1. Basics of energy modelling III: Time representation and considerations
CLEWS Summer School,
ICTP (Trieste), Italy,
13 June, 2017

2. Time representation Long-term energy system models:
Span a large time horizon (e.g – 2050)
Consider a large set of technologies
Span a large geographical region (e.g. USA, Africa, Europe, China)
Need to capture temporal variations:
Variability of supply (e.g. wind, solar, hydro)
Variability of demand (e.g. seasonal, monthly, weekly, daily)
Peak load requirements
Trade-off between level of detail and computational cost

3. What are Time Slices?
Each year divided into representative time periods known as Time Slices:
(Summer-Winter-Intermediate) x (Day- Night) = 6 Time Slices
(Jan-Feb-Mar-…-Dec) x (Weekday- Weekend) x (Day-Night) = 48 Time Slices
(365 days) x (24 hours) = 8760 Time Slices
Number of Time Slices in OSeMOSYS is practically unlimited
Time Slice definition is consistently applied for the entire model
8760
Electricity
demand
Water resources

4. Example of Time Slice definition
2017
2050
Model horizon
Annual
Seasonal
Weekly
Daily
Source: R. Loulou, U. Remne, A. Kanudia, A. Lehtila, and G. Goldstein. Documentation for the TIMES model: Part I. ETSAP, April 2005

5. Time Slice-related parameters
Year Split: Duration of each Time Slice as a fraction of a year
Capacity Factor: Fraction of a technology’s capacity that can be utilized in each Time Slice
Specified Annual Demand*: Fraction of annual demand for a commodity in a each Time Slice
*Accumulated Annual Demand: Total annual demand for a commodity. Can be balanced in any Time Slice.
Supply and demand for commodities is balanced for each Time Slice

6. Time Slice Definition (Example of Bolivia)
Yearly load curve and hydro production for Bolivia in Based on the hydro power production and the months with high electricity demand, the year was split into the following sections

7. Time Slice Definition (Example cont.)
Year divided in four Seasons
Season 1: 1st January to 30th April
Season 2: 1st May to 31st August
Season 3: 1st September to 30th November
Season 4: 1st December to 31st December

8. Time Slice Definition (Example cont.)
Season 1
Season 2

9. Time Slice Definition (Example cont.)
Season 3
Season 4

10. Time Slice Definition: Exercise 1
01:00-07:00
07:00-18:00
18:00-22:00
22:00-01:00
Seasons
6 hours
11 hours
4 hours
3 hours
Season 1 (Jan-Apr) ?
Season 2 (May-Aug)
Season 3 (Sep-Nov)
Season 4 (Dec)

11. Time Slice Definition: Exercise 1
Time (duration)
01:00-07:00
07:00-18:00
18:00-22:00
22:00-01:00
6 hours
11 hours
4 hours
3 hours
Total = 24 hours
Season 1 (Jan-Apr)
120 days
Season 2 (May-Aug)
123 days
Season 3 (Sep-Nov)
91 days
Season 4 (Dec)
31 days
Total = 365 days
Total = 8760 hours

12. Exercise 2: Earlier example, with TimeSlices
NOTE: ‘SpecifiedAnnualDemand’ instead of ‘AccumulatedAnnualDemand’
YearSplit
Day
Night
6:00-18:00
18:00-6:00
12 hours
Summer
4 months
0.1667
Winter
Intermediate
SpecifiedDemandProfile
Day
Night
7:00-19:00
19:00-7:00
12 hours
Summer
4 months
0.15
0.05
Winter
0.5
0.1
Intermediate

13. Exercise 2: Earlier example, with TimeSlices

14. Exercise 2: YearSplit

15. Exercise 2: SpecifiedAnnualDemand

16. Exercise 2: SpecifiedDemandProfile

17. Exercise 2: Demand

18. Exercise 2: Results

19. Exercise 2: Results