| The
Energetix Genlec unit, based on the Inergia prototype developed by the
Battelle Institute in the USA, was initially a 3kWe/30kWt unit intended
for small commercial applications. However, the benefits of the
organic Rankine design mean that it is possible to use off the shelf
components for the majority of the appliance, leading to low production
costs. In effect, it is a refrigeration unit working in reverse,
using the expanding working gas to power a scroll expander
(compressor). It is now being further developed as an add-on
module suitable for connection to a gas boiler, and is lightweight and
compact making it suitable for wall-mounting. It's relatively low electrical efficiency
means that it produces less electricity than some other units, although
this is compensated for by the expected low cost.
|
The
Climate Energy unit also uses a scroll expander, with benefits of
simplicity and potentially low manufacturing cost.
However, the
use of steam as a working gas raises technical challenges regarding
reliability and safety.
Against this, the developers claim that
the thermodynamic properties of steam permit high heat transfer rates
(resulting in compact heat exchangers), tolerate leakage and have no
inherent material risks. It is also non-toxic and thermally stable
which, combined with the zero cost make this a competitive technology.
Climate Energy LLC have recently launched
the Honda ICE based unit in the USA and it is uncertain as to whether they
intend to continue development of their external combustion unit.
|
Otag have developed a steam powered unit,
utilising a single cylinder with two opposing pistons. An integral
linear generator converts the reciprocating motion directly into
electrical energy with variable output 3 phase output.
Further details including an excellent
animation of the cycle are shown on the Otag website.
The unit was planned for launch in Germany
during 2006, although delays have resulted from obtaining CE approval. |
The
Enginion unit was initially developed as a small commercial unit with a
power output of around 50kWe. It too is now evolving into a
unit more appropriate for small apartments and hotels, although the believed
target power output of ~5kWe still makes it unsuitable for domestic
installations. Enginion was placed in receivership during
late 2005. |
The
Cogen Micro unit, developed by an engineering consultancy (Applidyne) in
Australia is unusual in that it uses reciprocating (single piston)
technology. Historically the very low efficiencies achievable at
reasonable temperatures and pressures have not been attractive.
However, novel injector design has enhanced the performance of prototype
units which may lead to an ultimately viable product.
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