Energy Supply and Demand

TIMER: Model outline and structure

Overview

The TIMER model describes the chain from demand for energy services (useful energy) to supply of energy by different primary energy sources and related emissions (Figure 2). The links in the chain are connected by demand for energy (from left to right) and by feedbacks, mainly in the form of energy prices (from right to left). The TIMER model has three types of submodels: 

1. the energy demand model; 
2. models for energy conversion (electricity and hydrogen production);
3. models for primary energy supply.      

Some of the main assumptions for the different sources and technologies are listed in the main assumptions table.

figure 2: Overview of the TIMER model.

Final energy demand

Final energy demand (for five sectors and eight energy carriers) is modelled as a function of changes in population, economic activity and energy intensity. The model distinguishes four dynamic factors: structural change, autonomous energy efficiency improvement, price-induced energy efficiency improvement and price-based fuel substitution. 

Electric power generation

The electric power generation sub-model simulates investments in various electricity production technologies and their use in response to electricity demand and to changes in relative generation costs (see also Hoogwijk, 2004). Fossil fuels and bio-energy can be used to generate electricity in a total of 20 different plant types that represent different combinations of 

1. conventional technology;
2. gasification and combined cycle technology; 
3. combined-heat-and-power;
4. carbon-capture and storage (see also Hendriks et al., 2004).      

The efficiency and capital requirement of these plant types are determined by exogenous assumptions that describe technological progress of typical components of these plants (the characteristics of the total set are derived from these typical components).

Hydrogen production

A similar model exists for hydrogen production (but with slightly less detail).

Resource depletion of fossil fuels and uranium

To model resource depletion of fossil fuels and uranium, several resource categories, depleted in order of their costs (12 categories for oil, gas and nuclear fuels, 14 for coal), are defined. Production costs thus rise as each subsequent category is exploited. The final production costs in each region thus represent the combined influence of learning-by-doing and resource depletion. Depletion is determined by subsequent depletion of the 10-14 fuel classes. The learning parameter leads to lower costs with increasing cumulated production. In the trade formulation, each region imports fuel from other regions, depending on the ratios between the production costs in the other regions plus transport costs, and the production costs within the region considered (multinomial logit). Transportation costs are the product of the representative interregional distances and time- and fuel-dependent estimates of the costs per GJ per km. To reflect geographical, political and other constraints in the interregional fuel trade, an additional parameter is used to simulate the existence of trade barriers between regions.

Biomass sub-model

The structure of the biomass sub-model is similar to that of the fossil fuel supply models but with a few important differences. 

• First of all, in the bio-energy model, depletion is not governed by cumulative production but by the degree to which available land is being used for commercial energy crops. 
• The total amount of potentially available bio-energy is determined on the basis of calculations of the IMAGE crop model. Potential supply is restricted on the basis of a set of criteria, most important, bio-energy is only allowed on abandoned agricultural land and part of the natural grasslands. The costs of primary bio-energy crops (woody, maize and sugar cane) are described using a Cobb-Douglas production function applying labour costs, land rent costs and capital costs as input.
• Subsequently, the biomass model describes the conversion of biomass (in addition to wood crops, maize and sugar cane as well as residues) to two generic secondary fuel types: bio-solid fuels and bio-liquid fuels. The solid fuel is used in the industry and power sector and the liquid fuel in other sectors, in particular transport.  
  
  
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