Setting the standard for renewables
by W van Zanten, Novem, the Netherlands

A protocol has been drafted in the Netherlands aimed at standardising all definitions and calculations associated with renewable energy sources. 

Production of briquettes from wood sawdust. Photograph: Hans Pattis


Until recently, renewable energy has barely featured in national and international energy overviews. However, as its share of the energy market increases, it will become increasingly important to ensure that all calculations associated with renewable energy are based on the same premises, definitions and assumptions. With this in mind, the Netherlands Agency for Energy and the Environment (Novem), the Association of Utilities (EnergieNed) and the Dutch Central Bureau for Statistics (CBS), together with the Ministry of Economic Affairs and the Electricity Producers (SEP), have drafted a protocol for renewable energy monitoring.

The protocol, which would be particularly useful for statistical purposes, covers the definition of renewable energy sources, characteristics of energy products, reference technologies, and calculations of avoided primary energy consumption and associated emissions.

“Renewable” or “sustainable”?

One of the key issues addressed by the protocol is the confusion that sometimes exists between the terms “renewable” and “sustainable”. All recurring energy sources are “renewable” whereas “sustainable” energy is non-exhausting or less polluting. For instance, wood is a renewable energy source that is also sustainable when used as fuel in a gasification plant; however, it is less sustainable when combusted in a fireplace with an inefficient chimney.

There is no universal agreement on which energy sources and energy conversion technologies should be classed as “renewable”. For instance, in the Netherlands, the use of heat pumps is considered to be a renewable conversion technology if the heat is sourced from the surroundings; but this description may be disputed elsewhere.

Gravitation, nuclear fusion in the sun and radioactive deterioration in the earth’s crust are the three main forces driving renewable energy. Gravitation powers the movement of tides and radioactive deterioration helps to supply geothermal energy. Nuclear fusion in the sun ultimately gives rise to all other renewable energy sources: hydro power (from evaporation and rain), wind and wave energy, glacial energy (from the melting of ice), tidal energy, ocean thermal gradients, biomass production and, of course, all solar energy - passive solar design, active solar heating and photovoltaics.

Energy from waste and biomass, on the other hand, is not always renewable. The Netherlands considers energy from waste and biomass to be renewable only if the basic constituents originate from renewable sources. Sometimes, however, the Dutch government classes the total energy production from waste incinerators as renewable energy. Eurostat, the European Commission’s statistical office, considers waste to be a separate fossil fuel, whilst classing the total energy content of waste as avoided primary fossil energy.

Basic principles

The draft protocol looks at a number of other underlying principles relating to renewables. “Net energy generation”, for example, is defined as the amount of energy available at the “gate” of the plant. The energy consumption of control and monitoring equipment is not included in net energy generation calculations.

A limited number of reference technologies are selected in the protocol, to enable calculations to be made of the primary energy savings resulting from the use of renewable energy. For electricity generation at the point of production, a mixed sample of all power plant is taken for reference, from the year in question; for electricity delivered to the consumer, transportation losses are included. For small heating installations (<100 kWth), gas-fired domestic heating installations are used as a reference, and, for larger installations, gas-fired boilers. The reference fuels for biomass plant are coal and petroleum.

The yields of the reference electricity power plant identified in the protocol rose from 40.0% in 1995 to 43.5% in 2000 and the delivered electricity increased from 38.3% to 41.7%. Carbon dioxide emissions from these plant decreased from 68.2 kg/GJ of production in 1995 to 68.0 kg/GJ in 2000.

Establishing a calculation

As the protocol points out, comparisons between different forms of energy (electricity, heat or fuel) and their energy and emissions savings can be made by calculating the amount of primary energy involved, in a two-step process. The first step involves adding up all the energy provided from renewable sources and all the avoided electricity, heat, gas etc, to give a total figure in joules. The second step is to express this figure as saved primary energy or saved emissions. To calculate primary energy, the yield (or emissions) of the preferred technology is needed for each of the renewable energy options.

Renewable energy production

Table 1 gives the current annual energy production (for the year 2000) from renewable energy sources in the Netherlands, in relation to the power of the plant.

Table 1: Net energy production figures of renewable energy sources

Energy source

Annual energy production

Hydro power

4,500 kWhe per kW installed

Wind power

1,945 kWhe per kW installed

PV grid-connected

900 kWhe per kW installed (peak)

PV autonomous

400 kWhe per kW installed (peak)

Active solar thermal boilers

(> 6 m2) 1,500 MJ per m2/year

Active solar drying

 (> 6 m2) 511 MJ per m2/year

Active solar space heating

(> 6 m2) 540 MJ per m2/year

Domestic solar hot water boiler

(> 6 m2) 540 MJ per m2/year

Passive solar heating

Dependent on local conditions

Heat and cold storage in aquifers

3,000 MJ per kWth/year

Geothermal heat

17,000 MJ per kWth/year

Domestic heat pumps

(5–6 kWth) 3,000 MJ per kWth/year

Waste incinerators (electricity)

5,300 kWhe per kWe/year

Biomass incinerators (electricity)

6,940 kWhe per kWe/year

Biomass incinerators (heat)

27,000 MJ per kWe/year

Co-firing of biomass in power stations

5,100 kWhe per kWe/year

Digestion of kitchen and garden waste (VGF) 

150 kWhe per tonne/year

Landfill gas extraction (electricity production)

10,000 kWhe per m3/hour

Landfill gas extraction (natural gas production)

4,530 kWhe per m3/hour

Gasification of biomass

7,000 kWhe per kWe/year




This protocol ensures consistent reporting and valid statistical reviews and comparisons in the field of renewable energy. The protocol also defines a reliable method for recording avoided primary energy use.

For more information contact the CADDET Dutch National Team in the Netherlands

The CADDET Renewable Energy Newsletter is a quarterly magazine published by  the CADDET Centre for Renewable Energy at ETSU, UK.

The articles published in the Newsletter reflect the opinions of the authors.  They do not necessarily reflect the official view of CADDET.

Enquiries concerning the Newsletter should be addressed to Pauline Toole, Editor, CADDET Centre for  Renewable Energy, ETSU, Harwell, Oxfordshire OX11 0RA, United Kingdom. Tel: +44  1235 432968, Fax: +44 1235 433595.