I believe wind and solar powered units are only 15% effiecient and would be very expensive to install without Government subsidy. Coal fired are 35% efficient, whereas Blugen units offer 60% + when used for water heating as well. So with all that in mind which would be the more efficient to use?
I can't see the Government subsidising solar power indefinetly, so what happens then?
Efficiency isn't really important when you have a free source of fuel (wind, sun etc) that is effectively unlimited. That is very different to using, say, oil where the resource is limited and costly, hence there is a benefit in efficient use. But we're not going to use up the sun or wind by installing inefficient solar panels or wind turbines.
What does matter is (1) cost and (2) practicality as a source of electricity generation.
Wind and solar are intermittent sources that can not be counted on to be operating at the time of system peak demand that is certainly true and a big downside. But unless the Bluegen is under centralised dispatch, that is the householder does not have control of the operation of the unit, then it too has serious limitations. It would work technically as a means of effectively reducing net residential / small business load on the distribution system, but not as a major source of generation for the system as a whole.
A more significant issue however is the inflexibility in operation. We already have a growing issue with variability in demand now that hydro development, the traditional and most flexible source of peaking generation, has effectively ended in this country.
Adding a new baseload source not under centralised dispatch, Bluegen, only makes the daily load changes on conventional power stations even larger than they are now. And the practical way to deal with that is to build less technically efficient power stations, and operate them less efficiently. That's what actually happens in order to meet high peaks relative to baseload demand on conventional generation. Other than hydro, peaking generation is either incredibly expensive or it is inefficient and polluting and in some cases it is both (a good reason to avoid using power at peak times if possible).
The same argument does apply to wind too. To some extent the benefits of wind energy are offset by a reduction in the design and ongoing operating efficiency of the conventional generating plant which still acounts for the majority of generation. Practical reality is that if you are adding conventional (coal, gas) plant to a system that incorporates a substantial amount of wind then you won't be building a state of the art plant designed for maximum efficiency. Instead you'll drop the efficiency by a third right at the design stage, simple due to the way in which it will need to operate.
In the Australian context Tasmania, due to being predominantly hydro, is the sole exception to that situation and the only state in which construction of wind (or other intermittent generation) represents an actual alternative to construction of additional conventional generation. However, a significant portion of that ability has already been utilised to support the system on mainland Australia (mostly Vic and SA) although there is certainly still potential to add what is effectively baseload wind (through integration with hydro) in Tas.
If Bluegen was capable of (1) reasonable load cycling on at least a daily basis (ie ramp up in the morning, ramp down in the evening) and (2) was capable of centralised dispatch in some way (so they can be forced down overnight and up again during the day) and (3) was cost competitive with gas turbines then I would be a lot more optimistic about it. But as it stands today, it is in the same category as solar - it will happen only if government props it up.
Meanwhile conventional gas turbines, and if allowable environmentally then also black coal, are far cheaper options to meet foreseeable electricity demand going forward. And if we did want to cut CO2, then wind is a cheaper (though still expensive) way of doing it than Bluegen.
It really comes down to price. The Bluegen unit has a viable use that is for sure. But not at the price being asked. It is simply far too expensive for what it actually is. And those attracted to it on environmental grounds would generally be the same people who have already installed solar for the same purposes.