The energy balance sheet is an overview of energy flows in the Netherlands. This consists on the one hand of the indigenous production, imports and exports and stock changes, and on the other hand of energy consumption. Energy transformations take place, e.g. in the production of electricity from natural gas. Energy balance sheets describe the supply and the type of consumption of energy commodities, but also the energy consumption by sector. The Dutch energy balance sheet is only compiled at the national level.
Energy commodities are hard coal, natural gas and crude oil from which energy is released during combustion. Electricity and heat are also energy commodities. Indigenous production is extraction of energy commodities from nature. Production is the transformation of an energy commodity into another useful form.
Primary energy commodities are energy commodities from nature and made available by indigenous production, e.g. hard coal, crude oil, natural gas, biomass and waste. The energy produced through nuclear energy is the heat released when splitting atoms. Wind energy is seen as a separate primary energy commodity which, after extraction, is transformed into electricity with a yield of 100 percent.
Secondary energy commodities, e.g. motor fuels, electricity and hot water, are energy commodities obtained by transformation of primary energy commodities. In refineries motor fuels are produced from crude oil; electricity is generated in a power plant, e.g. by combustion of natural gas and hard coal.
Natural gas is reported in standard cubic metres (m3) at a pressure of 1,013 mbar and a temperature of 0 degrees Celsius, electricity in kilowatt-hours (kWh), motor gasoline and fuel oil in units of weight (kg). These are the physical units you can not automatically add together. Therefore, the physical quantities are transformed to the quantities of heat released from the combustion, the heat content. The unit of heat used for this is the Joule (J). A joule is equivalent to 0.24 calories. Because this is a small unit, statistics use multiples, e.g. gigajoules (1 GJ = 109 J), the terajoule (1 TJ = 1,012 J) or the petajoules (1 PJ = 1.015 J).
The list of calorific value gives factors (specific calorific value) for all energy commodities in energy statistics for the transformation of the physical units observed into heats of unit.
Characteristic for energy is that its shape in indigenous production or imports differs from that in final consumption. That is because energy transformation takes place, e.g. refinery of crude oil into petroleum products or electricity production from natural gas or hard coal. At energy transformation all energy remains, but a small part of the energy input cannot be usefully used, e.g. in a power plant there is waste heat at the transformation of natural gas.
A combined production of electricity and heat in a Combined Heat and Power installation is also known as Combined Heat and Power (CHP). Companies which use of CHP provide figures on electricity, steam and hot water production and the energy input used. For smaller installations these energy flows are calculated through modelling. The production and consumption of heat without accompanying production of electricity is not surveyed. The fuel input for transformation is regarded as final energy consumption in the energy balance sheet. Only the heat that companies produce and deliver to another company is published in the energy balance sheet.
Final consumption is broken down into final energy consumption and non-energy use. Final energy consumption is the energy consumers utilize for energy purposes. Non-energy use is the use of an energy commodity for a product that is not energy. An example of non-energy use is the production of plastics from petroleum products in the petrochemical industry. The energy commodity is not only used for heating to run the production process, but part of the energy commodity remains in the final product. This distinction by consumption is shown in energy statistics.
Classification of companies
To describe the energy flows the energy sector is distinguished first. The main activity of these companies is indigenous production, assembling and/or transforming energy commodities making them suitable for consumption by energy consumers. In the Netherlands the energy sector is made up of extraction of crude oil and natural gas, coke-oven plants, manufacture of crude oil and manufacture of electricity and heat.
Energy consumers are all companies, households and institutions not belonging to the energy sector. It does include the energy consumption of transport. The Standard Industrial Classification (SIC 2008) is used as much as possible. SIC is an institutional classification, because companies are classified by main activity. The exception is the energy consumption by transport, because it follows a functional classification. Also excluded is energy consumption by households.
Energy consumers are the following sectors: industry (non-energy), transport, private households and other sectors. Energy consumption for private households is all consumption in dwellings. Energy consumption for transport is all passenger and freight transport by rail, road, water and air.
Energy consumers may also supply energy, because they can extract or produce energy. However, as long as production of energy is not their main activity, Statistics Netherlands classifies the company by main activity, e.g. chemical industry or agriculture.
Energy balance sheet: supply and consumption
The term balance refers specifically to the balance of supply and consumption of energy. The survey on the consumption of energy takes place primarily among individual consumers. Energy consumption of a consumer is supply of energy plus any indigenous production and stock change minus delivery of energy. In this way consumption is determined by terms of supply. The calculation of supply is as follows:
(1) supply = indigenous production + supply of energy -/- delivery of energy + stock change
In fact this is the general definition of energy supply. At the national level, all supply is equal to imports and all deliveries is equal to exports plus bunkers (delivery for international shipping and aviation). For the Netherlands as a whole, there is the following equation:
(1) supply = indigenous production + imports -/- exports -/- bunkers + stock change
The other way to determine the consumption is by consumption terms. Consumption can be broken down by final consumption and net energy transformation. Therefore:
(3) consumption = final consumption + net energy transformation
In transformation processes (e.g. in power plants) production (which is the usable form of energy commodities) is always less than the required input. The 'loss' is equal to the difference between the heat content of the produced energy commodity and the input and is mentioned net energy transformation in the energy balance sheet.
(4) net energy transformation = input -/- production
Finally, efficiency is defined as:
(5) efficiency = (production / input) x 100%
Negative net energy transformation
Net energy transformation of all energy commodities together by company is always positive. The same is true for the consumption. For individual energy commodities net energy transformation can be negative, e.g. production of that energy commodity is more than the required input. For energy companies the net energy transformation is positive for each of the fuel inputs, and the net energy transformation of the generated electricity is negative. Because energy companies have a relatively small consumption of electricity their net consumption of electricity is negative. However, consumption by individual energy commodity is always positive.