Advanced integrated systems and design methods for improved energy … · 2018-10-15 · “Advanced integrated systems and design methods for improved energy efficiency” Prof

Energy

Center

Advanced integrated systems and design methods for improved energy efficiency

Prof Daniel Favrat Prof. emeritus

[email protected] 1

World Future Energy Forum 2016, Beijing

h"p://powersave1200.tumblr.com/

“Advanced integrated systems and design methods for improved energy efficiency” Prof. Daniel Favrat

Energy, population, environment (historical evolution)

https://www.google.ch/search?q=%C3%A9volution+population+%C3%A9nergie+CO2&client=firefox-a&hs=aYm&rls=org.mozilla:en-US:official&channel=np&tbm=isch&imgil=YDNIUH-bNONiGM%253A%253Bhttps%253A%252F%252Fencrypted-tbn0.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9GcSti7OLA0pj7UXbkKnQdAvn2uivhQ2Nr5Gh5p8Z6IHNN5uGFeWk%253B580%253B376%253B1XM5pdun7gzYfM%253Bhttp%25253A%25252F%25252Fpoldev.revues.org%25252F687&source=iu&usg=__ZhYPNoZ9BdEQ2HizhjOh3KnRa3Y%3D&sa=X&ei=YEyGU9H7DaSd0AW-2IGAAg&ved=0CGEQ9QEwCQ#facrc=_&imgdii=_&imgrc=IfUT_IAR969EtM%253A%3BgDDb-FgjCqgIQM%3Bhttp%253A%252F%252Fstock.wikimini.org%252Fw%252Fimages%252F7%252F7b%252FR%2525C3%2525A9chauffement_climatique-temp%2525C3%2525A9rature-co2.png%3Bhttp%253A%252F%252Ffr.wikimini.org%252Fwiki%252FD%2525C3%2525A9veloppement_durable%3B1200%3B644

Years 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

CO2 [ppm]

250

270

290

310

330

350

370

390 2013: 400 [ppm]

0

1

2

3

4

5

6

7

World population

World primary energy consumption

Pop. [billion hab.] Energy

[109 tep]

10

8

6

4

0

2

Mean CO2 concentration in atmosphere

2


● Physics: conservation of mass and energy

● The confusion about the meaning of «energy»: Greek word “energeia”

(containing work)

● But: driving forces result from un-balances (of exergy levels, of con-centration in materials and fluids ...)

● Nature is a story of degradation: by degrading high “exergy” value from the Sun, Earth is able to generate vegetation and ultimately fuels, food for animals and humans

● Degradation is part of life, but …

Technological innovation objective: →less degradation

transformation

Input (mass / energy)

Output (mass / energy)

3


… would be sustainable if the tremendous potential of the Sun-Earth exergy unbalance would be used properly to:

●  satisfy energy services

●  recycle materials and wastes

●  clean or desalinate water

● …

Technological innovation objective: →less degradation

4 h"p://chandra.harvard.edu/edu/formal/ems/ems_earthMoon.html


Energy efficiency: best way to reduce CO2 emissions

From IEA outlook 2009 2005 2010 2015 2020 2025 2030

Gt C

O 2

20

25

35

40

45

30

550 Policy

scenario

450 Policy

scenario

CCS Nuclear Renewables Energy efficiency

5


● Heat (from high temperature energy processes in industry to low tempe-rature heating in building)

● Cold (from air conditioning to

refrigeration, freezing and cryogenic processes)

Energy services ● Mechanical energy (pumping, com-

pression, transport …) ● Electricity (previous services + coo-

king, lighting, computing, telecom-munication, etc.)

6


World fuel shares of CO2 emissions

From IEA outlook 2014

1973

15’633 Mt CO2

Other 0.0% Nat. gas

14.4%

Oil 50.6%

Coal 35.0%

2012

31’734 Mt CO2

Other 0.5% Nat. gas

20.3% Coal 43.9%

Oil 25.3%

7


Relative CO2 emissions per unit of energy of main fuels

0.0

0.5

1.0

1.5

2.0

2.5

8


From primary energy to electricity

Primary energy

Thermal Energy

Mechanical Energy

Electricity PV cells Electrical generator Electrical generator PV

cells Fuel cells

Geotherm. Nuclear Fossil Biomass Hydro Wind Solar

or engine

Nuclear energy Radioactive

decay Fission

Reactor Heat Exch.

Chemical energy

Combust.

Kinetic energy

Wind turbine

Potent. energy

Hydr. turbine

Solar Irradiation

Collectors

Compressible flow turbine

Compress. flow turbine

or engine

9 Favrat D. et al. “The information platform energyscope.ch on energy transition scenarios”, Proceedings of ECOS 2016, Portoroz Slovenia.


•  Develop better indicators for ecoeffi-ciency and sustainability (exergy effi-ciency, renewable energy ratio, ...)

•  Develop improved design and planning methods (holistic, able to optimize complex integrated systems towards increased efficiency, …)

•  Develop advanced technologies for a more rational use of both non renewable and renewable

Three main action paths towards energy efficiency

10 h"p://solex-un.ru/energo/formaty-energomarkirovok/h"p://www.purepropertycare.co.uk/commercial-services/insulaDon/


● Use of open fire for heating and cooking disco-vered more than 400’000 years ago

● Today’s heating systems are still mostly boilers

● The energy efficiency of boilers is close to 100% (sometimes improperly claimed to be > 100% in the literature!)

● Can this however really be considered as a 21st century technology?

Example: combustion and heating Use of fire:

> 400’000 years ago

FAVRAT D., MARECHAL F., EPELLY O. The challenge of introducing an exergy indicator in a local law on energy. Energy,33, No2, pp130-136 (2008)

11


Better alternative for heating with the same types of fuel

Oil or (bio-)gas

Hybrid fuel cell SOFC + GT

Electrical heat pump (COP:4.5)

Combined cycle 1.0

0.6

0.6x4.5=2,7

2.1

Environment

1.0

0.6 (electricity)

0.3 (heat)

0.6x4.5+0.3=3.0

Exergy efficiency > 16% 12

h"p://www.ztekcorporaDon.com/sofc_turbine.htm;h"p://www.britannica.com/science/geothermal-energy;h"p://www.power-technology.com/projects/uskmouth/


Waste heat recovery with Organic Rankine Cycle (ORC) ● Example: recovery from fluegas at

mean q = 120oC Thermal “efficiency”: ε = = 1 - For qa = 20oC, ε = 25%, but the true effi-

ciency of a Carnot ideal engine is100%

Exergy efficiency: η = = 1 Exergy efficiency is a better indicator!

● Power generation from waste heat

E Q

Ta

T

E Q 1- Ta / T

Heat collector grid Check

valve Pump Reservoir

Condenser grid

Waste heat

Generator

Power expander unit

13


TEMPERATURE COEN

ERGY

Exergy efficiency, a better indicator than 1st Law efficiency

BOREL L., FAVRAT D. Thermodynamics and energy systems analysis. EPFL Press (2010)

●  Indicates the true quality of energy conversion technologies (Carnot engine: 100% exergy efficiency)

● Always ≤ 100% ● Coherent ranking of most technologies ● To be comple- mented by renewable/non-renewable ratio

u+Pav-Tas

14

Coenergy=exergy of mass


Electric efficiency of different technologies

0

20

40

60

80

100

Elec

trica

l effi

cienc

y [%

]

ORC Organic Rankine Cycle

ECE External Combustion Engine

ICE Iinternal Combustion Engine

µGT Micro-gas turbine

PEFC Polymer electrolyte FC

SOFC Solid oxide fuel cell

CC Combined cycle 15


Fuel cell technologies

Oxidant in (air) Fuel in (H2, CH4)

Products and depleted fuel out

Depleted oxidant out e-

O2 H2 O2- H2O

O2 H2 H2O, CO2

O2

CO32-

CO2

SOFC 650-1000oC

MCFC 650oC

H2 O2

H2O H+ PAFC 200oC

AFC 50-100oC

PEFC 50-100oC

Toperation

OH- H2 H2O H2

H+ O2 H2O

16


Cogeneration with Solid Oxide Fuel Cell (SOFC)

Solid Oxide Fuel Cell stack

N2, O2

H2O CO2 H2, CO

O2-

Air

Reformed Natural Gas

Can potentially be inversed (High temperature electrolyser for storage)

Operating regime :

700-800oC 1 bar (to 5 bar)

17


Exergy efficiency in a Law (Geneva): System decomposition

Building

plant 3 fuel

Room convector or radiator

4

Power plant

1 Cogeneration District unit

with or without heat pump

2

Electricity

Key messages from exergy analysis: •  Heat in the coolest way (heating temperature the closest to the need) •  Cool in the warmest way (cooling temperature the closest to the need)

18 FAVRAT D., MARECHAL F., EPELLY O. The challenge of introducing an exergy indicator in a local law on energy. Energy,33, No2, pp130-136 (2008)


Managing the complexity of integrated systems: multi-objective optimisation

Em

issi

ons

(kgC

O2/

kWh)

Investment ($/kW) Infeasible

Min Investment, max emission

Min Emissions, max Investment

19


Ex: multi-objective optimisation of a trigeneration plant in a city From GIS to advanced integrated energy systems

Alliance of Global SustainabilityTokyo half: A collaboration with MIT & University of Tokyo:

[Bürer M. , Tanaka K. , Favrat D. , Yamada K. in: Energy 2003]

20


[tonC

O2/

year

]

[million US$/year]

Annual Cost [m$/year]

CO

2 E

mis

sion

s [T

ons/

year

]

anode cathode electrolyte

air -50%

2.2 2.8 4000

10000 Results from the optimisation of a trigeneration plant in a city

21


Advanced urban networks for increased synergy between users

Offer a Source /sink at intermediate temperature

HeaDngneeds

Coolingneeds


District heating and cooling CO2 network

Winter Summer

Henchoz S., Favrat D., et al. “Key energy and technological aspects of three innovative concepts of district energy networks” in Energy, June 2016

user user

user user

Central heat pump

heat pump

Central heat dissipater


After retrofit Before retrofit

Mechanical vapor recompression in industrial processes (pinch technology representation)

Tem

pera

ture

[°C

]

Tem

pera

ture

[°C

]

Heat rate [kW] Heat rate [kW]

24

STAINE F., FAVRAT D., Energy Integration of Industrial Processes Based on the Pinch Analysis Method Extended to Include Exergy Factors. Journal of Applied Thermal Eng., Vol.16, pp. 497–507, 1996


Hierarchy of energy saving actions in industry Detailed simulation

Extensive use of optimization

Advanced automation (e.g. adaptive control)

Tarification (liberalization), smart grids, therm. & electr. storage

Energy integration with other processes

Change of process (e.g. batch →con&nuous)

Energy recovery with power components (heat pumps, expanders on compr. gases, ORC, heat transf.)

Cogeneration, adapting utility network Energy recovery, (heat exchangers … )

Pump diameters adjustment …

Regulation (e.g. regrig-defrosting, thermostats) Maintenance (purge of condensate, filters, steam & air leaks)

Reference consumption (indicators + regular checks)

Automatic stops (lighting, fans, …) Insulation. sealing

25

Pinch technology


● Target of a 2000 W.year/(year.cap) (average world consumption in year 2000) ● 1 t CO2/(year.cap) ● Controversial definition and objectives but

intended to give a marketing impulse to the look for a better energy efficiency

Towards a 2000 watts society

http://www.novatlantis.ch/fileadmin/downloads/2000watt/Weissbuch.pdf Marechal F, Favrat D, Jochem E, “Energy in the perspective of the sustainable development: The 2000 W society challenge” Resources, Conservation and Recycling 44 (2005) 245–262

26 HALDI PA, FAVRAT D., Methodological aspects of the definition of a 2 kW society. Energy, vol 31, issue 15, Dec 2006., pp 3159-3170


Key energy saving approaches: a summary ● Better indicators (exergy efficiency) ● Better design methods: ●  For energy integration (pinch analysis) ●  Multi-objective optimization ● Better technologies: ●  Heat pumps ●  Fuel cells ●  Co- and tri-generation ● Better integration between electric and gas grids with storage

27 h"p://energycoaliDon.eu/indicaDve-naDonal-energy-efficiency-targets-fall-short


Thank you for your attention

The stone age did not end because of lack of stones (attributed to sheik Yamani !)

Let us not wait until the end of fossil fuels and an unbearable global warming to induce the necessary energy transition

28 Also thanks to the contribution of Dr Pierre-André Haldi

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Advanced integrated systems and design methods for improved energy … · 2018-10-15 · “Advanced integrated systems and design methods for improved energy efficiency” Prof