This document summarizes the results of a study quantifying Ireland's fossil fuel and CO2 emissions savings from renewable electricity in 2012. The study found that wind variation was less than electricity demand in 2012. Forecasts of wind output were on average 5.6% different than actual output. The analysis estimated that wind energy saved 826,000 tonnes of fossil fuels worth €225 million on Ireland's electricity system in 2012. This led to carbon savings of 2.33 million tonnes of CO2 worth €17 million. While individual fossil fuel units produced 6% less CO2 per unit of output with wind, Ireland's overall electricity system produced 14% more carbon per unit of electricity generated without wind.

1. Quantifying Ireland’s Fossil Fuel & CO2
Emissions Savings from Renewable Electricity
in 2012
Matthew Clancy & Fiac Gaffney
26th May 2014

2. 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

3. 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

4. Wind Characteristics in 2012

5. 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
Demand&windoutput
(MW)
7 Day Snapshot
Electricity
Demand
Net Load
Wind

6. Wind Energy Integration (2012 uncertainty)
Normalised Mean Absolute
Error: 5.6%

7. Model Details

8. 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

9. 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

10. Results

11. 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

12. Fossil Fuel Generation
+20%
100 MWh
saved
78 MWh 22 MWh
&

13. Fuel & Emissions Savings
)
1 unit 1.88 units
saved
1 MWh
displaced
0.46 tCO2

14. Fossil Fuel Unit CO2 Intensity
-6%

15. System-wide CO2 Emissions Intensity
+14%

16. Summary

17. 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

18. Thank you..