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ReNew 118 highlights
A pool to tank conversion, plus a solar wall!
With the pool water evaporating each dry, hot summer, and an ineffective northern wall, one homeowner converted both to be water and energy saving assets. Ken Self shares his story with ReNew.
Returning to Australia after six years in the UK, we were faced with an energy and water saving challenge, namely our 1950s house in the north-eastern suburbs of Melbourne. It was 2007 in the midst of a drought with tight water restrictions in place. The in-ground swimming pool was losing so much water through evaporation that we couldn’t keep the filter pump operating.
READ MORE »Water loss was temporarily fixed by connecting a downpipe diverter to send rainwater to the pool. A 5000 litre water tank was installed so we could keep the garden alive despite water restrictions.
Other small retrofits, such as fixing the dilapidated ceiling insulation and adding reflective foil in the ceiling to deflect the summer sun, helped a little with thermal comfort and efficiency, as did dismantling one of the two hot water systems (the old electric one in favour of the newer gas model).
The tanks filled slowly as there was little rainfall. The pool stayed unused and the summers were still hot and the winters cold. Removing the old electric hot water system halved our electricity usage, but most of that was taken up by gas usage.
Our efforts had been ad-hoc; to really make a difference we needed to invest more wisely.
Thoroughly tested
Before launching into renovations we tested the house from high to low to find its thermal weak points.
We estimated the R-value of all the external surfaces of the house such as ceiling, walls, windows, floor, and the area of each, to work out how much energy, in kilowatt-hours, was flowing out of the house per degree of temperature per hour, day or year. We also estimated how much energy was captured from the sun through windows. We studied passive heating and cooling and were particularly interested in the Passivhaus standard from Europe and the concept of thermal comfort.
Our measurements, using the concept of ‘heating degree days’ and ‘cooling degree days’, showed that more energy was going into keeping the house warm in winter. A heating degree day measures how much heating (in kWh) is needed to maintain a desired temperature, in Melbourne say 20°C.
Read the full article in ReNew 118
Building back after bushfires and floods
Progress has been slow after the 2009 Black Saturday bushfires, yet some people are now living in new homes built to higher standards, often with renewable energy systems designed to provide more backup in an emergency. This article is part of a sustainable rebuilds special in ReNew 118.
Left with just one shed standing after the Black Saturday bushfires destroyed their home, a year later Scottish couple Janet and Scott McLean installed a 2.1kW solar power system on its roof and called the shed home while their new improved dwelling was being built.
READ MORE »The grid-interactive system was installed with future fires in mind, with a battery backup to ensure electricity supply during a blackout. The system now fulfils most of their energy needs in the new house, although the true status of their bill, and usage, remains a mystery due to Tru Energy’s long billing delays.
The improvements don’t stop there, with the entire rebuild showing a greater resilience to future bushfires with the bonus of improved energy efficiency.
Learning from the past
The old home was a single-storey brick veneer with a W-roof profile that Janet describes as a perfect ember trap, single-glazing to the west and was like an oven inside in summer. “We had a big wooden deck which probably went up in flames quite nicely. We knew it was a risk but we were a bit naïve perhaps and didn’t think a fire would come through, or that it would be that severe.”
After losing everything it was difficult to know where to start with rebuilding. Two things helped shape their rebuild though: a meeting with architect Ian Weir and visiting open days at other sustainable homes.
They’d first seen Ian on television and discovered that he offered free consultations to people affected by the Black Saturday bushfires. His advice was to keep the building shape as simple as possible with few nooks and crannies to limit the places for embers to gather.
Visiting a house in Healesville, Janet grew to love a unique construction duo of rammed earth and scyon, a thick but lightweight cement composite cladding which looks just like weatherboard. “The house felt solid and inside it felt grounded and safe.” The couple engaged the designer of that house for their rebuild, heeding Ian Weir’s advice to simplify the shape and opting for a flat, slightly angled roof profile that the embers would slide off. After all, the roof had been a weakness in the old house.
Read the full article in ReNew 118
Bushfire zone windows and doors
A recent community workshop helped demystify window requirements in bushfire prone areas, writes Anna Cumming. Listen to the full workshop at www.ata.org.au/bushfire.
Its communities hit by Victoria’s Black Saturday bushfires in 2009, the Strathewen & St Andrews Sustainable Rebuilding Project recently held the first in a series of workshops designed to help those rebuilding homes and businesses to do it as energy efficiently as possible.
READ MORE »On the topic of windows and glazed doors, the workshop covered design considerations that can have a big impact on the passive thermal performance and energy efficiency of the house, including size, orientation, frame and glazing type and shading. It also addressed the extra issues that need to be considered when building in a bushfire prone area and looked at some windows, frames and shutters rated for use in the higher Bushfire Attack Level (BAL) zones.
Here’s an overview of the workshop’s main points on glazing in high BAL zones below. Listen to the full, highly informative presentations on the ATA website at www.ata.org.au/bushfire.
BAL zones
A home site’s Bushfire Attack Level (BAL) is determined by a number of factors including the area’s Fire Danger Index (a measure of the probability of a fire starting), the type of vegetation and its distance from the house, and the slope of the land. The recently introduced new building regulations impose more stringent requirements on design and materials as the site’s BAL increases; for the top two levels, BAL-40 and BAL-FZ (Flame Zone), these are aimed at protecting the house from ember attack, a fairly to very high likelihood of direct flame contact and radiant heat up to 40 kilowatts per square metre (for BAL-40) or even hotter.
Requirements for windows in high BAL zones
The requirements for lower BAL zones specify various combinations of frame material, toughened glass or double glazing, and steel or bronze mesh screens to openable windows to prevent ember attack. In BAL-40 and BAL-FZ zones, however, the requirements are stricter.
Cyclone resistant in the tropics
This tropical rainforest retreat, first featured in ReNew 95, has since survived two Category 5 cyclones. Owner builder Paul Michna explains why the structure holds up so well.
In 2006 we introduced ReNew readers to our Shipping Container Retreat in Far North Queensland (A shipping container retreat in the wettest place in Australia, ReNew 95). In the original article I wrote that we needed “a facility suitable for accommodation and rainforest research in a challenging environment.” Well, the challenges came early, with the eye of Cyclone Larry passing over our retreat the month that article was published. And in 2011 the northern side of Cyclone Yasi paid a visit. Here’s what happened and the reasons why the retreat survived so well.
READ MORE »The retreat consists of two 3m by 6m shipping containers set three metres apart, elevated and bolted on posts. The posts are 200mm PVC pipes, strengthened with a filling of concrete and steel. The two containers are joined at both floor and roof level with C-section and timber decking. Each of the containers has a door cut in the interior large wall, and a sliding picture window with external screens cut into the exterior large wall. A length of steel is bolted above each window to provide additional roof support.
Ready for Larry
Before Cyclone Larry and its winds in excess of 200km/h, we erected three light-duty single car steel and vinyl carports. The carports hung out a short distance over the sides of the containers to reduce the amount of rain blowing in the windows and we collected water from them into a 2000L plastic rainwater tank. The steel corner posts of the carports were screwed into structural timber which in turn was chained to the corner lifting assemblies of the shipping containers.
After Cyclone Larry the rainforest resembled a war scene, with trees up to about 1.5m diameter snapped off metres above the ground. The carports were totally destroyed but they helped to protect the main structure. The overhanging carport sides prevented large branches from taking out the windows and the external insect screens also had a role in deflecting flying debris. About three tonnes of vegetation, mostly very large branches, was removed from the tops of the containers. Some of these heavy branches came from trees over 100 metres away!
We replaced the vinyl carports with a double-car-sized steel Shadeshed, and connected the guttering from this structure to our rainwater tank. With an average of 4400mm of rain per year we only need to use half of the roof as a rainwater collector. Eyebolts, chain and turnbuckles secured the shed to the corners of the containers. The replacement roof was a bit narrower so we used timber recovered after Cyclone Larry and some secondhand vinyl tarps to protect the windows from rain.
Read the full article in ReNew 118Letters
Saving money using solar
We have installed a 1.5kWh system at our home which was purchased through our local sustainablity group for $2500 (after rebate) and are finally receiving a 60c p/kwh feed-in tariff from our supplier. We also have a stand-alone system connected to our shed.
READ MORE »We wash our clothes at night when the rate’s at 20c per kilowatt-hour, we don’t have a dryer so use the clothes line or, if it’s wet, the clothes horse in front of the fire. We turn everything off at the power point (including microwave) except the fridge and freezer. We don’t usually have the TV on until after 6pm, unless babysitting, but usually have the radio on.
We also power whatever we can using 12 volts from the stand-alone system. This includes 12 volt hand drills (converted cordless drills), fluoros over workbenches, charging cordless phones, charging cordless headphones, charging our Coleman camping lamp, running the CD/tuner, two 12 volt LED downlights and the media player and hard drive (they have voltage regulators built in and will operate from 11.8 to 14.5 volts). We also have a 12 volt to USB adaptor, with various leads to charge ipods and mobile phones.
I have also run a 12 volt feed from the batteries to our patio which powers our patio lights (I’ve removed the transformer) and a CD/tuner, which was a freebie from a mate. We also have a 12 volt pump for watering the garden.
My wife has finally sorted out all the paperwork with our supplier, after they buggered up the last couple of bills, so soon we will be able to see how much we are really saving.
Lee Saville
Panel orientation makes a difference!
I suspect a lot of people overestimate solar PV output for east and west facing panels. I recently recorded some figures when I stayed with friends near Coonabarabran in NSW (latitude 31°S).
On the property are two systems. Both have the same monocrystalline panels, with six panels in each system and no shading from buildings or trees. One system faces north with a 30° panel tilt and the other faces east with the same tilt. Both were connected to the grid in July 2011.
In 72 days, the north-facing panels produced 427kWh while the east-facing panels produced 310kWh, so the output from the east-facing panels was around 27% less.
I plan to compare the figures after they have been feeding into the grid for one year.
Ashley Campbell
Getting the units right
As a subscriber of a few years now, I’d like to congratulate you on the continuing excellence of the magazine. I look forward to its arrival every quarter.
As an engineer, I am continually irritated by people’s misuse of and misunderstanding of symbols and terminology related to energy—but not in your publication I hasten to add. I don’t think I have ever seen such misuse in ReNew except perhaps in readers’ letters.
Things like watts/hr instead of Watt-hours and the like are plentiful in the media, and especially so on the internet. Battery capacity is a particularly badly understood area. While it’s irritating, it is also understandable given that only people who followed the maths/science stream in high school are likely to have been formally taught such things. Unless you really understand the relationships between force, work, power and time it’s difficult to fully engage in discussions about energy.
My suggestion therefore is for an article or perhaps a series of articles explaining the basics of force, pressure, work and power in physical and electrical terms. I think there’s a real need for some basic knowledge to be disseminated. After all, knowledge is power (pun intended).
Anyhow, that’s my ten cents’ worth.
Neil Biggar
Thanks for the suggestion Neil, if other readers would like to see articles like this email us at renew@ata.org.au
Ed
High cost abatement PVs
I read with interest Alan Pears’ report on the concept of high cost abatement PVs (ReNew 116). I have to agree with everything he said.
What he did not cover was the fiscal side of the matter—money for greenPower is a finite resource so should be spent wisely.
Why should we as consumers pay 60c/kWh for domestic PV-generated electricity when we can get the same energy from (for example) large-scale wind for 9c/kWh? Put another way, we can pay a fixed amount per time frame (say $10 a week) and get 17kWh from PVs or 111kWh from wind. Which would you choose?
Productivity commission findings are that the abatement cost for domestic PV systems ranges from $400 to $1000 per tonne, which is very high on a global scale.
From a broad perspective, if as a society we put the same amount of dollars that have been put into domestic PV into large-scale wind, the green energy sent to the grid would have been seven-fold what we have, to say nothing of the night and winter time generation.
I am all for people having their own domestic PV systems, but why should the rest of us pay for this most expensive form of green energy?
Disclosure: I have grid-connected PV systems, for the generous feed-in tariff which all consumers are paying for.
Bruce Jeffery
Renewables better than underground cables
During the 2010 state election campaign in Victoria, the now-Baillieu government promised to implement all 67 Bushfire Royal Commission recommendations. The article in The Age on 12/09/11, Call for underground wires to cut fire risk, identifies issues being considered in relation to Recommendation 27. Instead of 20 tonne excavators digging through the bush and severely impacting fragile environments, a far better approach is to install alternate systems on properties, rather than incredibly expensive underground cabling. The cost of alternate systems could be borne by the government and the electrical transmission companies creating the rarest of outcomes: a win-win-win-win for the government, households, the electrical transmission companies and the environment.
Properties should be supplied with the appropriate systems, such as stand-alone photovoltaic (PV) systems, while others might need hybrid systems of PVs and wind, depending on the geographic location and the needs of each individual property. Residents should be fully supported to learn and manage these systems and not be lumped with a system they can’t manage. These systems should be maintained by an appropriate body for five years before becoming the responsibility of the property owner.
This approach is a far more sensible option, especially in rural/remote areas where the thousands of kilometres of underground cabling to only a few properties seems an outrageous undertaking.
Leon Trembath
We could not agree more. The ATA has been a contributing member of the Bushfire Powerline Safety Taskforce over the last 12 months, which has been considering bushfire mitigation approaches in fringe of electricity grid locations. The ATA has made the case that it will often be far cheaper for households to be provided with a stand-alone power system, under a properly managed service contract, than to pay for undergrounding or insulating of powerlines lines at hundreds of thousands or even millions of dollars per kilometre.
Damien Moyse
ATA Energy Policy Manager
Reducing fridge startup current
I recently converted a freezer to a fridge; the conversion was successful, with at least a 60% reduction in energy consumed, although I would expect this to be less during summer months. When I measured the starting current it was a whopping 180 amps from my 12 volt system and at times would drop the battery voltage too low for the inverter to cope. Upon measuring the phase angle between the starting and running currents, they were only displaced by about 15°. I expect this is standard for most small fridge compressor motors, as manufacturers do not consider correcting the phase angle as most of these units are plugged into a 10 amp grid powered outlet.
After doing a bit of research and reading I found that the best angle of displacement to provide maximum torque for the motor to start is 90°. I placed a 500 volt, 6uF capacitor bank in series with the starting winding. This required breaking into the three-pin starting relay attached to the motor, breaking the circuit and drilling a hole in the mechanism to bring out a wire to connect to the capacitor bank. The other end of the capacitor I was able to attach to an external terminal on the starting unit.
This modification reduced the starting current down to 60 amps and gave a far smoother startup in less time. At the moment of starting, my 600 watt inverter did not have any trouble starting the fridge, as the shorter starting time and lower current allowed the battery voltage to remain steady.
I believe this conversion will allow people with small to medium solar energy systems and inverters to be able to use standard off-the-shelf fridges. I would be happy to forward a schematic diagram to any ReNew readers who may need to reduce the starting current and increase the torque of any induction motor which has a start-run winding.
Out of interest, my system is a 720 watt capacity photovoltaic system with a 12 volt, 800Ah (C/10) battery bank and 600 watt continuous, 1200 watt surge capacity inverter.
Peter Rusanow, electenergy@yahoo.com.au
Peter’s modification is a good example of adapting off-the-shelf equipment to be a bit more efficient and much easier to run on smaller renewable energy systems. Unfortunately, most manufacturers don’t consider the use of their equipment on renewable energy systems when they design it, preferring to keep designs simple to keep costs down (which is fair enough, as most devices will never be used on small renewable energy systems).
We should state here though that this sort of modification can be dangerous if done incorrectly and that you absolutely must have a good understanding of electrical theory and practical applications before attempting any such modifications. These modifications will, of course, void any warranty on your fridge and should such modifications cause a fire, don’t expect your insurance company to pay up!
Lance Turner
Mythbusting electric vehicles
With so much interest being shown by car manufacturers, EVs have become all the rage, at least overseas. But are they a real solution for low carbon transport or a technological red herring? Members of ATA’s Geelong and Melbourne Electric Vehicle Branches investigate.
Like anything new, there is usually a mismatch between the public understanding and the reality. Remember when CDs first appeared we were told that they were indestructible! Electric vehicles have seen similar problems, although it would be more accurate to say that electric vehicles have been ‘rediscovered’ as opposed to calling them new.
READ MORE »The beginning of the 20th Century marked the beginning of electric vehicle dominance in the pleasure car field. In 1900 in the United States, 4200 cars were sold—38% electric, 22% petrol and 40% steam powered.
As members of the ATA Geelong and Melbourne Electric Vehicle branches we do have a passion for this technology. Several of us have been driving electric vehicles for some time, and if anything, we have found the passion to be stronger now, since we have become hooked on the experience of relatively quiet, arguably clean, oil independent, nearly service free, low-cost transport.
Acknowledging our bias, the following is our best attempt to address some electric vehicle myths and present what we can of the ‘facts’.
Batteries cannot store enough electricity for a useful driving distance
The fear of running out of battery charge is called ‘range anxiety’ and is certainly seen as the Achilles heel of a battery powered car. However, more than 90% of commuting trips in Perth, Sydney and Melbourne are 30km or less. This is well within the range of electric cars, which can currently give at least a 100km range, with many models going much further.
It takes too long to recharge
Interestingly, whilst recharging can be done at any point where the car is parked to give further distance, overseas experience has shown that this is rarely done as people prefer to charge at home while the car is garaged overnight. The actual time taken to recharge is arguably more accurately reflected in how long it takes to plug the car in at night and unplug it in the morning (as compared to the time spent finding a petrol station, pulling into it, waiting in the queue, refilling, waiting to pay and then pulling back into traffic).
Aren’t you just moving the pollution out of the cities to the countryside?
This is by far the greatest perceived issue with an EV. If you use solar panels as the charging source or elect to use accredited GreenPower, then running the vehicle is virtually emissions free. However, if you use the normal peak period electricity supply in Australia, with its fossil fuel generating plants, then there is pollution associated with charging an electric car.
Off the grid in the city
Solar PV owner Dr Rodney Bell explains why a battery backup on your grid-connect system can be an advantage.
Recent newspaper articles inferring that solar photovoltaic (PV) systems are not an economic proposition made me look again at the economics of grid-connected PV systems. I am a strong supporter of solar power systems, especially after seeing the results from my own system over the last five years.
READ MORE »Fortuitously my system has battery backup and is easily configured so that I will always get at least the current rate that the energy retailer charges for the electricity generated, irrespective of what they do with the feed-in tariff.
Further explanation
Without government rebates my costing for a nominal 2kW system is around $12,000. This is broken down into $6000 for panels (ten 200W panels), $2800 for an inverter/charger at Jaycar, $1500 for 10kWh capacity ex-Telstra gel battery pack, $400 for two 60 amp solar regulators and $1300 for installation. Such a system will generate 3285 kWh per year in the Sydney area. My nominal 3kW system produced 5091 kWh in the last 12 months so I have tried not to give over-optimistic figures.
The beauty of having a battery backup system is the flexibility of either selling the generated power to the grid or else storing it and using it yourself. This means that if you missed out on some of the generous feed-in tariffs offered in different states, you will at least be always guaranteed the current peak rate charged for electricity. From July 2011 it was 25c/ kWh or 35c/kWh if measured on a time of use meter, according to NSW figures.
Assuming that $12,000 was paid for the system (unlikely as the Federal Government Solar Credits Scheme would bring down the price) the return could be as much as 6.8% pa. This calculation uses the 25c rate: 3285kWh x 0.25c = $821.25.
A more serious investor would put in a system with double the number of solar panels and use a larger capacity inverter/charger such as one from Xantrex or Selectronics, resulting in an outlay of $22,000 and a return on investment of 7.5%. These returns, with their guarantees (the return will only increase over the next 10 years as electricity prices increase) make PV solar systems, particularly ones with battery backup, a very sound investment. Take into account the current Solar Credits Scheme then $3000 can be deducted from the capital outlay for the 2kW system lifting the return to 9.1% pa. The return on a 4kW system jumps to 10.3%.
Solar credits
Note that there is no tax on returns from these investments so, depending on your tax level, a normal investment return in the order of 15% could obtain the same monetary return. On the other hand, if you are a part-aged pensioner, as my wife and I are, and own your own house, then your part-aged pension could increase because the investment becomes part of the family home, which is a non-assessable asset. This will increase the effective return by a couple of percentage points, making a possible return on investment of over 10%.
Read the full article in ReNew 118
Product profile: An inverter for every requirement
Domestic-sized renewable energy systems have become more complex over the years as owners have demanded greater flexibility in their systems. This has resulted in quite complex systems using numerous individual components, making it harder to understand exactly what was happening in the system. Advanced inverters such as the Selectronic SP Pro and SMA Sunny Backup (which we will look at next issue) have changed that, integrating inverter, battery charger and system controller in one unit.
READ MORE »The PowerRouter range is a relatively new kid on the block but it is capable of being the hub of almost any type of small renewable energy system. It can act as a purely grid-interactive inverter, grid-interactive with battery backup (UPS) or as the hub of a stand-alone (off-grid) system, depending on the model.
The PowerRouter lets you connect solar, wind and water power sources to feed energy into the grid and/or a battery bank. It controls the flow of energy so that use of the renewable sources is optimised and the system is as reliable as possible, especially off-grid systems that rely on their batteries. Because the PowerRouter does everything, there is no need for extra inverters, switchboxes or inverter chargers.
The batteries are only cycled when necessary, reducing the number of load cycles and prolonging battery life. You can also remotely monitor and control your PowerRouter via the manufacturer’s web portal.
The PowerRouter is available in three models—3kW, 3.7kW and 5kW.
For more information contact Setec on 03 9763 0962 www.setec.com.au
Product profile: Ditch the smelly petrol quad
Almost all larger properties will have at least one quad bike as they are such amazingly useful things. Yet they can be noisy, smelly and you have to handle fuel and oil and regularly maintain their horribly inefficient internal combustion engines.
READ MORE »The range of all-electric quad bikes from Urban ATV eliminates these problems. The bikes range from little 800 watt units more suited to the kids, right through to a 3kW full-sized quad.
The 3kW model has twin brushless 1.5kW motors powered by a 48 volt battery bank, a high tensile steel frame, top speed of 60km/h, range of up to 70km, can climb 40 degree slopes, front hub and rear hydraulic brakes and double spring front and single spring rear suspension. It weighs 285kg and measures 1980 x 1080 x 1160mm.
RRP: $510 for the 800 watt models through to $3200 for the 3kW unit.
For more information and to buy, contact Urban ATV, ph:(07) 5493 0808, urbanatv@iprimus.com.au, www.urbanatv.com.au
Product profile: General purpose battery meter
While a voltmeter can give a rough idea on the state of charge of your batteries when under load, there’s nothing better than a meter that logs the outgoing energy and can display the real capacity still available.
READ MORE »The BMS-001 battery monitoring device from Diverse Power Systems continually monitors a 12 volt lead-acid battery and acts as a fuel gauge to estimate the state of charge and remaining discharge time.
It features a large LED backlit LCD which displays volts, charge/discharge current, remaining life and the total number of battery charge/discharge cycles. It has reverse battery connection protection and draws less than 3mA. Voltage accuracy is ±100mV and currents up to ±100 amps can be measured. Operating temperature range is -10°C to 60°C, so it should handle most Australian conditions.
The meter measures 170 x 110 x 20.6mm and weighs 381 grams, so it’s quite large as battery meters go. The meter is also designed and manufactured in Australia, something quite rare for electronics nowadays!
RRP: $375
For more information or to buy, contact Diverse Power Systems, sales@diversepower.com.au, www.diversepower.com.au
Product profile: The lowest flowing showerhead?
Over the years we’ve looked at some impressive water saving showerheads, some using as little as 6.5 litres a minute. Water saving showerheads don’t just save water, they also save energy by reducing hot water use.
READ MORE »The Perfect Flow Ultimate showerhead takes water saving even further, using just 5.5 litres per minute and has a 3-star WELS rating. Unlike many ‘low flow’ showerheads, the Ultimate is not simply a restricted higher flow unit, meaning the user cannot tamper with the flow rate by removing a restrictor.
The showerhead comes complete with articulated arm, or can be installed to an existing compatible shower arm.
RRP: $30
For more information and to purchase, contact Todae, ph:1300 138 483, www.todae.com.au
Product profile: The SP Pro grows up
Selectronic has recently released two new models of this multi-purpose inverter. Designated SPMC1201–AU and SPLC1201–AU, they are both designed for 120 volt battery banks and have rated outputs of 7500 watts and 18,000 watts continuous respectively, so they are ideal for larger home and small commercial installations that need grid interactivity and battery backup.
READ MORE »The new models have all the usual SP Pro features including AC transfer switch, a ‘grid lockout’ setting to allow for off-peak battery charging, automatic changeover on grid failure, 300% surge capacity, 100% charge capacity, five-stage battery charging with temperature compensation, simple LED display, full computer configuration, field-serviceable modular design, in-built data-logging with adjustable sample rate, silicone-coated PCBs for moisture resistance, four addressable relay outputs and three digital outputs for controlling external energy sources, four addressable digital inputs and two analogue inputs for system monitoring, and the list just goes on.
The SP Pro is Australian designed and manufactured and comes with a five-year warranty (or seven years when installed by an SP PRO accredited installer).
For more information, pricing and your local installer, contact Selectronic Australia, www.selectronic.com.au
Product profile: USB power in a wall socket
Anyone who owns a mobile phone or other small rechargeable device will own a wall charger. Once the device dies, odds are the new one will have yet another charger, leaving you with an old one with no use. The major players in the mobile phone industry have recognised this fact and have standardised their charging ports, and as of next year, many phones will come without chargers.
READ MORE »The sockITz range of power points combine an Australian Standard dual 240 volt power point with twin USB powered charging outlets for charging mobile devices. The inbuilt USB sockets are completely powered off until you slide the socket cover to the side. They then power up and a LED comes on inside the socket so you know it’s working. The USB sockets can provide up to 2 amps, which is enough for any portable device on the market that is designed for USB charging.
RRP: $37.95 but currently available on pre order for $24.95. An illuminated Apple or micro USB cable is available for $19. The aluminium finish wallplate model is $2 more.
For more information or to buy, go to www.sockitz.com.au
ReNew magazine’s Blog of the Year competition
Calling all keen sustainability e-scribes! Enter your blog in the ReNew Blog of the Year competition for your chance to win a pair of 110 watt solar panels!
We’re looking for blogs about sustainable homes on a budget, energy efficiency, DIY projects or wider issues to do with climate change or environmental policy.
READ MORE »The blog should provide new details or insights for those seeking information on sustainability and should have been regularly updated in 2011.
To enter simply email renew@ata.org.au with your blog’s URL, your contact details, your goals when you started blogging on this topic and a little about your audience, such as their age bracket, skill levels and level of engagement with you and your blog.
1st prize
A pair of 110 watt solar panels courtesy of Low Energy Developments. Valued at $500. www.lowenergydevelopments.com.au
2nd prize
An XL Woodgas Camp Stove plus a Solar LED Lantern with stove charger courtesy of Stickman Stoves. Valued at $178. www.stickmanstoves.com
Email entries (under $200 words) to renew@ata.org.au. Entries close Friday, 3 February 2012.
Solar panel buyers guide 2012
We’ve contacted photovoltaics manufacturers for details on warranties, cell types, size and price to help you decide which solar power system is best for your home.
While incentives such as feed-in tariffs and rebates have been reduced or removed completely of late, the steadily decreasing cost of solar PV panels and the steadily increasing cost of mains electricity means that despite the reduced incentives, house-holds and businesses are still installing solar photovoltaics for electricity. Best of all is that this electricity source is clean and renewable.
READ MORE »Photovoltaic panels produce electricity directly from sunlight in a solid-state process—there’s no moving parts to wear out, just large inert panels that have very long lifespans. The most popular use of PVs nowadays is to supplement mains grid power and reduce electricity bills. However, solar PVs have many other uses including to power off-grid houses, water pumping systems and remote communications systems, as well as in large commercial solar power installations.
The different technologies
There are three common types of solar cells: monocrystalline, polycrystalline and thin film.
Both mono and polycrystalline cells are made from wafers cut from blocks of silicon. Monocrystalline cells start life as a single large crystal known as a boule, which is ‘grown’ in a slow and energy intensive process. An example can be seen at right. Polycrystalline cells are cut from large cast blocks of silicon rather than single large crystals.
The cells are then modified by a process known as ‘doping’. This involves heating the cells in the presence of boron and phosphorus, which changes the structure of the silicon in such a way as to make it a semiconductor. This is the same method which is used to make integrated circuits.
Once the wafers have been doped, they then have a fine array of electrically conductive current-collecting wires applied to each side of them.
Thin film technology uses a different technique and involves the deposition of layers of different materials directly onto metal, glass or even plastic. The most common thin-film panels are the amorphous silicon type, which are found everywhere from watches and calculators right through to large grid-connected PV arrays.
In recent years, other types of thin film materials have started to appear. These include CIGS (Copper Indium Gallium (di)Selenide) and CdTe (Cadmium Telluride). They tend to have higher efficiencies than amorphous silicon, with CIGS cells rivalling crystalline cells for efficiency.
Read the full article in ReNew 118
The great gas debate
Moving to natural gas is not the ideal solution many would have us believe, writes Alan Pears. Plus, the case for running your PV system independent of the grid.
As energy expert Ian Dunlop pointed out at a recent Climate Alliance conference, humans are investing billions of dollars in exploration for more fossil fuels, when we cannot burn those we already know about without risking runaway climate change. Yet this investment is considered ‘conservative’ by many financiers.
READ MORE »Our energy market policy experts consistently overprice emerging sustainable energy technologies and underestimate their potential for growth. This is seen as prudent, even though it increases risk of overinvestment in outmoded technologies that could become stranded assets no one wants.
Study after study undervalues the benefits of sustainable energy. For example, a study for the Clean Energy Council on feed-in tariff pricing for PV power concluded it should be less than 10 cents per kilowatt-hour, when solar advocates argue for retail price equivalence. This study ignored the avoided and deferred energy infrastructure costs. It used an annual average percentage of net exports to estimate the avoided demand on hot days. And so on. Yet work like this is considered ‘safe’, because it makes ‘conservative’ assumptions. It makes assumptions that work against sustainable energy.
The problem is that what has been ‘conservative’ is now risky financially and for the climate. If we under-invest in innovation and over-invest in high emission solutions, we are wasting money and building future liabilities. We need to rethink our energy policy analysis approach, before the hole our energy policy people have been digging gets even deeper.
PV and feed-in tariffs
As usual, policy makers have accepted ‘conservative’ analyses like the one above, that claim limited benefit from photovoltaics (PV). In contrast, a more thorough analysis by Melbourne University’s Energy Institute and Beyond Zero Emissions, in which the hourly net output of the PVs was modelled, gave a very different result: PV is reducing energy prices for everyone.
Efforts by policy makers to cut FiTs assume that PV owners have no choice but to sell their excess power to the retailer when they generate it. They still fail to see customers as partners in a sustainable energy future. Their focus is to prop up the existing industry at the cost of emerging competitors—consistent with the terms of reference issued by misguided energy ministers.
But when some time-of-use electricity tariffs are charging over 40 cents per kilowatt-hour at certain times of the day, the economics of energy storage start to look interesting for PV owners (and, indeed, anyone who can store cheap electricity and use it at high cost times). If you have the choice of being paid less than 10 cents/kWh for PV exports at that price, the cost and energy losses of storage can be comfortably covered if the energy replaces electricity priced at 40 cents/kWh.
Already some inverter manufacturers offer the capacity to add storage and run independent of the grid. Battery technology is improving and costs are falling due to electric vehicle development.
Great gas emission debate
The gas industry has promoted shifting to gas as the panacea to cut greenhouse gas emissions. A recent study by climate specialist Tom Wigley has challenged this. Wigley uses a climate model to explore the year by year warming effects of replacing half of global coal use with gas by 2050 (phased in at 1.25 percent additional coal replacement each year to 2050). He includes a range of options for methane leakage from gas production from zero to ten percent. This provides some interesting insights.
Wigley’s work is much more useful than the Worley Parsons industry study, which uses warming factors averaged over 100 years: this understates the significance of the short term impacts of methane leakage and simplifies the complexities of atmospheric processes.
There are actually two independent factors at work in Wigley’s study. First, there is the effect of a reduction in coal use, which cuts emissions of CO2 and methane leakage from coal mines, reducing warming. But it also reduces air pollutants such as oxides of sulphur and carbon particulates, which reduces their short term cooling effects. Wigley’s paper suggests this loss of cooling will offset most of the reduction in warming from cutting coal use until mid-century, when the long-term effect of reducing CO2 begins to swamp the air pollution effect.
Reduction in coal use could happen independent of gas use, driven by strong energy efficiency improvement, rapid adoption of renewables or even economic collapse. Indeed, the only way to achieve significant reduction in net warming by 2050 from cutting coal use seems to be through replacing it with zero emission options, because of the loss of the air pollution cooling effect.
Second is the impact of increasing gas consumption, which depends on how much methane leaks during production, the amount and type(s) of energy used for processing, liquefaction and regasification (if sold as LNG), transport, and the efficiency of gas usage compared with the coal it replaces. Wigley assumes all extra gas is used at 60 percent efficiency to produce electricity that replaces 32 percent efficient coal-fired electricity. He ignores LNG (liquified natural gas) production and transport (which, according to the Worley Parsons industry study data adds 22% to gas CO2 emissions). So Wigley’s assumptions are generous to gas.
If we consider CO2 emissions only, replacing coal with gas does reduce net warming progressively from the first year, due to its lower greenhouse intensity and higher assumed efficiency of use.
The change in methane warming impact depends on the balance between the reduction in leakage from coal mines relative to the extra leakage from gas production. A net increase in methane leakage gives net warming, particularly in the first few decades after the methane is released, as methane is a very greenhouse-active gas over this period.
In Wigley’s study, the reduction in cooling from sulphur oxides and particulates as coal use declines, offsets the reduction in warming from gas replacing coal (at 1.25 percent additional substitution per year) until 2050. As I pointed out earlier, this air pollution effect will happen whatever causes a decline in coal use, not just gas.
Overall, the loss of air pollution cooling offsets the reduction in warming through gas replacing half of coal usage to 2050, even with no methane leakage from gas. At 2.5 percent leakage, the breakeven point is around 2055. At 10 percent leakage (a high scenario), it is 2140. Not good. So the net climate benefit of replacing coal with gas over the next century is very sensitive to the overall efficiency of production and use of gas relative to coal, and the extent of methane leakage.
If gas is to help achieve a sustainable energy future, the industry must change. It must drive efficiency improvement in gas production and usage hard, so that gas consumption at many sites actually declines. For example, combining on-site efficiency improvement with cogeneration can reduce total site gas consumption while replacing imported electricity.
The industry should use renewable energy for production and transport where possible. It must aim for zero methane (and CO2 from gas fields) leakage, and accept independent monitoring for credibility.
Gas companies should also buy offsets to balance all emissions in their supply chains, while encouraging consumers to buy offsets to balance emissions from gas usage.
They must invest in zero emission options such as biogas, renewable synthetic gas and possibly hydrogen. Lastly, coal seam and shale gas must prove they won’t damage our underground water resources.
Then the gas industry might be able to claim a transitional role in the path towards a sustainable future.
Alan Pears has worked in the energy efficiency field for over twenty years as an engineer and educator. He is Adjunct Professor at RMIT University and is co-director of environmental consultancy Sustainable Solutions.