Energy Glossary

Balance group

A balancing group is a group of electricity (gas) market participants and their off-take points for which a single common clearing entity has assumed responsibility for the deviation.

Price of heat

For households, the price of heat in Slovakia is regulated. This means that it is approved for heating companies by the Office for Regulation of Network Industries. The total price consists of a variable and a fixed component (see separately Fixed and Variable component of the heat price.) Since 2009, there has been a change in the technical units of both components – the variable component is expressed in kWh (which represents energy) and the fixed component in kW (which represents power input) – therefore it is not possible to add them up. Price comparisons are difficult for the layman to make – the most meaningful and technically correct expressions are those calculated through financial costs, not through technical units.

Centralised heat supply (CHP)

CHP is a system of heat and DHW supply in which several objects are supplied from one central source. It provides consumers with comfortable, economical and environmentally friendly use of heat energy with the possibility of switching to renewable energy sources.

Active power

In physical terms, active power is the power that can be converted into a type of energy suitable for the end use (mechanical, chemical, light, sound and thermal energy). Every energy conversion involves losses when part of the energy is uselessly converted into heat.

Active electricity

Active electrical energy is the “visible” component of electrical energy that is converted into one of the other types of energy (kinetic, thermal, light, etc.) by passing into an electrical appliance.

Daily Degree (Dº)

The degree day is a unit that expresses the heat demand for heating depending on the climatic conditions (changes in outdoor temperature). It is the difference between the room temperature and the mean outdoor temperature, assuming that the outdoor temperature is lower than the nominal room temperature. The number of day degrees is usually given for the month and is calculated as the product of the number of heating days in the month and the difference between the nominal room temperature (20°C) and the average monthly temperature. The number of day-days increases as the outside temperature decreases.

Distribution system

The distribution system is the interconnected power lines of very high voltage up to 110 kV (inclusive) and high voltage or low voltage and the power facilities necessary for the distribution of electricity to parts of the defined territory. Metering, protection, control, signalling, information and telecommunications equipment necessary for the operation of the distribution system shall also form part of the distribution system. In addition, the distribution system shall also include power lines and electricity transmission equipment which provide for the transport of electricity from part of the territory of the European Union or from part of the territory of third countries to the delimited territory or to part of the delimited territory, unless such power lines or electricity transmission equipment connect the national transmission system with the transmission system of a Member State of the European Union or with the transmission system of third countries.

Distribution system (local)

No more than 100 000 points of consumption shall be connected to the local distribution system.

Distribution system (regional)

More than 100 000 consumption points are connected to the regional distribution system.

Electricity supplier

A natural or legal person who is authorised to supply electricity.

EIC code (ETSO identification code)

A system for identifying operators in the European electricity market. The EIC identification has been developed by ETSO (European Transmission System Operators), based in Brussels, where there is also a central code database. The EIC code is specifically designed for the energy sector.

Fixed component of the heat price (FZ)

FZ accounts for approximately 30% of the total heat price. It includes the costs incurred in the production and supply of heat, regardless of whether it is a ‘hard’ or ‘mild’ winter in a given year. This includes depreciation of investments, certificates, mandatory inspections and tests, inspections, repairs, audits, pollution charges, etc. From 1 September 2009, the fixed component of the maximum heat price with a reasonable profit is determined in euros per kilowatt (previously in Sk/GJ) of the total regulatory input (see Regulatory input).
The fixed component is not identical to the company’s profit. The exact amount of reasonable profit in the thermal energy sector is determined by Section 3 of Decree No. 219/2011 Coll. of the Office of the Regulatory Office of the Czech Republic. The calculation itself is more complex and depends on several factors, but normally the profit is about 3-4 percent of the total heat price.

Hydraulic regulation

When heating objects by common, in our country used, heating methods, the carrier of thermal energy is heating water, which is piped and pipelined to the heated places. The hydraulic distribution system in our housing estates is a rather complex system and the delivery of heat energy to the required points of consumption can be disturbed by several influences. The hydraulic regulation of the heating system is intended to ensure that, under all operating conditions, all heated locations, and therefore all heat consumers, are supplied with an adequate quantity and temperature of heating water. This will ensure that thermal comfort can be achieved in the dwellings. Balancing means adjusting the flow rates throughout the system in proportion to the heat losses of the buildings, rooms and the current demand. This process is divided into two parts:

  1. hydraulic regulation of the heat source and external piping – provided by the heat supplier
  2. hydraulic regulation of the building in which the heat is taken – provided by the owners of the flats through the building manager

Hydraulic regulation alone does not significantly reduce heat consumption. However, it eliminates uneven heating and under-cooling in different parts of the building. The house receives only the amount of heat it needs and is not overheated. Once the heat is regulated, it is distributed within the house to maintain the same thermal comfort for all consumers. However, heat savings are only achieved by fitting thermostatic valves and thermostatic headers and installing proportional heating cost meters on all radiators in the house.

Hydraulic resistance

Hydraulic resistance is a property of water that is particularly pronounced if the thermal system is not hydraulically regulated. In this case, there are places with higher and lower, i.e. uneven, hydraulic resistance, in which the flowing water naturally chooses places with less resistance. It either does not reach the higher resistance points or cools down considerably due to the slower flow.

Reactive electricity

Reactive electrical energy is the energy that is produced when electric and magnetic fields interact. Reactive electrical energy is not a noble form of energy, although it is used, for example, in the operation of motor equipment or conversion to light energy in fluorescent lamps.

Units – transformations

1 GJ = 277.7777 kWh
1 kWh = 0.0036 GJ
1 MWh = 3.6 GJ

Kilowatt-hour (kWh)

Unit of active electricity consumption. It is the product of active power and time. 1 kilowatt-hour is the amount of electricity consumed by, for example: a 100 W light bulb in 10 hours of operation, a 15 kW direct-fired electric boiler in 4 minutes.

Cogeneration

Technological process of simultaneous combined production of electricity and heat. The energy of the fuel (natural gas) released by the combustion of the fuel-air mixture in the process plant is transformed into electricity and heat. The waste product is flue gas.

Contracted quantity of heat

The contracted quantity of heat (contracted production or supply), used for calculation purposes, is the ordered quantity of heat that is agreed or confirmed in advance by the customers (it is set for a certain period of time, usually one year).

Combined heat and power (CHP)

CHP is a source that produces electricity and at the same time uses the heat generated in the process to supply heat for heating and DHW.

Compensator

A device that is designed to compensate for reactive power in the power system. Compensation reduces line losses and voltage drop while allowing power lines and transformers to be sized for less apparent power.

End-user of electricity

A household or non-household electricity consumer who purchases electricity for their own consumption.

Condenser

A passive element of electrical circuits formed by a set of two conductors separated by a dielectric (insulator). Capacitors are included in circuits to increase their capacitance. Technically, capacitors are specified according to the capacitance range and voltage for which they are intended.

Maximum Reserved Capacity (MRC)

The MRC is the maximum value of the instantaneous power that can be transmitted by the system equipment, where at the voltage level of MV, HV and HV, the value of the maximum reserved capacity, which is agreed in the Connection Contract and specified in the Connection Conditions, is equal to the active power in megawatts (MW) that the TSO/DS is able to safely transmit to the point of connection of the off-take from the TSO/DS.

Off-take point (OM)

Indicates the place (location) from where the electricity is drawn. It is usually identical to the place where the consumption is measured. The consumption of one customer may also be measured at several points of consumption.

Heat transfer station (OST)

The OST (also known as a heat exchanger station) is used to adjust the pressure and temperature of the heating medium to conditions suitable for indoor house piping and radiators. At the same time, it heats the domestic hot water for the supplied objects. In addition, a control system located in the OST controls the heating according to climatic conditions and time of day.

Renewable energy sources (RES)

Renewable energy sources are wood or its products (wood chips, pellets), biomass, wind energy, hydropower, solar energy… In general, these are energy sources of non-fossil origin (oil, natural gas…). They are theoretically inexhaustible or replaceable.

Power

The input power of the device (appliance). The input power is greater than the useful power of the electrical appliance by the losses incurred in the conversion of electrical energy into heat. For electrical appliances, the input power (not the useful power) with which the appliance loads the electricity system is usually listed among the ratings. The efficiency of an appliance is determined by the relationship between input power and output power, which is expressed as the ratio of useful power to input power.

Regulating power

Regulatory input as a variable for calculation of the FZ price of heat was first introduced by Decree No. 6/2008 Z. z. for the regulatory period 2009-2011. According to this legislation, the regulatory input of the consumption facility was the ratio of the arithmetic average of the quantity of heat supplied for heating and hot water preparation in the years 2005-2007 in kWh and the number of hours 5 300 (constant).

The calculation of the regulatory power input is set out in Decree No. 220/2013 of the Regulatory Authority.

Reserved capacity (RK)

RK is the monthly, quarterly or annual capacity at the voltage level HV and MV is ¼ hourly power, which is provided to the customer by a mutually confirmed electricity distribution contract or a contract for the combined supply of electricity. Its value is specified in the Annex to the pooled electricity supply contract. The tariff for the reserved capacity shall be charged monthly. If the value of the reserved capacity is exceeded by the customer, the supplier shall charge a fee for exceeding it in accordance with the current Decision of the Office for Regulation of Network Industries. The monthly tariff for the reserved capacity in EUR/MW shall be based on the contractually agreed value of the reserved capacity. The value of the reserved capacity may be increased during the calendar year up to the level of the Maximum Reserved Capacity agreed in the connection contract.

Low voltage (LV) network

LV is a network in cable or outdoor design used for the distribution of electricity with an alternating rated combined voltage between 100 V and 1000 V inclusive.

High, very high and extra high voltage network (HV, VVN, ZVN)

Networks intended for the transmission or distribution of electricity with an alternating rated combined voltage exceeding 1000 V. Three-wire 6 kV and 22 kV systems with isolated or compensated nodes are used for HV lines.

Domestic hot water (DHW)

The basic issue is regulated by the Decree of ÚRSO No. 630/2005 Coll., which establishes the temperature of domestic hot water at the point of consumption, the rules for budgeting the amount of heat supplied for the preparation of domestic hot water and the budgeting of the amount of heat supplied.

Heat from gas

The fuel known as natural gas is a mixture of combustible hydrocarbons, of which 93 to 99 % by volume is methane and the remainder is other substances such as propane, butane, etc. It is a gaseous fossil fuel whose potential, unlike alternative sources (wood chips, solar energy, wind, water), is finite and non-renewable within a few generations. It was created millions of years ago, just like coal and oil, which are often extracted together.

Compared to wood, natural gas was discovered much later – only during the 20th century, and has been used for heat production in our conditions for about 150 years. However, during this short period of time, in an era of technical progress, improvements in gas-fired heat generation technologies have advanced considerably, both in terms of safety and efficiency of production. The boilers of the last generation were about 10-12% less efficient than their current competitors. Modern condensing boilers, which use waste heat from the production process, achieve much higher efficiencies. Where production is efficient, fuel consumption is reduced and therefore the price of heat is reduced.

The use of burners, which significantly reduce the formation of dangerous nitrogen oxides, and the fact that burning gas produces the least carbon dioxide of all fossil fuels, make natural gas a sensible choice today from an ecological point of view, especially where renewable sources cannot be considered for various reasons. Gas is also the fuel used in cogeneration technology – the combined production of heat and power.

Heat from wood chips

Wood chips are partially processed wood that is produced by chipping wood into small pieces. It is often calamity wood and waste wood from forests, but in any case it is pure wood without any admixtures. Compared to fossil fuels (coal, oil, natural gas), it isCO2-neutral, since burning wood chips releases only as muchCO2 as the plant has taken in during its growth. This means that the use of biomass for energy purposes does not have a negative impact on the greenhouse effect.

Modern boiler plants with biomass combustion equipment operate in fully automatic or intermittent mode. Fuel feeding and movement on the grate is controlled according to the fuel properties. All measured values, safety equipment interventions and faults are transmitted to the control room. The boilers are characterised by high efficiency and meet the emission criteria required by EU legislation.

Heat using cogeneration

Cogeneration is the technological process of simultaneous combined production of electricity and heat (CHP). It is the highest level of efficiency in converting fuels into other forms of energy. The equipment in which the process takes place is called a CHP unit. The energy of the fuel released by the combustion of the fuel-air mixture in the process equipment (generator) is transformed into electricity. As a by-product, heat is generated which is used for heating and the preparation of domestic hot water.

In the past, cogeneration units were more or less only used in large steam power plants. However, recent developments have made it possible to manufacture and install small units with a capacity of 5 kW or more, which corresponds to the needs of a family house. The engines in cogeneration units most often operate on the basis of natural gas, but they can also burn other liquid, gaseous or even solid fuels, both traditional and renewable sources. In addition, with technological advances, the possibilities of cogeneration have expanded from electricity and heat to include the simultaneous production of cold, which can be used for process purposes or air conditioning. At that point, we are already talking about so-called trigeneration.

Thus, project implementation and production economics are no longer limited by technical possibilities, but rather depend on the quality of the know-how of the implementer who puts the equipment into practice.

Transformer

An electrical non-rotating machine that is used in a power system to change the voltage in electrical networks or to galvanically isolate interconnected AC electrical circuits.

Performer

Ratio of active to apparent power. It is the cosine of the angle between the voltage and current vector in AC circuits.

Office for Regulation of Network Industries (ÚRSO)

The OTSO is an independent state institution tasked with overseeing the regulation of energy prices. It approves energy prices and protects end-users against abuse of monopoly power by energy suppliers. It also performs a legislative function – it issues decrees or decrees regulating pricing, standards and other areas of the energy sector.

Variable component of the heat price (VZ)

The RER accounts for approximately 70% of the total price of heat and includes the cost of primary fuels and energy. In our conditions, the bulk of the cost is the purchase of primary fuel (natural gas, wood chips, etc.), the rest is the cost of electricity and process water. The price of natural gas for household heat production is not set by the market, but is regulated by the Office of the Regulatory Authority for Heating and Cooling (ÚRSO). Since 1 August 2008, according to §4 of the Decree No. 6/2008 of the ÚRSO, the variable component of the maximum heat price is determined in euros per kilowatt-hour (previously in Sk/GJ) per ordered quantity of heat.

Power

Work done per unit of time.

Green energy

Electricity supplied that has been generated by alternative sources (small hydro, solar, wind,…). It is technically not possible to ensure that this particular part of the electricity is delivered to the selected customer, so such delivery is usually ensured by the supplier selling green energy only in an amount equal to its purchase from such sources.

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