Comparison of

Dispatchable Renewable Electricity

Generation Options

Comparison of

Dispatchable Renewable Electricity

Generation Options

Preliminary findings and implications for Bio Energy.

Bio Energy Australia Conference

Sydney 21 November 2017

Keith Lovegrove (ITP), Muriel Watt (ITP), Jay Rutovitz (ISF), Geoff

James (ISF), David Leitch (ITK), Ben Elliston (ITP), Joe Wyder

(ITP), Annie Ngo (ITP)

study commissioned by the Australian Renewable Energy Agency

Planning for a changing electricity mix

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Old world

New world

We need the least cost mix

This study

Looks at technology combinations from a whole of system viewpoint

Examining individual technologies and combinations, to classify their

characteristics, appropriate uses, costs and sensitivities in a

transparent and consistent way

Not a grid integration / NEM modelling exercise

Not picking winners – identifying choices.

The results should inform future grid integration studies.

The results should help inform rational debate and policy

development

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Technologies evaluated

Utility scale Wind or PV generation or a grid sourced mix of two

in combination with:

Large network connected batteries

Pumped hydro storage

Hydrogen storage (electrolysers, fuel cells, and combustion)

Behind the meter PV generation and batteries

Bio Energy

Anaerobic Digestion plus gas engine

Combustion boiler plus steam turbine

Concentrating solar power (CSP) with thermal storage

Geothermal generation

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Representative technologies that are ready

to be installed at utility scale

Tasks

Developing Dispatchability Value and Service Options

Collecting key cost and performance data.

Determining plausible ranges for cost reduction projecting into the

future.

Development and analysis of a range of cost of establishment and

cost of energy metrics.

Development and analysis of a range of value and revenue

generation metrics.

Consideration of policy and regulatory implications of modelled

outcomes.

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Some key terms used rather loosely

Dispatchable

Can generate and raise or lower output on

command from system operator

Firm

Can guarantee a level of reliable generation for

a certain period

Scheduled

“A generator with an aggregate nameplate

capacity of 30 MW or more is usually classified

as scheduled if it has appropriate equipment to

participate in the central dispatch process

managed by AEMO”

Flexible

Can be called on whenever needed to respond

to demand

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Services from dispatchable generators

Many different classifications and levels of detail..

Sending out electricity when most needed

Short term smoothing of wind and PV

Longer term firming and extending wind and solar

Targeting peak demand periods

Providing ancillary services (frequency, blackstart etc)

Supporting system security (inertia, fault current)

Supporting transmission and distribution networks

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Wind or solar based Generation

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Time of Day

Power level

VRE Generation

(cheapest)

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Time of Day

Power level

Immediately firm

Wind or solar based Generation

Add some energy

storage for:

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Time of Day

Power level

Extended firm

Wind or solar based Generation

Add more energy

storage for:

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Time of Day

Power level

Fully flexibleImmediately firm plus:

Wind or solar based Generation

Add more energy

storage for:

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Time of Day

Power level

Fully firm continuous generation

Bio Energy based Generation

Continuously available

resource means:

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Time of Day

Power level

Firm and Fully

flexible

Bio Energy based Generation

Or choose to reduce

capacity factor to

target high demand

periods:

Hypothesis

Continuing to grow VRE penetration until:

There is significant curtailment

There are persistent periods of very low or negative spot prices

Short term energy storage becomes mandatory for system security

Is probably not cost optimal

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A likely suboptimal outcome could follow:

Continuing to reward all renewable

MWhs equally as high penetrations

are reached

Trying to pick a precise specification

of required electrical storage

Over investing in a single technology

solution

Putting them together

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Time of Day

Power level

Demand

VRE

Immediate firm

Extended

firm

Fully flexible

Levelised Cost calculations are valuable

cost per unit energy by amortisation of capital investment over the project lifetime, plus O&M costs

and the cost of any inputs.

If Cashflows are simple, no tax and a single discount / interest rate:

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in

iable

c

fixedR cOM

PF

CFLCOE

var

Capital cost

Conversion

efficiency

Cost per unit of

input energy

Capital recovery

factor:

Variable O&MNameplate

power capacity

Annual

average

capacity

factor

Fixed O&M

n

n

RDR

DRDRF Discount

rate

Beware comparing apples with oranges

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Dispatchable

renewable but

only one

configuration

VariableContinuous

generationPeaking

Our installed cost model combines

subsystems

𝐶𝑜𝑠𝑡(𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝑥) = 𝐶𝑜𝑠𝑡 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝑦𝑥

𝑦

𝑛

Where: x - plant capacity of interest

y - base case plant capacity

n - between 1 (modular) and 0.7 (strong economy of scale)

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Collection:

Cost / MW

of output

capacity

Initial

conversion:

Cost / MW

of output

capacity

Storage:

Cost / MWh

of capacity

Final

Conversion:

Cost / MW of

output

capacity

Subsystems for Bio cases

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Waste at

0$/GJ

Digestor @

$1.42m/

MWth

Gas

accumulator

@ $12,400 /

MWhth

Gas engine

generator @

$0.91m/

MWe ,

Ƞ=34%

Dry

Biomass at

$5 /GJ =

$18/MWhth

+/-

naDepot

storage @

$7/ MWhth

Boiler plus

turbo-gen @

$4.89m/

MWe,

Ƞ=24%

Anaerobic Digestion plus gas engine:

Dry Biomass plus combustion boiler and steam turbine:

Bio Energy results

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Preliminary

results

subject to

revision

• 50 MW Biomass

combustion / steam

turbine,

• 10MW AD / gas

engine

• 7.8% WACC

AD Biomass/ gas

engine

Combustion / steam

turbine $5/GJ

Combustion / steam

turbine $2.5/GJ

Configure for

flexible / peaking

Bio Energy & the competition

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• Wind and solar

driven systems at

100MW output

• 7.8% WACC

Preliminary

results

subject to

revision

Bio specific observations

Bio Energy electricity LCOE’s are lowest for continuous generation

Running at 50% capacity factor increases LCOE but provides very

competitive fully flexible generation

Bio Energy ticks the boxes of; synchronous generation, inherent

inertia, fault current capability

Cost of Biomass for combustion is critical

Dry Biomass in a stockpile is a cost effective strategic reserve

(although it will require additional management techniques)

More complex and advanced combinations likely to be even more

competitive, eg:

Gasification plus combined cycle for higher efficiency

Combined heat and power systems with two revenue streams

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Conclusions

Australia and the world’s electricity needs to be 100% zero

emissions by 2050 for <2oC

We have multiple affordable options for firm and flexible

renewable generation over all time scales to balance lower

cost variable PV and Wind

A mix of technologies, configurations for duration and

geographical locations is likely to minimise to overall average

cost of electricity.

Pursuing a range of dispatchable RE options now maximises

the chance of a least cost transition.

A well designed NEG could send the market signals needed.

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