In ‘Renewable energy’ Category
Book review: Renewable Energy Superpower
Author: Beyond Zero Emissions
Published by Beyond Zero Emissions
Australia has been a laggard when it comes to emissions reductions, but with the rest of the world coming to the understanding that the future lies away from fossil fuels, we are set to see some far-reaching changes in not only the energy industry, but the traditional big exports such as coal and natural gas.
Over the next few decades, most countries will shift their energy generation towards renewables. Renewable Energy Superpower looks at what the post-fossil fuel world will be like, where those opportunities lie and how the changing economics of energy generation will affect us all.
The gist of this entire shift is summed up in the Executive Summary: “Every day that passes with uncoordinated development of the energy system adds cost and undermines Australia’s future renewable energy advantage.” We need to move now or risk being left behind the rest of the world and becoming an economic and energy backwater.
Renewable Energy Superpower lays out a plan for making this transition, including National Energy Market reform, cessation of investment in the gas network, promoting adoption of electric vehicles and increasing the efficiency of the nation’s appliances. If you want to get a grasp on what the world’s energy markets and systems will look like in the next decade or two, this report is a good place to start.
Review by Lance Turner
This book is available for order at
For more book reviews, buy ReNew 134.
Farming Renewably: Reaping the benefits
One person/farm can make a difference: David Hamilton describes how his farm’s sustainable conversion cut carbon, benefited the landscape and turned a profit.READ MORE »
I’ve read many inspiring articles in ReNew from individuals trying to live more sustainably and lessen their impact on the planet. This article takes a slightly different approach–a rural perspective–to demonstrate that it can be commercially viable to run a farming enterprise using systems that are truly renewable, whether that’s for water, electricity, housing, food, livestock, pasture or wildlife.
Our journey to sustainable farming began in 1993, when my wife Roberta and I purchased a 60-acre property in the south-west of WA with the twin objectives of restoring the degraded land and becoming as self-reliant as possible. The land included pasture that was totally lifeless and neglected, along with a dam, two winter streams, old gravel pits and two areas of magnificent remnant native forest. We wanted to be independent for water, electricity and as much of our food as was practical. Withe fewer bills to pay, we could work fewer hours off the farm–which was very appealing.
As a registered nurse with no farming experience, I was on a vertical learnign curve. Luckily, Roberta has a dairy farming background and, with her accounting experience, is a wizard at making a dollar go a long way.
When we began, we were both working full-time. We spent the first two years establishing a gravity-fed water supply, preparing the hosue and shed sites, and fencing the property, including to protect remnant bush from planned livestock. We also planted over a thousand native trees and shrubs, plus a few ‘feral’ trees for their air conditioning and fire-retardant properties.
Read the full article in ReNew 132.
Going hybrid: Adding batteries to grid-connected solar
Going off-grid may not be for everyone; a better route may be to ‘go hybrid’, by adding batteries to grid-connected solar. Andrew Reddaway explores the options.
The solar battery industry is on the verge of disruptive change. Traditionally, large batteries were only seen in houses at off-grid locations such as Moora Moora (see box on the solar hybrid training course held there, which I attended earlier this year and which provided input to this article).READ MORE »
For off-grid systems, reliability is crucial; failure prompts an emergency call to the solar installer, so such systems have been designed conservatively using proven lead-acid batteries.
Meanwhile, in towns and cities, grid-connected solar systems have gone mainstream. As feed-in tariffs for solar export have dropped far below the rates paid for grid electricity, householders are looking for ways to cut bills by making better use of their excess solar generation. One answer is to add batteries to create a hybrid system: a grid-connected solar system with batteries either for backup or load-shifting.
This article gives an overview of current hybrid technology and the options available for adding batteries to an existing grid-connected solar system.
Different batteries for hybrid
A hybrid solar system is tough on batteries. Unlike an off-grid system that may store enough energy to last multiple days, a hybrid system’s entire usable capacity will be charged and discharged daily. This requires a battery that can handle fast discharge rates at high levels of efficiency. Lithium batteries fit the bill, and have already become dominant in consumer electronics, power tools and electric cars. Compared to lead-acid, they are also smaller, lighter, don’t require monthly maintenance and don’t emit hydrogen gas. The only things holding them back in the solar market are unfamiliarity and price.
The recently announced lithium Powerwall battery from Tesla is priced well below previous products and has a 10-year warranty. Traditional lead-acid batteries cannot compete with this new benchmark, so it’s expected that systems will start to move away from them. Hybrid systems are now expected to become viable on pure economics in a few years or less. Early adopters are already installing lithium hybrid systems, as are some who value maintaining power during a blackout.
Read the full article in ReNew 132.
A micro-hydro buyers guide
A micro-hydro turbine can be one of the cheapest sources of reliable electricity—if you have the right site. Lance Turner looks at what’s available.
Solar panels are the energy generators of choice for most domestic renewable energy systems, but there are other forms of renewable energy generation that can provide supplementary or even primary power generation if you have the right site.READ MORE »
One possibility is a micro-hydro system: the production of energy from water, with domestic-scale systems sized up to 100 kW. If you have a rural property with a suitable water source, then micro-hydro may be a good option, particularly if a high tree canopy precludes the use of solar panels or wind turbines.
The kinetic energy stored in flowing water can be considerable. You just need to look at the deep pools often found below large waterfalls or how the rocks in a creek are worn smooth by the flow of water. To get an idea of the forces involved, try aiming the jet from an ordinary garden hose at your hand. You will feel the force of the water striking your hand and being deflected. This is basically how many hydro turbines work.
Run-of-river versus dammed
Hydro systems fall into two broad designs—run-of-river and dammed systems.
Run-of-river systems simply take water from a high point of the river or creek, pass it through the hydro turbine and return it to the river or creek at a lower point. Only a portion of the water in the water source is diverted through the system.
In a dammed system, the water source is dammed, producing a water reservoir. The height of the water behind the dam produces the required head for the hydro turbine (the head is the term commonly used to describe the vertical height of the water column that is producing the pressure to run the turbine).
Most domestic systems are run-of-river types, as these produce the least environmental impact and are the cheapest to install. They are also the type your council and/or water authority is most likely to approve. After all, damming a water source can cause considerable environmental disruption and should be avoided.
Some run-of-river systems do use a small dam, known as pondage, to ensure an adequate flow into the intake pipe. The amount of pondage can be small or may be increased to provide more reliable energy output from the turbine during times of lower water flows in the water source. It is possible to use pondage that is separated from the water source completely, to prevent any negative effects on the water source.
Read the full article in ReNew 132.
Revolving donations fund 35kW of community solar
A people-powered movement is helping to fast track Australia’s renewable energy revolution.READ MORE »
A recent solar PV installation at Camden Park, SA brings the total amount installed by CORENA’s Quick Win community solar projects so far to 35kW. Another 8kW has been added by recipient organisations in conjunction with these projects, giving an overall result of 43kW installed. Two of the projects have also included replacing lights with LED alternatives.
CORENA (Citizens Own Renewable Energy Network Australia Incorporated) provides interest-free loans to pay for solar installations and energy efficiency measures. The loans are repaid over about five years out of the resultant savings on power bills, meaning that non-profit organisations can reduce their carbon emissions without diverting funds from their core purpose. As the projects ‘pay for themselves’, the original donations are then used over and over again in new projects.
CORENA has now funded Quick Win projects for four non-profit organisations in three states: Tulgeen Disability Services in Bega (NSW), Gawler Community House (SA), Beechworth Montessori School (Vic), and Camden Community Centre (SA). The next project in line, in Nannup (WA), is already half-funded, and a community centre in Ravenshoe (Qld) is queued as Project 6.
“After just four projects the growth potential of our revolving funding model is looking quite exciting,” said CORENA spokesperson Margaret Hender. “The four projects completed so far have cost a total of $63,460. Climate-concerned citizens donated most of that, but $10,438 of it came from loan repayments from completed projects.
“The first project was funded entirely from donations, but already $5,000 of that loan has been paid back into the revolving pool of funds,” said Ms Hender. “As the number of completed projects increases, an increasing proportion of the cost of new projects is covered by loan repayments. Eventually the revolving loan repayments will cover 90%, or even 100%, of the cost of new projects.
“I could talk to politicians until I’m blue in the face in the hope of getting better renewable energy policies, and never know if I’ve had any effect,” said Ms Hender. “But if I put $100, or $10 a week, for example, into solar panels on a roof somewhere, within a matter of weeks my money will be reducing carbon emissions and keep on doing so forever as it is used again and again in future projects.”
For more information visit www.corenafund.org.au
A battery buyers guide
The battery bank in a stand-alone or backup power system can make or break the system. Lance Turner examines what to look for in a battery bank and how to get the right battery for your needs.
An extract of the article is below, or read the full article in ReNew 131.READ MORE »
As more people look to go off-grid due to the ever-increasing cost of electricity bills and the unreliability of the grid in some areas, the market for energy storage systems is set to expand massively in the next few years. That’s not to say there aren’t options available already—there are plenty, for both off-grid and on-grid use.
There are two main approaches to energy storage: you can buy the required number of individual batteries or cells and have them installed and connected together on-site, or you can buy an integrated ‘storage system in a box’, containing batteries, safety equipment such as fuses and disconnects, and possibly a charge controller or other equipment.
As we looked at integrated storage systems in ReNew 128, this guide looks mainly at the first of these options: buying batteries or cells for assembly into a large battery bank. We also don’t cover batteries for electric vehicles (EVs); see our All About EVs article on p. 38, for a discussion of batteries for EVs.
Battery selection is critical
Arguably the most important part of any renewable energy system involving energy storage is the battery bank. All other parts of a system can be upgraded or added to quite easily, but if you select too small a battery or one not suited to your needs then your system performance, and the battery’s usable life, will suffer. Unfortunately, the battery is the component most likely to be specified incorrectly, either due to a lack of understanding of how batteries perform, or budgetary constraints—the battery bank is now the most expensive single component in the average stand-alone power system (SAPS).
Batteries are designed for specific applications. In this article, we look at batteries suitable for use in renewable energy systems, either off-grid, in stand-alone power systems (SAPS), or on-grid, in a grid-connected system with storage for either load shifting or backup power.
Over time, and with changes in technology, the requirements for domestic energy storage systems have changed quite considerably. Once common, 12 volt DC systems are now mainly found in caravan and camping situations, though small SAPS systems may still run at this voltage.
Current homes instead usually run AC-based systems. They have 24 or 48 volt (or even 120 volt) DC power systems with inverters to convert the power to 240 volts AC, and use efficient AC appliances.
Such systems need large capacity battery storage to cope with the high surges required to start the motors in appliances such as water pumps and vacuum cleaners, and ensure long battery life through shallow discharge of the batteries. Generally speaking, the deeper a battery is regularly discharged, the shorter its lifespan will be.
Useful characteristics for batteries in renewable energy systems are:
- long life under a continual charge/discharge regime
- ability to withstand numerous deep discharges over the life of the battery (e.g. in winter when it may need to be discharged more deeply)
- low maintenance requirements
- high charging efficiency; some energy will be lost when the batteries are charged, but the lower this is, the better
ability to perform over a wide temperature range.
- low self-discharge; all batteries slowly discharge themselves over time, but the lower this is, the better.
Common renewable energy system battery types
The most common chemistry used in household energy storage systems is still the lead-acid battery. These have been around for more than a century and work well provided that the appropriate size and type are selected, and they are used and maintained appropriately.
As demand for more advanced energy storage grows, there has been much focus recently on lithium-based batteries. For household energy systems this generally means lithium iron phosphate (often called LiFePO4 or even just LFP) chemistry, which has seen considerable advancements in the last few years, with a steady decrease in cost as the scale of manufacturing has increased.
Nickel-cadmium batteries were used for a period in stand-alone power systems. However, their high cost and relatively high toxicity means they have all but disappeared. A related but much safer chemistry is the nickel-iron battery.
Other battery types found in commercial systems, though generally not used in domestic-scale systems, include flow batteries, sodium-sulphur batteries and even flywheel batteries.
Lead-acid batteries consist of lead and lead-sulphate plates suspended in a sulphuric acid electrolyte. They are a reliable and well-understood chemistry that is relatively forgiving to mild overcharging, although over-discharging can impact lifespan considerably.
In years past, the most common type of lead-acid batteries in household power systems were flooded cell types. At the time, these offered the longest life and best value for money over their lifetime.
However, in more recent times there has been a trend towards prioritising lower maintenance requirements, resulting in an increasing number of systems being installed with sealed lead-acid battery banks. With these, you no longer need to check cell electrolyte levels, and the corrosion by acid that occurs with flooded cells is virtually eliminated.
Sealed lead-acid batteries come in two main designs—AGM (absorbent glass mat) and gel cell. Gel cells have their electrolyte as a gel to prevent spillage and stratification (where the acid density of the electrolyte varies from the bottom to the top of the cells), while AGM batteries have liquid electrolyte, like flooded-cell batteries, but it is absorbed into fibreglass separators between the cells to provide the same benefits as the gel type. Either type can usually be mounted in either an upright or sideways orientation.
While lead-acid chemistry is still the mainstay of the renewable energy storage industry, this is steadily changing, with other battery chemistries such as lithium potentially offering considerable advantages over lead-acid batteries.
Lithium iron phosphate (LiFePO4) batteries have higher storage densities (more energy can be stored in a battery of a given volume), greater power densities (smaller batteries can produce greater instantaneous power outputs), much better charging efficiency and longer lifespans than any lead-acid formats.
They can be more expensive to purchase initially, but this is rapidly changing as the push for lower cost batteries for electric vehicles as well as domestic energy storage systems has spurred on many manufacturers to reduce prices and increase availability.
In addition, due to the longer life and higher efficiency of lithium cells, and the fact that their capacity is not affected by discharge rate like lead-acid cells, enabling lower capacity banks to be used compared to lead-acid, lithium batteries are already a cost-effective option when total cost of ownership is considered. While lithium batteries are still a relatively small segment of the domestic energy storage market, this is set to change in the next few years.
Lithium batteries must have an effective battery management system (BMS). This enables each cell in the battery bank to be individually monitored when charging and discharging. Overcharged cells and cells discharged below the minimum voltage point can fail, so a good BMS is a must.
Buy ReNew 131 to read the full article which includes:
- other battery technologies
- battery specifications (capacity, battery formats, voltage, battery charging efficiency, battery life)
- sizing the battery bank for a stand-alone system
- battery sustainability
- safety and a home for your batteries
- battery bank do’s and don’ts
- secondhand batteries.
The state of solar cooling
It’s the holy grail of cooling—using the sun to power your cooling system. Mike Dennis from ANU takes us on a tour of where the solar cooling market is now and where it’s headed.READ MORE »
Most Australian homes are now equipped with some kind of air conditioner, but their rise in popularity over the last decade has put substantial pressure on the electricity transmission and distribution network—and the required investment in ‘poles and wires’ has been blamed for recent spikes in retail electricity bills.
Some electricity retailers charge a premium for grid electricity drawn during afternoon periods when air conditioning may be in use, but offer a paltry sum in return for photovoltaic power supplied to the grid during the same period. One NSW retailer charges over 50c/kWh between 2 pm and 8 pm on weekdays while offering only 6c/kWh in return for net photovoltaic energy exported to the grid.
Water heating and air conditioning are usually the two main energy sinks in a residence. To some extent, water heating may be time-shifted to avoid exposure to peak tariffs, but air conditioning load offers less flexibility. What can be done about this?
The first consideration, of course, should be to try to reduce or eliminate the need for active air conditioning. A well-designed building with appropriate shading, insulation and thermal mass is a good start. Secondly, householders should explore opportunities for passive air conditioning using prevailing breezes and carefully designed cross and stack ventilation.
As a last resort, a householder may decide to install an electric air conditioning system. These devices are intoxicatingly effective in providing comfort with convenience and immediacy. The shopfloor price may not be as confronting as the first electricity bill, however!
So, how can householders sidestep peak electricity charges and be comfortable in their homes at the same time?
Active air conditioning options that minimise environmental impact
The obvious option is to install a photovoltaic (PV) system to drive a regular air conditioner. Several companies offer packages to do this directly, or it can simply mean installing a larger PV system to run the whole house (‘Solar cooling options available now‘ also in this issue).
However, electrical supply will be required late in the afternoon and into the evening to offer proper service during summer cooling and winter heating periods.
It is worth noting that peak summer cooling loads often occur late in the afternoon, while peak solar is at noon. In winter, peak heating loads are in the evening.
Hence, backup will be required in the form of either a grid connection or a local electricity storage device. Both of these options come at a price. It is likely that future electricity storage prices will make this option viable. No doubt someone will produce a simple Sunulator-type calculator to size the PV collector and battery bank for such purposes. [Ed note: Adding batteries is planned for the next phase of Sunulator development!]
Read the full article in ReNew 130.
Solar cooling options available to households now
Solar cooling is possible at home writes Lance Turner.READ MORE »
Solar cooling is perfectly achievable for homes and businesses using off-the-shelf technology. The simplest system, and the lowest cost to install, uses high-efficiency heat pumps (reverse-cycle air conditioners), which can have EERs (energy efficiency ratios) of up to 5.7 for the smaller models, combined with a grid-interactive solar power system. By running the heat pumps during the day, when the solar system is producing the most electricity, the heat pumps are, effectively, completely solar powered.
There are other cooling system types that can also be run directly from solar-generated electricity, with evaporative cooling systems being the most common. However, most common evaporative coolers use a simple system of passing air through wet filter pads, known as direct cooling. While this does cool the air somewhat, it also increases the humidity of the air, something often undesirable in hot weather.
Other options in the pipeline
An alternative system, the Climate Wizard (a domestic model will be available in 12 to 18 months), is an indirect evaporative cooler that uses a counter-flow heat exchanger to cool the air without adding moisture. The system uses a heat exchanger, which has both dry and wet channels isolated from each other, to keep the evaporating water and the airflow into the house separate. Air passes through the dry channels in the heat exchanger, while some of that air passes back through the heat exchanger via the wet channels, where evaporative cooling removes heat. This cools the air in the dry channels without adding moisture. The dry air then flows into the home, while the moist air is expelled outside. Seeley International, the supplier of the system, claims that this system results in cooler and drier air entering the home compared to a conventional evaporative cooler, and can provide cooling performance similar to a heat pump air conditioner, with lower energy use.
While not common in Australia, there is a combined solar heating and cooling system known as a Combi+ system. It uses a solar ‘combi’ system (which uses solar thermal collectors, backed up by another heat source, to provide both space heating and hot water) combined with a sorption chiller for summer cooling. Combi systems are common in countries such as Austria, Switzerland, Denmark, Sweden and Norway, although Combi+ systems are less so, due to the lower cooling requirements in much of Europe.
CSIRO has recently conducted research into the economics of PV-powered air conditioners. As presented at All Energy Expo 2014, their provisional results demonstrate that using PV to power the whole house, including the air conditioner, has a much better return on investment than using the PV to power only the cooling system. Systems with batteries could become cost-effective as battery prices decrease. The research is being published soon; watch out for it on their website.
Read The State of Solar Cooling in ReNew 130 for a look at the solar cooling market.
Know your renewables: meter matters
In ReNew 126 we looked at electrical terms covering energy, power and other basic electrical concepts. Here, Lance Turner looks at common terms and concepts used to discuss energy metering and monitoring.
Whether your renewable energy system is grid-connected or off-grid, monitoring the system’s output is important to ensure it has a long and healthy life. Even if you don’t have a renewable energy system, understanding your energy usage is an important first step to becoming more energy efficient.READ MORE »
There are a range of meters and gauges for all these uses. Here, we look at the most common types of meters, what they show, how they work and any limitations.
First up is the electricity meter. These come in a number of types, including the older ‘spinning disk’ types and the more recent ‘smart meters’. The latter enable remote communications with your electricity retailer, so they don’t need to come out to read your meter, and provide much more fine-grained information on your electricity usage, including half-hourly data.
We’ve covered smart meters in detail in previous issues of ReNew (for example, ReNew 124) and in the ATA’s Smart Meter Consumer Guide (www.bit.ly/ATASMCG), so we won’t go into them in detail here. Suffice to say that both older meters and smart meters record electricity usage over a period in kilowatt-hours.
Interaction of your electricity meter with a grid-connected PV system
It’s important to note that most electricity meters now use net metering. A net meter will show electricity you imported from the grid and exported to the grid, but not the electricity your PV system generated that was used on-site. Some states originally used gross metering, which showed all electricity generated and all electricity used, but this has now been phased out in all states (though some older systems will still have this type of meter).
Net metering leads to an issue in calculating the total energy you are generating and using. To get these figures, you need to use the metering that comes with your renewable energy system, usually available both as a display meter and as a set of data that can be stored and downloaded from your inverter. Even if your system uses microinverters (small individual inverters attached to each panel), this data will usually be available through the microinverter manufacturer’s web portal.
Your inverter will provide you with the total PV generation figure (over a period of time), while your electricity meter will provide you with the energy imported from and exported to the grid. To calculate the total amount of electricity consumed by your house, simply add the import and generation figures and subtract the amount exported.
Read the full article in ReNew 130
Biomass potential in rural communities
This community energy project is not just about energy, it’s also about improving agricultural practices and creating a new industry—definitely a trickier proposition, but potentially more rewarding, writes Robyn Deed.
Not that long ago, say about 60 years ago, before we moved to a more centralised grid, it used to be the norm in regional Australia for country towns to manage their own power supply. Residents in Cowra, 300 kilometres west of Sydney in NSW, are exploring options that could reinstate that local control, and at the same time bring new industries to the area.READ MORE »
CLEAN (Cowra Low Emissions Action Network), a local group of sustainability advocates, is working on a pilot system to run a portion of the town of Cowra on a microgrid using energy produced from biomass, and start up a bioenergy regional hub.
The proposal has gained broad support— from industry, the council, locals and farmers. The proponents believe it could provide a way of improving sustainable agriculture practices and reducing reliance on the grid, potentially decreasing costs for the local community.
Architect and local Dylan Gower, one of the people involved in initiating and developing the proposal, says that community engagement is particularly important for this type of project.
“It’s a community energy project that relies on creating a new industry around what’s already there, and in some ways that’s more complex than importing in renewable technologies such as solar and wind,” says Dylan.
The ‘what’s already there’ is the resource stream for a biomass-based plant. There are two streams that the proposal is considering as input, one of ‘dry’ waste from agriculture and the other from ‘wet’ municipal waste, such as green waste and waste water.
The latter is one reason that the local council is behind the project: pre-treatment of waste water by a biomass system could reduce the running costs of the local (newly built) waste water treatment plant, which currently has high energy needs—and would also yield energy in the form of biogas to run the plant.
In this mixed farming community with intensive cropping of canola and wheat, plus dairy and poultry, there’s also a lot of residual material from agriculture that could feed into a biomass plant.
Dylan resists calling the residual material ‘waste’, as much of the agricultural by-products are already reused. For example, the stubble from canola or wheat production (the two intensively farmed crops in the area) is currently left on the soil as mulch or used to create compost.
“That is something we’re discussing with farmers,” he says: whether there is higher value in using the stubble as compost or mulch (as is done currently), or in using it in the biomass process to generate biogas and biofertiliser.
The feasibility of a pilot system to power an industrial estate in Cowra on biogas is currently being investigated.
Read the full article in ReNew 129.
Dr Catriona McLeod reports on a project harnessing a large renewable resource, at a smaller scale, in Tasmania.
In south Tasmania, Nigel and Josh Tomlin, founders of River Power Tasmania, have designed, and custom built, a hydroelectric generator. This might not seem so unusual as the market is awash with domestic and micro-generators. These small-scale operations are designed to power one domestic site; however, even Nigel’s first ‘backyard’ working prototype, built several years ago, powers about 30 houses, near his property at Ellendale.READ MORE »
The prototype takes water from the Jones River, which runs through the Tomlin’s property. This small generator generates about 80 megawatt hours per year and is powered by water falling 30 metres along 500 metres of pipeline.
The newer, second and larger hydroelectric generator is on the Humboldt River, which starts below Tyenna peak, in Mt Field National Park, at an elevation of 896 m, and ends at an elevation of 248 m. The Humboldt River drops approximately 648 m over 10.3 km. The fall and water content of this river make it ideal for a hydro scheme.
The generator captures water in the last 2 km of river, where it flows through forested areas used for industrial-scale softwood plantations; over the last 2 km it falls 98 m vertically. It demonstrates the efficiency of physics: the energy of falling water is enormously powerful in terms of generating electricity, even at a smaller-than-commercial scale. This new system is expected to generate 2.2 gigawatt-hours per year.
Manufactured in Australia by Pentair Southern Cross, the Turgo impulse turbine installed by the Tomlins is a medium-to-high head turbine. It’s designed for ‘run of river’ schemes as it can tolerate some so-called ‘dirty water’ (although the water entering this system is incredibly clean) and has good efficiency over a wide flow range. It’s also designed for minimal maintenance; this is vital to the Tomlins as they also run a large, diverse farm in the area. Monitoring can be done remotely via the Citect program, with error alarms sent out via SMS.
This model can be manufactured in a range of materials to suit the customer’s requirements. Here, Nigel’s 30-plus years in the hydroelectric industry—dreaming on the job of his own generators—meant he was very clear about how he wanted his machines to be configured. He notes the system is actually incredibly simple: an induction generator converts the water’s energy, much like a large washing machine motor being run in reverse.
The hurdles to construct this turbine have, however, been anything but simple. As mini-hydro projects are rare, there are no local precendents for the authorities to observe, and no specialists who properly understand the project. For example, the water management board required the installation of expensive monitoring equipment on the assumption the tailrace would be a trench dug into the earth. However, as the tailrace has been constructed from concrete to the river’s edge, to avoid creating any muddy turbidity, the Tomlins’ are arranging to have this requirement lifted. The outwardly tapering tailrace also slows the water’s velocity as it rejoins the river, some two and a half kilometres downstream from its point of diversion.
Around 48% of the river’s flow will be diverted, and returned as clean as it enters the pipeline. Baseline levels of micro flora, micro fauna and water quality have been taken by consultants, for ongoing monitoring once the system is in operation. The project has required close liaison with the local forestry landowner, Norske Skog Boyer Mills, and other local and state stakeholders.
Read the full article in ReNew 129.
As easy as DC to AC: inverter basics
Almost all renewable energy systems use at least one inverter. But what exactly are they and how do they work? Lance Turner explains.
Solar panels produce DC electricity, and batteries store DC. However, common household appliances are all designed for the AC mains power grid and so can’t be used with DC electricity directly. The inverter solves this problem by converting DC into AC. There are a number of different types of inverters for different uses, and inverters have a number of different ratings that it is important to understand.
DC versus ACREAD MORE »
Firstly, let’s explain those two terms—DC and AC. DC is short for direct current. This means that current only flows in one direction. This is the type of current produced by batteries and solar panels. AC stands for alternating current. This is the type of current supplied by the mains power grid. It rapidly reverses direction 100 times per second and there are two reversals per cycle, so the mains grid frequency (in Australia) is 50 cycles per second, or 50 Hertz (Hz).
The reason AC is used in the mains grid is that, firstly, this is the type of electricity produced by rotating generators (more accurately called alternators) used to generate electricity in large power stations. Also, AC allows for simple voltage conversion using transformers, so power can be transported long distances at very high voltages and then stepped down using a simple transformer (basically a block of iron with some insulated copper windings wrapped around it) to voltages safe for domestic use. Converting DC to a different voltage takes a lot more effort— something that couldn’t be done efficiently when the grid was first designed. So too does converting DC to AC, but thanks to modern semiconductors, producing AC mains power from a DC source is now quite easy.
Grid-interactive inverters are now the most common type of inverter, with over 1 million of them installed across Australia as a part of rooftop solar systems. They take DC power from a renewable energy source, such as a solar panel array, and convert it into AC power.
Note that a grid-interactive inverter can’t supply power to the house if the mains grid is down. This is a safety feature called anti-islanding; it prevents export of power at the time of a grid failure, thus protecting people working on the powerlines. The inverter can’t just disconnect from the grid and still power the home as the output from the solar panels varies depending on conditions, so the inverter output is unknown at any given time. By shutting down, the inverter also prevents your appliances from being affected by fluctuations in voltage that could occur if powered directly
The power from grid-interactive inverters is used inside the home or, if you’re generating in excess of what you’re using, the excess gets fed in to the grid.
Microinverters are a subset of grid-interactive inverters. Rather than having one large inverter that all of the solar panels feed into (often called a string inverter), microinverters are tiny inverters that are mounted on the back of each solar panel. They only convert the energy from their own panel (or sometimes a pair of panels), so they are much smaller and lighter than a string inverter, and each microinverter feeds AC power independently into the grid/ home. This makes them better suited to some installations, such as when one or more panels in an array might be shaded or become dirty, as the reduced output from one panel has no effect on the rest.
Read the full article in ReNew 129.
Renewable energy courses guide
With enrolment time for next year approaching, we’ve updated our renewable energy courses guide. Mischa Vickas investigates what’s on offer and the opportunities available.
“Things will keep happening, almost regardless of what happens on the political stage,” says Associate Professor Alistair Sproul from the School of Photovoltaic and Renewable Energy Engineering at the University of NSW; a promising remark at a time of great uncertainty for the renewable energy industry in Australia.READ MORE »
Despite this uncertainty, there still remain many opportunities to become involved in renewable energy (RE) through study and training, whether you are a school-leaver or professional looking to diversify your career. TAFE, university and distance-education courses all provide avenues to entering an industry bound to flourish as Australia looks for sustainable, reliable and affordable energy.
At the front line of the industry are those who directly handle RE technologies. According to the Clean Energy Council, 21,000 people were directly employed by the industry in Australia in construction, installation, operation and maintenance roles at the end of 20131. As a comparison, 27,600 people were employed in oil and gas extraction as of May 20142.
David Tolliday, Renewable Energy Training Coordinator at Holmesglen Institute in Victoria, says the greatest opportunities are for licensed electricians looking to be trained in the design and installation of photovoltaic (PV) systems (both grid-connected and stand-alone) and small wind systems. David says the motivation for undertaking such study is often the prospect of new employment or business development, but at the core of this can be a personal drive to see RE developed in Australia; “I’ve got a passion for it,” he says. David, who has also worked as an electrician for 35 years, undertook training in RE about 10 years ago, and has since benefitted from opportunities to work and teach in RE both in Australia and overseas.
Importantly, RE training is additional to a basic electricians qualification, meaning electricians can diversify into RE while continuing to offer standard products and services.
These courses are offered at over 15 training schools across Australia. If you are not a qualified electrician, a small handful of schools also offer courses in related areas, such as solar sales, carbon accounting and energy auditing, and wind energy site assessment, as well as generalist RE courses that are most suited to architects, engineers and project managers in the construction industry.
An engineering qualification at the undergraduate or postgraduate level can also enable a career in RE research and project management, particularly for emerging large-scale solar and wind technologies. “Renewable energy and energy efficiency is going to be very disruptive to what we are doing now and we need people who can figure it out,” says Alistair.
Whilst a mechanical or electrical engineering degree can provide you with the general skills relevant to RE, students can also undertake engineering degrees majoring in RE, PV and solar, sustainable systems, as well as environmental engineering.
Although the majority of students at university are school leavers, Alistair says that some students are already professionals in engineering or the physical sciences looking to update their qualifications, and some of these go on to start up their own businesses in RE and energy efficiency.
Read the full article in ReNew 129, or download our extensive renewable energy courses table.
Efficient hot water buyers guide
If your old hot water system has seen better days, maybe it’s time for an efficient replacement. We show you how solar and heat pump hot water systems work, what’s available and how to choose one to best suit your needs.
As the price of energy keeps escalating, the idea of being able to reduce energy use has never been more attractive. One of the biggest energy users in any home is water heating—it can account for around 21% of total energy use (on average, according to YourHome). Water-efficient appliances are one way you can reduce energy use, but far greater energy reductions are possible if you replace a conventional water heater with a solar or heat pump system.READ MORE »
Such systems have the added advantage of also reducing your greenhouse emissions. For example, for an average family the reduction can be as much as four tonnes of CO2 per year— the equivalent of taking a car off the road!
Currently only SA and Victoria offer state government rebates for solar and heat pump water heaters, but STCs (small-scale technology certificates; each STC is equivalent to the one megawatt hour of electricity the system will displace over a 10-year period) are still available across Australia.
STCs can save you a great deal on the cost of a new water heater, making it more economically viable. Note that the rebates and STCs are usually arranged by the supplier so you don’t need to do any paperwork to receive the discount. The price will probably still be higher than a similarly sized conventional water heater but the savings made in running costs will pay for this difference in 5 to 10 years in most cases.
How they work
SOLAR HOT WATER SYSTEMS
A solar hot water system usually consists of a hot water storage tank connected via pipework to solar collector panels. These collector panels are placed on a (preferably) north-facing roof. The tank can be situated immediately above the panels on the roof (a close-coupled system), above and a small distance away from the panels within the roof cavity, or at ground level (a split or remote-coupled system). For split systems, a pump and controller are required to circulate water through the panels. The collectors are usually mounted at an angle of no less than 15° from the horizontal (the minimum angle for close coupled systems to ensure correct thermosyphon operation), although often a lot steeper to optimise the system performance for winter.
As the sun shines on a collector panel, the water in the pipes inside the collectors becomes hot. This heated water is circulated up the collector and out through a pipe to the storage tank. Cooler water from the bottom of the tank is then returned to the bottom of the collector, replacing the warmer water.
Some systems don’t heat the water directly but instead heat a fluid similar to antifreeze used in vehicle cooling systems. This fluid flows in a closed loop and transfers the collected heat to the water in the tank via a heat exchanger.
A heat pump is a process used in refrigeration where heat is moved, or ‘pumped’, from one medium into another. Air conditioners and refrigerators are the most common forms of heat pumps. For example, in a refrigerator, heat is pumped from the food and dumped to the air outside the fridge via the coil at the back.
Heat pump hot water systems are electric water heaters that concentrate low-grade heat from the air and dump it into the water storage tank. They are much more efficient than conventional resistive electric water heaters: compared to resistive heaters, they are generally capable of reducing year-round energy requirements for hot water by at least 50%, and by as much as 78% depending on the climate, brand and model.
The most common systems are air-source heat pumps, but ground-source heat pumps are also available. While their efficiency can be even higher than an air-source heat pump, they are a great deal more expensive and are often not economically viable. But if efficiency is the primary goal then they should be considered, especially if you are in the market for both water and space heating systems. We looked at ground-source heat pumps in ReNew 112.
The complete article looks at solar versus heat pumps, sizing, installation, retrofitting existing systems, warranties and more.
Read the full Efficient Hot Water Buyers Guide in ReNew 129.
Help for zero emissions homes
Beyond Zero Emissions has launched a project to help householders achieve a zero emissions home.
In BZE’s Energy Freedom initiative, householders take an online pledge to achieve ‘energy freedom’ and in turn are assisted by various expert organisations within the Energy Freedom alliance.READ MORE »
The Alliance, a network of sustainability business such as solar installers and LED lighting retailers, provides homeowners with easy to follow information to reduce energy use at home, as well as access to discounted energy saving products.
The project engages householders to turn their homes into ‘renewable energy powerhouses’ while driving change in government policies on residential energy efficiency and renewable energy. The project puts the recommendations of BZE’s Zero Carbon Australia Buildings Plan released earlier this year into action.
“With readily available technology, some know-how and some ambition, homeowners can move to higher energy efficiency, generate electricity from their own solar energy, and achieve energy freedom.”
For more information go to www.energyfreedom.com.au
The power of microgrids
Why is there a lot of research and commercial interest in microgrids right now? Mitchell Lennard explains.
The term ‘microgrid’ covers a large range of energy system architectures. Researchers with a background in utility-scale electrical engineering tend to refer to any system smaller than, for example, the Victorian state grid, as a microgrid. At the other end of the scale, many designers see remote area power systems (RAPS) as the best representation.READ MORE »
The Microgrids at Berkeley project, one of the centres of excellence in this area of research (building-microgrid.lbl.gov), uses the following definition.
“Microgrids are electricity distribution systems containing loads and distributed energy resources (such as distributed generators, storage devices or controllable loads) that can be operated in a controlled, coordinated way either while connected to the main power network or while islanded (disconnected from the grid).”
This definition covers a wide range of system capacities and technologies. It certainly covers the sorts of systems that ATA members have been perfecting over several decades. It could even cover power systems in ships and aircraft.
The main reason there is growing interest in microgrids is that many of the generating technologies referred to as renewable (think PV, small wind, small hydro, solar thermal, wave) are all suited to and in some cases best used in microgrid or distributed energy system configurations.
The 2009 CSIRO report A Value Proposition for Distributed Energy in Australia concluded that: “In general, distributed generation appears to be an effective early action greenhouse gas mitigation option for Australia when it is considered within a portfolio of other mitigation options…but before distributed energy achieves wide-scale uptake, technology and market development needs to be focused on reducing costs and improving reliability.”
This notion that distributed energy systems and microgrids are a quick way to get greenhouse advantageous renewable generation into the energy mix is the main driver for most microgrid development work presently underway.
While it is possible to categorise microgrids in a range of different ways (have a look at the Berkeley site for one such set of definitions) the main projects running around the world can be seen as falling into two broad categories: campus-scale and remote-area microgrids.Read the full article in ReNew 128
The Pears Report: The war on renewable energy
With neighbouring Asian countries investing millions or billions of dollars in renewable energy and energy efficiency, Alan Pears reflects on Australian policy in 2014.
Life is certainly interesting in Australia in 2014. What is most tragic is that our leaders seem to be uninterested in having transparent, balanced processes to work things through to a consensus position that is in the interests of society.READ MORE »
Every inquiry or audit seems to be stacked with partisan people, and has inadequate process to allow consensus to be built. Every announcement is full of PR spin and provides little information, much of which is selected to support a particular view. This is a serious challenge for democracy. Of course, in the energy sector, we’re used to this kind of behaviour.
Science also seems to be in disrepute. We are paying a high price for the lack of scientific training of our leaders and their advisers.
I visited China recently for an APEC sustainability workshop. I was the only westerner present at the invitation-only session, which made me feel very honoured. I was given the task of explaining Australia’s renewable energy policy to the attendees: they were all completely bemused. I then had to sit and listen as they took turns telling the group about the hundreds of millions or billions of dollars they were all investing in renewable energy and energy efficiency.
A recent report on Australia’s appliance energy efficiency program (at www. energyrating.gov.au) provided some great news, however. From a base year of 2000, the program is cutting greenhouse gas emissions by 13.5 million tonnes annually at a cost of minus $119 per tonne avoided (based on purchase and operating costs over appliance lifetime per tonne of emissions avoided). By my estimate, it is saving $3.2 billion on energy bills each year, $2.7 billion of which is saved by households. That’s around $300 per household on average. Just think, the average annual energy bill of $2000 could have been $300 higher! If we look at carbon pricing as part of a broader package, it is quite clear we can deliver a lot of abatement at zero or low cost by using a combination of policy tools.
Things are moving fast. On the one hand we have even more aggressive attempts to kill renewable energy and energy efficiency. But on the other hand, the incumbent industry is beginning to fragment and shift, as players come to accept the futility of trying to hold back the tide.
Apparently the Western Australian and Queensland governments, and the networks they own, are now subsidising fringe-of-grid consumers by more than a billion dollars a year. Two of their network operators have announced that they will help people in these areas go off-grid. It will save their governments a lot of money.
There may be a role for local governments to take over existing grids and manage a transition to microgrids. Network operators can offer services such as maintenance, monitoring and sale of equipment to make a profit—as I suggested in my column in ReNew 123. I hope there’s a nice big cheque in the mail in recognition of my advice!
This is not news. In its 1991–92 annual report, the State Electricity Commission of Victoria pointed out that residents in rural towns cost 50% more to supply than they paid, while rural outlying homes cost double what they paid. Most state governments have maintained these subsidies for political reasons.
The retailer sector is also undergoing rapid change. A number of community groups are serious about setting up not-for-profit energy retailing businesses. And some new business models are appearing, such as the (presently) Victoria-only PowerShop. Check out the blog on PowerShop’s website for some interesting views on the direction of energy markets.
The Productivity Commission and the federal government are keen to see more privatisation of the electricity industry. PV, shifting off-grid, investment in large renewable energy projects, energy efficiency and demand management all do that: so why is the government opposed to them? The government’s Green Paper is due out in May, so it will be interesting to see what position it takes.
This review’s design is a clear declaration of war on renewable energy by government on behalf of the incumbent electricity industry. It will be very interesting to watch the attempts to manipulate economic analysis and policy objectives to fit the outcome.
I have made a submission to the Inquiry pointing out that renewable energy policy operates within a broader context, and that, when this is considered, a stable RET is a sensible and financially responsible policy— as concluded by the 2012 Climate Change Authority Review.
From the limited information available, the Emission Reduction Fund will cost around $12 per tonne of avoided emissions. This alone justifies a RET if its net cost is under 1.2 cents per kilowatt-hour—which most agree it is. While the incumbent industry wants to shift to a (lower) target based on the actual percentage of 2020 electricity sales, keeping the existing fixed target is very important for investor certainty. The industry itself has argued strongly for a fixed target in the past, when that option suited them. They can’t have it both ways.
Indeed, the uncertainty created by this review has unnecessarily increased the cost and difficulty of meeting the 2020 target by undermining investment. That extra cost should not be counted against the RET: it is an outcome of poor policy.
A 2009 report by the Australian Academy of Technological Sciences estimated that air pollution from coal-fired power stations cost Australians 1.3 cents per kilowatt-hour. The RET reduces this cost.
The decline in electricity demand is largely due to a range of separate factors and policies implemented by government such as successful energy efficiency programs (which are saving consumers much more than any RET cost); the high exchange rate driven by the mining boom that has made Australian industry uncompetitive; and big increases in electricity prices caused by unnecessary investment in electricity network infrastructure. So why is the RET blamed for these impacts on the incumbent electricity industry?
The electricity industry is supposed to be a competitive market. The incumbent industry can choose to invest in renewable energy and other emerging technologies to make profits from the RET—as they have done in the past, and WA and Qld network operators seem poised to do. They can even write off losses from existing infrastructure against profits from new activities.
The present high electricity costs are outcomes of their decisions. Independent consultant Bruce Mountain estimates that networks need not have spent about $20 billion of the $40 billion invested over the past few years. If they had saved this money, electricity prices would be at least a cent per kilowatt-hour cheaper: this would have offset much of the claimed RET cost for consumers.
So when we look at claimed costs for the RET, we see they are small compared with the outcomes of many other decisions, some taken by governments, and others by existing industries. On this basis, the RET looks like good value for money. It is also positioning Australia for a better, more competitive future.
In any case, how many Australians outside the energy sector would see the RET over-achieving as a bad thing? For decades, surveys have shown that most Australians want an efficient, renewable energy future. Governments and the industry has chosen not to deliver what we want. This is their chance to catch up.
We must remember that change usually brings challenges, creates winners and losers, and can even create some short-term costs. But just think where we would be if the government had helped Telstra’s landline business to block the rollout of mobile phones and the internet.
Alan Pears has worked on sustainable energy issues since the late 1970s. He is one of Australia’s best recognised and most highly awarded commentators on sustainable energy and climate issues. He teaches part time at RMIT University and is co-director of Sustainable Solutions, a small consultancy.
Read more articles on energy efficiency in ReNew 128.
An eye for detail
Stephen Whately is ReNew’s dedicated proofreader and long term member of the organisation. He talks to Beth Askham about his favourite places and zero carbon house.
Every word in ReNew (and there are a lot of them) has been read and re-read before it reaches your eyes. With a coffee in one hand and a pen in the other, one person in particular has pored over every page, searching carefully through text and tables for errors. There are very few spelling or grammatical mistakes that escape Stephen’s eagle eye.READ MORE »
Stephen comes into ReNew HQ, the ATA office, with dependable, regular timing, two to three weeks before each issue goes to print. He bravely volunteers his time to make sure the ReNew that reaches you is not studded with errors. He has been proofreading ReNew’s pages for around eight years and has become a valuable and indispensable member of the ReNew team, contributing not just proofreading expertise but also technical knowledge, a dry sense of humour and article ideas.
Stephen’s knowledge of sustainable technology extends to his home where he has a 1 kW grid-connected solar system that exports more than the low 1.6 kWh he uses (on average) each day. He also has a separate 400 W stand-alone system, incorporating an old 12 V Telstra battery bank he picked up from a scrapyard in Bairnsdale. Many of his appliances, including his TV and radio, employ 12 V plugpacks, so the appliances can connect to the battery bank.
Being a lover of detail, he writes his energy consumption down in a spreadsheet from daily readings from his inverter. Gas use and petrol consumption are also written down in the spreadsheet and he then totals them all up for the month, converting everything to kilowatt-hour equivalents. At the end of each month he comes out mostly in the negative thanks to his solar panels. It’s really a very thorough, exact system. In his own words: “I take things too seriously; it’s dreadful.”
The north-facing back of his house has a passive solar extension that he built himself and in the backyard he has fruit trees, a veggie patch and not a single scrap of lawn.
When not proofreading ReNew or sampling the classical musical offerings around Melbourne, Stephen might be removing the weed sea spurge from Wilsons Prom or the southwest of Tassie, where he recently took part in a program that has largely eliminated sea spurge from 600 km of coast.
If you come into the office you might see him, and if you do, bring him a coffee or perhaps some vegan sorbet, because he deserves it.
This article was published in ReNew 127. Buy your copy here.
Low-cost solar heating
Solar hydronic systems don’t have to be complex and expensive. Chris Hooley describes his simple and low-cost solar hydronic heater.
WINTERS in Melbourne used to be predictable: four months of sog from May to September. However, whether due to climate change, El Niño or simple drought, the winter of 2010 had a particular impact on me in that I kept coming home in the late afternoon to a very cold house, lit by shafts of brilliant winter sunshine. “Wouldn’t it be good,” I thought to myself, “if I could catch some of that energy and keep the house warm?”READ MORE »
I had a rough idea of what was available to make water hot using sunlight. Being a devoted handyman and incurable tinkerer, the seed of an idea took root and grew. My basic parameters were simple: I wanted a completely off-grid, stand-alone system that would ‘catch’ some energy in cooler months and put it to good use, without having to be plugged in or modified seasonally. Since the house already had gas central heating, the system would not need to meet all heating requirements but would rather take the edge off the cold on days when the sun happened to shine.
With this in mind I prowled eBay and mentally drew up plans until I could stand it no more and started buying parts. The key elements consisted of an evacuated-tube array piped to a fan-forced radiator. The collector heats the water and a pump transfers the hot water to the radiator in the house. A fan forces air through the radiator and into the room, heating it.
The system would be controlled by a thermo-switch and powered by a pair of 20 W PV panels. To avoid it freezing solid overnight or boiling away in summer and to eliminate the need for seasonal draining and refilling, I resolved to fill the whole system with car radiator coolant.
Read the full article in ReNew 127.