f97.beERIK SCHMIDT’S WORKSHOP
← All terms

Glossary · Energy industry & energy transition

Embodied energy

Embodied energy life cycle primary energy Infrastructure Carbon footprint

Definition and delimitation

Embodied energy is the amount of energy expended for a product, a plant or an infrastructure outside its actual operation. This includes raw material extraction, processing, manufacturing, transport, construction and maintenance. Depending on the delimitation, dismantling and disposal are also included. For a photovoltaic system, for example, this covers the energy for silicon production, module manufacturing, inverters, mounting structures, transport and installation. For the power grid, it includes steel, aluminium, copper, concrete, transformers, construction work and maintenance. Embodied energy is therefore a life-cycle concept. It does not describe the ongoing consumption of a plant, but the energy expenditure that is, in a sense, materially contained in it. It can be thought of as an energy backpack that every component carries with it before it is put into operation for the first time.

In German-speaking countries, the term is closely linked to the cumulative energy demand (CED, in German: kumulierter Energieaufwand, KEA) under guideline VDI 4600. However, it is not always used in the same way. The CED is the sum of all primary energy expenditures across the life-cycle phases of production, use and disposal. It therefore also includes the energy input during use. Embodied energy generally means only the portion without the direct energy consumption during operation, and thus roughly corresponds to the CED for production and disposal. Anyone adopting figures should therefore check whether a value is meant as CED including the use phase or as embodied energy in the narrower sense.

Units and system boundaries

Embodied energy is stated in energy units, usually kilowatt hours, megajoules or gigajoules, related to a reference unit such as one module, one tonne of material or one square metre of usable floor area. Under VDI 4600, the expenditure is evaluated as primary energy. The reason: materials and intermediate products are made with very different energy carriers such as electricity, gas, coal, oil or process heat. Primary energy makes these contributions comparable. In addition to energy consumption, the CED also includes non-energy expenditure, i.e. energy carriers used as material, such as crude oil as a raw material for plastics. Furthermore, the expenditure can be split into a renewable and a non-renewable share.

Values are therefore comparable only together with their system boundary. This raises the following questions: Is final energy or primary energy meant, and which conversion factors were used? Which process steps and life phases are included? Which manufacturing region with which electricity mix was assumed? And does the value apply to a whole plant or only to a single component? One kilowatt hour of embodied energy in one dataset can mean something different from that in another if the boundaries were drawn differently.

Relationship to life cycle assessment and embodied emissions

Embodied energy is closely related to life cycle assessment, but is not the same thing. A life cycle assessment can capture, besides energy, also greenhouse gas emissions, water consumption, land impact, raw material demand, pollutants or recycling potential. The CED is an important indicator of energy expenditure within it and can serve as a simplified short-form life cycle assessment. However, it does not replace a full impact assessment.

Embodied emissions are to be distinguished from embodied energy. They measure the greenhouse effect of production and provision, usually in CO₂ equivalents. Both quantities are related but not identical. A product can contain a lot of embodied energy and still cause comparatively low embodied emissions if the energy used was predominantly renewable. Conversely, a small energy expenditure can cause high emissions, for example when process-related CO₂ is released in cement production or when coal-based electricity is used.

Energy payback: the example of photovoltaics

A common misconception is that a plant is questionable in energy terms if its manufacture requires a lot of energy. What matters, however, is the ratio between embodied energy and the amount of energy generated or saved over its lifetime. There are two indicators for this. The energy payback time, also called energy recovery time, indicates how long a plant must run until it has provided the energy expenditure invested in it again. The energy return factor (harvest factor) relates the energy delivered over the entire lifetime to the expenditure.

For photovoltaics, Fraunhofer ISE, in its Aktuelle Fakten zur Photovoltaik (version of January 2026), states an energy payback time of under 1.3 years for systems with standard market monocrystalline silicon modules in Germany. An older analysis commissioned by the Federal Environment Agency (Umweltbundesamt) arrived at roughly 1.6 to 2.1 years for PV power plants in Germany, depending on module type. The difference shows how strongly such values depend on production year, technology, irradiation and place of manufacture. With a service life of 25 to 30 years, the plant thus generates the bulk of its electricity after the manufacturing expenditure has already been offset, and without fuel. The same applies similarly to wind energy. Concrete values, however, depend on location, plant size and study. Blanket figures without these details are of little reliability.

Significance in the power system

In the power system, embodied energy becomes visible above all with renewable generation plants, storage, grid expansion and electrification. Wind turbines, solar modules, battery storage, heat pumps, electrolysers, charging stations and lines require materials, factories, logistics and construction services. A power supply with a high share of renewable energy therefore shifts part of the energy expenditure from fuel consumption during operation to the manufacture of the plants. For coal and gas power plants, the largest part of the energy and emissions balance arises during operation. For wind and solar plants, a large part lies at the beginning of the life cycle. This shift changes the assessment, but does not cancel out the benefit of renewable generation.

Embodied energy must also not be confused with ongoing electricity consumption. If a household operates a heat pump, the meter shows the ongoing electricity demand. The energy contained in manufacture, refrigerant, installation and materials does not appear there. For the electricity bill it is irrelevant. For assessing technology pathways, support programmes, building standards or infrastructure decisions, however, it is important. An efficiently operated heat pump can significantly reduce fossil final energy and emissions over its lifetime, especially if the electricity mix is further decarbonised. Embodied energy helps determine how quickly this advantage materialises.

Grids and storage: attribution is a question of method

For infrastructure, attribution is particularly difficult. A substation, a high-voltage line or a storage facility does not serve a single consumer, but many feed-ins, withdrawals and operating states. Embodied energy can be distributed by service life, transmitted electricity volume, connection capacity or provided grid function, and each of these methods answers a different question. Distribution over transported kilowatt hours is suitable for average life-cycle indicators. For the investment decisions of a grid operator, however, capacity, redundancy and controllability count for more. A line that is rarely fully utilised may nevertheless be necessary for security of supply and for avoiding bottlenecks.

With a battery storage system, too, embodied energy can only be understood together with its mode of operation. The storage system contains expenditure from raw material extraction, cell manufacturing, housing, power electronics and fire protection. How sensible this expenditure is depends on how often it is cycled, what quantities of electricity it shifts in time, which grid bottlenecks it avoids, and whether it reduces fossil peak load or the curtailment of renewable plants. A high embodied energy per kilowatt hour of storage capacity does not automatically mean a poor balance. It does, however, require a use that justifies the manufacturing expenditure over many cycles and a relevant system function.

Economics, regulation and data

Embodied energy is contained in the purchase price of a plant only indirectly and incompletely. Energy-intensive materials can be cheap if energy is subsidised, environmental costs are passed on to the general public, or production takes place under low standards. Conversely, higher acquisition costs can be justified if a product lasts longer, can be repaired, needs less material or was made with lower-emission energy. The indicator becomes reliable only with comparable data, for example from environmental product declarations, information on material origin, recycling rates and supply chain reports.

In the EU, what is currently legally anchored is above all the climate impact over the life cycle, not embodied energy itself. The EU Energy Performance of Buildings Directive (EU) 2024/1275, in force since 28 May 2024, obliges the Member States in Article 7(2) to calculate the life-cycle global warming potential of new buildings and to disclose it in the energy performance certificate. This applies from 1 January 2028 to new buildings with more than 1,000 square metres of useful floor area and from 1 January 2030 to all new buildings. Under Annex III, the value is stated in kg CO₂ equivalent per square metre of useful floor area for each life-cycle phase over a reference period of 50 years. This mainly captures embodied emissions of buildings, not their energy expenditure in kilowatt hours. The obligation is addressed first to the Member States and must be transposed into national law. No direct obligation for generation plants and grids arises from it.

Assessment

For the energy transition the concept is useful because it corrects a false expectation: no energy infrastructure is materially free of cost. Renewable plants, too, require mining, industry, transport, land and maintenance. It does not follow, however, that all technologies should be assessed equally. They differ in how the expenditure is distributed over the life cycle, how strongly they depend on fuels, how much they emit during operation, how long they last and how well their materials can be recovered. Used precisely, this means: with details on life phases, form of energy, service life, use and comparison technology. Embodied energy then supplements the operating data with the manufacturing side and makes investments assessable across the whole life cycle. Without these details it easily becomes a slogan against any new infrastructure.

Sources

Related glossary entries

Edited by eCMS on 12.11.2026 05:05

© 2026 Erik Schmidt. All rights reserved. Quotations with a link to the source are welcome.