Decentralized Poly-generation of Energy: Basic Concepts - Design for Micro-Combined Cooling, Heating and Power Systems - page 41

ciency in winter
when electricity production is injected into the grid and heat distribution is done to

In the first case, the cogeneration unit operates with high ef

ciency during the warm season, of the centralized cogeneration
units is low, same as power separate systems, because the heat production is not
used.
A very important role in the conversion of primary energy into useful energy is
played by the capacity of each component of conversion, transformation, and the
distribution. For example, the conversion of fuel primary energy into electric
energy, in a thermal station, is achieved with an ef

final consumers. Ef

ciency of maximum 35 %. The
electric energy produced by the station is transported along the energy distribution
line and reaches the consumer as delivered energy, with an ef ciency of 85 %.

Then, the consumer uses it to supply various devices, becoming useful energy. For
example, the consumer converts electric energy into useful energy under the form
of light, with an ef

ciency of 5 % — in the case of using an incandescent light bulb,

of 20 % fluorescent light bulb, or converts it into mechanical

energy, with the aid of an electric engine, with an ef

— in the case of using a

ciency of 90 %.

ciency of converting the
energy into different component elements of the chain of energy production, dis-
tribution, and use.
Increasing the energy ef

In its turn, the ef ciency factor is dependent on the ef

ciency factor may be achieved in two different ways:
1. by reducing the energy losses, as a result of increasing the energy conversion
ef ciency in each component element of the chain of converting primary energy

into useful energy;
2. by recuperating the energy losses in the component elements of the chain of
converting primary energy into useful energy and transforming these losses into
useful energy.

first applies to systems of separate heat and power generation (SHP sys-
tems), where the effort is concentrated on achieving ef

The

cient systems (technologies)
of energy conversion. This may be achieved in the case of centralized generation, as
indicated in Fig. 3 a.
The second implies modifying the management of primary energies and their
conversion into useful energy. This may be achieved in the case of distributed
generation, as indicated in Fig. 3 b.
Decentralized power generation combined with heat supply (CHP) is an

important technology for improving energy ef ciency, security of energy supply,

and reduction of CO 2 emissions. The need to introduce several “ environment

friendly installations (like microturbines, fuel cells, photoelectric installations,

small wind turbines, and other advanced technologies for distributed generation)
have determined an increase in the interest for distributed generation, particularly
for local (

”

“ ”

) generation. Introducing environment friendly installations
implies the implementation of two concepts: distributed energy resources (DER)
and renewable energy sources (RES). In fact, the DER concept encompasses three
main aspects, whose focus is set on the electrical standpoint:

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