Quantifying Ireland’s Fossil Fuel & CO2 Emissions Savings from Renewable Electricity in 2012

Matthew Clancy & Fiac Gaffney

26th May 2014

Context

• Misconceptions on how wind acts to save fossil fuel and

CO2 emissions

• Individual aspects of the impact of wind energy out of

context

• “Unpredictable”, “Unreliable”, “Intermittent” “Only online 1

out of every 3 hours”, “Requires additional backup”,

“does not reduce CO2”,

• Complete or net ‘bottom line’ impact all important

Background

• SEAI paper aimed at taking account of all significant

factors influencing the impact of wind* on overall fossil

fuel use and CO2 emissions

• What influences fossil fuel and CO2 displacement?

• What level of displacement happened in 2012 on the

All-Island system?

• Three parts:

– Context (includes influencing factors, and estimates from

previous studies)

– Methodology (model and scenarios)

– Results (‘bottom line’ and intermediate)

*Study included other renewables, but focus here is confined to

wind generation

Wind Characteristics in 2012

Wind Energy Integration (2012 variability) 2012 Variation Metrics

15 Minutes 1 hour 4 hours 12 hours

Standard

Deviation (MW)

Maximum

Change (MW)

Standard

Deviation (MW)

Maximum Change (MW)

Standard

Deviation (MW)

Maximum

Change (MW)

Standard

Deviation (MW)

Maximum

Change (MW)

Demand 36 277 130 778 370 1,458 470 2,241

Wind Output

26 238 69 444 69 825 308 1,263

Net Load 38 293 131 902 368 1,798 496 2,877

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

1 2 3 4 5 6 7

De

ma

nd

& w

ind

ou

tpu

t (M

W)

7 Day Snapshot

ElectricityDemand

Net Load

Wind

Wind Energy Integration (2012 uncertainty)

Normalised Mean Absolute

Error: 5.6%

Model Details

All Island Electricity Model Inputs

2012 Base

Model

Wind: • Installed Capacity for wind in each

month in 2012

• Wind energy profiles for day ahead

forecasts and actual wind output

Hydro: • Daily output for hydro

based on actual 2012

production

Bioenergy: • Installed bioenergy

capacity in 2012

System network

constraints in 2012: • All RoI & NI system

constraints included

Reserve requirements and

frequency stability limits: • Primary, secondary, tertiary

and replacement reserves for

both RoI & NI

• 50% synchronous non-

synchronous penetration

limit

Generator technical characteristics: • Maximum output and minimum stable

generation output

• Start up/shut down time and cost

• Heat rates at different levels of output

• Actual schedule and forced outages

• Ramping capabilities

Quarterly fossil fuel & CO2 prices in 2012: • Coal, natural gas, distillate oil and heavy fuel oil

prices

• Transportation costs of fossil fuels included

• CO2 prices for each quarter

All-island system demand: • Actual electricity demand

• Day ahead forecast error

Simulation details: • Model uses PLEXOS electricity system

optimisation software

• Unit commitment based on day-ahead forecasts

for wind, demand and scheduled outages

• Real time dispatch is based on actual wind

output data, actual demand and recorded 2012

generator forced outages

Interconnection: • The actual recorded 2012 flows

across the East-West and Moyle

Interconnectors

Generator commitment & dispatch

24 hours ahead

Forecast for:

• Electricity demand,

• Wind Output

Generator commitment

Actual:

• Electricity demand

• Wind Output

Generator dispatch (30 minutes)

Real time

Scheduled generator

outages

Scheduled & forced

generator outages

Results

Results documented

• ‘Bottom line’ impacts:

• Overall net fossil fuel displacement

• Overall net emissions displacement

• Valuation of savings

• Intermediate influencing factors:

• Operational and start-up fossil fuel uses:

• Ramping

• On-line hours per start-up (Cycling)

• On-line capacity factor

• Combined impact on CO2 emissions

• Seasonal variations

• North-South interactions

Fossil Fuel Generation

+20%

100 MWh

saved

78 MWh 22 MWh

&

Fuel & Emissions Savings

)

1 unit 1.88 units

saved

1 MWh

displaced

0.46 tCO2

Fossil Fuel Unit CO2 Intensity

-6%

System-wide CO2 Emissions Intensity

+14%

Summary

Summary

• Wind variation was less than electricity demand in 2012

• The average forecast error at 24 hours ahead was 5.6%

of installed wind capacity

• Wind is estimated to have saved 826 ktoe of fossil fuel

worth €225 million on the All-Island system

• The associated carbon savings are 2.33 MtCO2 worth

€17 million

• Fossil fuel units produce 6% less CO2 per unit output

without wind on the system

• But the overall electricity system produces 14% more

carbon per unit of electricity generated without wind on

the system

Thank you..