The very high level of hydro-power in Tasmania shown on the graph above was typical; it is normal for Tasmania to run on almost entirely renewable energy.
At the time of writing, mid 2016, South Australia averaged around 37% wind power and 5% small-scale solar; on this occasion there was 72% wind and 18% solar.
(By late 2017 SA was averaging about 48% renewable power.)
|A turbine of Clements Gap Wind Farm
|Near my home in Crystal Brook, South Australia
|The innovative Sundrop Farm
|Solar thermal power station and some of the greenhouses, of
Sundrop Farms installation at Port
Augusta, South Australia
Tasmania runs on renewable energy most of the time and, as shown in the graph
above, SA runs on an average of about 50% renewables all the time and on mostly renewable energy some of the time, the Australian Capital Territory has a target of 100% renewable energy by 2020.
The other Australian states rely heavily on coal power.
There is little potential for more hydro power development in Australia; the
country is predominantly low-lying and dry.
There is, however, huge untapped potential for more wind and solar power.
Australia could easily achieve 60% renewable electricity, 80% would not be
particularly difficult, getting to 100% would be much more challenging.
coalition) federal government is holding Australia back
because it is fixated on trying to prop up the
dying coal industry.
Tasmania has a lot of untapped wind power potential, less solar.
Mainland Australia has huge untapped wind and solar potential.
The NEM grid connects South Australia with Tasmania through Victoria,
but the capacity of the links involved is small.
If the capacity of the links was greatly increased mainland Australia could
feed large amounts of solar power into the Tasmania when it was plentiful,
and Tasmania's hydro power could be conserved for
the times when wind and solar were less plentiful on the mainland.
South Australia has more potential for increased wind and solar power than
many other parts of the country.
If the electricity link capacities were greatly increased this potential could
readily be developed and the power exported to the eastern states.
Renewable electricity does not generally come as it is needed.
Coal can be mined as required, oil and gas can be pumped out of the ground
as they are needed, but the wind does not necessarily blow, nor the sun shine,
when we need electricity.
Biomass can be burned to generate electricity in high demand periods, but
if we are to change to high proportions of renewably generated electricity
we must develop more energy storage systems.
|Energy storage capacity plotted against discharge time
|No single method of storing energy is suitable for all needs.
Some methods are good for storing and recovering energy over very short times,
others over much longer times.
Generally those methods used for short-term energy storage have low capacity,
while those used over the long-term have much higher capacity.
CAES: Compressed air energy storage
PHS: Pumped hydro storage
SNG: Substitute natural gas
At the time of writing more than 99% of the world's energy storage was in
pumped hydro (not considering water in hydropower dams as energy storage).
Hydrogen and SNG were not proven on a commercial scale.
By mid 2018 the upper limit to the size of batteries had gone from the 30-40 MWh shown on the graph to more than 120 MWh.
Hydrogen Energy Storage: A New Solution ot the Renewable Energy Intermittency
Problem, Renewable Energy World; written by Mark Schiller; July 2014
Rather than me writing in detail about the energy storage options here I
suggest the reader looks at the following:
- Pumped hydro has been little developed in Australia and has a lot of potential for medium-term (hours up to a few days) energy storage.
There is very little pumped hydro in Australia:
Snowy Mountains, NSW, commissioned 1973; Wivenhoe, Qld, commissioned 1974;
and the proposed
Kidston Mine, North Qld.
Globally more than 99% of the world's stored energy is in pumped hydro;
Australia is again a slow adopter in this technology which has great value
in partnering renewable energy.
(I've written about the practicality of the proposed
Snowy 2 and mentioned four smaller
South Australian pumped hydro schemes elsewhere on these pages.)
- Conventional hydro stores energy in the longer-term (months to
years), but has the disadvantage that it is only recharged by rainfall.
- Compressed air energy storage uses electricity, when it is cheap
and abundant, to compress air which can then be stored underground.
When electricity is in high demand the compressed air is used to run
It is not yet a fully developed technology.
- Fly wheels are particularly suited for storing and retrieving
electrical energy over very short time periods – fractions of seconds
up to about an hour.
- Batteries have major potential for behind-the-meter electricity
storage, and for grid-stabilisation functions, but at the time of writing were
too expensive for anything but very short-term storage in the power grid.
- Hot water can be used in a domestic and some commercial situations.
Rather than exporting domestic solar power at very low prices it can be
useful to use the electricity to heat water for later use.
Similarly, in commercial situations, when electricity is plentiful and its
wholesale price is low, it can be used to heat water.
Storing hot water for periods of hours to a few days is relatively cheap.
- Biomass can be stored for long periods and burned to generate
when it is needed, but the capital cost of building enough biomass power
stations to fill-in for wind and solar would be enormous, and the amount of
biomass that can be grown is small in terms of total electricity demand.
- Huge amounts of energy could be stored as hydrogen gas long-term
in geological formations, and hydrogen could be burned to generate electricity
in existing gas-fired power stations with only slight modifications.
At the time of writing conversion of water into hydrogen and oxygen powered by electricity was expensive, but the cost was decreasing.
Increased amounts of renewable energy in a power grid create challenges
that must be met with innovative responses.
Roof-top solar power is, by its nature, widely distributed rather than having
the centralisation of conventional power stations.
Renewables do not provide the ancillary services such as voltage and frequency
stabilisation that comes with conventional generation.
Demand-side management, for one thing, is needed to help handle the variable nature of renewable energy generation.
This involves adjusting retail electricity prices dynamically as the amount of
power in the grid changes so that consumers can modify their times of
electricity use to better match consumption with generation.
DTU International Energy Report 2015.
Nuclear power has little roll to play in the transition to sustainable energy.
I have written on the
of nuclear power on another page on this site.