Transcript * A secure supply of power and heat is of paramount

COGENERATION AND
DISTRIBUTED RESOURCES
Professor Akhtar Kalam
Victoria University
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* A secure supply of power and
heat is of paramount importance,
and it must be provided at the
lowest possible cost.
* The privatisation of the
electricity supply industry has
brought competition in to the
market place for electricity supply
and buyers.
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EcoGeneration in Australia
Based on industry growth trends and current
government initiatives, by 2010 EcoGeneration
should almost double to represent approximately
14 per cent (7000 MW) of total installed
generation capacity in Australia compared to 7.8
per cent (3390 MW) at the end of 1999 (AEA’s
estimate). Of this total, renewables should
quadruple form 530 MW to approximately 2100
MW by 2010. Non-renewable EcoGeneration
should increase by some 70 per cent to
approximately 4900 MW. These growth rates
reflect international trends where ecologically
sustainable power production technologies are
recording by far the highest growth rates.
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EcoGeneration: EcoGeneration includes
cogeneration, renewables, waste-to-energy
and distributed generation technologies.
EcoGeneration is a natural grouping of
environmentally sustainable energy delivery
technologies as they offer similar benefits
and face similar challenges in the National
Electricity Market.
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Cogeneration (also known as combined heat
and power - CHP): Cogeneration involves the
production of combined heat and power. Heat
that would otherwise be wasted is recovered
and used in commercial and industrial
applications. Cogeneration is typically two to
three times more efficient than major
conventional, coal-fired, centralised power
stations. On average it produces one-third the
greenhouse gas emissions of conventional
power production.
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Renewable generation: Renewable
generated power produces no net
greenhouse emissions. Includes power
generated from natural resources such
as biomass, hydro, wind, solar and
tidal. It also includes power generated
using certain wastes.
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Waste-to-energy: This is electricity
produced using waste fuels, some of
which may otherwise cause local
environmental challenges. A number of
waste fuels are deemed to be
renewable including: cane residue
(bagasse) from the sugar industry;
sludge gas from sewage treatment
plants; and methane from landfill sites.
Fossil fuel-based waste streams
include coal waste methane, refinery
waste gases and coal tailings.
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Distributed generation: This is power
generation generally located close to
where it is consumed, for example,
supplying electricity on-site or overthe-fence. Also referred to as
decentralised, embedded or localised
generation. Can be as small as a 1 kWe
solar photovoltaic system, or even
larger than a 450 MW industrial on-site
cogeneration system.
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Embedded generation: This refers
to smaller-scale generators that
are connected to electricity
distribution networks. This is in
contrast to large-scale coal-fired
generators that are connected to
very high voltage electricity
transmission networks.
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THE TECHNOLOGY
Cogeneration - is essentially a
philosophy. It describes the use of
technology, that combines the
generation of heat (Mechanical energy)
and electricity (Electrical energy) in a
single unit in a way that is more
efficient than producing heat and
electricity separately in boiler plant
and at the power station.
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In other words, cogeneration is the
energy process whereby waste heat,
produced during the generation of
electricity, is utilised for steam raising
or heating. This is no different than
any other power stations. The only
difference being that the waste heat
from the electricity generating plant is
harnessed & made used of rather than
being thrown away in the form of
Waste Heat.
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The mechanical energy can be used
for any mechanical application such as
driving
motors,
compressors,
extruders, etc. The electrical energy
can be used to meet in-house demand
and any surplus sold back to the
electricity grid. The thermal energy can
be converted to steam or hot water for
process application, or for drying
purposes.
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In brown coal and gas fired power
stations, 28% to 35% of the energy in
the fuel is converted to electricity, the
other 65% to 72% becomes heat which
must be disposed of. In cogeneration,
both the recovered heat and the
electricity or mechanical energy are
used, so efficiency increases to 70% to
82% depending on the prime mover
used. This utilisation is well over twice
that of a large conventional power
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station.
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WASTE HEAT
STEAM
Hot Water
(Industrial Process)
(Space heating
in a commercial
building or district
heating scheme)
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CONVENTIONAL PLANT
 WASTE
HEAT rejected to the
environment
this will result in η of 90%
to be achieved
• cf. 36% (Conventional plant)
• 52% (Combined Cycle Gas
Turbine)
 Capturing
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The economics of cogeneration
schemes are most compelling for
organisations with a high heat
requirement. Units range from as
little as 20kW to hundreds of MW
and can be linked to public and
commercial buildings, industrial
sites and community heating
schemes.
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Cogeneration has a very wide
application in the industrial and
commercial sectors, and also in
public institutions. In the industrial
sector
potential
exists
in
manufacturing
(petroleum,
chemical, food and beverage,
textiles, paper, iron and steel,
motor vehicles, glass and clay),
mining and forestry.
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20
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There are two obvious times to
consider
investing
in
cogeneration: first, when existing
boiler capacity needs to be
replaced and second, when new
buildings are being planned.
Hospitals, for example are already
being designed to include a
cogeneration
system
from
inception.
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Once the economics have been
worked out and the investment
has been made, financial savings
quickly offset the initial additional
costs incurred, giving a payback
in as little as two or three years.
The life of a cogeneration system
can exceed fifteen years, so the
savings accrue long after the
initial capital costs have been
recouped.
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Cogeneration cycles
TOPPING
BOTTOMING
COMBINED-CYCLE
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In a topping-cycle system,
fuel is burned to generate
electricity;
the
thermal
energy exhausted from this
process is then used either
in an industrial application
or for space heating.
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In a bottoming-cycle
system, the waste heat is
recovered from an industrial
process application and
used to generate electricity.
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Combined-cycle systems
generally use a topping-cycle gas
turbine; the exhaust gases are
then used in a bottoming-cycle
steam turbine to generate more
electricity and process thermal
energy. Heat pumps may also be
used with a cogeneration system
to upgrade low-temperature heat
for process use.
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Cogeneration plants vary widely in size and
packaged micro-cogen units in the size
range 20kW to 60kW are commercially
available for suitable office buildings,
restaurants, hotels, etc. For units below
800kW, diesel and gas engines are the most
common type of prime motor. From
approximately 800kW to 10MW, gas turbines
or large reciprocating engines can be used.
Steam cycles (steam turbines) can also be
used especially in coal, waste gas or
biomass fired cogeneration systems. For
applications above 10MW, gas and steam
turbines are generally used.
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THE MARKET
The recent privatisation of the electricity
supply industry (ESI), together with a
number of business and technical changes,
have provided new impetus to the
development of cogeneration. It is not these
factors alone that are providing renewed
interest in cogeneration, but their
conjunction at this time. Taken together, the
factors provide a window of opportunity for
the exploitation of cogeneration. The
development of cogeneration has increased
since the restructure of the ESI, but there is
still a long way to go to catch on to the rest
of
the world. Cogeneration and Distributed Resources
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HEAT AND POWER
PRODUCTION - A BRIEF
HISTORY
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Cogeneration is not a new idea
Old days  Factories  Had their own
power stations  Supplied their own Heat
+ Power
 1965  66% of the electricity consumed in
the UK paper industry was generated onsite from COGEN schemes
 1990  66% went down to 20%

Grid systems (CEGB)  reliable supply + real lower prices

REASONS
(acted against Cogeneration
in the last 2 decades  decline)
Development in Boiler plants
Relatively cheap oil
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The Situation Today
Recent years  Renaissance
1990  privatisation of ESI 
competition
 Gas used for generation  
Since 1989  1500MWe of new
COGEN capacity (U.K.)
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ADVANTAGES
Efficient way of converting primary fuel to
useful energy
 Process Industries benefit viz. commercial
+ Environmental sectors
 Targets have been set by Governments
and this will depend on:

Future gas and electricity prices
 Development in electricity trading
 Environmental pressures

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The Future
INDUSTRY TODAY:
Market Driven energy market
 Needs specific legislation
 COGEN CAN BECOME A DRIVING
FORCE

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In total contrast to coal, gas can be
moved relatively easily and without
impacting
on
the
environment.
Therefore, the engineering case for
gas-fired cogeneration meeting local
heat and power needs is very strong.
There might well be seen a reversal of
the trends of the last 60 years, with the
use of the Grid declining and heat and
power production being combined
close to the point of need.
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WHY
NOW?
COGENERATION
Regardless of the engineering case
for cogeneration, it will not "take off"
unless it is economically attractive.
The two fundamental parameters that
dominate commercial viability are:(a) primary fuel costs;
(b) the capital costs of cogeneration
schemes.
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Fuel Prices
Most
cogeneration
schemes
currently being developed are fuelled
by gas. Until comparatively recently
the pricing policy, did not encourage
the
development
of
gas-fired
electricity generation. It was argued
that gas was a premium fuel, too
valuable for this application. This
view has now changed.
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Capital Cost
Industrial cogeneration schemes in
general
utilise
either
reciprocating
engines or, more commonly now for larger
installations, gas turbines. Concentration
here is on gas turbines because they are
generally preferred for schemes of several
megawatts. Gas turbine technology has
been improving rapidly in recent years
producing more efficient machines. The
market is developing with more players
offering a greater range of machines.
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The "Green" Ticket
Cogeneration can genuinely be labelled a "Green"
technology. The overall thermodynamic efficiency
of cogeneration is very high. Further, when gas
fired, no sulphur dioxide is produced and NOx
can be effectively controlled either by steam
injection or dry NOx control through the design of
burners. Finally, the application of cogeneration
reduces the production of CO2 compared with the
grid/boiler approach. Although it is difficult to put
a value on "green" benefits in money terms, it can
do no company any harm to be associated with
environmentally friendly technology.
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Ageing Boiler Plant
In the fifties and sixties falling
electricity prices, in real terms,
encouraged industry to import
electricity and produce steam and
hot water in conventional boiler
plant. Significant amounts of low
cost, efficient package boilers were
installed in the 1960's. Much of this
plant is now reaching the end of its
useful life. Cogeneration and Distributed Resources
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Security of Supply
Security of supply can be of paramount
importance in industrial environments. An
on-site cogeneration scheme can enhance
the security of both heat and electricity
supplies. In particular, it is possible to
design the electrical connections to
ensure continuity of supply for the
complete failure of the Grid. Such
arrangements can prove most beneficial
from both commercial and, in certain
situations, safety viewpoints.
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Cogeneration in Australia
VICTORIA (SECV) + State Government
– INCENTIVE PACKAGE - 1987
SOUTH AUSTRALIA (SAGASCO) –
Established a COGEN division
At the end of 1999, cogeneration and
distribution generation represented
8.3% of installed capacity.
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Cogeneration data
No authoritative information is available on
the extent of non-utility cogeneration and
power production.
The best available estimate puts
cogeneration capacity in Australia at about
2,200MW, made up of the following
industries:

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Alumina industry is the most significant industry,
accounting for 23% of operational capacity, 38% of
electricity generation and 36% of thermal production
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Industry
Capacity(MW)
No. of projects
Alumina
498.5
6
Sugar
332.1
30
Paper
271
9
Nickel
261
6
Chemical
215.7
6
Misc Manufact
189.7
4
Oil Refining
183
4
Steel
73.8
3
Mineral Process
66.9
3
Health
60
25
Water
20
6
Food
13.2
10
Building
7.8
7
Education
7.6
3
Recreation
2.9
11
2203.2
133
TOTAL
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WA is the greatest user of cogeneration by State/Territory accounting for 35% of
operational capacity, 39% of electricity generation capacity and 32% of thermal
production
State
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Capacity (MW)
No. of projects
ACT
0.1
1
NSW
281.9
18
NT
105
1
QLD
413.5
35
SA
215
25
TAS
15.5
2
VIC
409.7
34
WA
762.5
17
TOTAL
2203.2
133
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Steam turbine projects accounted for 58% of operational capacity by prime mover
technology, 57% of electricity generation and 95% of thermal production
Type
Capacity (MW)
No. of projects
CCGT
538
4
GT
285.9
19
RCP
77
53
FCELL
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0.2
1
ST
1302
56
TOTAL
2203.2
133
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Natural gas projects accounted for 56% of operational capacity by primary fuel, 66% of electricity generation and
38% of thermal production. Renewable generation capacity accounted for 360.3MW of capacity, representing 16.4%
of total generation capacity
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Fuel Type
Natural Gas
Bagasse
Coal
Waste Gas
Oil
Digester Gas
Landfill Gas
Waste Biomass
LPG
TOTAL
Capacity (MW)
1224.5
332.1
363.5
144.3
109
19.1
7.1
2
1.6
2203.2
No. of projects
71
30
8
6
2
6
2
1
7
133
Renewable
Fossil Fuel
TOTAL
360.3
1842.9
2203.2
40
93
133
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Non-Cogeneration – State/Territory
State
No. of projects
ACT
2
2
NSW
162.1
8
65.4
3
501.5
5
SA
74.5
6
TAS
10
1
VIC
75.2
13
WA
569.3
9
TOTAL
1460
47
NT
QLD
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Capacity (MW)
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Non-Cogeneration – Prime Mover
Technology
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Type
Capacity
(MW)
No. of projects
CCGT
415.9
4
GT
553.5
19
RCP
191.2
53
HT
75
1
ST
224.5
3
TOTAL
1460.1
47
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Non-Cogeneration – Primary Fuel
Fuel Type
Capacity (MW)
No. of projects
Natural Gas
1123.9
12
Landfill Gas
94.4
21
Water Hydro
75
10
Coal
Steam
Meth
Waste Gas
96.8
2
60
1
Oil
10
1
1460.1
47
Renewable
169.4
31
Fossil Fuel
1290.7
16
TOTAL
1460.1
47
TOTAL
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1999 – 7 Cogen projects totalling 234MW & 10 non-Cogen, grid connected, distributed generation project totalling 295MW were
committed and under construction. Renewable projects amounted to 13% of the overall total
Plant
COGENERATON
FOSSIL FUEL
Worsley Alumina
Worsley Alumina
Bulwer Island
QLD Phosphate
Macquarie Uni
Location
Type/Fuel
MW Capacity
Worsley, WA
Worsley, WA
Bulwer Is., QLD
Mount Isa, QLD
Nth Ryde, NSW
GT/natural gas
ST/natural gas
CCGT/natural gas
ST/natural gas
RCP/natural gas
120
34
37
20
1
212
RENEWABLE
Visy Paper
Energy Developments
Tumut, NSW
Wollongong, NSW
ST/woodwaste
RCP/munic.waste
TOTAL COGEN
1460.1
47
17
5
22
234
NON-COGENERATON
FOSSIL FUEL
Redbank Power Plant
Ladbroke Grove Power
Plant
East Coast Power Plant
GRID CONNECTED
Redbank, NSW
Ladbroke Grove, SA
Bairnsdale, VIC
DISTRIBUTED
GENERATION
ST/coal tailings
ST/natural gas
GT/natural gas
Burrinjuck, NSW
Ravenhoe, QLD
Blayney, NSW
Koomboloomba, QLD
Werribee, VIC
Subiaco, WA
Jacks Gully, NSW
HT/water
WT/wind
WT/wind
HT/water
RCP/digester gas
RCP/effluent sludge
RCP/landfill gas
RENEWABLE
Pacific Power
Stanwell Corporation
Pacific Power
Stanwell Corporation
Melbourne Water
Water Corporation
Energy Developments
TOTAL COGEN
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84
42
246
15
12
10
7
2.4
1.5
1
48.9
294.9
56
Victorian support
Within five years, it is conservatively
expected that about 500 MW of
Victoria's power will be fed into the
SEC grid from private and public
cogeneration and renewable energy
projects, the equivalent to the output
from one Loy Yang power station
unit.
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COGENERATION
COMMERCIAL VIABILITY
It would be irresponsible to give the
impression that cogeneration offers
a panacea to all energy problems.
Commercially viable opportunities
are still small in number. The main
factors
influencing
commercial
viability are dependant on site's heat
to power ratio and equipment
utilisation.
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GREENHOUSE EFFECT
WORLD ENERGY CONSUMPTION 
1945-90  ELECTRICITY
CONSUMPTION IN Vic  25 FOLD.
SIMILAR TRENDS IN OTHER
PLACES. NOT POSSIBLE TO
SUSTAIN SUCH GROWTH
 CONSERVATION REQUIRED
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GREENHOUSE EFFEST IS A
SERIOUS PROBLEM
AUSTRALIA  MAJOR
CONTRIBUTOR TO GREENHOUSE
GASES
6 TIMES MORE THAN THE WORLD
AVERAGE RATE
 GREATER THAN BOTH JAPAN & USA
 VICTORIA HAS AN EVEN HIGHER PER
CAPITA OUTPUT

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GOAL SET FOR 20% REDUCTION
IN CO2 EMISSION BY 2010.
IN GLOBAL SENSE:
ELECTRICITY CONTRIBUTES 25%
OF ALL CO2 EMISSIONS
REPRESENTING 14% OF ALL
GREENHOUSE GASES GENERATED
AND VICTORIA IS RESPONSIBLE
FOR 0.1%.
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ALTERNATIVES:
COGENERATION & RENEWABLE
ENERGY
REMOTE AREA POWER SUPPLIES
ENERGY AUDITS

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COGENERATION -- PROVEN
REDUCTION OF GREENHOUSE GAS
EMISSION REDUCTIONS
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CALCULATIONS OF POTENTIAL
EMISSION SAVINGS DEPENDS ON:



 HOW MUCH COGEN IS ASSUMED TO BE
POSSIBLE
 TYPE OF GENERATION BEING DISPLACED BY
COGENERATION
 HEAT TO POWER RATION AND CAPACITY
FACTOR OF THE COGENERATORS
NO AGREED UPON ESTIMATES OF THE
TECHNICAL AND ECONOMIC POTENTIAL
FOR CONERATION IN AUSTRALIA
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AVERAGE EMISSIONS SAVINGS WILL
BE ASSUMED SUCH THAT:
* RECIPROCATING ENGINE
COGENERATORS DISPLACES 910
gCO2/kWh
* & GAS TURBINE COGENERATORS
DISPLACES 870 gCO2/kWh
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ASSUME GAS TURBINE COGEN
PLANT TO OPERATE AT
CAPACTITY FACTOR OF 80% AND
RECIPROCATING ENGINE COGEN
PLANT TO OPERATE AT
CAPACTITY FACTOR OF 40%
HEAT TO POWER RATIO = 1.5
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500 MW OF GAS RECIPROCATING
COGENERATOR OPERATION AT A CAPACITY
FACTOR OF 40%, THE ANNUAL REDUCTION
IN CO2 EMISSIONS IS CALCULATED AS
FOLLOWS:
500,000 kW X 8760 h X 40% X 910 g/kWh = 1,600 kt
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1000 MW OF GAS TURBINE
COGENERATOR OPERATING AT A
CAPACITY FACTOR OF 80%:
1,000,000 kW X 8760 h X 80% X 870 g/kWh = 6,100 kt
ONLY CO2 EMISSIONS CONSIDERED!
ANALYSIS SHOULD CONSIDER CH4 &
NOx .
THEREFORE CO2 EMISSION
WILL CHANGE BY FEW %.
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Species
Gas
turbine
g/kWh
Gas
engine
Gas
boiler
Black
coal
power
station
Brown
coal
power
station
CO2
520620
420650
220
900990
1,1601,400
0.5-0.6 4-20
0.3-0.6 1.5-2.5
0.26
0.07
6.8-6.9
0.1-0.2
0.1-0.2 1.5-2.5
0.07
4-5
0.090.16
0.250.27
NOx
CO
CH4
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68
CO2 SAVINGS FROM
COGENERATION
400 kW GAS TURBINE
CO2 SAVINGS DUE TO DISPLACED
ELECTRICITY ARE THE DIFFERENCE
BETWEEN
COAL FIRED POWER STATION EMISSION
950 g/kWh (BLACK COAL)
GAS ENGINE EMISSION 530 g/kWh
NET
420 g/kWh
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HEAT TO POWER RATIO = 1 (TYPICAL
GAS FIRED COGENERATOR)
CO2 SAVINGS DUE TO DISPLACED BOILER
FUEL ARE FOR 400 X 1.0 = 400 kW
(THERMAL) OF HEAT
CO2
EMISSIONS FOR GAS FIRED BOILER ARE
220 g/kWh (THERMAL) AND THE
COGENERATOR PLANT GENERATES NO
ADDITIONAL CO2 IN MEETING THE HEAT
REQUIREMENTS.
THEREFORE TOTAL CO2 SAVING IS THUS
(420 + 220 X 1.0) = 640 g/kWh (ELECTRICAL)
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GAS FIRED COGEN CAPACITY
Country
Cogen
capacity
(MW)
Generator
capacity
(MW)
Cogen as
% of the
total
Australia
Japan
2082
41000
180000
5.1%
6.5%
UK
45000
7.0%
USA
745600
8.0%
Netherlands
15900
29%
Spain
28420
6.5%
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