METHODOLOGY FOR
OVERALL ENERGY BALANCE SHEET
The overall energy balance sheet is prepared in accordance with Eurostat’s methodology. It presents the state energy
sources by three groups of indicators:
● Primary energy sources
● Transformed energy
● Final energy consumption.
A ton of oil equivalent (toe) is used as unified measure for the composition of overall energy balance sheet. The
transformation of each energy source from specific measure (ton, cubic metre, kWh) to unified energy measure is made by
factors, reflecting the net calorific value of energy products (quantity of heat that can be used – it is gross quantity of heat,
derived by burns of fuels, reduced with the necessary heat for evaporation of water in fuel).
Relation between different measure units is as follows:
1 GJ = 0.239 Gkal = 278 kWh = 0.0239 toe
Energy products in overall energy balance sheet are presented in aggregate groups:
● Coal
« Anthracite – high rank coal used for industrial and residential applications. It has generally less than 10% volatile
matter and a high carbon content (about 90% fixed carbon). Its gross calorific value is greater than 24 000 kJ/kg on ash-free
but moist basis.
« Other Bituminous Coal (Steam Coal) – high rank coal used for steam rising purposes. Includes all bituminous coal
that are not included under coking coal or anthracite. It is characterized by higher volatile matter than anthracite (more than
10%) and lower carbon content (less than 90% fixed carbon). Its gross calorific value is greater than 24 000 kJ/kg on ash-free
but moist basis. If bituminous coal are used in coke ovens they should be reported as coking coal.
« Coking coal – bituminous coal with a quality that allows the production of a coke suitable to support a blast furnace
charge. Its gross calorific value is greater than 24 000 kJ/kg on ash-free but moist basis.
« Brown Coal and Lignite – non-agglomerated coal with a gross calorific value less than 24 000 kJ/kg and greater
than 31% volatile matter on a dry mineral matter free basis.
● Coal fuels
« Coke oven coke - this category includes coke used in the iron and steel industry, foundry coke and coke breeze.
« Coal tar – it is a result of the destructive distillation of bituminous coal or of the low-temperature carbonization of
brown coal.
« Derived gases – are the obtained coke oven gas as by-product of the manufacture of coke oven coke and blast
furnace gas during the combustion of coke in blast furnaces in the iron and steel industry.
● Natural gas – natural gas comprises gases occurring in underground deposits, consisting mainly of methane.
● Crude oil and refinery feedstock – a refinery feedstock is a processed oil destined for further processing, excluding
blending. This definition also covers returns from the petrochemical industry to the refining industry (pyrolysis gasoline, C4
fractions, gasoil and fuel oil fractions).
● Petroleum products – include all finished products, manufactured in refinery and/or blending enterprises. This
definition also covers petroleum products, consumed in support of the operation of the refinery.
● Biomass consumed as fuels:
« Firewood – directly by forestry (since 2008 is included in group “Renewables and non-renewable industrial wastes”)
« Wood wastes – woody materials generated by wood, paper and other industrial process (since 2008 are included in
group “Renewables non-renewable industrial wastes”)
« Vegetable wastes – bagasse, straw, rice husks, nut shells, poultry litter, crushed grape dregs etc. (since 2008 are
included in group “Renewables non-renewable industrial wastes”).
● Hydro power, excluding pumped storage, and other renewable energy sources (RES)
« Hydro power is potential and kinetic energy of water converted into electricity in hydroelectric plants (since 2008 is
included in group “Electricity from renewable sources, excl. pumped storage”).
« Other renewable energy sources (RES) – include geothermal energy used, electricity generated from wind and
solar energy (since 2008 are included in group “Electricity from renewable sources, excl. pumped storage”), liquid biofuels
(since 2008 are included in group ” Renewables and wastes”).
● Other fuels – include non-renewable industrial wastes (since 2008 are included in group “Renewables non-renewable
industrial wastes”).
● Electricity – reports the gross electricity, generated in conventional thermal power plants and in nuclear power plants.
Electricity generated in hydro power plants (excl. pumped storage plants), from wind generators and solar collectors is reported
as “Interproduct transfers”. The data
“For pumped storage stations” show net electricity consumption in these stations
(electricity consumed for pump out of water decreased with generated electricity).
● Heat – only generated heat for sale should be reported. Heat produced by autoproducers, used for its own processes
is not included here. The fuels used are reported as final energy consumption in the relevant economic activity.
Overall energy balance’s indicators
● Primary energy – production of coal (calculated after any operation for removal of inert matter), crude oil, natural
gas, firewood, nuclear energy, hydro energy and other primary energy sources (geothermal energy, solar energy, wind energy
and others).
● Recovered products – this category includes restored products.
● Imports and Exports – include amounts having crossed the national territorial boundaries, whether customs clearance
has taken place or not. The transit is not reported (excl. electricity).
● Stock changes – reflect the difference between Opening stock level and Closing stock level for stocks held by the
producers, big traders and users. A stock build is shown as a negative number, and a stock draw as a positive number.
● Marine Bunkers – report the quantities of fuels delivered to ships of all flags that are engaged in international
navigation.
● Gross inland consumption – it is calculated indicator (Primary energy + Recovered products + Imports – Exports +
Stock changes - Marine Bunkers).
● Transformation input – fuels and energy used for production of other energy products.
● Transformation output – secondary energy products, result of transformation processes.
● Exchanges and transfers, returns include:
« Interproduct transfers – cover movements between products which represent real reclassification of products due
to: changes in quality (for example, aviation turbine fuel is reclassified as lighting kerosene); the aggregation of a commodity
supplied from different sources into a single balance for disposal (for example, electricity produced from non-thermal sources –
hydro, wind or solar are transferred from these commodity balance to the electricity balance).
« Products transferred – cover reclassification of oil products which are imported as finished petroleum products for
use within refineries as feedstock or blending products.
« Returns from petrochemical industry – by-products of ethylene production from naphtha and other feedstock
returned to refinery for further treatment.
● Consumption of the energy sector – shows the quantities of energy commodities consumed within the energy
enterprises supporting their main activity and another energy products do not appear.
● Distribution losses – include the losses by gas and heat distribution, in transmission of electricity and in transport of
other fuels.
● Available for final consumption - the quantities of commodities available for final use from which other energy
products do not appear. This indicator is calculated as: Gross inland consumption - Transformation input + Transformation
output + Exchanges and transfers, returns - Consumption of the energy sector - Distribution losses.
The final consumption is divided into non-energy and energy purposes.
● Final non-energy consumption shows fossil fuels used as raw materials for the manufacture of non-fuel products.
● Final energy consumption – this sub matrix contains data for consumed energy commodities which are not
transformed into others. The quantities of fuel consumed for the production of heat which is not sold by autoproducers are
reported in the figures for the final consumption of fuels by relevant sector of economic activity.
Total final consumption is the sum of consumption by the different end-use sectors:
● Industry – fuels used for transport by industry are not included here, but are reported under transport sector. The
following subsectors are included:
« Iron and steel industry
« Non-ferrous metals industry
« Chemical industry (incl. Petrochemical)
« Non-Metallic Mineral Products
« Mining (excluding energy producing industries) and Quarrying
« Food, Beverages and Tobacco
« Textile, leather and clothing industry
« Wood and wood products
« Paper, pulp and printing
« Engineering and other metal industry
« Transport equipment
« Construction (since 2008)
« Others in industry (incl. construction down to 2008).
● Transport - energy and fuels used for all transport activity, regardless of the sector in which the activity occurs, are
reported. Energy and fuels used by transport enterprises for non-transport activity are not included (they are reported in the
“Households, commerce, public authority, etc.”).
« Railways – report all fuels and electricity (incl. city electricity transport) consumed in rail traffic, including industrial
railways.
« Road transport - fuels for use in road vehicles (incl. households) are shown. It excludes fuels used in construction
stationary engines (included in “Other industry”), for non-highway use in tractors and for timber industry (included in
“Agriculture and forestry”).
« Air transport - aviation fuels supplied in Bulgaria to aircrafts of foreign flight companies and also for domestic and
international flights of Bulgarian flight companies. Aviation fuels supplied to Bulgarian aircrafts in abroad are not included.
« Inland navigation - include small craft and coastal shipping that are not included under marine bunkers.
● Households, commerce, public authority, etc. - cover Residential, Agriculture and forestry, Fishing, and Others.