Energy Systems Modeling at ERC

The SA TIMES Model

Overview of Modeling

Inputs to optimization modelOutputs from optimization modelIntermediary information flow

Economic Analysis

Demand Sectors (commercial and agriculture omitted from diagram)

MARKAL/TIMES optimization

energy model (GAMS with CPLEX

solver)

Base Year Energy Balance

Residential sector Demand

projections

Industrial sector future

technologies

Industrial sector Demand

projections

Transport sector future technologies

Transport sector Demand

projections

Supply Technology

Existing power system

Existing liquid fuel supply

system

Socio-Economic Variables (GDP,

Population)

Energy Resources/Import and Exports

Residential sector future technologies

Policy objectives/constraints

Socio-economic growth

objectives

Environmental objectives,

taxes

Energy security objectives

Future power generation

technologies

Existing coal/gas supply

system

Future coal/gas supply

technologies

Future liquid fuel supply

technologies

Fossil fuel reserves

Renewable energy resource

potential

Import/export (elc, oil, gas)

Residential sector base-

year calibration

Results Analysis

Industrial sector base-year calibration

Transport sector base-

year calibration

Investment Schedule/Plan

Imports, exports, consumption,

production, Emissions

System costs, energy costs

Components of a MARKAL/TIMES model

Components of an Energy System ModelComponents of an Energy System Model

** Energy systemtopology & organization

RES

0

25

50

75

100

125

150

1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020

GWh** Numerical data Time Series

P P

O P

Q P

BHKW S BHKW Coal BHKW

BHKW CO Coal BHKW

BHKW H BHKW Coal BHKW

_ _

_ _

_ _ _

2

2

** Mathematical structure– transformation equations– bounds, constraints– user defined relations

GAMS Model

** Scenarios and strategies Cases

Simple Reference Energy System

Energy model components

• Made up of 2 simple components:– Energy Carriers (e.g. fuels, demand)– Technologies (e.g. Light bulb, power plant) all

characterized in the same way:– Input and Output Carrier– Efficiency– Investment Costs per unit of capacity– Annual Activity Costs– Existing Capacity– Annual Availability– Expected Life– Emissions

Useful energy demand

• Calculated using spreadsheets• Based on assumptions

– Useful energy calculated for base year– Projected into future

• Affected by– GDP assumptions– Structure of the economy– Changes in per capita income– Assumed income distribution, electrification etc

SectorsSector Disaggregation Driver

Agriculture By end use, irrigation, transport etc Agriculture GDP

Residential High, medium and low income/ electrified and non-electrified

POPULATION, Household income

By end use, cooking, lighting etc

Commercial By end use, lighting, HVAC, etc Commercial GDP, building stock

Industrial By sector, Iron and Steel, Pulp and paper etc Sectoral GDP

By end use, thermal fuel or electricity (compressed air, cooling, motive, etc

Transport Air, Freight, passenger, pipeline Transport GDP, Population and household income

By end demand, passenger km, ton km

By end use, diesel car, petrol car, taxi etc

Variation of the Load (electricity)

• 20 Time-slices• Year divided in 3 seasons• Each season represented by 2 typical days• Season 1 and 3 (summer), each day is broken

up into 3 parts (night, day, evening)• Season 2 (winter) week day is broken up into

5 parts (night, morning, afternoon, evening, peak)

Other elements

• Emissions:– Emissions coefficient/energy carrier– Emissions Tax

• Constraints:– Committed build plans– Resource limits– Mode shares– Fuel shares– Policy Objectives (e.g. CO2 limit)

Model Outputs• Reported globally:

– Total Costs– Total tax/subsidy– Total Investments– …

• Reported for demands each year:– Actual energy demand met– Marginal Price (Shadow price/cost of supplying one extra unit of demand)

• Reported for each energy carrier each year:– Imported/exported– Mined

Model Outputs (Continued)• Reported for technologies each year:

– Fixed costs– Capacity Level and Marginal– Capacity Unused– Fuel Used– Investment Costs– Investment Levels and Marginal costs– …

• Reported for emissions each year:– Emission Levels

• Reported for tax/subsidy each year:– Tax/Subsidy

The SAGE Model• Calibrated to a 2005 SAM (Arndt et al., 2011)

– 54 industries and 46 commodities – 7 factors of production (4 education-based labour groups; energy and non-

energy capital; agricultural productive land) – 14 household groups based on per capita expenditures – Energy Supply Sector disaggregated

• Resource constraints – Upward sloping labour supply curves for less-educated workers – Sector Specific capital and endogenous capital accumulation

• Macroeconomic closures – Fixed current account with flexible real exchange rate – Savings-driven investment

• Model has already been used by Treasury to look at some CO2 tax scenarios and recycling options

SAGE Model (continued)

• Previous Runs of SAGE model with Power sector production shares and investment fixed by IRP plan

The CGE-TIMES Link

-GDP and sectoral growth -Household income growth

- Electricity Generation Shares-Investment-[Electricity production costs]

- Simple Extrapolation of sectoral and income growth, used to re-calculate useful energy demand.

Sectoral Linkage

The CGE-TIMES link continued

• The Idea is to replicate IRP/IEP process in TIMES• Fix committed build• See how the economy responds• Adjust forecast and update investment plans• Re-iterate