Emergy, method to valuing the environmental real wealth.
Emergy
Emergy spelled with an "m" is a different term from the word
"energy" which we have known since we learn the thermodynamics law.
Energy was defined as the
potential ability of a physical
system to do work on
other physical systems (Harper, 2007). Rather than the ability to do work, emergy is
energy required to compose those system. Emergy is defined as “the available energy of one kind of previously used up directly and
indirectly to make a service or product", its unit is the emjoule” (Odum,
1996). Emergy also often understood as "the energy memory" of one
kind of product or service. Emergy analysis is a technique to measure the real
value of a system of one kind product or service based on the total energy
required to compose it system. In the emergy analysis, many kind of energy type
which were involved in the process of a system will be converted into the same
energy quality, so then the mathematical calculation could be perform on
its. The conversion from one energy type
into another form of energy could be done through the conversion ratio, this
ration called “transformity”. Base on the transformity, various kind of energy
could be converted into the same kind of energy and can easily analyze each
contribution to the system. Furthermore, emergy indices are used for better
evaluation of the concerned system. These indices indicate various performance
of the system in term of efficiency and sustainability (Campbell, 1997).
Associated with the emergy analysis for fisheries production, some indices need
to be calculate are Emergy Yield Ratio (EYR), Emergy Investment Ratio (EIR), Environmental
Loading Ratio (ELR), and Environmental Sustainability Index (ESI) (Odum
and Odum, 1983; Ulgiati et al., 1995; Odum, 1996; Brown and Ulgiati, 1997;
Ulgiati and Brown, 1998)
1. Emergy Concept
Biosphere in the earth surface where we are living on is a system which is
supported by so many resources either renewable or nonrenewable. Along with the
economic development, diminishing of earth resources has reached a new stage.
Enterprises for private profit are consuming the environmental systems that are
the basic of public welfare. The conflict between those intent on protecting
the environmental and those intent on further economic development are becoming
increasingly important in public policy discussion and politic development.
Trying to solve the problem and search the middle course between these
two issues, H.T.
Odum (Odum, 1996) introduces the “EMERGY” theory. Emergy is a science-based
evaluation system to represent both the environmental values and the economic
values with a common measure. Emergy measures both the work of nature and that
of humans in generating product and services. While the available energy is
potential energy which can do work, the Emergy is “energy memory”. That the
meaning was, emergy is a measure of the available energy which has been used up
to make the products or services.
2. Definition
To build and maintain the products or services
(energy storage) of available resources, environmental work has to be done,
this proses certainly requiring energy use and transformation. The storage can
be evaluated quantitatively by the work done in its formation. Work of energy transformation can be measured
by the availability of energy that is used up. Thus, real wealth can be
measured by the work previously done. EMERGY is a scientific measure of real
wealth in term of the energy required to do the work of production.
EMERGY is the available energy of one kind of
previously used up directly and indirectly to make a product or service. Its
unit is the emjoule (H. T. Odum, 1986a,
1988; Scienceman, 1987)
However, on the further application of energy calculation,
each energy source has different contribution as the energy of one kind is not
equivalent in its ability to do work to energy of another kind. Therefore, in
adding up the available energies of different kinds contributing process, all
have to be expressed in unit of one kind of energy. In the development of
emergy analysis, there are several energy type were used as the calculation
base, yet commonly solar energy were used as the calculation base. In the solar
energy base, all form of energies contributing on a system was expressed in
unit of solar energy and it would be required to generate all the inputs. The process of converting every kinds of
energy contributing in the system into solar energy called “transformation”
process. Transformation proses will involve the ratio of conversion which hereinafter
referred to as transformity.
3. Transformity
An energy transformation is a process that one
or more kinds of available energy are converted to a different type of
available energy. Most often, inputs to a process are the result of another
process, in which energy has been concentrated and upgraded. In figure 2.1 its
clearly shows that the quality of 1 joule of humans physical work equal with 10
joule of meat energy from cattle, and 10 joule of energy from cattle can be
generated from 1.000 joule of energy from plant or 1.000.000 joule energy from
sun and rain.
Fig. 1. Emergy quality chain from cattle ranch
supporting humans, with levels of energy transformation.
Further, the quotient of a product’s emergy divided by its
energy is defined as its transformity (H.
T. Odum. 1976b, 1988). In above figure (fig. 2.1), it’s explaining that
transformity for plant is quotient of sun energy divided by energy produce by
plant, its means 1.000.000 joule divided by 1.000 joule, and then the
transformity is 1.000. As well as plants, cattle and humans energy also
subjected with the same process and resulting the transformity number about
100.000 and 1.000.000 for cattle and humans respectively. The units of
transformity are emjoules perjoule. As in the previous statement that commonly
solar emergy were used as the calculation base, the units for this transformity
are solar emjoules per joule (abbreviated sej/J).
Solar transformity is the solar EMERGY required to
make one joule of a service or product. Its units are solar emjoule per joule
(sej/J). A product’s solar transformity is its solar EMERGY divided by its
energy. (H. T. Odum, 1996).
There
have been a lot of transformities for various kinds of energies, materials, and
services such as emergy per energy, emergy per mass, and emergy to money
ratios. The more energy transformations there are contributing to a product,
the higher is the transformity. This is because at each transformation,
available energy is used up to produce a smaller amount of energy of another
form. Thus, the emergy per unit energy increases but the energy decreases, and
therefore the emergy per unit energy increased sharply. The human energy has a
larger transformity than meat flash from cattle that contributed to produce it.
Fig. 2. Concepts of energy transformation hierarchy and transformity, (a) All
units view together; (b) Units separated by scale; (c) Units as a web of energy
flows; (d) Processes shown as an ordered series; (e) Flows of energy per unit
time; (f) Transformities (Brown et al., 2004)
All the energy transformations could be arranged
in ordered series to form an energy hierarchy. The hierarchy is that many units
at lower level generate a few units at higher level, with the higher level
feeding controls back to lower level units. Transformity shows the position of
an energy transformation in the energy hierarchy and increases gradually from left
to right (Figure 2.2). Therefore, it can be considered as a comparison factor
for different types of energy. High transformity means high quality, and vice
versa. Many transformities have been determined by Odum and the other authors
over the past years and used in emergy analyses. New transformities are based
on emergy driving the biosphere reevaluated as 15.20 E+24 sej/yr.
