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

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Conference Presentation

Reference

FAESSLER, Jérôme

Abstract

En partant de quelques considérations générales concernant l'énergie et la géothermie, cette conférence montrera que les réseaux thermiques ont très certainement un grand rôle à jouer pour la valorisation directe de la géothermie

FAESSLER, Jérôme. Valorisation de la Géothermie : le rôle clé des réseaux de chaleur. In: 25.

Fachtagung von GEOTHERMIE.CH, Berne, 1. octobre, 2015, p. 34 p.

Available at:

http://archive-ouverte.unige.ch/unige:76522

Disclaimer: layout of this document may differ from the published version.

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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

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Key Elements

• 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

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Energy : two main principles

• First law :

• Conservation of energy

• Energy balance (neutral)

• Second law :

• Entropy

• Energy is irremediably degraded → waste energy

• Efficiency

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Carnot’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

Q_in, T_in

Q_out, T_out

W_out

T_out T_in

η_c: Carnot’s efficiency

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Source http://www.energiestatistik.ch

Energy Statistics (CH)

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Source http://www.energiestatistik.ch

Observation 1

> 75% fossil fuels Observation 2 Electricity < 25%

Observation 3 : Nuclear ≈ 10%

Energy Statistics (CH)

Observation 4 : Geothermy ≈ 1.5% (Umweltwärme)

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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

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Power in MW

Energy/Power and heat load profile

Data source : CGC 2009

Profil of an annual heat demand

Times in hours

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Energy/Power and heat load profile

Data source : CGC 2009

Profil of an annual heat demand

Times in hours Energy in MWh

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Power (heat load duration curve) Energy

Source : Hollmuller, UNIGE

Power and Energy

Note : dwellings with space heating and DHW

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Géothermal energy : 2 dimensions

• Primary Energy (E

_prim

) → Final energy (E

_final

)

• Hot water / steam: Energy = Flow * Temperature

• Low electrical efficiency (5 to 20%)

• Large quan ty of heat → district hea ng (DH)

V E R T I C A L

HORIZONTAL : USE

Geo‐RESOURCE

Source : CREGE, Neuchâtel

E_prim

E_final

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Geo‐Resource and Geo‐uses

Source : M. Antics, GPC IP

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Renewable Resources in Switzerland

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

“Brutto“ Potential

Swiss Heat Consumption today = 84 TWh (300 PJ)

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Geothermal 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 kWh

_el

≈ 5‐10 kWh

_th

Source http://www.bine.info/

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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

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Multi Resources DH (Lausanne)

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

Day

Load duration curve by resource (DH Lausanne ‐ 2010)

Daily Power [MW]

Sewage plant Waste plant Wood

Gas

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Multi Resources DH (Lausanne)

Gas

Power and Energy (DH Lausanne ‐ 2010)

Relative Energy%

Relative Power %

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Multi Resources DH (Lausanne)

Renewableshare

Fossil share

Gas

Power and Energy (DH Lausanne ‐ 2010)

Relative Energy%

Relative Power %

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What role for District Heating (DH) ?

• Benefits of DH:

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

• Major constraints:

1. Minimum heat density

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Linear 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]

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What role for District Heating (DH) ?

• Benefits of DH:

• Major constraints:

2. District heating temperatures

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District 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

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District heating Temperature optimize for Geothermy : an example

• Example in Paris region

• GEOTHERMY :

• 25% Power = 60% Energy

• multi‐tube district

• Sequential system

• Average return

Temperature : 35‐40°C

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

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What role for District Heating (DH) ?

• Benefits of DH:

• Major constraints:

3. Substantial investments ("capital cost")

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Boundaries 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

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Sale price of DH – France 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

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What role for District Heating (DH) ?

• Benefits of DH:

• Major constraints:

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/

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Retrofit Logic

Demand Evolution VS expansion of DH

DH expansion Logic

Source : UNIGE project REMUER, adapt from L. Quiquerez

Example DH «CADIOM‐CADSIG» in Geneva

DH Demand [GWh]

Base Load Peak Load

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Demand Evolution VS expansion of DH

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Demand Evolution VS expansion of DH

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Demand Evolution VS expansion of DH

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Demand Evolution VS expansion of DH

For a same heat demand (370 GWh), we can :

• Use more waste heat

• Improve relativ share of waste heat ine the 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)

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Conclusions – key 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 !

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