Solar effectiveness is regional
A number of readers have commented that I appear to have
condemned electric cars in my article "How to Reduce Your Greenhouse Gas
Emissions, Pt.3" (SILICON CHIP, September 2007). Electric
cars are quite advantageous in countries or regions where the electricity
produced generates less than about 0.9kg of CO2 per kWh. Victoria
averages about 1.4kg/kWh and the Australian average is about 1.0kg/kWh.
In the USA, the average is about 0.7kg/kWh, so electric cars
would be better there than petrol. For Australia at present, gas-powered cars
may be the best option since, apart from being relatively low in CO2
emissions, they reduce our dependency on foreign oil.
In the case of solar hot water heating, there are several
factors which determine whether a booster is required and what sort of booster
is appropriate. To give some examples: if you live in Victoria, with high
CO2 per kWh and your solar system supplies only 60% of the energy,
then a gas booster is appropriate. In Tasmania, most of the electricity is hydro
and so even though the solar fraction is lower, electricity produces the lowest
greenhouse gas emissions.
If you live in the sunnier areas of Australia, where the solar
fraction can be very high or 100%, again electricity may be the best. So
essentially the decision is based on solar insolation (how sunny your location
is), your usage level and the "dirtiness" of the electricity supply you would
use to heat the water.
Peter Seligman,
Essendon, Vic.
Australia on the right wavelength with digital radio
I wish to comment on the letter concerning DAB+ in the
September 2007 issue of SILICON
CHIP. It’s a shame a letter writer has
attacked Australia’s plans for digital radio without the facts and without being
prepared to put their name to their opinion.
Commercial radio broadcasters have every confidence that
Australia can successfully lead the way with digital radio. We have a long
history of innovation that has seen radio adapt and flourish over the years
despite the advent of technologies such as TV, CD players and the internet. The
development of portable and in-car listening, the introduction of top 40 music
formats, talkback radio, pioneering live news and sports reports from the scene,
interactivity, streaming online and radio podcasts are examples of the way radio
has continually evolved both its content and distribution over the years.
Digital radio is the next step.
The decision to go with DAB+ was not driven by "bureaucracy"
but by radio stations who understand what listeners want. DAB+ technology allows
us to offer exciting new features and a multitude of content that just isn’t
possible with AM and FM.
We should be proud that Australia was the first country in the
world to switch on a high power DAB+ test - but we are far from alone. Trials
have been conducted in Italy, Czech Republic and France, while many other
countries including Canada, Hungary, Israel, Kuwait, Malaysia, Malta, New
Zealand and China are making preparations for trials and launches. DAB+ is our
opportunity to move the industry forward and those who don’t embrace this change
will most likely be left behind. If our anonymous critic would like to come out
from behind the cloak of anonymity then we can make sure he or she is acquainted
with the facts of digital radio, both here and globally, and will thus be
equipped to make, in the future, an informed comment. Joan Warner,
Chief Executive Officer,
Commercial Radio Australia.
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