Methodology
Methodology for indicator calculation
CO2 emissions from fuel combustion are derived from the detailed projections of energy consumption. The projections are made with the use of the World Energy Model 2004.
Overview of the World Energy Model 2004 (WEM)
The WEM is a mathematical model made up of five main modules: final energy demand, power generation; refinery and other transformation; fossil fuel supply and CO2 emissions. Figure C1. (World Energy Outlook, 2004, p.532) provides a simplified overview of the structure of the model.
The main exogenous assumptions concern economic growth, demographics, international fossil fuel prices and technological developments. Electricity consumption and electricity prices dynamically link the final energy demand and power generation modules. Primary demand for fossil fuels serves as input for the supply modules. Complete energy balances are complied at a regional level, and the CO2 emissions of each region are then calculated using derived carbon factors.
For each sector and fuel, CO2 emissions are calculated by multiplying energy demand by an implied carbon emission factor. Implied emission factors for coal, oil and gas differ between sectors and regions, reflecting the product mix. They have been calculated from year 2002 IEA emission data for all regions.
The IEA's WEM is a principal tool used to generate detailed sector-by-sector and region-by-region projections for the Reference and the Alternative Scenarios. (see definitions of scenarios under section reference scenario). The model has been updated and revised over years and the development process continues.
Key model assumptions for the reference case
The central projections derived from a Reference Scenario. They are based on a set of assumptions about governmental policies, microeconomic conditions, population growth, energy prices and technology.
Governmental policies and measures
The reference Scenario takes into account only those governmental policies and measures that were already enacted - though not necessary implemented - as of min-2004. The Reference Scenario does not include possible< potential or even likely future policy initiatives. Major new energy policy initiatives will inevitably be implemented during the projection period, but it is difficult to predict which measures will eventually be adopted and how they will be implemented, especially towards the end of the projection period.
Although the Reference Scenario assumes that there will be no change in energy and environmental policies through the projection period, the pace of implementation those policies and the way they are implemented in practice are nonetheless assumed to vary by the fuel and region. For example electricity and gas market reforms are assumed to move ahead, but at varying speeds among countries and regions. In all cases, the share of taxes in energy process is assumed to remain unchanged, so that retail process are assumed to change directly in proportion to international prices. Similarly, it is assumed that there will be no changes in national policies on nuclear power. As a result, nuclear energy will remain an option for power generation only in those countries that have not officially banned it or decided to phase it out.
Macroeconomic factors
Economic growth is by far the most important driver of energy demand. The link between total energy demand and economic output remains close. Detailed GDP assumptions by region are set out in Table below.
Economic Growth Assumptions (average annual growth rates, in %)
| 1971-2020 | 2002-2010 | 2010-2020 | 2020-2030 | 2002-2030 |
| OECD-Europe | 2.4 | 2.4 | 2.2 | 1.7 | 2.1 |
Transition Economies total | 0.7 | 4.6 | 3.7 | 2.9 | 3.7 |
- Russia | -1.1 | 4.4 | 3.4 | 2.8 | 3.5 |
- Other transition economies | -0.5 | 4.8 | 3.9 | 3.0 | 3.8 |
European Union | 2.4 | 2.3 | 2.1 | 1.7 | 2.0 |
| World | 3.3 | 3.7 | 3.2 | 2.7 | 3.2 |
Population
Population growth affects the size and composition of energy demand, directly and through its impact on economic growth and development. The WEO population growth rate assumptions are drawn from the most recent UN populations' projections contained in World population Prospects: the 2002 Revision. Detailed populations assumptions by region are set out in Table below.
Population growth assumptions (average annual growth rates, in %)
| 1971-2020 | 2002-2010 | 2010-2020 | 2020-2030 | 2002-2030 |
| OECD-Europe | 0.5 | 0.3 | 0.1 | 0.0 | 0.1 |
Transition Economies total | 0.5 | -0.2 | -0.2 | -0.4 | -0.3 |
- Russia | -0.3 | -0.6 | -0.6 | -0.7 | -0.7 |
- Other transition economies | 0.0 | 0.0 | 0.1 | -0.1 | 0.0 |
European Union | 0.3 | 0.1 | 0.0 | -0.1 | 0.0 |
| World | 1.6 | 1.2 | 1.0 | 0.8 | 1.0 |
Energy Prices
As in previous additions of the WEO, average and-user process for oil, gas and coal are derived from assumed price trends on wholesale or bulk markets. Tax rates are assumed to remain unchangeable over the projection period. Final electricity prices are based on marginal power generation costs. The assumed price paths assumed in the table presented below should not be interpreted as forecasts. Rater, they reflect IEA judgment of the prices that will be needed to encourage sufficient investment in supply to meet projected demand over the Outlook period.
Fossil-Fuel Price Assumptions (in year-2000 dollars)
| 2003 | 2010 | 2020 | 2030 |
IEA crude oil imports ($/barrel) | 27 | 22 | 26 | 29 |
Natural gas ($/Btu): | | | | |
- US imports | 5.3 | 3.8 | 4.2 | 4.7 |
| - European imports | 3.4 | 3.3 | 3.8 | 4.3 |
OECD steam coal imports ($/tonne) | 38 | 40 | 42 | 44 |
Technological development
Technological innovation and the rate of development of new technologies for supplying or using energy are important considerations. In general, it is assumed that available end-use technologies become steadily in use and the overall intensity of energy consumption will depend heavily on the rate of retirement and replacement of the stock of capital. Since the energy-using capital stock in use today will be replaced only gradually, most of the impact of technological developments that improve energy efficiency will not be felt until near the end of the projection period.
The rate of capital-stock turnover varies considerably according to the type of equipment. Most cars and trucks, heating and cooling systems and industrial boilers will be replaced by 2030. on the other hand, most existing buildings, roads, railways and airports, as well as many power stations and refineries will still be in use then. The very long life of this type of energy-capital stock will limit the extent to which technological progress can alter the amount of energy needed to provide a particular energy service. Retiring these assets before the end of their normal lives is usually costly and would, in most cases, require major new governmental initiatives - beyond those assumed in the Reference Scenario. Refurbishment can, however, achieve worthwhile improvements in energy efficiency in some cases.
Technological developments will also affect the costs of energy supply and the availability of new ways of producing and delivering energy services. Power generation efficiencies are assumed to improve over the projection period, but at different rates for different technologies. Towards the end of the projection period, fuel cells based on hydrogen are expected o become economically attractive in some power generation applications ad, to a much smaller extent, also expected to improve, lowering the unit production costs and opening up new opportunities for developing resources. But the Reference Scenario assumes that no new breakthrough technologies beyond those known today will be used before 2030.
The World Alternative Scenario
WEO also considers Alternative policy Scenario to analyze how the global energy market could evolve were countries around the world to adopt a set of policies and measures that they are either currently considering or might reasonably be expected to implement over the projection period. The purpose of this scenario is to provide insights into how effective those policies might be in addressing environmental and energy-security concerns.
Methodology for gap filling
The development and running of the WEM requires access to huge quantities of historical data on economic and energy variables. Most of the data are obtained from the IEA's own databases of energy and economics statistics. A significant amount of additional data from a wide range of external sources is also used.
The parameters of the demand-side modules' equations are estimated econometrically, usually using data fro the period 19971-2002. Shorter periods are sometimes used where data are unavailable or significant structural breaks are identified. To tae into account expected changes in structure, policy or technology, adjustments to these parameters are sometimes made over the Outlook period, using econometric and other modeling techniques. In regions such as transition economies, where most data are available only from 1992, it has not been possible to use econometric estimations. In such cases, IEA results have been prepared using assumptions based on cross-country analyses or expert judgment.
Simulations are carried out on annual basis. Demand modules can e isolated and simulations run separately. This is particularly useful in the adjustment process and in sensitivity analyses of specific factors.
The WEM makes use of wide range of software, including specific database management tools, econometric software and simulation programmes.
Methodology references
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World energy outlook 2004
IEA (2004) International Atomic Agency (2004) . World energy outlook 2004, OECD/IEA, Paris. Online not available
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