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SILICON
SILIC
CHIP
www.siliconchip.com.au
Publisher & Editor-in-Chief
Leo Simpson, B.Bus., FAICD
Production Manager
Greg Swain, B.Sc. (Hons.)
Technical Editor
John Clarke, B.E.(Elec.)
Technical Staff
Ross Tester
Jim Rowe, B.A., B.Sc
Mauro Grassi, B.Sc. (Hons), Ph.D
Nicholas Vinen
Photography
Ross Tester
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Phone (02) 9939 3295
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glyn<at>siliconchip.com.au
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Rodney Champness, VK3UG
Kevin Poulter
Stan Swan
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2 Silicon Chip
Publisher’s Letter
Gas-fired trigeneration is a
worthwhile concept
While you may be concerned about your everincreasing energy bills, there is another electricity
problem that may soon confront a lot of Australians:
power blackouts. The truth is that all the eastern States
have a chronic shortage of electricity generators. For a
variety of reasons, the States have not been building
new coal-fired power stations and they are increasingly
using the available generation capacity. And while they
have been trumpeting wind farms and roof-top solar
installations, these will provide a very small fraction
of the total demand.
It will only need a series of very hot days this summer or perhaps a major power
station or grid fault to cause some serious blackouts. And since all the eastern
States, including Tasmania, are interconnected, the blackouts could potentially
be state-wide or even more extensive.
There is no easy solution to this problem. Since there is a lack of generating
capacity and since everyone with an air-conditioner is likely to run it whenever
the temperature rises, the result is likely to be power rationing to wide areas or
worse, the blackouts may be sudden and widespread. Or maybe the authorities will
be proactive and if very hot weather is predicted, they may appeal to consumers
to curtail their use of air-conditioning.
All of which makes a recent proposal by Sydney’s Lord Mayor, Clover Moore,
all the more interesting. Ms Moore is proposing that all of the Sydney CBD should
be powered from small gas-fired trigeneration plants. Undoubtedly, this is partly to
appeal to inner-city “green voters” anxious about “carbon emissions” but it makes
a lot of sense anyway.
While many readers are probably familiar with gas-fired co-generation plants, they
may not be familiar with trigeneration, which is not a new concept, incidentally.
Co-generation refers to a plant which typically has a gas-fired turbine running an
alternator to generate electricity. Waste heat from the exhaust of the gas turbine
is then used to flash water into steam to drive a steam turbine and alternator to
generate more electricity. Trigeneration typically takes waste heat from the water
condensate of the steam turbine to run an absorption refrigeration system for airconditioning. Other variations use the waste heat for heating in a building.
Whatever variant is used, it is a great deal more efficient than coal-fired power
stations or gas-fired co-generation plants and that means that far less hydrocarbons
are burnt to generate a given quantity of energy, so that is a big advantage. Furthermore, the proposed trigeneration plants would be installed in existing buildings
and would no doubt be able to be brought on line much more quickly than any
large conventional power plant.
The concept also has the advantage of being a local power source which means
that there are less transmission losses from the point of generation to where it is used.
Of course there has been criticism of the idea. One problem to be solved, apart
from matters like planning regulations and finance, is the large quantity of natural
gas that will be required and whether existing supplies in the city will be adequate.
And some people have been concerned about the amount of local pollution that
might be created by these gas-fired plants. I would say, “Don’t worry about it!”
After all, any pollutants generated by clean-burning gas turbines are likely to
be minimal compared to those from all the diesel-powered standby generators already present in the central business districts of our State capitals. Many of those
standby generators are already committed to the grid via lucrative contracts with
electricity distributors.
So if you notice a haze over your capital city during hot days this summer, it
could well be due to those diesel generators.
Maybe we really should consider nuclear power!
Leo Simpson
siliconchip.com.au
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