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With electrical outputs
around 1kWe and thermal outputs around 3kWt, these products are suited
to homes with an annual thermal demand of around 20,000kWh, typical for
family homes in most North European countries. Generally with
electrical efficiencies of around 25%, the relatively low heat output
(compared with Stirling engines) means that, if properly controlled,
they will operate for several thousand hours annually, greatly enhancing
their electricity production and thus shortening payback times.
However, the need to
incorporate an additional heat source for periods of high peak thermal
demand, means that it is very important to ensure the engine is
controlled so as to maximise its operating hours, otherwise the
potential benefits of higher electrical output can be lost. |
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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 inclusion 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! |
The Proenvis prio 5.2, (presumably indicating its nominal thermal and
electrical outputs respectively) and designated by its manufacturer as
"nano-CHP" is another German ICE based micro CHP product. It is
capable of modulating its electrical output between 1.3-2.0kWe.
At the same time it produces between
3.0-5.5kWt of heat with an overall efficiency of 93%, 25% electrical and
68% thermal.
The floor-mounted product is 66x66x115cm
with a weight of 185kg.
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Kirsch have developed a range of small CHP systems with electrical
outputs up to 50kW. Kirsch nano, the smallest is
based on Briggs & Stratton ICE technology with a power output of 1.9kWe.
However, with an electrical efficiency of
only 19% and thermal output of 9kWt, it is unlikely to achieve
significant running hours in any but the largest family homes, so that
payback will be challenging. It is configured to run in thermally
led mode.
Evidence of an "off the shelf" engine rather
than a bespoke micro CHP design, is clear from the service requirement
every 2,500 hours and a major overhaul at 20,000 hours. It is of
course also apparent from the efficiency, well below its competitors.
It is currently only available in Germany. |
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