Bazz
It is worth repeating that the main sources of renewable energy are hydro, wind, biomass, solar thermal, and solar PV . Hydro and biomass can produce power on demand, solar thermal can produce power 24 hours straight (using heat storage), wind can be stored using hydro pump storage and all can be stored using large scale batteries. It is simply a mistake to think that any one source is going to produce all our power. The combination of wind along the coast and solar thermal on the inland side of the Great Divide, could actually supply a high proportion of our power needs, also it is fairly typical of our weather systems, that when the wind does not blow we have clear skys. On the few occasions when both wind and solar are insufficient, we then have the option of hydro, biomass, and storage. Technically it is not a problem to achieve 100% renewable electricity for Australia, the only questions are how quickly we wish to get there and over what period do we wish to make for the transition.

There is good data available for hours of sunshine and wind speeds for many parts of Australia.

http://www.bom.gov.au/climate/averages/tables/cw_086282.shtml

Despite adequate wind speeds at this location there might be a problem with large birds.

http://www.bom.gov.au/climate/data/index.shtml

I am not a fan of the ERoEI concept as it is being used to prove anything you like, by those who wish to push a political agenda, as far as I can tell the ERoEI of wind is better than most of the other sources of power.

There is a problem with hydro in Australia in that it rquires lots and lots
of bulldozer work to build the dams, if the greenies will allow them
to be built. Question; is our rainfall adequate anyway ?
You cannot ignore ERoEI, it is a numerical measure of overall performance
and is only criticised by those who find it rules out their favourite
system that they have been pushing for ages.
It was indeed the cause of the fall of the Roman Empire !

If it uses as much or more energy to produce its output, whats the point ?

True wind is the best of the renewables, it does in fact exceed the
minimum viable figure of 7, just, from figures I have seen.
The problem that arises is that the ERoEI falls greatly when backup
is provided, and you will always need backup.

Biomass, don't know much about that, only figure I saw was that to
fuel Europe ponds the size of Ireland were needed, but Rhosty told me
about a continous flow system to produce diesel.

Solar thermal; the one plant in Spain went broke which suggests that
its ERoEI was not good enough. That of course is the ultimate measure
as if it cannot sustain itself it is not producing enough output
for its input, (costs).

You said;
Technically it is not a problem to achieve 100% renewable electricity for Australia,

Oh yes ? That is indeed a brave statement, why has no country even
got near it ?

Have I misunderstood the graph you sent ?
45 clear days in a year around Melbourne ?
Well Victoria will need a lot of candles !
I admit it agrees with my experience of Melbourne, they don't call
it bleak city for nothing !

Bazz
Biomass in this case simply means waste usually from agriculture and forestry that can be burnt, it actually accounts for a considerable amount of power generation in Europe. It is also possible to grow wood solely for the purpose of power generation which at least in theory is carbon neutral. There is no reason why we could not harvest some of the fuel that goes up in smoke during controlled burns. We do not need more hydo to cover the short fall, we have enough especially if we use other renewables to pump the water back up to the dams, also it is possible to add some small scale hydro as in stream flow units.

Solar thermal is proven Technology there are numerous examples world wide, the price is coming down, but has a bit to go before it can compete on equal terms with coal.

There are several in Spain (12?) I don't know of any that went broke.

http://en.wikipedia.org/wiki/Extresol_Solar_Power_Station
http://en.wikipedia.org/wiki/List_of_solar_thermal_power_stations

Wind is a lot more reliable than people realize, the wind farms at point Grim in Tasmania only loses a handful of days a year due to lack of wind, in fact they lose more days due to excessive wind. I notice a number people are confused about the meaning of capacity when it comes to wind, typical figures of around 1/3 are quoted for wind. It does not mean that the only produce power only 1/3 of the time it means that on average the produce 1/3 or more of their rated power most of the time.

There are some 12 countries in the world that generate more 98% of their power from renewables.

The Romans used water power, wind power and horse power I don't believe that ERoEI had anything to do with their demise.

http://www.history.com/news/history-lists/8-reasons-why-rome-fell

"Technically it is not a problem to achieve 100% renewable electricity for Australia, the only questions are how quickly we wish to get there and over what period do we wish to make for the transition."

You're absolutely right, not a problem at all!

We'll dig holes to make mountains wherever there are none. When it rains we capture the water for hydro. And, when it comes downhill, we'll pump it up again!

Yeah, and anothery.....we subsidize ourselves cheaply into wind/solar with enough batteries to get us through the night (I can already hear the ad campaign jingle!), then burn trees we plant and harvest for longer periods of windless darkness.

Then there's solar thermal. Just harvest the potential (a la smell the two-stroke)!

Of course EROEI is of no consequence to these plans because none of them costs money or energy. It's all free, free from the sun and air, enough for all!

You nuke people don't get physics.

Warmair, right on que Gail Tvberg publishes an article on the subject
of our discussion.

http://www.resilience.org/stories/2015-08-11/how-economic-growth-fails

Section 9 refers directly to the subject of our discussion.

You said;
if we use other renewables to pump the water back up to the dams,

Here ERoEI raises its head again, the energy needed to build the
storage at the bottom of the race, remember it has to involve a
massive earth moving project, the loss in the generating turbines
and the losses in the pump motors are all subtracted from the output.
As I said providing backup always means a large reduction in efficiency ie ERoEI.

You mention biomass and obtaining trees from forestry etc.

When you say things like that I suspect you have no understanding of
the scale of the problem. Think about all the effort required to get
the trees to the power station and it would all be gone in 10 minutes.

I find these discussions would be very much assisted by a visit to
a power station, it might give you an idea of the scale involved.

Aidan,

Sorry, but the unreliability of any supply is exactly the reason that networks become unstable. IF demand too closely approaches available supply, or exceeds it parts of the network start dropping out of sync, protection systems try to compensate and network outages cascade, and it takes hours to bring the network back.

As stated before, blackouts and brownouts have quadrupled in Germany over the past decade.

Warmair,

We don't have the hydro capacity, nor the biomass that can supply more than about 6% of peak demand, and battery storage of anywhere near that capacity is not likely to be technically possible for many decades.

All of the renewable generation is going to cost a fortune to replace existing generation, which is essentially paid by a tax on electricity.