A Proposal for a Standard With Innovation Management System

Ana Ferreira et al.
Operation costs can also represent a significant fraction and, for some technologies, maintenance
service may represent a significant charge for CHP plants below 30kWe. Optimally, the challenge is to
produce power plants with long life expectancy, low service and maintenance requirements.
Regarding the technical aspects, the micro-CHP plant should be compatible with the operational
parameters of central heating, such as water flow rates or temperatures, avoiding, for example,
additional large storage tanks to provide thermal buffering.
Most micro-CHP systems are currently heat-led, so the plants only operate when there is a heat
demand, being the electricity a by-product. The most likely situation corresponds to a higher number
of hours heat demand. According to (Pehnt, 2008), micro-CHP plants are only economically viable if
operated at least for about 3,500 to 5,000 hours at full load, and if the electricity is used at the
production site. Thus, applications with a rather constant heat demand and an electricity demand
matching the CHP electricity production profile are particularly well suited for micro CHP installation.
The economic incentive to export electricity from a CHP installation linked to the improvement of
system electrical efficiency turn micro-CHP systems on a more attractive investment. Also, micro-CHP
units must meet the consumer expectations: similar in size when compared with the power devices
they are trying to be a replaceable solution, quiet and free from excessive vibration.
4.2 Sustainability drivers and market constraints
The performance of micro CHP technologies, regarding environmental aspects, depends mainly on
the total conversion efficiency that can be achieved. The introduction of these systems in the
residential sector is intended to the replacement of gas-condensing boilers that are their competing
heat-supply technology. The actual challenge is to make those technologies more competitive. The
emission reduction and potential of micro-CHP could partially be offset by a “rebound effect”, implying
that energy savings achieved by a more efficient technology are annulled, by an increase in energy
demand. This depends, among other aspects, on the degree to which micro-CHP possession is
perceived as ecologically relevant, and on an understanding of its effects. Micro-CHP systems have
mainly relied on natural gas, although other fossil fuels, and in a limited extent, renewable energy
carriers, can be used with most technologies. One of the important questions that arise nowadays is if
most micro-CHP systems, which operate on fossil sources, can compete with renewable energy
supply systems, for example, solar collectors or biomass boilers. Although micro-CHP and solar
collectors require different integration in the respective building, for a new building that can be
equipped with a micro CHP plant, this could improve the competitiveness of developing renewablefuel-based
technologies for operating micro CHP systems, particularly Stirling engines (Chicco &
Mancarella, 2009).
Therefore, several important advantages regarding to key sustainability criteria can be summarized:
micro CHP reduces greenhouse emissions and resource consumption, when compared to the
average energy supply and even when compared to efficient and state-of-the art separate production
of electricity in conventional power plants and heat in condensing boilers; micro-CHP systems are
part of the transformation process for power generation, since the use of micro CHP allows more
flexibility solutions when compared to centralized power production; micro CHP plants can have
positive effects on the supply security of electricity grids, particularly where heat storage facilities exist
and an integration with smart grids is possible; and finally, micro-CHP reduces the external energy
dependency through cuts in fossil fuel imports (Pehnt, 2008). Figure 3 summarizes the growth drivers
and the most relevant constraints that micro-CHP units have to overcome.
Summarising, it can be said that assessing the sustainability of the micro cogeneration may be based
on the balance between the growth drivers of these technologies and the market constraints they
face. Therefore, the most relevant growth drivers for micro CHP are: the reduction of the external
energy dependency, by reducing the fossil fuel imports; the favourable policies that ensure improved
tariffs; the environmental concerns and the need to reduce the pollutant gas emissions; the possibility
to replace the heat production systems (e.g. boilers) by a system able to supply the thermal needs
and additionally produce electricity where the surplus production can become an economic profit.
The key market constraints that micro-CHP face are: the high manufacturing costs of these power
plants; the lack of available money for risky investments; the competition from the conventional power
production, as it’s still the easier way to access energy; and, finally, fuel prices fluctuations which can
be determinant in the determination of these plants profitability.
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