### Primary energy

#### Indicators:

Total primary energy use Total primary energy production Export ( + ) and Import ( - ) of Fuel | Energy costs as share of GDP Energy investments

This view presents the use and production of primary energy carriers. Primary energy use is defined as the sum of all energy consumed, including losses at various stages of energy upgrading and processing. The terms 'use', 'demand', 'consumption' and 'supply' are often used for the same energy flow in energy statistics and modelling, as it is assumed that demand is fully met. This is also the case in the TIMER model scenarios. Our definition of primary energy use is equal to the term 'Total Primary Energy Supply' as defined by the International Energy Agency

The following categories are distinguished: coal, oil, gaseous fuel, modern biofuel (in the form of bio-liquid fuels BLF or bio-gaseous fuels BGF), traditional fuel (wood, straw, dung, charcoal, etc.), non-fossil electricity generation options (nuclear, wind, solar, etc.) and hydropower. It is slightly different from the secondary fuel categories and corresponds to those used by the International Energy Agency (IEA).

| #### Total primary energy use
| unit: PJ/yr (Gigajoule per year) dimension: region, primary energy carrier

Total primary energy use shows the use of all primary energy carriers for each region. Primary energy use is defined as the sum of all energy consumed, including losses at various stages of energy upgrading and processing. It also includes non-energy use and feedstocks.

The definition of the eight primary energy carriers corresponds to those used by the International Energy Agency (IEA). The distinction between the two categories of liquid fuels (heavy and light) is not made for primary energy use - and all crude oil use has been indicated as 'heavy oil' (the distinction is only relevant for secondary fuels). The categories bio-liquid fuels and bio-gaseous fuels are aggregated into the category modern biofuels.

In TIMER, use of primary energy carriers is calculated from the secondary energy use and includes the energy losses in the system in the chain from primary fuel production to secondary fuel use. The most important losses are associated with the generation of electricity and are calculated in the electric power generation submodel. The conversion efficiency from fuel-based thermal power plants is based on exogenous time, region and fuel dependent data and assumptions. The conversion efficiencies for other electricity generation options (hydropower, nuclear, wind, solar, etc.) are set at unity. For fossil fuel production the conversion losses are among other due to refining, transformation and interregional transport.

| #### Total primary energy production
| unit: PJ/yr (Gigajoule per year) dimension: region, primary energy carrier

Total primary energy production shows the production of primary energy carriers for each region. On a global scale, total primary energy production equals total primary energy use. Regional differences between primary energy use and primary energy production are a result of fuel trade. The definition of the eight primary energy carriers corresponds to those used by the International Energy Agency (IEA).

| #### Export (+) and Import (-) of Fuel
| unit: PJ/yr (Gigajoule per year) dimension: region, primary energy carrier

Net fuel trade shows the fuel exports minus fuel imports of fossil and biomass-derived fuels in a region. Fuel trade is based on the assumption that each region desires to import fuel from another region depening on the ratio between the production costs in that other region plus transport costs, and the production costs in the importing region. Transport 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, some additional parameters are used to simulate the existence of trade barriers between regions.

As TIMER is a long-term energy model, it is more important to focus on long-term trends than on short-term fluctuations in energy trade. Some of these are caused by sudden increases in production costs in specific regions - after which the model needs to find a new balance in trade flows.

| #### Energy costs as share of GDP
| unit: none (fraction) dimension: region

Total energy costs are defined as the product of the secondary energy carriers and the corresponding prices for end-use consumers, plus the annual investments made by end-users in energy efficiency. These energy costs divided by GDP are a measure of the economic importance of the energy system. In general, this ratio tends to decline as result of a slower growth of energy consumption than GDP. In early stages of economic development, however, the ratio between energy costs and GDP might increase along with a growing share of the industry sector. For regions with a large share of heavy industry the ratio is clearly higher than in other regions. Regions with limited energy supply (i.e. Eastern Africa, India) might in low-trade scenarios suffer from high fuel prices and thus from high energy costs compared to GDP.

| #### Energy investments
| unit: 1,000,000,000 US$(1995)/yr (billion 1995-US Dollars per year) dimension: region, investment type

Energy investments show the 5 year running-average investment flows in each region associated with:

- the production of fossil fuels;
- the production of modern biofuels;
- electricity generation and distribution; and
- end-user investments in energy efficiency.

Energy investments are based on estimates of the required capital stock, given a forward estimate of demand and capital-output ratios. They include expansion as well as replacement investments. Energy system investments are an indicator of the economic inputs required to satisfy energy demand or use it more efficiently. Unless otherwise stated, it is assumed that the required investments are always available in time so that energy carrier demand is fully satisfied and thus equals the energy carrier use. Investments have fluctuated strongly in the past; in some of our scenarios they do as well in response to regional depletion and trade patterns.