Valorisation de la Géothermie : le rôle clé des réseaux de chaleur

25. Fachtagung von GEOTHERMIE.CH

Dr Jérôme Faessler

Energy Systems Group

University of Geneva

1. Oktober 2015

Jerome.faessler@unige.ch (phone +41 22 379 06 48)

www.unige.ch/energie

Key Key Key Key ElementsElementsElementsElements

• Energy Introduction

• Geothermal Energy : multi-resource for multi-uses

• Importance and Role of District Heating and Cooling (DHC)

• Multi-ressource

• Linear Heat Density

• Temperature level

• Funding model (capital cost)

• Conflits or synergies with retrofits buildings

• Conclusions

Energy : two main principlesEnergy : two main principlesEnergy : two main principlesEnergy : two main principles

• First law :

• Conservation of energy

• Energy balance (neutral)

• Second law :

• Entropy

• Energy is irremediably degraded → waste energy

• Efficiency

Carnot’s principleCarnot’s principleCarnot’s principleCarnot’s principle

• Importance of Temperature difference

• Typical efficiency for electricity generation :• Geothermy 10-15%

• Wood 20%

• Nuclear 35%

• Coal 35-45%

• Gas turbine combined cycle 55-60%

• Hydoelectric 100%

Source at high

temperature

Heat

Engine

Low

temperature

Qin, Tin

Qout, Tout

Wout

Tout < Tin

ηc : Carnot’s efficiency

Source http://www.energiestatistik.ch

Observation 1

> 75% fossil fuels

Observation 2

Electricity < 25%Observation 3 : Nuclear ≈ 10%

EnergyEnergyEnergyEnergy StatisticsStatisticsStatisticsStatistics (CH)(CH)(CH)(CH)

Observation 4 : Geothermy ≈ 1.5% (Umweltwärme)

Demand Characteristics (CH)Demand Characteristics (CH)Demand Characteristics (CH)Demand Characteristics (CH)

• Household AND Industry / Services

Source : OFEN 2010

• Heat use :

• Space heating + Domestic Hot Water (DHW) + process heat

• Different level temperature

• Different future development

Power in MW

Energy/Power and heat load profileEnergy/Power and heat load profileEnergy/Power and heat load profileEnergy/Power and heat load profile

Data source : CGC 2009 (1 year = 8760h)

Profil of an annual heat demand

Times in hours

Energy in MWh

Power (heat load duration curve) Energy

Source : Hollmuller, UNIGE

Power and EnergyPower and EnergyPower and EnergyPower and Energy

Note : dwellings with space heating and DHW

Géothermal Géothermal Géothermal Géothermal energyenergyenergyenergy : 2 dimensions: 2 dimensions: 2 dimensions: 2 dimensions

• Primary Energy (Eprim) → Final energy (Efinal)

• Hot water / steam: Energy = Flow * Temperature

• Low electrical efficiency (5 to 20%)

• Large quan7ty of heat → district hea7ng (DH)

V

E

R

T

I

C

A

L

HORIZONTAL : USE

Geo-RESOURCESource : CREGE,

Neuchâtel

Eprim

Efinal

Renewable Resources in SwitzerlandRenewable Resources in SwitzerlandRenewable Resources in SwitzerlandRenewable Resources in Switzerland

Source : Eicher&Pauli, 2014, Weissbuch Fernwärme Schweiz – VFS Strategie

“Brutto“ Potential

Swiss Heat Consumption today ≈ 84 TWh (300 PJ)

GeoGeoGeoGeo----Resource and GeoResource and GeoResource and GeoResource and Geo----usesusesusesuses

Source : M. Antics, GPC IP

Geothermal Heat UseGeothermal Heat UseGeothermal Heat UseGeothermal Heat Use

• If Temperature <100 °, direct use with DH more interesting than electrical production

• Using heat pumps to upper resource temperature and / or to lower return temperature is possible (better geothermal efficiency)

• Coupling with electrical production possible but more complex (in parallel or in cascade)

• Generally, 1 kWhel ≈ 5-10 kWhth

Source http://www.bine.info/

What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?

• Benefits of DH:

1. Integration of renewable energy in the urban heating

2. Waste energy recovery (waste, combined heat and power, industry)

3. Mutualisation of resources and investments

Multi Resources DH (Lausanne)Multi Resources DH (Lausanne)Multi Resources DH (Lausanne)Multi Resources DH (Lausanne)

Source : data SIL, adapt from Ms thesis MUSE L. Michel, 2012

Day

Load duration curve by resource (DH Lausanne - 2010)

Da

ily P

ow

er

[MW

]

Sewage plant

Waste plant

Wood

Gas

Multi Resources DH (Lausanne)Multi Resources DH (Lausanne)Multi Resources DH (Lausanne)Multi Resources DH (Lausanne)

Re

ne

wa

ble

sha

re

Fossil share

Source : data SIL, adapt from Ms thesis MUSE L. Michel, 2012

Sewage plant

Waste plant

Wood

Gas

Power and Energy (DH Lausanne - 2010)

Re

lati

ve E

ne

rgy

%

Relative Power %

What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?

• Benefits of DH:

1. Integration of renewable energy in the urban heating

2. Waste energy recovery (waste, combined heat and power, industry)

3. Mutualisation of resources and investments

4. Stabilization of power grid by coupling CHP and HP in winter

• Major constraints:

1. Minimum heat density

Linear Heat density and Heat lossesLinear Heat density and Heat lossesLinear Heat density and Heat lossesLinear Heat density and Heat losses

Source : Nussbaumer and Thalmann, 2014, Status Report on District Heating Systems in

IEA Countries, http://www.ieabcc.nl/publications/IEA_Task32_DHS_Status_Report.pdf

Source : District Heating and Cooling, Euroheat&Power, 2011 survey

Linear Heat density in Europe [MWh/m/y]

What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?

• Benefits of DH:

1. Integration of renewable energy in the urban heating

2. Waste energy recovery (waste, combined heat and power, industry)

3. Mutualisation of resources and investments

4. Stabilization of power grid by coupling CHP and HP in winter

• Major constraints:

1. Minimum heat density

2. District heating temperatures

District heating Temperature EvolutionDistrict heating Temperature EvolutionDistrict heating Temperature EvolutionDistrict heating Temperature Evolution

• Temperature and heating consumption of buildings decrease

• But Temperature and consumption DHW not changed (55-65 °)

• If DH Temperature decrease, then resources Temperature could decrease

Source : Hongwei Li et al, 2014, TOWARD 4th GENERATION DISTRICT HEATING:

EXPERIENCE AND POTENTIAL OF LOWTEMPERATURE DISTRICT HEATING, The

14th International Symposium on District Heating and Cooling, Stockholm

District District District District heatingheatingheatingheating TemperatureTemperatureTemperatureTemperature optimizeoptimizeoptimizeoptimizefor for for for GeothermyGeothermyGeothermyGeothermy : an : an : an : an exampleexampleexampleexample

• Example in Paris region

• GEOTHERMY :

• 25% Power = 60% Energy

• Tresource = 75°C

• multi-tube district

• Sequential system

• Average return Temperature : 35-40°C

source Semhach (http://semhach.fr/)

What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?

• Benefits of DH:

1. Integration of renewable energy in the urban heating

2. Waste energy recovery (waste, combined heat and power, industry)

3. Mutualisation of resources and investments

4. Stabilization of power grid by coupling CHP and HP in winter

• Major constraints:

1. Minimum heat density

2. District heating temperatures

3. Substantial investments ("capital cost")

Boundaries of the cost of DHBoundaries of the cost of DHBoundaries of the cost of DHBoundaries of the cost of DH

Source graphique : ViaSeva, guide des usagers du chauffage urbain, 2009

R1

R2

P1+P2

primary District (R)

Secondary District (P)

R1 : consumption proportional to the heat consumed (variable component)

R2 : fixed subscription corresponding to the size of the substation ("pipe size") (fixed component)

→ typical Contract : 10 to 25 year

PRODUCTION CONSUMPTION

Sale price of DH Sale price of DH Sale price of DH Sale price of DH –––– France exampleFrance exampleFrance exampleFrance example

Source : AMORCE, Prix de vente de la chaleur en 2013

Sale price based on the majority

of the energy use in the DH

Sharing between fixed (red)

and variable (blue) price

What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?What role for District Heating (DH) ?

• Benefits of DH:

1. Integration of renewable energy in the urban heating

2. Waste energy recovery (waste, combined heat and power, industry)

3. Mutualisation of resources and investments

4. Stabilization of power grid by coupling CHP and HP in winter

• Major constraints:

1. Minimum heat density

2. District heating temperatures

3. Substantial investments ("capital cost")

• Conflicts and / or synergies between development of DH and retrofits buildings ?

�REMUER project ongoing (multi-efficient and renewable resource district heating)

http://www.unige.ch/energie/fr/activites/axes/energie/remuer/

RetrofitLogic

Demand Evolution VS expansion of DHDemand Evolution VS expansion of DHDemand Evolution VS expansion of DHDemand Evolution VS expansion of DH

DH expansion Logic

RetrofitLogic

For a same heat demand (370 GWh), wecan : • Use more waste heat

• Improve relativ share of waste heat inethe DH energy mix

• Lower the heat production cost• Decrease consumption of total fossil

fuels

This requires combining two approaches::

• DH Expansion

AND

• Retrofit Buildings (on the DH)

Source : UNIGE project REMUER, adapt from L. Quiquerez

Example DH «CADIOM-CADSIG» in Geneva

DH

Dem

an

d [

GW

h]

Base Load Peak Load

Conclusions Conclusions Conclusions Conclusions –––– key pointskey pointskey pointskey points

• 2 dimensions of geothermal energy :

• Geo resource vertical AND use horizontal

• First energy use = thermal use (heating and cooling)

• Geothermal resource → low temperature (<150°C)

�Easier to use with DHC

• Key Elements of DHC:

� Importance of multi-resource

� Importance of inventory uses (SH, DHW, Industrial, Cold)

�Need for a minimum heat density

� Importance of temperature levels

�Substantial initial investments (capital cost)

�prices and costs of heat, competitiveness (economic approach)

�development scenarios (geographical approach)

�Possible synergies with retrofits buildings

� It takes time !

Thank you for your attentionThank you for your attentionThank you for your attentionThank you for your attention

• http://www.unige.ch/formcont/geodh