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Combustion Engines offer significant advantages over external combustion
in many applications, particularly automotive where there is a need for
rapid variation in power output, which can be achieved by changing the
fuel supply rate. However, for continuous operation with extended
service intervals, as required for domestic heating systems, the
challenges facing ICE are formidable; until recently it was considered
that the cost of the components required to achieve the appropriate emissions,
sound attenuation,
efficiency and reliability parameters would be excessive.
Early products, based on automotive ICE
technology, operated with some success in niche applications, but were unable to overcome these technical challenges and beset
with high service and operating costs. The products mentioned
below, however, have all been developed for long life with relatively low service
intervention and incorporate a range of features aimed at achieving the
performance desirable for domestic and small commercial applications.
For further discussion of the relative
merits of these engine types see section on
papers,
or check out the definitive book on
micro CHP technologies. |
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Honda’s
1kWe cogeneration unit was the world’s first practical micro CHP unit for home use;
the majority of installations globally (i.e. those in Japan) are
external to the home.
The incorporation of catalytic converters and an elaborate acoustic
attenuation system, together with novel engine design, have overcome the
principle limitations of ICE design, namely noise, emissions and service
intervals. However, the cost of
these additional components results in a very high installed cost, which
is difficult to justify on economic grounds. In the Japanese
market, high
electricity prices and capital grants greatly improve the economic
viability for the end user.
With nearing 100,000 units installed in
Japan since 2003, the Ecowill is now being marketed by
Climate Energy in the USA.
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Launched onto the German market in early
2011, also based on the successful Honda ICE. Similar in
performance to the Ecowill, but differing in significant respects:
1) It is suitable for indoor installation,
although rather bulky when account is taken of the numerous
additional components required to complete the installation.
2) It has a slightly higher electrical and
overall efficiency (26% & 92% LCV respectively), compared with an
overall efficiency of 85% for the Ecowill.
Not surprisingly this enhanced
performance comes at a price, more than double that of the Japanese
product! |
Developed
and manufactured by the Baxi Group company Senertec GmbH, the DACHS is a
European manufactured packaged mini-CHP unit based on reciprocating
engine technology. Operating reliably and successfully across Europe for
many years, the DACHS is proven technology and has become an established
choice in mini-CHP. Over 8,000 units have now been installed by Senertec
GmbH, and its partner network, mainly in Germany.
Its primary application is for small
hotels and apartment blocks (e.g. sheltered housing) where there is a
continuous electrical and thermal baseload. The resulting high
annual operating hours provide the substantial savings required to pay
back the relatively high capital cost.
However, it is physically too large and has too
high an electrical output to be suitable for anything but the largest
family homes, or those with swimming pools. |
Based
on the Marathon gas engine designed for dry operation and can be modulated
to match electrical load. This feature is believed by its
developers to offer significant benefits over its competitors.
However, the high capital cost of this products
will require very high
running hours at full load in order to generate sufficient electricity
to recover the investment. It is only in remote (off-grid)
applications where this feature offers significant benefits.
Ecopower has been acquired by Vaillant, the
German boiler manufacturer who are also developing the Plug Power based
fuel cell micro CHP unit and a 1kWe unit based on the Honda engine.
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This product incorporates a package of components including the
engine/generator, a supplementary boiler, heat exchanger and integrated
control system. Rather uniquely it offers a sophisticated control
with the option of heat or electrically led operation, with the engine
being capable of a wide modulating range. It is ideally suited to that difficult
to address middle ground between individual homes and multi-occupancy
buildings and is included here for those with an interest in
small apartment blocks, sheltered housing etc.
Both diesel and gas-fired versions are available, each with electrical
output around 15kWe. The gas-fired model is based on a
Toyota
engines renowned for reliability and long life, whilst the diesel and
biodiesel models use Deutz engines.
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The Yanmar product was recently launched
in the UK market following installation of around 600 units in
Japan.
Unlike the EC Power unit, Yanmar offer a
packaged system which is somewhat less flexible than the EC Power
unit, although this should be offset by their offering the product
in a range of sizes between 4-25kWe.
In late 2007 Yanmar initiated a 3
year demonstration programme of their biodiesel variant which will
eventually become available with an output of 25kWe.
Yanmar packaged units, suitable for
external location, are now available from
ENER.G with outputs of 4kWe, 10kWe
and 25kWe. |
In September 2009, VW announced a plan
to install 100,000 of their 20kWe "EcoBlue" mini CHP units in
collaboration with energy service partner Lichtblick.
Initially units will be available in the
Hamburg area, then from 2010, Lichtblick plan to expand their market
into the remainder of Germany.
The units will be leased by customers
who will pay an initial deposit, a monthly service charge and a
favourable unit price for each kWh of heat and electricity consumed. |
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