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heat is also produced as primary as well as secondary energy primary heat is obtained from natural sources such as geothermal and solar thermal power secondary heat is obtained from the nuclear fission of nuclear fuels and by burning primary combustible fuels such as coal natural gas oil and renewables and wastes

heat can be produced and used on site or distributed through a system of pipes to structures remote from the point of production

this wide use of electricity is of course reflected by statistics the share of electricity in world total final consumption increased from 9.6% in 1973 to 15.6% in 2001 the biggest increase for all fuels

The reporting of electricity and heat production is analysed at several levels reflecting energy source, function of producer, and plant type.

Recent blackouts in various parts of the world (Latin and North America, Europe, etc.) underscore the need for reliable, detailed and timely data on electricity.

In order to complete the tables of the questionnaire, it is important to understand that it facilitates reporting of electricity and heat production at several levels. It reflects the energy source, the function of the producer, and the plant type.

There are two functions for the producer: i)a public producer of electricity or heat is an enterprise which supplies electricity or heat as its main business. The supplier may be publicly or privately owned. And ii)an autoproducer of electricity or heat is an enterprise which produces electricity and heat for its own use in support of its main business but not as its main business.

As regards the plant type, the questionnaire classifies electricity and heat-generating plants into three types: Electricity-only plants which generate electricity only. Combined heat and power plants (CHP) which generate heat and electricity simultaneously. Heat-only plants which generate heat only.

General information Electricity production, consumption and trade are measured and expressed in a multiple of watt-hours. The choice of the multiple (mega, giga, tera, etc.) depends on the size of the quantities produced and consumed.

Quantities of combustible fuels consumed for electricity and heat production are expressed in physical units such as metric tons, cubic metres, litres, etc., according to the type of fuel. They also should be expressed in energy units in order to calculate efficiency.

The electricity-generating capacity for the various classes of generating plants is measured and expressed in a multiple of kilowatts. Annual peak load and capacity available at peak are also measured and expressed in a multiple of kilowatts.

Specific information related to the joint questionnaire The quantities of combustible fuels consumed for electricity and heat production are expressed in physical units, in some cases according to the type of fuel; and in energy units in all cases.

The data for generating capacities should be net generating capacities. Net generating capacity is the gross (or “nameplate”) capacity minus the capacity that must be used to operate the auxiliary equipment and transformers within the subject plant.

A flow chart from production to consumption for electricity is shown in Figure 2.1. This flow chart is deliberately simplified in order to give an overall view of the supply chain.

Production, trade and consumption are the main elements necessary to have a comprehensive view on the flow of electricity in a country. The details of reporting depend on the use of the information.

Usually the output from the power plants is expressed in energy units, most often in a multiple of kilowatt-hours. However, the inputs to the plant (coal, oil, etc.) are often reported in physical units, respectively tonnes for coal and tonnes or litres for petroleum products.

It is important that the fuel input data are also reported in energy units because they are used to derive plant efficiencies in the data-checking process.

The specific conversions from volume or mass to energy are explained in the chapters related to oil, natural gas, solid fossil fuels and renewables, and in Annex 3.

The flow of heat is very much similar to that of electricity with just two exceptions: there is no real possibility to store heat, and heat is transformed into electricity (see Figure 2.2).

Specific information related to the joint questionnaire The Electricity and Heat Questionnaire consists of nine tables, the first four tables following a conventional balance format.

Since there are no stocks for electricity and heat, supply only includes production and trade. Each of these two components will be detailed in the next paragraphs.

Production General information Electricity and heat are produced from several sources in two basic types of plants, by two types of producers. To cover all necessary information about production of electricity and heat, production must be viewed from the perspectives described by the questions: “how,where and who?”

The first perspective is the source fuel from which electricity and heat are produced respectively; the sources include coal, petroleum products, natural gas, renewables, etc. The second one is the type of plant; there are two types to consider: electricity-only plant and CHP plant for electricity production, and heat-only plant and CHP plant for heat production. The last perspective is the type of producer; there are two types: public producers and autoproducers.

The data are used for several purposes: assessing security of supply, analysing changes in fuels used for generating electricity over time, the evolution of efficiencies for each fuel, environmental impacts of electricity production, etc.

Over the last 30 years, with a 250% increase, electricity production has experienced the fastest growth compared to oil, coal and natural gas. This large increase had to be accompanied by an enormous investment in new capacity, especially of nuclear plants in the 1970s and 1980s.

Production of electricity is reflected in five tables in the questionnaire: Table 1 provides for reporting a three-level breakdown (fuel, function of producer and plant type) of the gross production of electricity and heat. To complete the table, statistics for gross electricity production must be available separately for public electricity producers and autoproducers and the production must be further subdivided according to the type of plant.

Electricity produced at hydropower stations should include all electricity produced from pumped storage stations. The amount of electricity produced from pumped storage hydro plants must always be smaller than total electricity produced by hydro plants since this pumped storage electricity is only a part of this number.

Gross production of heat is the amount produced and sold. It is the amount of heat leaving the plant for use by persons unrelated to the producer. Similar detail is required for a breakdown of gross heat production.

The fuel used should be reported within its own commodity balance as consumption for electricity generation.

However, they are not in widespread use and make only a small contribution to national energy supplies.

Electric boilers are used to provide hot water and steam for space heating or other purposes in countries where low-cost electricity (usually hydroelectricity) is available.

For secondary heat (produced from the combustion of fuels), net production is the amount sold from the plant and is identical to the amount reported for heat in Table 1. In other words, for secondary heat the figures for gross and net heat production are identical.

When a CHP plant is involved, reporting separate figures for the amounts of fuel used for the production of electricity and heat sold requires a method of dividing the total fuel use between the two energy outputs.

In other words, the fuel input is divided between the electricity and heat in proportion to their shares in the output.

With increasing globalisation and opening of countries' economies, trade of electricity has been growing. On all continents, countries are connecting their grids in order to improve security of electricity supply and take advantage of generating cost differentials.

Therefore, it is more and more important to collect information about trade disaggregated by countries of origin and destination. These statistics also help in identifying potential transmission congestion and provide means for the most efficient operation of an evolving international transmission grid.

The dynamics of trade is reflected in world import and export statistics. World trade has increased by more then five times over the last 30 years. Moreover, trade, which has often been limited to neighbouring countries in the past, has started to have a much wider dimension such as in Europe where a customer from South Europe can buy electricity from North Europe.

As regards heat, a similar principle applies for the reporting of heat trade. However, heat trade is rare, and unlikely to involve transit quantities.

The consumption of electricity in the transformation sector is limited to heat pumps and electric boilers. There is none for heat.

Consumption in the nuclear industry refers to the enrichment of nuclear fuel, not to own use at nuclear power plants.

Electricity and Heat Consumption The consumption of electricity and heat occurs in several sectors: In the transformation sector, and by the energy industry within the energy sector. In the transmission and distribution of electricity and heat. In the various sectors and branches of final consumption (industry, transport, residential, services, etc.).

Consumption of electricity and heat in the transformation and energy sectors General information Electricity is transformed only to heat using heat pumps or electric boilers. Heat has no transformation sector.

The transformation and energy sectors consume around 10% of global electricity supply and around 9 % of global heat supply.

Specific information related to the joint questionnaire The transformation and energy sectors are reflected in Tables 3 and 4 of the questionnaire.

All quantities of electricity and heat lost during transportation and distribution should be reported under transmission and distribution losses.

The final consumption of electricity and heat is all electricity and heat consumed in industry, transport, agriculture, commercial/public services and residential sectors. These sectors are broken down in accordance with the ISIC classification. The final consumption is a major part of the electricity and heat consumption, accounting for about 80% of total consumption. It is also the most dynamic part of

Transmission and distribution losses are all losses due to transport and distribution of electricity and heat. For electricity, losses in transformers which are not considered as integral part of the power plant are also included. For electricity, the distribution losses account for anywhere from 7% to 15% of electricity supply. The amount of losses is mainly dependent on the size of the country (length of power lines), voltage of transmission and distribution and quality of network.

For heat, distribution losses account for about 15%. The heat is usually distributed only over short distances, otherwise it becomes inefficient.

Figures for electrical losses should be obtained from national grid operating companies and electricity distribution companies. Losses of heat should be obtained from the district heating companies and other heat sellers.

With the growing importance of the environmental debate, it has become essential to identify total consumption of fuels in each respective industry and consuming sector, so that for each sector appropriate measures can be developed to conserve energy and reduce greenhouse gas emissions.

The final consumption of electricity and heat is the sum of electricity and heat consumed in industry, transport, agriculture, commercial/public services and residential sectors. There is no provision for reporting non-energy use of electricity and heat.

Much of the growth in electricity consumption since 1973 has taken place in residential and commercial/public sectors. The share of residential and commercial/public service sectors combined increased from about 38% to 52% over the last 30 years.

Although the amount of electricity consumed in the industry sector has constantly increased, it has increased at a slower rate than in the residential and commercial/public sectors. Consequently, the share of industry has decreased from 51% in 1973 to currently around 42%.

The transport (rail) and agriculture (mainly irrigation pumps) sectors are relatively small consumers of electricity.

Because of the importance of electricity in the industry sector, consumption of electricity is further disaggregated by sub-sectors in Table 4. There is no provision for the reporting of electricity for non-energy use as all electricity consumption is considered to be for energy use.

These tables provide information on the fuel used by autoproducers of electricity and heat for sale according to their principal economic activity. The table is separated into columns corresponding to three recognised types of generating plant: Electricity-only, CHP, and Heat-only. The data are used for tracking fuel inputs and electricity and heat outputs by autoproducers as part of the United Nations efforts to understand CO2 emissions.

In the case of CHP plants, reporting separate figures for the amounts of fuel used for the production of electricity and heat requires a method of dividing the total fuel used between the two energy outputs. The division is required even if no heat is sold because the fuel used for electricity production must be reported in the transformation sector. The method proposed is described in Annex 1, Section 1 and should be followed carefully.

Net electrical capacity, peak load and date of peak load occurrence are monitored to measure energy security-related factors like reserve margin, capacity available during load peaking periods, etc.

54Data on fuel firing capability are important inputs into planning responses to national and international fuel disruptions.

Total peak load on the national grid is not the sum of the peak loads during the year on every power station as they may occur at different times.

The capacity at time of peak is the total available net capacity at that time and may differ from the maximum available capacity reported above because of plant maintenance or other outages at the time of peak load.

As its name suggests, natural gas is taken from natural underground reserves and is not a chemically unique product.

At this stage natural gas is still a mixture of gases but the methane content predominates (typically greater than 85%).

Natural gas which is produced in association with oil is called associated gas, whereas production from a gas reservoir not associated with oil is non-associated gas.

When mining for coal in underground mines, some gas can be released from the coal deposit. This gas must be removed for safety reasons, and where this is collected and used as a fuel, the amounts involved should be included in marketed production.

Natural gas supply and demand are growing fast. Natural gas now accounts for more than 21% of global total primary energy supply, compared to 16.2% in 1973.

General information Natural gas can be measured in several units: either according to energy content (also referred to as heat) or volume .

Natural gas can be measured in several units: either according to energy content (also referred to as heat) or volume.

When using volume measurements for natural gas, it is important to know at which temperature and under which pressure the gas has been measured.

In the Natural Gas Questionnaire , the supply balance and trade data are to be reported in both energy units and volume units.

Furthermore, gross and net calorific value data for the flows on the supply balance are to be stated.

The most common method of metering and accounting for gas is by volume (e.g. Mm3). However, natural gas prices are often determined on the basis of the calorific content per volume unit, as gas is purchased for its heating value.

The Natural Gas Questionnaire structure follows the flow chart of Figure 3.1. The questionnaire contains five tables.

Each of the above tables will be presented in the next paragraphs. However, there are a number of key totals which must be preserved across the various tables. These are illustrated in Figure 3.2.

The following totals have to be consistent between the various tables: Imports by Origin in Table 3 should be summed, and the sum should be reported under Total Imports in Table 1. Exports by Destination in Table 4 should be summed, and the sum should be reported under Total Exports in Table 1.

It is obvious from the flow chart in Figure 3.3 that it is not always simple to draw the statistical boundary between flows which are to be included in the statistics and those which are not.

However, figures for vented and flared gas are required by environmental agencies for estimates of fugitive emissions from oil and gas production activities.

IQuantities of gas used within the natural gas industry (often in non-marketable state) in the various separation and treatment processes should be included in the production data.

Because of the relative difficulty and high cost for transporting natural gas, trade of gas remained limited until recently. In 1971, the gas traded accounted for 5.5% of total natural gas consumed. However, in the last decades natural gas trade experienced a fast development and is now representing more than one-quarter of all gas consumed.

Moreover, if in the past the gas market was essentially local, the development of more efficient gas pipeline technologies has made the market more regional (for instance Europe, North America). The development of gas fields far from consumption regions and the expansion of the spot market will soon make the gas market more global.

As a consequence, because of the growing role of natural gas in the energy market, it is essential to have detailed and reliable data on gas imports and exports. However, the reporting of the origins and destinations for gas trade is sometimes complicated by the fact that natural gas is often transported through pipelines which may cross many territorial boundaries.

For purposes of energy security, origins and destinations of natural gas are an important part of the data collection. For imports, it is important to know (therefore to report) the ultimate origin of the gas (the country in which it is produced), while for exports it is essential to show the ultimate destination (the country in which the gas will be consumed) of domestically produced gas. The companies responsible for the commercial arrangements leading to the trade should be able to provide the data.

Imports concern gas which is to be consumed within the country, and exports concern gas which has been domestically produced. Transit trade and re-exports are therefore not to be included in the trade reported.

General information Natural gas demand is very seasonal in most countries; in the winter, demand for gas often places strains on the transmission and distribution systems. To limit the need for long-distance gas transport, many countries have started to build gas-storage facilities. Additionally, strategic reserves of gas improve the security of gas supplies.

As in the case of oil, timely, detailed and accurate data on the levels and the changes in stocks are becoming essential for policy-makers and market analysts, especially at a time when the share of natural gas is increasing in total energy supply.

Gas storage facilities fall into two basic categories, which define their characteristics: seasonal or peak. Seasonal storage sites, which may also serve as strategic purpose, must be able to store huge volumes of gas built up during low-demand times for slow release during periods of high demand. Peak facilities stores smaller quantities but must be able to inject gas quickly into the transmission network to meet surges in demand.

Gas storage and stocks are to be distinguished from gas reserves. The former refer to gas already produced, but used for strategic, seasonal or peak-shaving purposes. The term gas reserves refers to estimated quantities of gas not yet produced, but which analysis of geological data demonstrates with reasonable certainty to be recoverable in future years from known oil and gas reservoirs.

The perception of natural gas today is radically different from what it was 10 or 20 years ago. In the past, natural gas was perceived as a noble fuel, reserved for premium uses, therefore not often consumed in the transformation sector. Today it is used in a variety of sectors and applications, and it is experiencing significant growth as a fuel for power generation.

Enhancement of gas turbine technology has substantially improved the position of gas in power generation, both for combined-cycle gas turbine (CCGT) generators and combined heat and power (CHP) plants. Gas offers many advantages in this sector compared with other fossil fuels: high efficiency, relatively low capital costs, and cleanliness. Gas is the cleanest fuel among fossil fuels and its demand will be favoured for environmental reasons.

Specific information related to the joint questionnaire The Transformation Sector includes statistics of electricity and heat generation according to the type of plant ( i.e. electricity-only, heat-only or combined electricity and heat) as well as the separation between type of producer ( i.e.public and autoproducer).

Natural gas used as feedstock for conversion to liquids, e.g.methanol production, should be reported in the transformation sub-sector: Conversion to Liquids (Table 2a).

The output of natural gas liquids should be reported in the Oil Questionnaire (Table 1) under Other Sources.

Report in the transformation sector inputs of energy which are transformed into other forms of energy.

Within the Energy Sector , the sub-sectors are the various energy-producing industries. Moreover, special for natural gas is the sub-sector Liquefaction Plants .

For the Liquefaction Plants , report in this sub-sector the amounts of gas used as “own use” to liquefy natural gas. This often can only be measured by the difference between natural gas inputs into the liquefaction plant and LNG output (but will include some losses in energy).

calibrations of the flows or differences in temperature and pressure at the momentof measurement. Moreover, there may be smaller or larger leaks in pipelines.

For information, those losses account for less than 1% in global gas supply,although the percentage can obviously vary substantially between countries.

Essential Gas can be used for energy and non-energy purposes. Report both uses in the appropriate sector.

Methane in natural gas is an important source of carbon and hydrogen for several industrial processes in the chemical industry. The most widely known use is for the manufacture of ammonia, which is used for agricultural fertiliser production. However, methane may also be used for the manufacture of methanol and carbon black. Each of these processes has its own heat requirements, which may be obtained by burning some of the natural gas.

For information, natural gas represents roughly 16% of global final energy consumption. The shares between energy and non-energy use can vary significantly between countries, depending on the size of the petrochemical industry activity.