Skip to main content

Science – Society – Technology

Table 3 Parametrization for Case 1 (conventional geothermal system) and Case 2 (enhanced geothermal system)

From: Sustainable operation of geothermal power plants: why economics matters

Parameter

Symbol

Case 1

Case 2

Unit

Source/section

Thermal capacity of reservoir rock

\({c}_{\text{r}}\)

800

1000

(J kg−1 K−1)

Proske (undated: 7)

Stober and Bucher (2014: 10)

Density of reservoir rock

\({\rho }_{\text{r}}\)

2600

2700

(kg m−3)

Proske (undated: 7)

Specific thermal capacity of fluid

\({c}_{\text{f}}\)

4120

4120

(J kg−1 K−1)

Density of heat carrying fluid

\({\rho }_{\text{f}}\)

1000

1000

(kg m−3)

Porosity

\(\Phi\)

20

1

(%)

Björnsson and Bodvarsson (1990: 19)

Moeck (2014: 878)

Reservoir volume

\(V\)

4.5  109

3  109

(m3)

Bine.info (2009)

Reservoir temperature

TR

270

180

(°C)

Björnsson and Bodvarsson (1990: 19)

Gerard and Kappelmeyer (1987: 399)

Surface temperature

TS

14

14

(°C)

Walter (2016: 7)

Measured drilling depth

MD

1500

4000

(m)

Bignall et al. (2010: 6)

Moeck (2014: 875)

Recovery factor

R

20

5

(%)

cf. “Recovery factor

Temperature of produced fluid

\({T}_{\text{prod}}\)

260

175

(°C)

Björnsson and Bodvarsson (1990: 19) bine.info (2009)

Temperature of reinjected fluid

\({T}_{\text{rein j}}\)

65

65

(°C)

cf. “Reinjection

Bine.info (2009)

Heat from radioactive decay

\({H}_{\text{R}}\)

2.7  10–6

3  10–6

(W m−3)

Hasterok and Webb (2017: 925)

Rybach (1976)

Heat flow from earth’s interior

\({H}_{\text{F}}\)

13.3

0.105c

(W m−2)

O'Sullivan et al. (2010: 315)

Reservoir surface area

\(A\)

3∙107

3  106

(m2)

O'Sullivan et al. (2010: 315)

Bine.info (2009)

Net conversion efficiency

\(\eta\)

14

8

(%)

cf. “Conversion efficiency

Average productivity per well

\(\bar{w}\)

5

1.5

(MWe)

cf. “Well productivity

Electricity price/feed-in tariff

\(p\)

50

240d

(€ MWh−1)

EEX (2019)

BDEW (2017: 36)

Discount rate

\(i\)

5

5

(%)

Reference initial production decline rate

\({D}_{\text{i}}\)

5

5

(%)

cf. “Production decline

Reference initial capacitya

\({W}_{\text{i}}\)

100

25

(MWe)

cf. “Production decline

Well reserve factor

\(r\)

10

0

(%)

cf. “Production decline

Tax rate

\(\text{tax}\)

20b

e

(%)

Surrounding thermal compensation

\(\beta\)

1

6

(%)

cf. “Recovery factor

Plant type

 

Flash

Binary

 

O'Sullivan et al. (2010: 315)

Bine.info (2009)

Capacity factor

cap

0.95

0.95

(%)

cf. “Capacity factor

Start for make-up well drilling

 

1

1

(a)

cf. “Costs (Number of wells required)”

  1. aDue to the strong convective setting, reference production decline capacity was set to 100 MWe
  2. bWe chose a very moderate tax rate, as the model currently does not take into account realization of tax savings
  3. cValue of the heat flow from Cooper Basin, an HDR project in South Australia (O'Sullivan et al. 2010: 315)
  4. dCase 2 is calculated with the current German feed-in tariff for geothermal electricity as normal electricity prices were not sufficient for profitable operation
  5. eTaxes have been neglected for Case 2