As I said before, why waste your time on it?  If people don't understand an issue, they'll believe what they want to.

Even for those who don't understand the serious implications of Climate Change will understand that we''re going to run short of fossil fuel.

Either way, the answer is the same - renewable energy. You'd have to question the motivation of anybody who was against clean renewable energy.

Quote:

You'd have to question the motivation of anybody who was against clean renewable energy.

You could imagine the implications if people are one day able to produce enough energy from their own homes to not only power their household needs, but also their vehicles or a mode of transport as well.

I don't see any problem with debating the GW issue as long as the responsible course of action is being taken in the mean time. The problem is, that it gives people a reason to reject change.

We're only beginning to scratch the surface as far as domestic energy generation is concerned. When we had our new solar hot water installed about  5 years ago, it produced piping hot water after an hour or two of sunshine. Just imagine how much spare capacity there must be in all the solar hot water systems around Australia put together, and what it could be used for.

Imagine a retrofitted secondary heat exchanger that draws energy from the hot water tank so that the solar heater works for the full day. The energy is used to drive a domestic ducted airconditioning unit using a small gas turbine (direct drive - no electricity is generated. If you generate electricity, losses become too high).

Well, I didn't tell you what's in the secondary heat exchanger, or what pressure it runs at.  ;)  

Think of how much energy it would save.  15kWhr per day during the summer months would be my estimate for the tropics.  That's more than enough for airconditioning. Design the house a bit better and you would use a small fraction of that.

Why does everyone seem to assume that decentralisation is inherently more efficient or better for the environment?

freediver wrote on Nov 6^th, 2008 at 4:11pm:

Why does everyone seem to assume that decentralisation is inherently more efficient or better for the environment?

Er... because the environment is decentralised?

Is that a joke?

Which one? The question or the answer?

freediver wrote on Nov 6^th, 2008 at 4:11pm:

Why does everyone seem to assume that decentralisation is inherently more efficient or better for the environment?

I didn't actually assume that at all, and I agree that centralised power production is by far the most efficient.

I was just pointing out a possible opportunity that happens to be decentralised. In that case, it's a neat solution that doesn't require electricity.

Mine is a pilot installation. The biggest potential for solar air conditioning is in large buildings, using a Lithium Bromide absorption cycle system.

Do you know what the payback time (even without environmental accounting) can be for solar hot water alone? Add that extra feature of aircon and you can potentially have payback within 6 months to a year, depending on consumption. It's a no brainer.

http://www.solarpanelsplus.com/yazaki-solar-HVAC/

Solar hot water makes sense, because there is limited conversion of the heat between various forms. It goes from radiant energy to thermal energy. Solar electric does not make sense, especially in a decentralised scenario. That's why the government rebates for solar panels are a bad idea.

A big reason why people are experimenting with their own decentralised systems is the inertia of the Electricity producers. I don't know what the situation is in your State, but here we can only buy 10% clean energy. Even if I wanted to increase that to 20%, the Electricity company can't do that.

Some people in remote areas are already going it alone with solar PV systems, and the cost of installation is about the same as connecting to the grid. Following Cyclone Larry in Innisfail, it took forever to get new houses connected, and quite a few people installed solar as a result.  

freediver wrote on Nov 7^th, 2008 at 11:57am:

Solar hot water makes sense, because there is limited conversion of the heat between various forms. It goes from radiant energy to thermal energy.

Conversion efficiencies are almost as high with Solar Air conditioning - and the solar energy comes just when you need it.

For solar heating it would be. You just install a window. I'm not sure how solar cooling could work anywhere near as well.

muso : -  
Quote:

Do you know what the payback time (even without environmental accounting) can be for solar hot water alone? Add that extra feature of aircon and you can potentially have payback within 6 months to a year, depending on consumption. It's a no brainer. http://www.solarpanelsplus.com/yazaki-solar-HVAC/

really ! That's amazing.
In all likelihood I will be having to get a new hot water system in 5 years or so, will be researching for that sort of system for sure.

thanks

Retrofitting them can be expensive.

freediver wrote on Nov 7^th, 2008 at 1:25pm:

Retrofitting them can be expensive.

You don't even have to retrofit them. All you need is hot water.

huh?

Well for starters, take a look at the link that explains how the cooler works. All you need is a hot water supply.

The absorption cycle is driven by a thermal transfer fluid (hot water or glycol mixture) at 158 o F to 203 o F from solar thermal energy or other heat source and the condenser is cooled through a cooling tower. ....

The Yazaki absorption chiller or chiller-heater uses a solution of lithium bromide and water, under a vacuum, as the working fluid. Water is the refrigerant and lithium bromide, a nontoxic salt, is the absorbent. Refrigerant, liberated by heat from the solution, produces a refrigerating effect in the evaporator when cooling water is circulated through the condenser and absorber.

These are commercially built units. Now these actually use some electricity, but there is no theoretical need to do so. As it works by a thermal exchange system, efficiencies as high as 97% can be achieved.

By the way Sprint - the link shows a solar cooling system not solar hot water, but I'd still recommend solar hot water, especially if you have daughters or gf's staying over (when they get older).

Here's another excellent link to the topic of solar cooling:

http://www.climatemanagers.com/index.php?option=com_content&task=view&id=74&Itemid=34

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As it works by a thermal exchange system, efficiencies as high as 97% can be achieved.

97% of what?

Did you notice the scheme has a cooling water supply? So people would either have to leave the hose running constantly, or have a small lake in the backyard to act as a heat sink. It basically takes a convoluted, expensive way to cool your house and makes it even more convoluted by powering it from the sun instead of electricity. A simple evaporative cooler would use less water, less dangerous chemicals and cost a tiny fraction of this cumbersome machine.


muso wrote on Nov 7^th, 2008 at 1:28pm:

freediver wrote on Nov 7th, 2008 at 1:25pm: Retrofitting them can be expensive. You don't even have to retrofit them. All you need is hot water.

Do you know what retrofitting means?

freediver wrote on Nov 7^th, 2008 at 2:35pm:

As it works by a thermal exchange system, efficiencies as high as 97% can be achieved. 97% of what? Did you notice the scheme has a cooling water supply? So people would either have to leave the hose running constantly, or have a small lake in the backyard to act as a heat sink. It basically takes a convoluted, expensive way to cool your house and makes it even more convoluted by powering it from the sun instead of electricity. A simple evaporative cooler would use less water, less dangerous chemicals and cost a tiny fraction of this cumbersome machine. muso wrote on Nov 7th, 2008 at 1:28pm: freediver wrote on Nov 7th, 2008 at 1:25pm: Retrofitting them can be expensive. You don't even have to retrofit them. All you need is hot water. Do you know what retrofitting means?

Feeding from a hot water tap would hardly count as retrofitting, although you'd need to feed the water back into the hot water system. For a gravity fed system, that's hardly a big deal.

The pictured unit is a large scale solar cooler designed for an office block or a warehouse. It can be used in reverse cycle mode to work as a heater during the winter months.  Units like that have been installed all over Europe, and they don't use anything like as much water as an evaporative cooling system, because the cooling tower is tiny by comparison in this unit.  

Of course the ideal situation is passive heating/ cooling systems, which just require a smarter building design, but this unit works well in older buildings.

Feeding from a hot water tap would hardly count as retrofitting, although you'd need to feed the water back into the hot water system. For a gravity fed system, that's hardly a big deal.

I'm talking about retrofitting the solar collector to an existing roof. It is expensive. I have no idea what you are going on about.

What I mean is that if you have an existing solar hot water system, it's relatively easy to use the heat from the hot water (the excess capacity) to power a solar cooler in a domestic situation. (No extra solar collector required.)

You can either use electricity to pump the water around the coils, or use a direct gas turbine arrangement with no electricity required.

There are of course other possibilities, such as a heat pump for colder climates.

"There is no escape"

S = k_B ln Omega

Entropy. The science of little stitches keeping big wounds closed.

tallowood wrote on Nov 10^th, 2008 at 10:07pm:

"There is no escape" S = kB ln Omega Entropy. The science of little stitches keeping big wounds closed.

Unless of course humans will break out of boundary of the close system.

Outside of the square  8-)

Mate, there is nothing controversial about Solar Cooling. Energy is conserved. We're not reinventing physics. You can reduce entropy by consuming energy. All refrigerators do that using electrical energy. In this case, the source of that energy is the sun. Many commercial units have been installed throughout Europe.

As far as this 'perpetual motion engine' is concerned, I'd like to know where it draws its energy from :)

Can you give some references about their use in Europe?

freediver wrote on Nov 14^th, 2008 at 6:02pm:

Can you give some references about their use in Europe?

Sure:

http://cat.inist.fr/?aModele=afficheN&cpsidt=3304132

http://www.sciencedaily.com/releases/2008/07/080714151427.htm

Pdf:

http://www.eurac.edu/NR/rdonlyres/E7869E44-95BB-4422-87C0-77E193248DBE/0/EuropeanSCinstallations_abstract_Eurac_Wien08.pdf

muso wrote on Nov 14^th, 2008 at 5:55pm:

Mate, there is nothing controversial about Solar Cooling. Energy is conserved. We're not reinventing physics. You can reduce entropy by consuming energy. All refrigerators do that using electrical energy. In this case, the source of that energy is the sun. Many commercial units have been installed throughout Europe. As far as this 'perpetual motion engine' is concerned, I'd like to know where it draws its energy from :)

There was nothing controversial about diverting rivers flow and using irrigation till we reached boundary of limitation. The same will eventually happen with solar energy.
Fridges don't reduce entropy in environment only within own walls but extra energy dissipates outside increasing temperature around them. Harnessing solar will mean not consuming the energy but redirecting it and changing its form but doing so more energy will be consumed then saved. None of human build devices are 100% or more thermodynamic efficient.

However with all that if efficiency can be increase from say 90% to 91% it is worth doing providing that generation of energy and it's usage don't produce harmful wastes. In this way solar is preferable to burning carbon or to nuclear.

tallowood wrote on Nov 14^th, 2008 at 8:44pm:

There was nothing controversial about diverting rivers flow and using irrigation till we reached boundary of limitation. The same will eventually happen with solar energy. Fridges don't reduce entropy in environment only within own walls but extra energy dissipates outside increasing temperature around them. Harnessing solar will mean not consuming the energy but redirecting it and changing its form but doing so more energy will be consumed then saved. None of human build devices are 100% or more thermodynamic efficient. However with all that if efficiency can be increase from say 90% to 91% it is worth doing providing that generation of energy and it's usage don't produce harmful wastes. In this way solar is preferable to burning carbon or to nuclear.

Re your comments on Fridges, yeah it's always a local effect. I understand the Laws of Thermodynamics.

All refrigerative cooling diverts heat outside. In the scheme of things, that's not a big problem. As I'm sure you're aware, the greenhouse effect is all about increased solar heating of the planet, and this extra heat captured from the sun makes all other heat sources look insignificant by comparison.

As far as your comments on harmful wastes are concerned, tell me more. Full Life Cycle Analysis has already been carried out on these devices. It's an EU requirement for any renewable energy devices that are used as carbon offsets.

The efficiency is actually much higher than electrically powered refrigeration systems, especially if you take into account transmission and generation losses, electric motor efficiency losses etc.

Solar Cooling is a no-brainer in cases where passive cooling is not practicable - in other words existing buildings that can't be redesigned.

The only reason it hasn't been adopted in Australia yet is that we're a little behind the 8-ball in adopting it. However in terms of passive cooling and building design concepts, we're actually world leaders. We export the technology.

The heat generated by burning fossil fuels (eg to run refridgerators) does not have a detectable impact on global temperature. It is the impact of the gasses released during the burning that is significant, as they hang around for a century or more and prevent the heat from the sun from radiating back out into space.

freediver wrote on Nov 15^th, 2008 at 12:40pm:

The heat generated by burning fossil fuels (eg to run refridgerators) does not have a detectable impact on global temperature. It is the impact of the gasses released during the burning that is significant, as they hang around for a century or more and prevent the heat from the sun from radiating back out into space.

Yes, thank you. I probably explained that badly in my second paragraph, but that's it in a nutshell.