default of the real discount rate.

    Market range IRENA: 5-7.5 % real.

    5%
    IRENA RPGC 2023 p. 199

  • High real WACC used by the sensitivity output lcoe_at_wacc_high_eur_per_mwh.

    Market range IRENA: 5-7.5 % real.

    7.5%
    IRENA RPGC 2023 p. 199

  • Default economic life and the service life exported to the project.

    25years
    IRENA RPGC 2023 p. 199

  • Lower end of the lifetime slider.

    20years
    IRENA RPGC 2023 p. 199

  • Upper end of the lifetime slider.

    30years
    Quoilin 2013 §4

  • Default of the avoided electricity price (EUR 2026).

    180EUR/MWh
    Eurostat H1 2026

  • Gross efficiency = Carnot fraction x Carnot efficiency between the source inlet temperature and a 15.6 °C sink, capped at 24 % (Quoilin). Net efficiency removes 7 % auxiliaries.

    Market range Not applicable.

    —
    ORNL/ICF 2015

  • The installed CAPEX depends on the gross electric output only. At low source temperature the heat exchangers grow with the heat input (about 1.5x more heat per kWe at 150 °C than at 280 °C), which this law does not capture: the CAPEX, and so the LCOE, is likely understated below about 200 °C.

    Market range Not applicable.

    —
    Model limit

  • All costs, the CAPEX and the LCOE are in EUR 2013, not escalated. The avoided electricity price is in EUR 2026; the two are not compared directly without indexation.

    Market range Not applicable.

    —
    Currency convention

  • The waste heat has no cost. The LCOE is a pure cost of service: annualised installed CAPEX plus fixed O&M, per MWh net.

    Market range Not applicable.

    —
    Scope convention

  • The CAPEX is declared 'installed': the project adds only its working layer and contingency.

    Market range Not applicable.

    —
    Battery limit