Thread: energy sources

Originally Posted by Christopha

Looking at wind, apparently a much cheaper install than solar and prettyt good here on the coast

Christopha

I think wind has a part to play and it may well be cheaper, but it is less reliable (I am told that you can only rely on 10% of a wind generator's capacity as overall this is what it will produce.) Wind generators are noisey, an eyesore and take up space. As usual nothing is perfect.

Solar does not produce at night, but there is a technology where heat from the day can be put into salt beds and used to generate steam for the night. This is not at a stage of development where it is viable.

To my mind there will be a long transition period from thermal power to so-called alternative energies. I don't see that it can be any other way. It will be a rocky road too.

Just a parting comment. There is a great deal of hype about gas fired stations, but remember that gas also produces CO2. Not quite as much as the most efficient of coal-fired but still a huge quantity.

Regards
Paul

Problem is people in general have no idea where power comes from... They flick on a switch and see light but make no correlation between that light and how it comes to be..

They seem to be under the delusion that renewables are cheap, plentiful and will work at 100% all day every day regardless of season...

Getting back to the original Straight Dope article for a minute, one wonders why it makes no mention of Solar?

If you look at the current installed PV and solar thermal capacity, it's significant, and growing : List of renewable energy topics by country - Wikipedia, the free encyclopedia

Originally Posted by wikipedia

At the end of 2009, cumulative global photovoltaic (PV) installations surpassed 21 GW[5][6][7] and PV power stations are popular in Germany and Spain.[8] Solar thermal power stations operate in the USA and Spain, and the largest of these is the 354 MW SEGS power plant in the Mojave Desert.[9] The world's largest geothermal power installation is The Geysers in California, with a rated capacity of 750 MW.[10] Brazil has one of the largest renewable energy programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 18 percent of the country's automotive fuel.[11] Ethanol fuel is also widely available in the USA.

Alternative energy is not the complete answer as it sits at the moment and perhaps it never will be, but it has never been given much more than lip service and token support in this country. If we are ever going to have significant alternative energy capacity it will need compelling long term policy space and capital expenditure. All this start/stop solar rebate/FIT nonsense is ridiculous and a perfect example of how not to do it - we still have Australians in one state able to get 60c/kWh and others elsewhere unable to get as much as their marginal kWh cost back for energy exported!

woodbe.

Originally Posted by BEKKY

Bushmiller,
As I understood it from my solar installer if there is no power in the grid system the solar system automatically closes down as a safety measure.
This may or may not be correct.
Regards,
Keith.

Keith

I have made further enquiries.

You are quite right in your asertion and it is there as protection to the solar panels. As you may be aware, electricty canot be stored, but is generated as required, at least in AC form.

Therefore if the grid goes down for any reason the panels have an automatic cutout. However this is an insufficent isolation for maintenance work to proceed. In the old days a physical break was required in the transmission line, but today that is no longer the case. However isolation is still provided by an approved switch and it appears that there is one per house.

Regards
Paul

Originally Posted by woodbe

All this start/stop solar rebate/FIT nonsense is ridiculous and a perfect example of how not to do it - we still have Australians in one state able to get 60c/kWh and others elsewhere unable to get as much as their marginal kWh cost back for energy exported!

woodbe.

Woodbe

Absolutely. There is no continuity in contracts offered and no consistency between states. Mostly it seems like knee-jerk reactions and pure tokenism.

Just bear in mind that the mainstream generators earn for their power between 3c and 4c per kw/hr. We have to ask how long any government is either prepared or even able to pay from 22c up to 60c for solar power.

That is clearly unsustainable.

There was a time when Australia was a world leader in solar technology and nobody could persuade the government to contribute to research. So much of it went offshore.

Regards
Paul

Originally Posted by Bushmiller

if the grid goes down for any reason the panels have an automatic cutout. However this is an insufficent isolation for maintenance work to proceed. In the old days a physical break was required in the transmission line, but today that is no longer the case. However isolation is still provided by an approved switch and it appears that there is one per house.

Regards
Paul

Its not the panels that have the cutout, it's the inverter, and its a requirement for grid connect systems. The inverters have to match voltages with the grid for current to flow, and when the grid drops out, so does the inverter.

If you think about it, the electricity authorities would be pretty silly not to require effective isolation for the reasons you state.

There is also a requirement for isolation switches on the installation, near the panels - these isolate the panels from the inverter and would be used in home emergencies like fires, floods, etc.

Originally Posted by bushmiller

Just bear in mind that the mainstream generators earn for their power between 3c and 4c per kw/hr. We have to ask how long any government is either prepared or even able to pay from 22c up to 60c for solar power.

Yes. Except that the FIT is paid at retail, not at the generator. Also, most of the state governments aren't subsidising the FIT at all, they are just allowing it to happen within the power pricing structure - all the solar FIT is paid for by power consumers. I _think_ WA is different, but not sure.

The price we pay for power is broken up between generator cost, transmission cost, losses cost between generator and consumer, and retailer margins. With Solar exports from a domestic installation, the transmission costs and losses are very small as the power is delivered very close to where it is consumed (next door, probably) As I understand it, Transmission costs lead the pack, followed by retail margins, then generation costs and then transmission losses.

So, exported PV power is equivalent to generated power + transmission costs and losses. I don't care for the retailers, happy to cut out the middle man - that should make it worth at least 16c/kWh even before we add in a margin for green power.

woodbe.

Originally Posted by woodbe

The price we pay for power is broken up between generator cost, transmission cost, losses cost between generator and consumer, and retailer margins. With Solar exports from a domestic installation, the transmission costs and losses are very small as the power is delivered very close to where it is consumed (next door, probably) As I understand it, Transmission costs lead the pack, followed by retail margins, then generation costs and then transmission losses.


woodbe.

Woodbe

I think you are right on the money with the split in costs. The problem is that the existing infrastructure has to be paid for (by consumers) on a continuing basis. The electricity retailers (Ergon, Origin, Energex etc) administer this side of the equation. Transmission lines, maintenance, substations, transformers and all the other trappings of electrical generation will not change significantly whilever you are connected to the grid and it is the grid that provides stability and continuity of supply.

PV solar power still does not perform when the sun goes down and indeed on cloudy days it is less efficient. We may not complain if the fridge heats and the food goes off, but what if the beer gets warm?.

Regards
Paul

Originally Posted by Bushmiller

PV solar power still does not perform when the sun goes down and indeed on cloudy days it is less efficient. We may not complain if the fridge heats and the food goes off, but what if the beer gets warm?.

To keep beer cool, all you need is a chest freezer modified to run at fridge temp (4C) Even winter daytime only solar would keep that cool 24/7. Chest freezers don't lose all their stored cold air every time you open them like a normal fridge, and they generally have better insulation as well...

Next question?

PV systems use the grid as a battery. We pump power into the grid during the day and suck it back at night.

woodbe

Originally Posted by woodbe

PV systems use the grid as a battery. We pump power into the grid during the day and suck it back at night.

woodbe

woodbe

You may have taken my facetious comment a little too literally.

In a way you have answered my next question with the statement above. To import electricity at night or indeed any other time your demand exceeds the capacity of your solar system, you need the existing infrastructure.

That is why you are not going to see a reduction in your electricity tarrif. In fact it is going to go up as a result of the push for renewable energy, but probably nowhere near as much as the scaremongerers would have you believe.

Regards
Paul

Paul,

What can I say, I'm a very literal kind of guy.

I agree that we will not see a reduction in energy tariffs. Apart from wanting to do something about our carbon footprint, this was the main reason we installed PV at home: to drive a truck through our power bills.

All I can say is that it's working.

Really, the only way to see a complete and permanent reduction is to disconnect, but this would be very expensive and probably the natives would get extremely nervous.

woodbe.

Hi Bushmiller,
I'm not very far away from you, and our 1.5kw grid feed system does seem to work.

We installed it during the last billing cycle, so it hasn't run the full 3 months - even so we consumed $190 of Ergon's power and exported $120 of solar power.

In Queensland the feed in tariff is 44c while the consumer tariff 11 is 19.41c - this means that a kwh sent out is worth twice as much as a kwh consumed. With politicians in charge this could change at any time...

So it's not just replacing Ergon's power with solar - there's a factor of 2 in the pricing.

The other thing is to get cunning about when you use your power - try to limit daytime consumption. If you run (say) the washing machine on a sunny day, then first it will try to draw power from the inverter - then if more power is needed then the balance comes from the grid. So power you would have sold for 44c is getting consumed by your washing machine. But if you run the washing machine at night, then it will draw all it's power from the grid at 19.41c - and during the day the solar will export all it's power at 44c - so you are making more from the solar in this scenario.

Regarding the earlier comments about using DIY panels. With a grid feed system the solar panels are connected in series, so they are not low voltage any more - ours puts out up to 380VDC - needs to be treated with care. Another thing is that the home builder can't get the same weather seal around the cells that the store bought ones have - so DIY panels are not likely to last as long as commercial ones.

Cheers, Bob.

Originally Posted by woodbe

Paul,

What can I say, I'm a very literal kind of guy.

I agree that we will not see a reduction in energy tariffs. Apart from wanting to do something about our carbon footprint, this was the main reason we installed PV at home: to drive a truck through our power bills.

All I can say is that it's working.

Really, the only way to see a complete and permanent reduction is to disconnect, but this would be very expensive and probably the natives would get extremely nervous.

woodbe.

woodbe

I am with you in principle and I have to say you have done something about it as opposed to just talking about it and theorising like me.

I am afraid my practical side comes into play and my brain overrules my heart. I still believe in solar power and I hope to see the day when it reaches greater than 50% of power we produce.

Regards
Paul

Citybook

It's good to see you on the forums Bob: Welcome.

I understand the way you are managing your electrical useage and it is exactly the way to go. In fact these systems particularly suit households where nobody is at home during the day. Actually if you grab one of woodbe's chest freezers, you can probably reduce your weekday daytime consumtion to zero.

True words spoken in jest there.

Regards
Paul

http://www.ted.com/talks/lang/eng/steven_cowley_fusion_is_energy_s_future.html

this is a talk by one of the people that knows what he is talking about and what the state of nuclear power actually is.