Эмергия: измерение энергии, затраченной на создание продукта или услуги.

Total energy consumed, directly and indirectly, to make a product or service
Emergy is the amount of energy consumed in direct and indirect transformations to make a product or service. Emergy is a measure of quality differences between different forms of energy. Emergy is an expression of all the energy used in the work processes that generate a product or service in units of one type of energy. Emergy is measured in units of emjoules, a unit referring to the available energy consumed in transformations. Emergy accounts for different forms of energy and resources (e. g. sunlight, water, fossil fuels, minerals, etc.) Each form is generated by transformation processes in nature and each has a different ability to support work in natural and in human systems. The recognition of these quality differences is a key concept.

The theoretical and conceptual basis for the emergy methodology is grounded in thermodynamics, general system theory and systems ecology. Evolution of the theory by Howard T. Odum over the first thirty years is reviewed in Environmental Accounting

The term "embodied energy" was used for a time in the early 1980s to refer to energy quality differences in terms of their costs of generation, and a ratio called a "quality factor" for the calories (or joules) of one kind of energy required to make those of another. However, since the term embodied energy was used by other groups who were evaluating the fossil fuel energy required to generate products and were not including all energies or using the concept to imply quality, embodied energy was dropped in favor of "embodied solar calories", and the quality factors became known as "transformation ratios".

Use of the term "embodied energy" for this concept was modified in 1986 when David Scienceman, a visiting scholar at the University of Florida from Australia, suggested the term "emergy" and "emjoule" or "emcalorie" as the unit of measure to distinguish emergy units from units of available energy. The term transformation ratio was shortened to transformity in about the same time. It is important to note that throughout these twenty years, the baseline or the basis for evaluating forms of energy and resources shifted from organic matter to fossil fuels and finally to solar energy. After 1986, the emergy methodology continued to develop as the community of scientists expanded and as new applied research into combined systems of humans and nature presented new conceptual and theoretical questions. The maturing of the emergy methodology resulted in more rigorous definitions of terms and nomenclature and refinement of the methods of calculating transformities. The International Society for the Advancement of Emergy Research and a biennial International Conference at the University of Florida support this research.

+Table 1: Development of emergy, transformity and conversion ratios. Years Baseline Unit Emergy Values Units Reference 1967–1971 Organic matter the baseline. All energies of higher quality (wood, peat, coal, oil, living biomass, etc.) expressed in units of organic matter. Sunlight equivalent to organic matter = 1000 solar kilocalories per kilocalorie of organic matter. g dry wt O. M.; kcal, conversion from OM to kcal = 5kcal/g dry wt. 1973–1980 Fossil fuels and then coal the baseline. Energy of lower quality (sunlight, plants, wood, etc.) were expressed in units of fossil fuels and later in units of coal equivalents. Direct sunlight equivalents of fossil fuels = 2000 solar kilocalories per fossil fuel kilocalorie Fossil fuel work equivalents (FFWE) and later, coal equivalents (CE) 1983–1986 Recognized that solar energy, deep heat, and tidal momentum were basis for global processes. Total annual global sources equal to the sum of these (9.44 E24 solar joules/yr) Embodied solar joules per joule of fossil fuels = 40,000 seJ/J Embodied solar equivalents (SEJ) and later called "emergy" with nomenclature (seJ) 1987–2000 Further refinements of total energy driving global processes, Embodied solar energy renamed to EMERGY Solar Emergy per Joule of coal energy ~ 40,000 solar emjoules/ Joule (seJ/J) named Transformity seJ/J = Transformity; seJ/g = Specific emergy

Emergy— amount of energy of one form that is used in transformations directly and indirectly to make a product or service. The unit of emergy is the emjoule or emergy joule. Using emergy, sunlight, fuel, electricity, and human service can be put on a common basis by expressing each of them in the emjoules of solar energy that is required to produce them. If solar emergy is the baseline, then the results are solar emjoules (abbreviated seJ). Although other baselines have been used, such as coal emjoules or electrical emjoules, in most cases emergy data are given in solar emjoules. Unit Emergy Values (UEVs) — the emergy required to generate one unit of output. Types of UEVs:
Transformity — emergy input per unit of available energy output. For example, if 10,000 solar emjoules are required to generate a joule of wood, then the solar transformity of that wood is 10,000 solar emjoules per joule (abbreviated seJ/J). The solar transformity of the sunlight absorbed by the earth is 1.0 by definition. Specific emergy — emergy per unit mass output. Specific emergy is usually expressed as solar emergy per gram (seJ/g). Because energy is required to concentrate materials, the unit emergy value of any substance increases with concentration. Elements and compounds not abundant in nature therefore have higher emergy/mass ratios when found in concentrated form since more environmental work is required to concentrate them, both spatially and chemically. Emergy per unit money — the emergy supporting the generation of one unit of economic product (expressed in monetary terms). It is used to convert money into emergy units. Since money is paid for goods and services, but not to the environment, the contribution to a process represented by monetary payments is the emergy that money purchases. The amount of resources that money buys depends on the amount of emergy supporting the economy and the amount of money circulating. An average emergy/money ratio in solar emjoules/$ can be calculated by dividing the total emergy use of a state or nation by its gross economic product. It varies by country and has been shown to decrease each year, which is one index of inflation. This emergy/money ratio is useful for evaluating service inputs given in money units where an average wage rate is appropriate. Emergy per unit labor — the emergy supporting one unit of direct labor applied to a process. Workers apply their efforts to a process and in so doing they indirectly invest in it the emergy that made their labor possible (food, training, transport, etc). This emergy intensity is generally expressed as emergy per time (seJ/yr; seJ/hr), but emergy per money earned (seJ/$) is also used. Indirect labor required to make and supply the inputs to a process is generally measured with the dollar cost of services, so that its emergy intensity is calculated as seJ/$. Empower — a flow of emergy (i. e., emergy per unit time). +Table 2. NomenclatureTerm Definition Abbreviation Units Extensive Properties Emergy The amount of available energy of one type (usually solar) that is directly or indirectly required to generate a given output flow or storage of energy or matter. Em seJ (solar equivalent Joules) Emergy Flow Any flow of emergy associated with inflowing energy or materials to a system/process. R=renewable flows; N= nonrenewable flows; F= imported flows; S= services seJ*time−1 Gross Emergy Product Total emergy annually used to drive a national or regional economy GEP seJ*yr−1Product related Intensive Properties Transformity Emergy investment per unit process output of available energy Τr seJ*J−1 Specific Emergy Emergy investment per unit process output of dry mass SpEm seJ*g−1 Emergy Intensity of currency Emergy investment per unit of GDP generated in a country, region or process EIC seJ*curency−1Space related Intensive Properties Emergy Density Emergy stored in a volume unit of a given material EmD seJ*volume−3Time related Intensive Properties Empower Emergy flow (released, used) per unit time EmP seJ*time−1 Empower Intensity Areal Empower (emergy released per unit time and area) EmPI seJ*time−1*area−1 Empower Density Emergy released per unit time by a unit volume (e. g. a power plant or engine) EmPd seJ*time−1*volume−3Selected Performance Indicators Emergy released (used) Total emergy investment in a process (measure of a process footprint) U= N+R+F+S (see Fig.1) seJ Emergy Yield Ratio Total emergy released (used up) per unit of emergy invested EYR= U/(F+S)(see Fig.1) — Environmental Loading Ratio Total nonrenewable and imported emergy released per unit of local renewable resource ELR= (N+F+S)/R(see Fig.1) — Emergy Sustainability Index Emergy yield per unit of environmental loading ESI= EYR/ELR(see Fig.1) — Renewability Percentage of total emergy released (used) that is renewable. %REN= R/U(see Fig.1) — Emergy Investment Ratio Emergy investment needed to exploit one unit of local (renewable and nonrenewable) resource. EIR= (F+S)/(R+N) (see Fig.1) —

Emergy accounting converts the thermodynamic basis of all forms of energy, resources and human services into equivalents of a single form of energy, usually solar. To evaluate a system, a system diagram organizes the evaluation and account for energy inputs and outflows. A table of the flows of resources, labor and energy is constructed from the diagram and all flows are evaluated. The final step involves interpreting the results.

The table allows a unit emergy value to be calculated. The final, output row (row “O” in the example table above) is evaluated first in units of energy or mass. Then the input emergy is summed and the unit emergy value is calculated by dividing the emergy by the units of the output.

Figure 2 shows non renewable environmental contributions (N) as an emergy storage of materials, renewable environmental inputs (R), and inputs from the economy as purchased (F) goods and services. Purchased inputs are needed for the process to take place and include human service and purchased non renewable energy and material brought in from elsewhere (fuels, minerals, electricity, machinery, fertilizer, etc.). Several ratios, or indices are given in Figure 2 that assess the global performance of a process. Emergy Yield Ratio (EYR) — Emergy released (used up) per unit invested. The ratio is a measure of how much an investment enables a process to exploit local resources. Environmental Loading Ratio (ELR) — The ratio of nonrenewable and imported emergy use to renewable emergy use. It is an indicator of the pressure a transformation process exerts on the environment and can be considered a measure of ecosystem stress due to a production (transformation activity). Emergy Sustainability Index (ESI) — The ratio of EYR to ELR. It measures the contribution of a resource or process to the economy per unit of environmental loading. Areal Empower Intensity — The ratio of emergy use in the economy of a region to its area. Renewable and nonrenewable emergy density are calculated separately by dividing the total renewable emergy by area and the total nonrenewable emergy by area, respectively. Other ratios are useful depending on the type and scale of the system under evaluation. Percent Renewable Emergy (%Ren) — The ratio of renewable emergy to total emergy use. In the long run, only processes with high %Ren are sustainable. Emprice. The emprice of a commodity is the emergy one receives for the money spent in sej/$. Emergy Exchange Ratio (EER) — The ratio of emergy exchanged in a trade or purchase (what is received to what is given). The ratio is always expressed relative to a trading partner and is a measure of the relative trade advantage of one partner over the other. Emergy per capita — The ratio of emergy use of a region or nation to the population. Emergy per capita can be used as a measure of potential, average standard of living of the population. Emergy based energy return on investment was introduced as a way to bridge and improve the concept of Energy returned on energy invested to also include environmental impacts.

The concept of emergy has been controversial within academe including ecology, thermodynamics and economy. Emergy theory has been criticized for allegedly offering an energy theory of value to replace other theories of value. The stated goal of emergy evaluations is to provide an "ecocentric" valuation of systems, processes. Thus it does not purport to replace economic values but to provide additional information, from a different point of view. The idea that a calorie of sunlight is not equivalent to a calorie of fossil fuel or electricity strikes many as absurd, based on the 1st Law definition of energy units as measures of heat (i. e. Joule's mechanical equivalent of heat). Others have rejected the concept as impractical since from their perspective it is impossible to objectively quantify the amount of sunlight that is required to produce a quantity of oil. In combining systems of humanity and nature and evaluating environmental input to economies, mainstream economists criticize the emergy methodology for disregarding market values.