Industrial Ecology Favrat December 2006 1 Integrated energy systems: a key to sustainability Prof...

1Industrial Ecology Favrat December 2006

Integrated energy systems: a key to sustainability

Prof Daniel Favrat

LENI-ISE-EPFL

Industrial Ecology Favrat December 20062

Energy integration as a key word

• Integration of technologies and/or energy services offers a large potential:– Combined cycle (Brayton-Rankine) or hybrid FC-GT

plants– Integrated solar combined cycle systems (ISCCS)– Hybrid vehicles, – Energy networks with tri-generation…

• Strong need for improved indicators (exergy efficiency)

• Need for better information structuring tools (pinch technology, environomic multi-objective optimisation, improved LCA,…


Evolution of Worldwide key parameters

400 800 1200 1600 2000 year0.

10

20

30

ener

gie

[G

tep

]

x

x

x

xx

x

x

yearly primary energy consumption

En

erg

y

0

1000

5000

7000

[Mill

ion

s]population

230

250

270

290

310

330

350

CO

2 [p

pm

]

mean CO2 concentration in atmosphere


Energy Trends• Significant projected increase of

energy use (mainly in dev. countries, electricity and transport)

• Part of thermal conversion processes > 90% (>80% of non renewable), and major source of pollutants and inefficiencies

0

2

4

6

8

10

12

14

Developing countries

OECD

Eastern Block

world

1900 1930 1960 1990 2020

Coal0.26

Oil0.32

Gas0.19

Nuclear0.05

Hydro0.06

Non Com.0.1

Renew.0.02

Efficiency Costs

Emissions

Disponibility


Society and sustainability• Difficulty to define sustainability and to have a

holistic view– complex systems with many factors but major ones

are:• Environment (local and global)• Resource conservation or even better, closed loop (including

recycling, renewable resources, etc)• Economics (in line with available capital)• Social (the most difficult!! - not dealt with in this talk)

• How to:– match top-down with bottom up frameworks

and have cross-domain coherence– account for the dynamics of technological and

economical evolution


Reactions to complexity• Over simplification

• Focalisation on isolated criteria, one at a time

(example: CO2)

– Partial view, potentially negative action (ex: taking

out car catalysts would reduce CO2)

• Environmental policies mainly based on fixing

of regulatory limits without economical benefits

for better technologies or combinations of

technologies


Major Methodologies for Design

• Structure independant (pinch technology, etc.)

• Structure based (environomic optimization, etc.):• Starts from a superstructure of all feasible components and heavy use of operations research tools• Easier extension to LCA and other factors (pollution, reliability-availability, time dependant investments, etc.)


Energy systems and Environomics

• Background:– Energy systems increasingly consist of integrated

technologies– Technologies are not fixed but, like living bodies,

adapt to their environment (based mainly on economic factors and regulatory issues)

– Assessments should be made in a coherent framework allowing all technologies to freely compete (particularly when a major departure from the present day economic environment is anticipated)


Thermoeconomic & environomic

min. Cuseful energy = f(Cfuel + Cinves + Cemissions - Bproducts)

External costs

emissions

Cemissions

min. Cuseful energy = f(Cfuel + Cinvest - Bproducts)

ThermoeconomicDesign

EnvironomicDesign

min. Cénergie. = f(Cfuel + Ccapital)min. Specific pollution

orMulti-objective


Pelster (98)

Combined cycle superstructure


40

42

44

46

48

50

52

54

56

58

60

basecase

0 1 2 2.5 3 4

CO2 unit costs (cts/kg)

percent

0

50

100

150

200

250

300

350

400

450

500

specific emissions

efficiency CO2 (g/kWh)

NOx (mg/kWh)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

basecase

0 1 2 2.5 3 4

CO2 unit costs (cts/kg)

(cts/kWh)

CO2

NOx

CO2 sep.,disposal

resourcecosts

capitalcosts

300 MW: Exergetic efficiency, emissions, costs versus CO2 unit cost

Pelster (98)


•Collaboration within AGS with MIT and University of Collaboration within AGS with MIT and University of Tokyo Tokyo•Development of QMOO (multiobjectif, multimodal, Development of QMOO (multiobjectif, multimodal, evolutionary optimisation algorithm) evolutionary optimisation algorithm)•« Environomic » optimisation of integrated energy systems« Environomic » optimisation of integrated energy systems

Two objective optimisation of trigeneration in part of a large city

Post Combustion

anode cathodeelectrolyte

reformer

naturalgas

air

Heat Pump

ColdSource

District Heating water

District Cooling water

Compression Chiller

Absorption Chiller

Heat Recovery Device

Gas Turbine

Solid OxideFuel Cell

Boiler

AdditionalFiring

Feasible Domain

Pareto Frontier

Cost

CO2 emissions

Burer M, Favrat D., Tanaka K., Yamada K, Multicriteria optimisation of a district heating cogeneration plant integrating a Solid Oxyde Fuel Cell-Gas Turbine combined cycle, heat pumps and chillers, Energy. The International Journal, 28/6 pp 497 – 518, 2003

Part of Tokyo: Results with different Pareto Curves

[ton

CO

2/ye

ar]

[million US$/year]

50

Annual Cost [m$/year]

CO

2 E

mis

sio

ns

[T

on

s/y

ea

r]

anodecathodeelectrolyte

air -50%

2.2 2.84000

10000

14Industrial Ecology Favrat December 2006

Power generation technology typification

Thesis Li 2006


Overall Technology Assessment (China)

1MW

10MW

100MW

1000MW

CO2 Abatement Cost vs CO2 Abatement Percentage

0

50

100

150

200

250

300

350

0 20 40 60 80 100

CO2 Abatement Percentage (%)

CO

Abatement Cost (US$/ton)

Supercritical Coal plant + ESP +FGD

IGCC

PFBC GCC

GCC+CO2

separationIGCC+CO2

separationCHP(GT)Wind Power

PV

SOFC/GT

AZEP

SOFC/GT

Cogeneration

Gas Engine

SOFC

SOFC

Cogeneration

Gas Engine Cogeneration

Possible Baseline Assumption

For Power Generation: The conventional 600MW coal plant is taken as the reference plant.

For Cogeneration:

Heating Gas boiler for heating, power need by pump is imported from the electricity grid

Electricity National average CO2 emission rate from power generation


Relative Consumption of technology combinations for heating

1 2 3 4 5 6 7 8 9 10 11

0.0

0.5

1.0

1.5

2.0

2.5

3.0

PAC

Q

PAC

PAC

PAC

PAC

Q

PAC

Q

PAC

Q

Tch=65°C

Tch=35°C0.270.310.38

hydro

PAC= pompe à chaleur

Q = cogénération

pile à combustible

turbine à gaz

Moteur thermique

Electricité nucléaireFlamme (chaudière)

Résistance électrique


Two examples for a more rational use of fuel or Nat Gas for heating

Fossil or biofuel resources

Environnement 1.43

Twice as much heat

Electricity0.44

Heat0.46

1.00

Cogeneration with Fuel cells

or engines

Electricity0.57

1.00

Combined cycle power plant

(ou 1.1)


Illustration of heating and cogeneration services in the exergy bowl

Source (partielle): Borel L, Favrat D Thermodynamique et énergétique. PPUR 2005


Previous solar power plant work at EPFL: thermo-economic optimisation of an ISCCS plant for Tunisia (120 MWe)

KANE M, FAVRAT D ET AL. Thermoeconomic analysis of advanced solar-fossil combined cycle power plants. Int. Journal of Applied Thermodynamics, vol.3, No 4, pp191-198, 2000


Better indicators: Exergy

• Introduction of an energy concept including an exergy performance index, in the Law on Energy in Geneva

• Necessary simplifications (engineers and architects, diverse customers, etc.)

• Initial focus on large projects with the following main services:– electricity, heating, air conditioning and

refrigeration


From local to global

€

η = η1 η 2 η 3 η 4Example: Combined cycle power plant without cogeneration (1)+District heating heat pump (2) + DH heat exchanger in the building (3) +convector (4)

€

η = ˙ E el,1

−

˙ E y,1+

⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟

˙ E y,2−

˙ E el ,2+

⎛

⎝ ⎜

⎞

⎠ ⎟

˙ E y,3−

˙ E y,3+

⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟

˙ E q,4−

˙ E y,4+

⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟=

˙ E q,4−

˙ E y,1+

Building plant 3

fuel

Room convector or radiator 4

Power plant

1 Cogeneration District unitwith or without heat pump 2

electricity


Examples de technologies Power plant

Dist. plant

Building plant Room convector Overall exergy efficiency [%]

Supply/return temperatures 45°/35°

65°/55°

75°/65°

45°/35°

65°/55°

75°/65°

45°/35°

65°/55°

75°/65°

Direct electric heating (nuclear power) 0.32 0.07 0.07 0.07 2.2 2.2 2.2

Direct electric heating (combined cycle cogeneration) 0.55 0.07 0.07 0.07 3.7 3.7 3.7

Direct electric heating (hydro power) 0.88 0.07 0.07 0.07 6.0 6.0 6.0

District boiler 0.2 0.54 0.76 0.86 0.53 0.38 0.33 5.8 5.8 5.8

Building non-condensing boiler 0.11 0.16 0.18 0.53 0.38 0.33 6.1 6.1 6.1

Building condensing boiler 0.12 0.53 6.6

District heat pump (nuclear power) 0.32 0.61 0.54 0.76 0.86 0.53 0.38 0.33 5.6 5.6 5.6

Domestic heat pump (nuclear power) 0.32 0.45 0.45 0.45 0.53 0.38 0.33 7.6 5.4 4.8

Domestic cogeneration engine and heat pump

0.22 0.25 0.26 0.53 0.38 0.33 11.8 9.4 8.7

District heat pump (combined cycle power)

0.54 0.61 0.54 0.76 0.86 0.53 0.38 0.33 9.4 9.4 9.4

Domestic heat pump (combined cycle power)

0.54 0.45 0.45 0.45 0.53 0.38 0.33 12.9 9.2 8.1

Domestic heat pump (cogeneration combined cycle power)

0.55 0.45 0.45 0.45 0.53 0.38 0.33 13.2 9.4 8.3

Cogeneration fuel cell and domestic heat pump

0.25 0.27 0.28 0.53 0.38 0.33 13.4 10.4 9.5

District heat pump (hydropower) 0.88 0.61 0.54 0.76 0.86 0.53 0.38 0.33 15.4 15.4 15.4

Domestic heat pump (hydropower) 0.88 0.45 0.45 0.45 0.53 0.38 0.33 21.2 15.1 13.325


Transport and car

One of the largest inefficiency inherited from the 20th century:

• Non recovery of the kinetic and potential energy

• Regulation by throttling of Otto engines


Conclusions• Rational Use is an essential strategy• Structuring knowledge is a key word in design

and planning of energy systems• Multi-objective optimisation is a major tool• Better indicators like the exergy efficiency can

help• Systems integrating several technologies

and/or energy services (cogeneration) represent major opportunities


Stone age did not end because of lack of stones!

Let’s not wait until the end of oil resources to be more intelligent

Industrial Ecology Favrat December 2006 1 Integrated energy systems: a key to sustainability Prof...

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