A chilling future for solar power
Everyone seems pretty comfortable with the idea that the energy from the sun can be captured to heat stuff and create electricity. But what if we were able to use it to address one of Australia’s greatest needs: how to cool things down, particularly the air inside your home; and one of its greatest challenges – reducing peak loads on the network?
This is one of the ideas being developed by the CSIRO at its Energy Research Centre in Newcastle. And the technology – known as Solar Cooling – is now at the point of commercialisation. And it is so simple it can be bolted on to the solar hot water systems that are already so prevalent in suburbia – and add space heating in winter and cooling in summer to the hot water that is already delivered by the solar collectors.
The irony of this development is that it offers the opportunity for a renewable energy source to provide a solution for a problem it is often blamed for creating – rising electricity costs.
The reality is that the greatest component of rising energy bills is the cost of network upgrades, and the biggest reason for these is the growth in peak energy demand, driven largely by the rush to install household air conditioning systems, which now account for around 50 per cent of peak demand on some networks.
Indeed, such is the scale of the rollout of domestic air-con, and its impact on networks, that it now qualifies as the most heavily subsidised sector of the electricity grid – far greater than rooftop solar, or large-scale wind farms.
For every $1000 invested in an air-conditioning system, it is estimated that another $3000 is required to upgrade the network. That translates into an added cost of $100 per year on the electricity bills of those who either choose not to have air-con in their home, or who can’t afford it.
Reducing peak demand is one of the biggest challenges facing energy market operators. In Australia, it is estimated that one quarter of the nation’s electricity costs go to catering for around 40 hours of peak demand – those occasions of extreme temperatures when everyone turns on their air-con at the same time and when the electricity demand is nearly doubled. If this technology based around solar panels on the roof can be rolled out at scale, it could offer one of the best opportunities to significantly lower those peak loads and reduce the need to upgrade and expand networks and help flatten the anticipated spikes in domestic electricity bills.
The principle behind Solar Cooling systems being developed by the CSIRO is simply to integrate technologies that are already understood – the rooftop panels on the roof that heat the water, and which can then be used to heat air; a desiccant wheel to dry the air; and evaporative systems to cool the air.
Stephen White, the manager of the CSIRO’s Energy for Buildings division, says the advantage of this system is that it can operate at relatively low temperatures – 50°C to 70°C – which are common for solar hot water systems.
Incoming hot, moist, humid air is dehumidified using a desiccant such as a silica gel on a rotating wheel to create a dry air stream which is then cooled using an evaporative cooler. The desiccant absorbs the moisture from the air. This material is then stripped of moisture (regenerated) using solar heat.
The CSIRO believes that electricity costs could be reduced by half – and would be a much more efficient use of resources, because the solar collectors would be in use all year round, while a conventional air conditioner system might be in use for just 7 per cent of the time.
“We see it as three in one solar thermal product for the home – a solar hot water system, and space heating in winter, and cooling in summer when the sun is shining the hardest,” Dr White says. “It matches very nicely.” It is likely that these systems will be able to bolt on to already installed solar hot water systems.
The CSIRO has already developed a prototype called REDEcool which can be used in households and is now looking for a manufacturing partner to help refine the design, and the costs, for mass production. Dr White says the capital cost of the system will be more than the $1000 that people pay for the air-con systems they buy from shops, but it should be cheaper than the $4000 network cost.
“We cannot claim we can make it cheaper than $1000,” Dr White says. “But the fact that we are using the heat, can use gas as a back up and so can offer a firm cooling product, means that we can fit under the system cost. If we can capture the system benefits, then we can say we've got a cost effective product.”
Getting agreement on how that value is recognised within the regulatory environment and investment rules for network distributors is a different proposition.
But a Solar Cooling interest group – including 200 members from interested parties such as governments, architects, product suppliers, network operators and utilities – has been created to try and work out how this technology will fit in to the current grid, and how its value will be captured – a question that needs resolving for a number of new technologies and developments including renewables, energy storage, and distributed energy.
White says Solar Cooling systems may qualify for credits under an energy efficiency scheme, but not for renewable energy credits under the current arrangements. He says this is a pity because RECs are more valuable, and the technology is based around the principle of renewable energy displacing coal-fired power.
Dr White says there is a very real chance that this technology can provide a solution to some of the critical network restraints that threaten to plague the supply of electricity in this country – and elsewhere for that matter.
“Out there is an audacious dream: proving that there is an overall system benefit,” he says. “It’s more than just a householder saying ‘I feel green and I’m going to install this renewable product’, this also tackles a major problem.”
Comments on this article
Solar power is the conversion
Solar power is the conversion of sunlight into electricity, either directly using photovoltaics, or indirectly using concentrated solar power. Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaics convert light into electric current using the photoelectric effect. Thanks. Regards, email search
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We already have the answer, thanks to CSIRO!
The solution to the problem is already here; thank to the inventive minds of our CSIRO scientists. The commercial development of Ceramic Fuel Cells is completed and ready to provide an alternative to massive electricity network expansions. I am sure some Government support for this invention during the initial commercialisation phase would be cheaper than to pour money into unproven ideas.
adsorption chillers
great
U think that the reinvention of adsorption chillers (carre 1858) hasnt been used before. ??
for gods sake, how u think carre" got transferred to carrier"
where have u people been sleeping all these years. been used both residentially and commercially for many years
Might as well reinvent the timber fired boiler (carbon neutral remember) in every back yard to produce heat at night to provide ac at night to dehumidify the air. Every household could have a 50 Tonne heat strorage system as well.
cant deny it wouldnt save peal power, so does a capacitor. or battery
A chilling future for solar power
Evacuated tube solar hot water panels overcome the problem in the winter. My unit produces 300 liters of hot water per day even when the outside temperature is only 14 degrees. So long as the sun is shining.
Peak demand points
In response to Lawrence Cummings - the peak usage occurs in summer, which is greater than winter; summer and winter have different load profiles. There are many locations where peak summer load occurs closer to 4pm, but is also fairly high throughout the middle of the day. So this kind of invention can indeed make a substantial contribution to reducing system load. This is a complex area.
One resource is http://www.integral.com.au/wps/wcm/connect/50300580405ac174b244badccb7f5...
cost of network
So the voltage dropped to 200v!
Probably all those air conditioners. That is why money needs to be spent on the network!
Air-con network impacts
A WA office of Energy report in 2004 estimated:
' that an air-conditioner costing around $1000 (around 2 kW input power) could require around $6000 of expenditure on new generation and network infrastructure to enable it to be used whenever required, however rarely that may be.
http://www.energy.wa.gov.au/cproot/603/2759/Air%20conditioning%20paper.pdf
I also recall the BCSE (now CEC) used to make claims on the network cost impact of air-conditioning.
Maybe someone needs to redo the calc and document the assumptions and methodology.
Cost of Network
Where does the cost of $3000 per $1000 come from, sounds like political bulldust to me. Lets not forget that EVERYONE pays the additioanl costs.
The highest peaks this year were on the hottest days, at this time the voltage fell to 200vac so the solar panels dropped out further increasing the load on the generators and the network, what a good idea!!
Evaporate cooling anyone?
All very well pinning hopes of a nation on this, the Csiro are no mugs.
How about the now ubiquitous (on new houses especially) evaporative cooler? Proven, uses stuff all power than refrigerative air con.
The issue I can see with this 'new' application of existing technology is that's it's evaporative ie uses lots of water. Unless that water is somehow recondensed..
Ultracapacitors
It's remarkable the amount that has been spent to cater for peak energy usage. I think they have attacked it from the wrong angle. Electric cars are utilising ultracapacitors to supply the energy loads required for acceleration. We need to use utilise these in our homes too. An ultracapacitor is simply an energy storage device like a battery and although does not store as much energy, can be charged and discharged a million times before degrading. They also discharge at a rapid rate so they can meet the energy needs demanded from an A/C starting and running. By installing these in our homes (an inverter would also be required), the energy companies can supply power at a more constant rate (not having to worry too much about peaks and troughs). Basically the coal turbines can spin a little faster at low peak times to charge the ultracaps in our homes, and in peak times the ultracaps can supply the increase in energy required. With an bank of ultracaps in every home, they would act like a massive buffer for energy companies. This means their peak loads will be reduced and they would even burn less coal as the supply would be more predictable. We are currently very inefficient in the way we generate power, in that we burn more coal than is required to satisfy peak needs, this should be addressed first and formost...
Winter house warming
The summer air con sounds great. However winter warming will be more difficult. Our solar hat water system simply doesn't heat the water past 32 deg C in winter. All my friends have the same problem.
Just as the installer was leaving he said "I've connected the electric heating for rainy days". It took a few days before I realised that if I showered at night, then the off peak heating will take over leaving nothing for the sun to heat in the morning. So turn the electricity off in summer and on in winter. Otherwise you have bought a system and are still using electricity to heat it.
Sure Chill
Once again, as I have pointed out BEFORE in these pages no mention whatsoever of the outstanding (and actually already commercialised) British Sure Chill(TM) technology. Refer:
http://www.surechill.com/
IMHO anyone who starts importing Sure Chill refrigerators and chillers into Australia will make a killing in a true, non-subsidised sustainable technology market.
Can you imagine it, a refrigerator which needs to only be powered-on 9 - 10% of the time!
Wakey, wakey.
Nothing new under the sun
I once worked in a building in Alice Springs which had just such a system (i.e. cooling via solar-heated water) installed when it was built, circa 1982. Apparently it never worked properly, and had long since been replaced by a conventional aircon system by the time I arrived in 2001.
Here's hoping some progress has been made since then, and this isn't a reinvention of a (rather squarish) wheel.
Heat Pumps miss out?
We usually need our A/C in the evenings and at night here on the Gold Coast. How would the system (described above) help when the sun isn't shining? Retrofit a vanadium redox battery perhaps????
The other problem I'd face is my recently installed, very expensive (in terms of savings) hot water heat pump couldn't contrbute. But it would seem that the CSIRO could come up with a similar solution using the heat pumps over-night to provide coolong and de-humdification while providing the next day's hot water..
solar powered airconditioning - keep it simple
There is no need to rush to complicated multipurpose systems. What we need is very basic solar powered airconditioning. For obvious reasons most airconditioning is needed during sunlight hours. It can't be that hard to devise a way of running it easily from solar power. Most people would happily add it to existing systems.. There is a fortune to be made here
A new retrospective solution
Rumour has it that Barry O and the other state premiers are contemplating retrospective legislation to charge all those electricity customers who have air-con a one-off $3000 network fee. This will save those who don't have air-con $100 per year on their bills. However, this may anger the constituency that is using air-con to battle the Anthropogenic Domestic Warming (ADW) problem that has swept the developed and developing world in recent years, and who feel entitled to such subsidisation. Given the science on ADW is not yet settled, Barry might just get the measure up. However, rumour has it Alan Jones is organising a rally in support of ADW and against the proposed retrospective network fee because it just suits him (and Daikin has sponsored him to do so).
Heat of the moment
Lawrence a good point but if the cooling is automatically occurring during the day when the house would normally be heating up, it would reduce the need for air conditioning when the sun goes down.
I'm very interested to see how this pans out.
Hot Water Can take Pressure off Network
Agree with Lawrence's comments re Solar PV, but he has missed the point on this. Solar hot water is more promising because most systems have a storage tank (several hundred litres of it), which means you can choose when to use the stored energy (make chilling when the sun doesn't shine so to speak). Storing energy in hot water is a fraction of the cost of batteries.
Existing storage of hot water through tariffs reduces queensland winter peak demand by around 10% (800 MW) and has been the single most effective demand management measure in the country.
Storing hot water to subsequently turn it into cooling offers even greater potential. Climate control accounts for about 25% of system summer peak demand.
Looking forward to reading more about the CSIRO solution.
Air conditioning! You mean the consumer is responsible again?
Giles, love your articles, and reference them often. I love that you look at the issues with both eyes open. Can you provide more info or background on this statement please?
"For every $1000 invested in an air-conditioning system, it is estimated that another $3000 is required to upgrade the network. That translates into an added cost of $100 per year on .... electricity bills...."
Chilling Future for Solar Power
If the CSIRO cares to check daily load charts they will find out that daily and annual peak residential demand and indeed peak overall demand for electricity occurs around sunset. Consequently, the supply of residential solar energy during peak demand periods is negligible. Nonetheless, the assertion that roof top solar panels reduce the need to build power stations to supply peak demand and the need to build distribution networks to supply residential peak demand is still made.