Division of Energy Systems
at Linköping University,
SWEDEN
Professor Baharm Moshfegh
Chairman of Division
Division of Energy Systems
• Established in 1980
• Belong to the Department of Management and
Engineering
• 25
Employees
• 16
Active PhD students are registered today
• 55
Academic theses
• >400 Scientific articles in journals and proceedings
of international conferences
• >100 Master theses
• Thousands of students have read the division's
courses
Definition of Energy Systems
Energy systems consist of technical artefacts and
processes as well as actors, organizations and
institutions which are linked together in the
conversion, transmission, management
and utilization of energy.
The view of energy as a Socio-technical system
implies that also knowledge, practices and values must
be taken into account to understand the on-going
operations and processes of change in such systems.
Levels of the Energy Systems
•
•
•
•
•
•
Global energy systems
National energy systems
Regional energy systems
Local energy systems
Industrial energy systems
Building as an energy system
Sources, transport, resources, distribution,
history-future, policy, rules, etc.
Energy Systems
Interplay, analysis and optimisation of energy
supply, use and conservation
Many possibilities to satisfy energy
demand
Hydropower
Nuclear
power
Global
fuel
market
Coal
Natural gas
Waste
Wasted
heat
Condensing
power
plants
Combined
Heat and
Power plants
Electricity
distribution
District
heating
network
Industrial
manufacturing
Electricity / fuel / heat
possible
Space heating,
hot tap water
Industrial
heating
Biofuel
Waste heat
from
industries
Electricity required
Lighting
Electric appliances etc
Wind power
Solar cells
Energy demand
Utilised
heat
Absorption
refrigeration
Space
cooling
District cooling
network
Enhanced coal utilisation
• Increasing energy demand
makes coal more valuable.
• Better coal use in an efficient CHP plant
that uses the heat than
in a condensing plant that wastes the heat
• If the heat is used:
Less coal needed to satisfy energy demand
Lower CO2 emissions caused by
satisfying energy demand
Incomes from electricity and heat sales,
which may reduce electricity price
Condensing power plant
and
Combined Heat and Power plant
100
90
80
70
Losses
Utilised heat
Electricity
60
50
40
30
20
10
0
Coal
Condensing
power plant
CHP plant
Combined Heat and Power plant
Electricity
CHP plant
Absorption process
Domestic hot
water
District heating
Space cooling
District cooling
Space heating
Process cooling for
industry
Steam for industry
Sustainable electricity utilisation
• Electricity is valuable
• Minimised electricity consumption
• Heat can be used instead of electricity
in many cases, e.g. for heating and cooling.
• Heat from
combined heat and power (CHP) plants
or boilers that produce only heat
District heating supply
Electricity
market
Electricity grid
Gas
CHP
Combined heat and
power production
Waste
CHP
Wood
Heat-only boilers
Oil
Heat
pump
DH network
Heat demand
Industrial waste heat
DH system in Göteborg (Gothenburg)
District heating and cooling systems
• Networks for hot and cold water are built
from plants to industrial premises, commercial
centres, houses etc when a district is built.
• Convenient for inhabitants
District heating enables
• Utilisation of resources that otherwise might be
wasted, e.g. industrial waste heat, municipal waste
• Cogeneration of electricity, heat, steam and cooling
Absorption vs vapour compression process
Compression process
Fuel
Electricity grid
Condensed
power
plant
Electricity
Compression process
Absorption process
Fuel
CHP plant
Cooling
Electricity grid
Electricity
Heat
Absorption process
District cooling
District heating
Absorption vs vapour compression process
Condensed power plant+Compressor cooling machine
355 MWh
Fuel
Condensed
power plant
135 MWh 50 MWh
El
Compressor process
Combined heat and power plant+Absorption chiller
Fuel
El
Et grid=85 MWh
87 MWh
CHP plant
tot  90%
el  34%
  0,61
Cooling=100 MWh
COP  2
el  38%
255 MWh
El grid= 85MWh
2 MWh
Heat
143 MWh
Absorption process
COPel  50
COPvärme  0,7
District cooling=100MWh
Absorption cooling – Heat driven
cooling
Efficiency
• Absorption cooling machine 0.7
• Compressor cooling machine 3-4
CHP system that generates district heating
and cooling as well as electricity
Boiler
Steam turbine
Fuel
Generator
Electricity
Condenser
Pump
District heating
system
District cooling
system
Condensed power plant+heat pump is it a
good idea!
Boiler
Steam turbine
Fuel
Generator
Electricity
100 kWh
33,3 kWh
Condenser
Avgivet värme
100 kWh
K
Pump
tt 
wnetto
 33,3%
q ÅP
qK
Komp
SV

qK
wKomp
F
 3,0
qF
wKomp
33,3 kWh
Heat recovery
Industrial
processes
Steam
Hot water
District heating network
Buildings
Space heating
Domestic hot
water
Heat can be recovered
for repeated use
at different temperatures
in industry
and finally for
low-temperature
space heating.
Influencing demand
• Energy conservation
reduces energy demand
• Load management
reduces capacity demand
• Energy carrier switching
e g from electricity to fuel
or district heating
Foundry Load Duration Curve, top
24 hours
Demand [ kW ]
9250
STEP:
60 (MIN)
DURATION DIAGRAM
9000
8750
8500
8250
8000
6
12
Time [ hours ]
18
24
Foundry Load Duration Curves
10
Original load curve
”A”
Demand (MW)
8
”B”
6
4
2
1
2
3
4
5
6
7
Time (months)
8
9
10
11
12
Demand-side measures
Energy
conservation
Electricity
supply
Electricity
demand
Load
management
Energy carrier
switching
System analysis
Energy system
Management
Aim: Supply energy at low cost
Components: Available capacity
Resources: Limited supplies
System boundary
Boundary conditions
Fuel prices, Laws, Demand ?
How to use components and resources to achieve aim best?
Use a model that describes important properties of the system.
Energy system optimisation model
•
•
•
•
•
•
•
Country, region, municipality, district-heating system
Electricity and heat production
Short and long-term variations
Cost minimisation
Optimisation method: Linear programming
Investments in new plants: type, size, occasion
Given energy service demand
Which combinations of energy sources, conversion plants
and energy conservation measures are most beneficial?
Energy
supply
Energy
demand
Energy
conservation
MODEST
an energy system optimisation model
Model for Optimisation of
Dynamic Energy Systems with
Time dependent components
and boundary conditions
• MODEST calculates how energy demand
should be satisfied at lowest possible cost.
• MODEST can handle many kinds of energy
sources, forms, plants and demand
• MODEST has been used for
50 Swedish district heating systems,
regional biofuel supply and use and
national electricity supply and conservation
Hydro
Nuclear
Electricity
trade
Wind
Condensing
Gas turbines
Electricity
distribution
Electricity
demand
industry
Business
Bransch 1, 2,
CHP
Oil, wood
boilers
Other
electricity
demand
Process a, b,
...
District
heating
Energy carrier
switching
Swedish
electricity
supply
and
conservation
Conservation
Oil, gas
boilers
Wood
boilers
Studerade branscher och processer
Electricity supply without and with
electricity conservation
of which
is export
Energy-carrier
switching
Nuclear power
Hydropower
Biofuel Wind Fossil Import
CHP power CHP
Energy
conserv ation
-20
0
20
40
60
80
TWh / y ear
MODEST optimisation result
100
120
140
160
450
Swedish electricity supply during one year
SEK/MWh
35000
Effekt MW
300
vardag
Kondenskraft
Condensing power
dag
vår
höst
Weekday
30000
25000
vardag
dag
sommar
250
Marginal cost
spring
autumn
daytime
vardag
Weekday
dag
winter
vinter
daytime
nätter o helger
Weekday
summer
daytime
20000
Nights and weekends
Import
Hydro
Vattenkraft
15000
0
1000
2000
3000
4000
Import
KV
CHP
10000
Wind
power
Vindkraf
t
Import
5000
6000
Hydro
Vattenkraft
7000
8000
Kraf tvärme
o mottryck
CHP
Import
CHP
5000
Nuclear
Kärnkraft
of which is export
0
0
1000
2000
3000
4000
5000
6000
7000
8000
seltv69
h/year
h/år
Electricity supply and conservation in Sweden during one
year
Effekt MW
Kondenskraft
Condensing
28000
power
24000
vardag
Weekday
dag
vinter
winter
daytime
20000
Weekday
vardag
spring
dag
vår
autumn
höst
daytime
vardag
Weekday
dag
summer
sommar
nätter o helger
Nights and weekends
daytime
Elproduktion
Electricity
supply
Vattenkraft
Hydro
16000
Import
12000
Vindkraf
t
Wind power
Import
KV
CHP
KV
CHP
8000
Kärnkraft
Nuclear
4000
varav export
of which is export
0
Energy Konvertering
conservation
-4000
-8000
Effektivisering
Energy carrier
switching
Demand-side Elhushållning
measures - Megawatts
-12000
-16000
0
1000
2000
3000
4000
5000
6000
7000
8000
h/year
Supply curve for Swedish electricity
1400
Marginal cost
1200
SEK/MWh
GT
Gas
turbines
1000
800
CondensingKondens
power
600
400
Import
200
KV
CHP
Average
marginal cost
Demand
now,
Bef
elbehov
after hushållning
conservation
efter
Nuclear
Kärnkraf
t
Hydrot
Vattenkraf
Vindkr
Windaftpower
0
Avfalls-KV
0 Waste-fired
CHP
-200
50
100
150
200
250
TWh/år
TWh/year
30
30
25
20
30
Mton CO2 / år
Mton/year
CO2 emissions
due to
25
Swedish electricity
demand
20
15
15
10
10
Import
5
5
0
Sverige
Sweden
Export
0
Sweden
Sverige
Netto
-5
-10
-10
-20
Import
Netto
-5
-15
Mton CO2 / år
Without electricity conservation
-15
-20
Export
With electricity conservation
Assemblies of energy
systems between the energy
companies and industries
give big financial and
environmental benefits
RESO
Regional Energy System Optimatization
Project idea
RESO is a project that examines and highlights the
conditions for
Regional cooperation between different actors by
creating a common
HEAT MARKET
where several businesses can buy and sell heat.
RESO, Studied region
Sandviken
Sandvik
Gävle
Korsnäs
Sweden
StoraEnso
Skutskär
40 km
Heat demand aprox.7 TWh/year
Heat market
Solution with the highest saving
compared to BAU
• 240 MSEK/year cost reduction which can be used for
investment for measures
– Process integration (Skutskär och Korsnäs)
– New CHP plant (KEAB)
– Increasing the heating market (Sandvik)
• District heating will be increased by 600 GWh/year
• Electricity production will be increased by 1150
GWh/year
Research Competence Basis
Energy Systems, Linköping university
• Customer energy systems analysis
– Reducing energy costs
– Energy efficiency measures
– Analyzing temporal patterns
• Customer solutions
– Communicated load management
– Demand Side Management in a Systems Perspective
– The proactive End User
• Local, regional (and larger) energy systems analysis
– CHP, bio-fuels, cooperation between manufacturing
industry and energy suppliers
Continued
• Influence of Deregulated Energy Markets on Demand
Side Management and Local Generation
• Local Distribution, Generation and End Use
– Business Perspectives
– Customer Behavior in a ”small scale” system
– Communication Perspectives
– Environmental Perspectives
– Requirements for IT solutions
Continued
• System related issues:
– Energy users as alternative energy suppliers through their
own generation capacity or through their capability to
reduce energy demand
– Competition between generation and energy end use
measures
– IT solutions for communication of the energy end use
measures and their availability in parallel with the supply
measures
Concluding benefits of
energy systems analysis
• Systems analysis can consider interplay among energy
supply, use and conservation and improves understanding
of complex energy systems
• An optimisation model can consider many parameters that
influence energy supply:
Energy prices
Environmental impact
Time fluctuations
and presents the best system design and operation
considering present and possible plants, available resources
etc.
Dimensions of Energy Systems
• Energy systems can be treated from different
aspects or crossing points
– User
• Knowledge, norms, behavior etc
– Formal and informal regulations
– Policy and economy
• Actors, driving forces, taxes etc
– Technical conditions
Study of 20 low-energy houses in
Sweden
•
•
•
•
Well insulated construction
Energy efficient windows
Passive solar architecture
Air-to-air heat exchanger
(integrated heater)
• Solar heating for DHW
• Mechanical ventilation system
Annual energy demand
1530; 19%
775; 10%
3900; 48%
Totally 8020 kWh/annually
1810; 23%
Household appliances
Domestic Hot Water
Space heating
Fans
Monitored annual energy demand
kWh/a
25 000
20 000
15 000
10 000
5 000
0
New typical
Old typical
Swedish building Swedish building
Low-energy
building, Lindås
Space heating
Fans
DHW
Household appliances
Energy demand and indoor climate in
low-energy buildings
• The building sector stands for about 40% of the
energy demand in the world
• People spend more than 80% of their time inside
buildings
• Indoor climate and the energy issue are essential
issues for achieving sustainability
Definition of low-energy buildings
• Low-energy building is “a building that is built according to a
design criteria aimed at minimizing the operating energy”
• Passive buildings – a kind of low-energy building using mainly
passive techniques
• Plus energy buildings – a low-energy building using solar energy
by means of both passive and active technologies and supply
electricity to the grid
• Yesterdays low-energy buildings are today's energy-efficient
buildings
Passive
techniques
• Well-insulated envelope
• Minimized amounts of thermal
bridges
• Airtight construction
• Energy efficient windows (3- or 4panes)
• Air-to-air heat exchanger,
• Heat exchange of waste water by
heat pump and heat exchanger
• Passive solar gains
• Thermal mass
• Pre-heating of ventilation air by
buried pipes
Active techniques
•
•
•
•
•
Exhaust air heat pump
Ground source heat pump
Solar heating and PV
Fuel cells
Small-scale CHP using biomass
Some data
Ground area
Total floor area
Floor plan
Total volume
Ceiling height, ground floor
Ceiling height, upper floor
ACH at a differential pressure of 50 Pa
Geographical situation
60 m2
120 m2
60 m2
340 m3
2.5 m
2.2 to 4.3 m
0.2-0.4 l/s m2
Lat. 57.5º, long.
reference
Structure
Area
[m2]
U-value
[W/m2K]
External walls
Roof
Floor
Windows (average for all windows)
Average U-Value
38
66
62
18
0.1
0.08
0.09
0.85
0.16
–11.5º
from
Common
Swedish Uvalues
0.25
0.18
0.40
2.43
CO2-emissions
20000
16000
kg
New typical Swedish building
Low-energy building
12000
8000
4000
0
Swedish
Nordic
Nordic European District
District
District Pellets and Pellets and Pellets and
average
average
present
average heating and heating and heating and Swedish
present European
electricity electricity marginal
Swedish
present European average
marginal
average
production production production,
average
marginal
average electricity production
coal
electricity production
mix
condense
mix
Embodied and operational energy
kWh/m2 usable floor area
10 000
8 000
1410
6 000
4 000
2 000
7100
1954
3125
0
Typical new Swedish
Low-energy building
house
Production and maintenance, 50 years
Operation, 50 years (end-use)