Coal-fired steam-cycle generator Gas turbine · PDF fileSteam Steam turbine ... Steam cycle thermal plant: – Start-up time can be many hours ... 2003 Load duration curves for NEM

Power systems: generation technologies & demand characteristics© CEEM, 2006

2Power systems: generation technologies © CEEM 2006

The electricity industry conversion chain

primaryenergyformse.g:

coal, gasrenewable

electricalenergyin thet&d

network

end-useenergyformse.g: light,heat,

motivepower

powerstations

end-useequipment

energy losses & external impacts

Electrical equipment providers


Coal-fired steam-cycle generator

660 MWAlternator

Electricity600 MW

1650 MWBoiler540oC,16 MPa

Ash: 50 t/hHeat: ~165 MWCO2: ~600 t/h

Coal250 t/h

Air2,500 t/h

660 MWTurbine

Steam1485 MW

825 MWlow-grade

heatSteam/water

cycle

>

800 MWlow-grade

heat

Cooling water70000 t/h

CondensorWater @ 30oC,

0.005 MPa


Gas turbine generator

Electricity

Generator

Air

Aircompressor

Exhaust gasesincluding CO2, NOX

Gasturbine

GasorOil

Combustor

Hotcompressed

gases


Combined cycle gas turbine (CCGT)

Generator

Electricity

Steam

Steamturbine

Heat recoveryboiler Hot gases including

CO2, NOX

Air

Aircompressor

Gasturbine

GasorOil

Combustor

Hotcompressed

gases


Energy flow in a CCGT (%)

GT100 %

30%

28%

Electricity58%

ST70 % 42 % Waste heat42%


Trends in key Combustion Turbine parameters (Cogeneration & On Site Power Production, Jan-Feb 2000)

Year 1967 1972 1979 1990 1998

Inlet Temp 0C 900 1000 1100 1250 1400

Comp Ratio 10.5 11 14 15 19-23

Exh Temp 0C 430 480 530 580 600

Max Rtg MW 60 80 100 250 280

Eff (OC) % 29 31 34 36 39

Eff (CC) % 43 46 49 53 58 54

46

100

GE LMS100

2005


Conversion efficiencies(from primary energy to electricity)

0

10

20

30

40

50

60

Blackcoal

Browncoal

OCGT CCGT

Efficiency %


Australia’s coal resources (www.industry.gov.au & SKM)


Australia’s natural gas resources& pipelines(www.ena.asn.au)

Reserves:• 90% in NorthwestAustralia

Linepack:• Hours in Victoria to days in other states

Trading arrangements:• Market in Victoria• Contract carriagein other states


Integrated coal gasification & combined cycle with carbon collection & storage(Simhauser, 2004)


Geosequestration options for CO2(Simhauser, 2004)


CCS does not mean zero emissionsIGCC with geosequestration will still have CO2 emissions– Energy-cost tradeoffs in CO2 capture from flue or gasifier stream;

also energy for transport and pumping underground

IEA (2001)

Coal IGCC with CO2 capture emits approx. 40% of standard CCGT (without capture)


CCS scenarios to 2100(IPCC CCS report, www.ipcc.ch, 2005)

CCS:1. Not before 20202. Gas before coal.


Key findings of IPCC CCS report (www.ipcc.ch, 2005)

A portfolio of mitigation measures will be needed (CCS alone not sufficient)Large-scale CCS power plant don’t yet existBy 2050, 20-40% of fossil fuel CO2 technically suitable for CCS at cost of 13 to 67 A$/MWhDeployment needs CO2 price of 25-30 US$/MWhCCS might contribute 15-44% of cumulative mitigation effort to 2100, limited beyond that (identified storage sites would then be full)


Nuclear (fission) energyKey issues:• Power station safety• Nuclear waste storage • Terrorism & nuclear weapon proliferation


The civilian nuclear fuel cycle

Radioactivewastes

(Uranium Information Centre)

(COGEMA)

Uranium


Global possession of nuclear weapons(www.wikipedia.org)

Five NPT “nuclear weapon states”

Known to have nuclear weapons

Suspected to havenuclear weapons

Have had a nuclear weapon program

Could quickly build

nuclear weapons


Geothermal energy - radioactive rockAustralia has plentiful radioactive rock at ~3,000m covered by insulating layers:- safe nuclear energyTrial in Cooper Basin, SA

(www.greenhouse.gov.au)


Geothermal energy - grid connection (Geodynamics, 2006)


Cost estimates: coal, gas, nuclear, geothermal (Geodynamics, 2006)


Hydro energyFrom potential energy of water in storage damTo rotational kinetic energy in turbine and then electrical energyAt good sites, large hydro can be cheaper than coal-fired power stations


Electrical power (kW):P ~ 10xFxHxE

Where:•F = water flow (metres3/sec)•H = gross head (metres)•E = efficiency (0.7-0.9)


Lake Eucumbene(3900 GWh/yr)

Snowy Mountains Scheme

Jindabyne pumps(240 GWh/yr)

Geehi

Tumut 1 & 2600 MW

Talbingo

Tumut 3Gen: 1500 MWPump: 600 MW Jounama

transfer tunnels

Murray 1 & 21500 MW


Tasmania’s power stations(Tas Govt 2000)

Derwent

GreatLake

Mersey

Gordon

King

Pieman

Woolnorthwind farm

65 (+75) MWMusselroewind farm (130 MW)

Bell Bay240MW

2500

1500

1000

750

500

Rainfall(mm)

www.hydro.com.au


Tidal energy

Low-head hydro with two-directional flowTidal range varies with solar-lunar alignmentSea water more corrosive than fresh waterLow head implies less cost-effective than most hydro



Biomass energy

Energy crops, possibly also for salinity controlAgricultural by-products - eg bagasse (sugarcane)Municipal wastes (a difficult fuel due to diverse nature)Burn directly or convert to liquid or gaseous fuels



Albany wind farm, Western Australia


(European Commission, 2005)


Australian wind resource(Approximate estimates, with average speeds in m/s)

(www.greenhouse.gov.au)30Power systems: generation technologies © CEEM 2006

Wave energyWave energy derives from wind energy:– Energy density varies

dramaticallyNeed strength to survive storms yet cheap & sensitive enough to produce energy from small wavesStill under development



Emerging wave power technologies


Distributed resources (DR)Small generators or storage embedded in an electricity distribution network:– Cogeneration:

Useful heat (or cooling) as well as electricity

– Emerging technologies:Micro gas-turbines, fuel cells

– Renewables Biomass, small hydro, wind, photovoltaics

– Reversible storage:eg batteries, flywheels

Demand-side resources


A regional electricity network

Transmission(220-500 kV)

Sub-transmission(33-132 kV)

Distribution(11-33kV)

Reticulation(240/415 V)

Inter-connectorto another region

Transmissionsubstation

SmallConsumers

LargeGenerators

100-700 MVA

EmbeddedGenerators≤ ~30 MVA

LargeConsumers

Meshed transmission network Radial distributionnetwork

Zone substation


Potential benefits of cogeneration (CHP)compared to gas steam cycle (or CCGT)

100

FuelFuel

85 (57)

56

Separateproduction

Power stationefficiency

40% (60%)

Boilerefficiency

90%

34 units ofelectricity

&50 unitsof steamper hour

Industrialprocess

50

3434

50

Total141

(113)

Total100

CHP

Electricalefficiency

34%

Heatefficiency

50%

Benefit of CHP depends on balancebetween electricity & steam requirements

& efficiency of retail electricity & gas markets


Capstone Micro-turbine

• 30 kW• 400-480 V, 50-60 Hz• 25% efficiency whenfuelled by high pressurenatural gas (LHV)

• 500 kg• 1.9x0.7x1.3 metres• Became commerciallyavailable in 1999


PEM fuel cell (PEFC)(http://www.ballard.com, 2001)

Anode:-• Hydrogen disassociates into

protons & electrons at ~90oC• Electrons flow to cathode via

external circuit(~0.6 volts/cell DC)

Membrane:• Protons pass through to

cathodeCathode:• Returning electrons combine

with protons & oxygen to produce water vapour

250 kW prototype PEFC


Ballard residential fuel cell concept(http://www.ballard.com, March 2001)

1 kW PEFC Engineering Prototype Feb 2001:~40% elec efficiency & ~40% heat efficiency


Solar energy - photovoltaicsPV cells convert solar energy directly to DC electricity

– Use inverter to create ACStand-alone or building integrated

650 kW, Newington (Pacific Power)

200kW, Singleton (EnergyAustralia)


Solar thermal concentrators for electricity generation(www.greenpeace.org)

Parabolic trough (~350MWe):– Most mature but low efficiency

Central receiver (~10MWe):– High efficiency but pre-commercial

Parabolic dish (<1MWe):– High efficiency but pre-commercial

Tower (50MWe)– Artificial wind;

pre-commercial


Building Integrated PV & Solar Hot Water assessment:Key variables:– System efficiency– Solar radiation– Temperature– Rooftops

area,orientation, tilt, shading

Further work needed:– Rooftop resource– ShadingAustralia has excellent solar resources but best in NW

Solar Resource



Australian Primary Energy Use 2000-01(ABARE, quoted in Energy & Resources Working Group, 2003; www.greenhouse.gov.au)

28%

13%

34%

20%

5%

Black coalBrown coalCrude oilNatural gasRenewables


Comparing electricity generation options(CO2 Coefficients & Costs: Securing Australia’s Energy Future (most); Energy payback: Wind:www.windpower.dk; PV: www.eere.energy.gov)

<1

<1

<1

2-5

<1 (unknown)

<1(unknown)

Egy Payback (yr)

3-11

9-21

6-29

100-280

450-660 (80-150)

700-1100 (150-200)

CO2 g/kWh

30-70Hydro

n/a (Aust.)Nuclear

50-80Wind

250-400Solar

35-45 (unknown)

Gas CC (CCS)

30-40 (unknown)

Coal SC (CCS)

Cost in 2010 ($/MWh)

Type


Inter-temporal linksEnergy-limited hydro:– Use water now or save till later?

Which strategy will give greater return?

Steam cycle thermal plant:– Start-up time can be many hours– Fuel stockpile management– Maintenance schedulingGas turbines:– Maintenance penalty if start/stop too often– Start-up time & fuel stockpile management


EnergyAustralia System - Summer 2000/01 Profiles - Peak and Average Days

0

1000

2000

3000

4000

5000

2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00

MW

23 Jan 2001

Avg Workday

Avg NonWorkday

Air conditioning usage

0

2000

4000

6000

8000

10000

12000

14000

Sunday Monday Tuesday Wednesday Thursday Friday Saturday

07 to 13 March 2004 27 to 02 August 2003NSW summer & winter peak demand


2003 Load duration curves for NEM states(NEMMCO SOO documents, 2004)

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90Percentage of time

New South Wales Victoria Queensland South Australia Tasmania


Demand side resources

Any cost-effective action taken on the demand side of the electricity industry, e.g:– Reducing demand at times of supply constraint:

load shifting; curtailment of lower-value end-uses

– Improving end-use efficiency:e.g. compact fluorescent light globe

– Fuel switching at the point of end-use, eg:to natural gas or an end-use renewable such as solar water heating


Evidence of demand side response:NEM Victorian region, 8/2/01 (NECA, 2001)


Demand-side participation & projected low reserve conditions (NEMMCO SOO Executive Summary, 2006)


Deterministic method to compare resource investment options: “optimal resource mix”

Key attributes for comparison of generation or demand side resource options:– Investment lead time– Direct costs:

Investment cost (expressed as K $/kW/yr)Operation and maintenance (O&M) cost:

– Fixed: F $/kW/yr; Variable:- V $/kWh

– External impacts:Land, water, air, visual, noise

– Operating characteristics:Starting time, operating constraints, fuel availability


Annual cost of resource option ‘i’(assumed to be known with certainty & network costs or benefits ignored)

Direct cost can be expressed as:– Cost independent of output: (Ki + Fi) $/kW/yr– Cost that varies with output: Vi $/kWh

Total annual cost of operation (TC) is:TC = (Ki + Fi) + (Vi x CF x 8760) $/kW/yr

– Where annual capacity factor, CF is:

annual energy in kWh(rated kW)x8760

CF = Where 0≤CF≤1


‘Optimal’ resource mix (generation & demand)‘peak duty’ option

‘base duty’ option

‘intermediate duty’ option(voluntary)

demandreduction

envelope of cheapest available options

breakevenpoints

C1 C2 C3

$/kW/yr

Capacityfactor


Capacityfactor0 1

MW

Load duration curve & resource mix(ideal case: no uncertainty in demand or unit availability & no load growth)

base duty resources

C3C2

intermediate duty resources

C1

peak duty resourcesdemand reduction

load duration curve


Summary

Large steam-cycle turbo-generators:– The “workhorse” of the electricity industry:

Coal, oil, gas or nuclear

– Combined cycle - a recent enhancement“Embedded” & renewable energy generation:– CHP, fuel cells, hydro, wind…– Demand-side options - neglected to date:

End-use efficiency, voluntary demand reduction

Procedure to track the “optimal mix”:Centralised (traditional) or decentralised (competitive)


Many of our publications are available at:www.ceem.unsw.edu.au

Documents

Coal-fired steam-cycle generator Gas turbine · PDF fileSteam Steam turbine ... Steam cycle thermal plant: – Start-up time can be many hours ... 2003 Load duration curves for NEM