How protons can power our future energy needs

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The proton battery, connected to a voltmeter.
RMIT, Author provided

John Andrews, RMIT University

As the world embraces inherently variable renewable energy sources to tackle climate change, we will need a truly gargantuan amount of electrical energy storage.

With large electricity grids, microgrids, industrial installations and electric vehicles all running on renewables, we are likely to need a storage capacity of over 10% of annual electricity consumption – that is, more than 2,000 terawatt-hours of storage capacity worldwide as of 2014.

To put that in context, Australia’s planned Snowy 2.0 pumped hydro storage scheme would have a capacity of just 350 gigawatt-hours, or roughly 0.2% of Australia’s current electricity consumption.

Read more:
Tomorrow’s battery technologies that could power your home

Where will the batteries come from to meet this huge storage demand? Most likely from a range of different technologies, some of which are only at the research and development stage at present.

Our new research suggests that “proton batteries” – rechargeable batteries that store protons from water in a porous carbon material – could make a valuable contribution.

Not only is our new battery environmentally friendly, but it is also technically capable with further development of storing more energy for a given mass and size than currently available lithium-ion batteries – the technology used in South Australia’s giant new battery.

Potential applications for the proton battery include household storage of electricity from solar panels, as is currently done by the Tesla Powerwall.

With some modifications and scaling up, proton battery technology may also be used for medium-scale storage on electricity grids, and to power electric vehicles.

The team behind the new battery. L-R: Shahin Heidari, John Andrews, proton battery, Saeed Seif Mohammadi.
RMIT, Author provided

How it works

Our latest proton battery, details of which are published in the International Journal of Hydrogen Energy, is basically a hybrid between a conventional battery and a hydrogen fuel cell.

During charging, the water molecules in the battery are split, releasing protons (positively charged nuclei of hydrogen atoms). These protons then bond with the carbon in the electrode, with the help of electrons from the power supply.

In electricity supply mode, this process is reversed: the protons are released from the storage and travel back through the reversible fuel cell to generate power by reacting with oxygen from air and electrons from the external circuit, forming water once again.

Essentially, a proton battery is thus a reversible hydrogen fuel cell that stores hydrogen bonded to the carbon in its solid electrode, rather than as compressed hydrogen gas in a separate cylinder, as in a conventional hydrogen fuel cell system.

Unlike fossil fuels, the carbon used for storing hydrogen does not burn or cause emissions in the process. The carbon electrode, in effect, serves as a “rechargeable hydrocarbon” for storing energy.

What’s more, the battery can be charged and discharged at normal temperature and pressure, without any need for compressing and storing hydrogen gas. This makes it safer than other forms of hydrogen fuel.

Powering batteries with protons from water splitting also has the potential to be more economical than using lithium ions, which are made from globally scarce and geographically restricted resources. The carbon-based material in the storage electrode can be made from abundant and cheap primary resources – even forms of coal or biomass.

Read more:
A guide to deconstructing the battery hype cycle

Our latest advance is a crucial step towards cheap, sustainable proton batteries that can help meet our future energy needs without further damaging our already fragile environment.

The time scale to take this small-scale experimental device to commercialisation is likely to be in the order of five to ten years, depending on the level of research, development and demonstration effort expended.

Our research will now focus on further improving performance and energy density through use of atomically thin layered carbon-based materials such as graphene.

The ConversationThe target of a proton battery that is truly competitive with lithium-ion batteries is firmly in our sights.

John Andrews, Professor, School of Engineering, RMIT University

This article was originally published on The Conversation. Read the original article.


Greenwashing the property market: why ‘green star’ ratings don’t guarantee more sustainable buildings

Igor Martek, Deakin University and M. Reza Hosseini, Deakin University

Nothing uses more resources or produces more waste than the buildings we live and work in. Our built environment is responsible for half of all global energy use and half of all greenhouse gas emissions. Buildings consume one-sixth of all freshwater, one-quarter of world wood harvests and four-tenths of all other raw materials. The construction and later demolition of buildings produces 40% of all waste.

The sustainability of our buildings is coming under scrutiny, and “green” rating tools are the key method for measuring this. Deakin University’s School of Architecture and Built Environment recently reviewed these certification schemes. Focus group discussions were held in Sydney and Melbourne with representatives in the field of sustainability – including government, green consultancies and rating tool providers.

Two main concerns emerged from our review:

  1. Sustainability ratings tools are not audited. Most ratings tools are predictive, while those few that take measurements use paid third parties. Government plays no active part.

  2. The sustainability parameters measured only loosely intersect with the building occupants’ sustainability concerns. Considerations such as access to transport and amenities are not included.

Focus group sessions run by Deakin University helped identify problems with current sustainability ratings.
Author provided

Read more:
Construction industry loophole leaves home buyers facing higher energy bills

That’s the backdrop to the sustainability targets now being adopted across Australia. Australia has the highest rate of population growth of any developed country. The population now is 24.8 million. It is expected to reach between 30.9 and 42.5 million people by 2056.

More buildings will be needed for these people to live and work in. And we will have to find ways to ensure these buildings are more sustainable if the targets now being adopted are to be achieved.

Over 80% of local governments have zero-emissions targets. Sydney and Canberra have committed to zero-carbon emissions by 2050. Melbourne has pledged to be carbon-neutral by 2020.

So how do green ratings work?

Each green rating tool works by identifying a range of sustainability parameters – such as water and energy use, waste production, etc. The list of things to be measured runs into the dozens. Tools differ on the parameters measured, method of measurement, weightings given and the thresholds that determine a given sustainability rating.

There are over 600 such rating tools worldwide. Each competes in the marketplace by looking to reconcile the credibility of its ratings with the disinclination of developers to submit to an assessment that will rate them poorly. Rating tools found in Australia include Green Star, NABERS, NatHERS, Circles of Sustainability, EnviroDevelopment, Living Community Challenge and One Planet Communities.

So, it is easy enough to find landmark developments labelled with green accreditations. It is harder to quantify what these actually mean.

Read more:
Green building revolution? Only in high-end new CBD offices

Ratings must be independently audited

Government practice, historically, has been to assure building quality through permits. Planning permits ensure a development conforms with city schemes. Building permits assess structural load-bearing capacity, health and fire safety.

All this is done off the plan. Site inspections take place to verify that the building is built to plan. But once a certificate of occupancy is issued, the government steps aside.

The sustainability agenda promoted by government has been grafted onto this regime. Energy efficiency was introduced into the residential building code in 2005, and then into the commercial building code in 2006. At first, this was limited to new buildings, but then broadened to include refurbishment of existing structures.

Again, sustainability credentials are assessed off the plan and certification issued once the building is up and running. Thereafter, government walks away.

We know of only one longitudinal energy performance study carried out on domestic residences in Australia. It is an as-yet-unpublished project conducted by a retiree from the CSIRO, working with Indigenous communities in Far North Queensland.

The findings corroborate a recent study by Gertrud Hatvani-Kovacs and colleagues from the University of South Australia. This study found that so-called “energy-inefficient” houses, following traditional design, managed under certain conditions to outperform 6- and 8-star buildings.

Sustainability tools must measure what matters

Energy usage is but the tip of the iceberg. Genuine sustainability is about delivering our children into a future in which they have all that we have today.

Home owners, on average, turn their property around every eight years. They are less concerned with energy efficiency than with real estate prices. And these prices depend on the appeal of the property, which involves access to transport, schools, parks and amenities, and freedom from crime.

Commercial property owners, too, are concerned about infrastructure, and they care about creating work environments that retain valued employees.

These are all core sustainability issues, yet do not come up in the rating systems we use.

The ConversationIf government is serious about creating sustainable cities, it needs to let go of its limited, narrow criteria and embrace these larger concerns of “liveability”. It must embody these broader criteria in the rating systems it uses to endorse developments. And it needs an auditing and enforcement regime in place to make it happen.

Igor Martek, Lecturer In Construction, Deakin University and M. Reza Hosseini, Lecturer in Construction, Deakin University

This article was originally published on The Conversation. Read the original article.

The other 99%: retrofitting is the key to putting more Australians into eco-homes

Ralph Horne, RMIT University; Emma Baker, University of Adelaide; Francisco Azpitarte, University of Melbourne; Gordon Walker, Lancaster University; Nicola Willand, RMIT University, and Trivess Moore, RMIT University

Energy efficiency in Australian homes is an increasingly hot topic. Spiralling power bills and the growing problem of energy poverty are set against a backdrop of falling housing affordability, contested carbon commitments and energy security concerns.

Most people agree we need modern, comfortable, eco-efficient homes. This article is not about the relatively few, new, demonstration “eco-homes” dotted around Australia. It is about the rest of our housing.

These mainly ageing homes might have had energy efficiency improvements done over the years, but invariably are in need of upgrading to meet modern standards of efficiency and comfort.

Read more:
Thinking about a sustainable retrofit? Here are three things to consider

Since 2006, all new-build housing must meet higher energy efficiency standards. But we add only around 1% to the new housing stock each year.

Policies to improve energy efficiency in the other 99% are more fragmented. The focus is almost entirely on market-based incentives to “retrofit”. By this we mean material upgrades to improve housing energy and carbon performance.

The transition has begun

Nevertheless, a major retrofit transition is under way. In the last decade, around one in five Australian households has installed solar panels. More than three million upgrades have been carried out through the Victorian Energy Efficiency Target (now Victorian Energy Upgrades) initiative.

These impressive numbers describe a nationally important intervention. But does this mean we will soon all get to live in eco-homes, rather than just a lucky few?

Current retrofitting activity has occurred unevenly and may contribute to longer-term inequalities.

For example, rebates for deeper retrofits often are more accessible to the better-off home owners. They have matching cash and also rights to make major upgrades (as opposed to renters). This entrenches the existing reality that low-income renters tend to live in less energy-efficient homes.

Similarly, in the UK, retrofit incentives haven’t always successfully targeted those most in need. The distribution of costs has contributed to pushing up energy prices for those already in energy poverty. In Australia, up to 20% of households were already in energy poverty before recent price rises.

Thus, if poorly targeted and funded, energy efficiency initiatives might make existing dynamics worse and add to the cumulative vulnerabilities of housing affordability stress.

Read more:
Housing stress and energy poverty – a deadly mix?

Keeping track of how homes rate

We cannot effectively monitor this. This is because Australia has no robust, longitudinal national database of property condition. There is no established, widespread practice of property owners obtaining property condition reports that set out the energy-efficiency performance and the most viable improvements that could be made.

This means we do not have a systematic way of knowing what we should do next to our homes, even if we are lucky enough to own them and have some cash available, as well as the time and motivation to retrofit.

To the rescue, at least in Victoria, is the new Victorian Residential Efficiency Scorecard. This is an advance on previous attempts (as in the ACT and Queensland) to develop comparable assessments of the energy efficiency and comfort levels of your home. Although voluntary, the scorecard will provide owners with a report on their home and a list of measures they can consider to transform it “eco-homewards”.

So, is the scorecard the answer to our problems? Will it bring forward the date when we can all live in comfy eco-homes? It will certainly help.

Since 2010, the European Union has mandated ratings of how a building performs for energy efficiency and CO₂ emissions.

The European Union has had a mandatory system since the Energy Performance in Buildings Directive. The evidence suggests this has raised awareness of energy efficiency by literally putting labels of buildings in your face when you are deciding where to buy. It’s much like Australians have become used to energy efficiency labels on fridges and other appliances. However, evidence of this awareness actually leading to upgrade activity is more mixed and, in some cases, disappointing.

In short, we need the scorecard and should welcome it. However, we also need a set of other measures if we are to make the transformations to match our national policy objectives and our desires for a comfy eco-home.

What else needs to be done?

The research agenda is also shifting to explore the social and equity dimensions of the retrofit transition.

In areas where installation work on energy-efficiency/low-carbon retrofits is increasing, how is this working in households? Who makes decisions? How do they decide and with what resources? What or who do they call upon? And, more broadly, what are the positive or problematic consequences for equity and, therefore, for policy?

Read more:
What about the people missing out on renewables? Here’s what planners can do about energy justice

Emerging retrofit technologies and behaviours have broader social and economic contexts. This means we need to understand the wider meanings and practices of homemaking, the uneven social and income structures of households, and the home improvement service industry.

While the retrofit transition is arguably under way, its consequences and dynamics are still largely unknown. We need to refocus away from simply counting solar systems towards understanding retrofitting better. This depends on understanding both the households that are retrofitting their homes and the industries and organisations that supply them.

The ConversationTo get energy policies right and overcome energy poverty, we need to bring together studies and initiatives in material consumption, sustainability and social justice.

Ralph Horne, Deputy Pro Vice Chancellor, Research & Innovation; Director of UNGC Cities Programme; Professor, RMIT University; Emma Baker, Associate Professor, School of Architecture and Built Environment, University of Adelaide; Francisco Azpitarte, Ronald Henderson Research Fellow Melbourne Institute of Applied Economic and Social Research & Brotherhood of St Laurence, University of Melbourne; Gordon Walker, Professor at the DEMAND Centre and Lancaster Environment Centre, Lancaster University; Nicola Willand, Research Consultant, Sustainable Building Innovation Laboratory, RMIT University, and Trivess Moore, Research Fellow, RMIT University

This article was originally published on The Conversation. Read the original article.


Charging ahead: how Australia is innovating in battery technology

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Since sodium is abundant, battery technology that uses it side-steps many of the issues associated with lithium batteries.
Paul Jones/UOW, Author provided

Jonathan Knott, University of Wollongong

Lithium-ion remains the most widespread battery technology in use today, thanks to the fact that products that use it are both portable and rechargeable. It powers everything from your smartphone to the “world’s biggest battery” in South Australia.

Demand for batteries is expected to accelerate in coming decades with the increase in deployment of electric vehicles and the need to store energy generated from renewable sources, such as solar photovoltaic panels. But rising concerns about mining practices and shortages in raw materials for lithium-ion batteries – as well as safety issues – have led to a search for alternative technologies.

Many of these technologies aren’t being developed to replace lithium-ion batteries in portable devices, rather they’re looking to take the pressure off by providing alternatives for large-scale, stationary energy storage.

Australian companies and universities are leading the way in developing innovative solutions, but the path to commercial success has its challenges.

Read more:
A month in, Tesla’s SA battery is surpassing expectations

Australian alternatives

Flow batteries

In flow batteries the cathode and anode are liquids, rather than solid as in other batteries. The advantage of this is that the stored energy is directly related to the amount of liquid. That means if more energy is needed, bigger tanks can be easily fitted to the system. Also, flow batteries can be completely discharged without damage – a major advantage over other technologies.

ASX-listed battery technology company Redflow has been developing zinc-bromine flow batteries for residential and commercial energy storage. Meanwhile, VSUN Energy is developing a vanadium-based flow battery for large-scale energy storage systems.

Flow batteries have been receiving considerable attention and investment due to their inherent technical and safety advantages. A recent survey of 500 energy professionals saw 46% of respondents predict flow battery technology will soon become the dominant utility-scale battery energy storage method.

Redflow ZBM2 zinc-bromine flow battery cell.
from Redflow


Lead-acid batteries were invented in 1859 and have been the backbone of energy storage applications ever since. One major disadvantage of traditional lead-acid batteries is the faster they are discharged, the less energy they can supply. Additionally, the lifetime of lead-acid batteries significantly decreases the lower they are discharged.

Energy storage company Ecoult has been formed around CSIRO-developed Ultrabattery technology – the combination of a lead-acid battery and a carbon ultracapacitor. One key advantage of this technology is that it is highly sustainable – essentially all components in the battery are recyclable. Ultrabatteries also address the issue of rate-dependent energy capacity, taking advantage of the ultracapacitor characteristics to allow high discharge (and charge) rates.

These batteries are showing excellent performance in grid-scale applications. Ecoult has also recently received funding to expand to South Asia and beyond.

Ecoult Ultrabatteries photographed during installation on site.

Read more:
Politically charged: do you know where your batteries come from?

Repurposed storage solutions

Rechargeable batteries are considered to have reached their “end of life” when they can only be charged to 80% of their initial capacity. This makes sense for portable applications – a Tesla Model S would have a range of 341 km compared to the original 426 km. However, these batteries can still be used where reduced capacity is acceptable.

Startup Relectrify has developed a battery management system that allows end of life electric vehicle batteries to be used in residential energy storage. This provides a solution to mounting concerns about the disposal of lithium-ion batteries, and reports that less than 5% of lithium-ion batteries in Europe are being recycled. Relectrify has recently secured a A$1.5m investment in the company.

Relectrify’s smart battery management system.
from Relectrify

Thermal energy storage

Energy can be stored in many forms – including as electrochemical, gravitational, and thermal energy. Thermal energy storage can be a highly efficient process, particularly when the sun is the energy source.

Renewable energy technology company Vast Solar has developed a thermal energy storage solution based on concentrated solar power (CSP). This technology gained attention in Australia with the announcement of the world’s largest CSP facility to be built in Port Augusta. CSP combines both energy generation and storage technologies to provide a complete and efficient solution.

1414 degrees is developing a technology for large-scale applications that stores energy as heat in molten silicon. This technology has the potential to demonstrate very high energy densities and efficiencies in applications where both heat and electricity are required. For example, in manufacturing facilities and shopping centres.

Research and development

Sodium-ion batteries

At the University of Wollongong I’m part of the team heading the Smart Sodium Storage Solution (S4) Project. It’s a A$10.5 million project to develop sodium-ion batteries for renewable energy storage. This ARENA-funded project builds upon previous research undertaken at the University of Wollongong and involves three key battery manufacturing companies in China.


We’ve selected the sodium-ion chemistry for the S4 project because it sidesteps many of the raw materials issues associated with lithium-ion batteries. One of the main materials we use to manufacture our batteries is sodium chloride – better known as “table salt” – which is not only abundant, but also cheap.

We’ll be demonstrating the sodium-ion batteries in a residential application at University of Wollongong’s Illawarra Flame House and in an industrial application at Sydney Water’s Bondi Sewage Pumping Station.

Sydney’s iconic Bondi Beach – the location for the demonstration of sodium-ion batteries.
Paul Jones/UOW

Gel-based zinc-bromine batteries

Gelion, a spin-off company from the University of Sydney, is developing gel-based zinc-bromine batteries – similar to the Redflow battery technology. They are designed for use in residential and commercial applications.

The Gelion technology is claimed to have performance comparable with lithium-ion batteries, and the company has attracted significant funding to develop its product. Gelion is still in the early stages of commercialisation, however plans are in place for large-scale manufacturing by 2019.

Challenges facing alternatives

While this paints a picture of a vibrant landscape of exciting new technologies, the path to commercialisation is challenging.

Not only does the product have to be designed and developed, but so does the manufacturing process, production facility and entire supply chain – which can cause issues bringing a product to market. Lithium-ion batteries have a 25 year headstart in these areas. Combine that with the consumer familiarity with lithium-ion, and it’s difficult for alternative technologies to gain traction.

One way of mitigating these issues is to piggyback on established manufacturing and supply chain processes. That’s what we’re doing with the S4 Project: leveraging the manufacturing processes and production techniques developed for lithium-ion batteries to produce sodium-ion batteries. Similarly, Ecoult is drawing upon decades of lead-acid battery manufacturing expertise to produce its Ultrabattery product.

Read more:
How to make batteries that last (almost) forever

Some challenges, however, are intrinsic to the particular technology.

For example, Relectrify does not have control over the quality or history of the cells it uses for their energy storage – making it difficult to produce a consistent product. Likewise, 1414 degrees have engineering challenges working with very high temperatures.

The ConversationForecasts by academics, government officials, investors and tech billionaires all point to an explosion in the future demand for energy storage. While lithium-ion batteries will continue to play a large part, it is likely these innovative Australian technologies will become critical in ensuring energy demands are met.

Jonathan Knott, Associate Research Fellow in Battery R&D, University of Wollongong

This article was originally published on The Conversation. Read the original article.


Semitransparent solar cells: a window to the future?

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Looking through semitransparent cells – one day these could be big enough to make windows.
UNSW, Author provided

Matthew Wright, UNSW and Mushfika Baishakhi Upama, UNSW

Can you see a window as you are reading this article?

Windows have been ubiquitous in society for centuries, filling our homes and workplaces with natural light. But what if they could also generate electricity? What if your humble window could help charge your phone, or boil your kettle?

With between 5 billion and 7 billion square metres of glass surface in the United States alone, solar windows would offer a great way to harness the Sun’s energy. Our research represents a step toward this goal, by showing how to make solar panels that still let through enough light to function as a window.

Read more:
Solar is now the most popular form of new electricity generation worldwide

The economics of renewable energy are becoming increasingly favourable. In Australia, and many other parts of the world, silicon solar cells already dominate the rooftop market.
Rooftop solar power offers an increasingly cheap and efficient way to generate electricity.

But while great for roofs, these silicon modules are opaque and bulky. To design a solar cell suitable for windows, we have to think outside the box.

When we put a solar panel on a roof, we want it to absorb as much sunlight as possible, so that it can generate the maximum amount of power. For a window, there is inevitably a trade-off between absorbing light to turn into electricity, and transmitting light so we can still see through the window.

When thinking about a cell that could be fitted to a window, one of the key parameters is known as the average visible transmittance (AVT). This is the percentage of visible light (as opposed to other wavelengths, like infrared or ultraviolet) hitting the window that travels through it and emerges on the other side.

Semitransparent solar cells convert some sunlight into electricity, while also allowing some light to pass through.
Author provided

Of course we don’t want the solar window to absorb so much light that we can longer see out of it. Nor do we want it to let so much light through that it hardly generates any solar power. So scientists have been trying to find a happy medium between high electrical efficiency and a high AVT.

A matter of voltage

An AVT of 25% is generally considered a benchmark for solar windows. But letting a quarter of the light travel through the solar cell makes it hard to generate a lot of current, which is why the efficiency of semitransparent cells has so far been low.

But note that electrical power depends on two factors: current and voltage. In our recent research, we decided to focus on upping the voltage. We carefully selected new organic absorber materials that have been shown to produce high voltage in non-transparent cells.

When placed in a semitransparent solar cell, the voltage was also high, as it was not significantly lowered by the large amount of transmitted light. And so, although the current was lowered, compared to opaque cells, the higher voltage allowed us to achieve a higher efficiency than previous semitransparent cells.

Having got this far, the key question is: what would windows look like if they were made of our new semitransparent cells?

Do you see what I see?

If your friend is wearing a red shirt, when you view them through a window, their shirt should appear red. That seems obvious, as it will definitely be the case for a glass window.

But because semitransparent solar cells absorb some of the light we see in the visible spectrum, we need to think more carefully about this colour-rendering property. We can measure how well the cell can accurately present an image by calculating what’s called the colour rendering index, or CRI. Our investigation showed that changing the thickness of the absorbing layer can not only affect the electrical power the cell can produce, but also changes its ability to depict colours accurately.

A different prospective approach, which can lead to excellent CRIs, is to replace the organic absorber material with one that absorbs energy from the sun outside the visible range. This means the cell will appear as normal glass to the human eye, as the solar conversion is happening in the infrared range.

However, this places limitations on the efficiency the cells can achieve as it severely limits the amount of power from the sun that can be converted to electricity.

What next?

So far we have created our cells only at a small, prototype scale. There are still several hurdles in the way before we can make large, efficient solar windows. In particular, the transparent electrodes used to collect charge from these cells can be brittle and contain rare elements, such as indium.

Read more:
Solar power alone won’t solve energy or climate needs

If science can solve these issues, the large-scale deployment of solar-powered windows could help to bolster the amount of electricity being produced by renewable technologies.

The ConversationSo while solar windows are not yet in full view, we are getting close enough to glimpse them.

Matthew Wright, Postdoctoral Researcher in Photovoltaic Engineering, UNSW and Mushfika Baishakhi Upama, PhD student [Photovoltaics & Renewable Energy Engineering], UNSW

This article was originally published on The Conversation. Read the original article.


Home biogas: turning food waste into renewable energy

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The home biogas system offers a zero-emissions alternative to paying for fossil gas.
Samuel Alexander, Author provided

Samuel Alexander, University of Melbourne

Last night I cooked my family a delicious pasta dinner using biogas energy. This morning we all had eggs cooked on biogas. I’m not sure what’s for dinner tonight, but I know what will provide the energy for cooking: biogas.

And not just any biogas – it’s home biogas, produced in our suburban backyard, as part of my ongoing “action research” into sustainable energy practices.

Read more: Biogas: smells like a solution to our energy and waste problems

In an age of worrying climate change and looming fossil energy decline, the benefits of biogas are obvious. It is a renewable energy source with zero net greenhouse emissions. And yet its potential has largely gone untapped, at least in the developed world.

Based on my research and experience, I contend that home-produced biogas is an extremely promising technology whose time has come. In fact, I believe it could provoke a domestic green energy revolution, if only we let it.

What is biogas?

Biogas is produced when organic matter biodegrades under anaerobic conditions (that is, in the absence of oxygen). This process produces a mixture of gases – primarily methane, some carbon dioxide and tiny portions of other gases such as hydrogen sulfide.

When the biogas is filtered to remove the hydrogen sulfide, the resulting mixture can be burned as an energy source for cooking, lighting, or heating water or space. When compressed it can be used as fuel for vehicles. On a commercial scale biogas can be used to generate electricity or even refined and fed into the gas grid.

The types of organic matter used to produce biogas include food waste, animal manure and agricultural byproducts. Some commercial systems use sewage to produce and capture biogas.

Biogas benefits

The primary benefit of biogas is that it is renewable. Whereas the production of oil and other fossil fuels will eventually peak and decline, we will always be able to make biogas as long as the sun is shining and plants can grow.

Biogas has zero net greenhouse emissions because the CO₂ that is released into the atmosphere when it burns is no more than what was drawn down from the atmosphere when the organic matter was first grown.

As already noted, when organic matter biodegrades under anaerobic conditions, methane is produced. It has been estimated that each year between 590 million and 800 million tones of methane is released into the atmosphere. This is bad news for the climate – pound for pound, methane is a far more potent greenhouse gas than CO₂.

But in a biogas system this methane is captured and ultimately converted to CO₂ when the fuel is burned. Because that CO₂ was going to end up in the atmosphere anyway through natural degradation, biogas has zero net emissions.

There are other benefits too. The organic matter used in biogas digesters is typically a waste product. By using biogas we can reduce the amount of food waste and other organic materials being sent to landfill.

Furthermore, biogas systems produce a nutrient-rich sludge that can be watered down into a fertiliser for gardens or farms. All of this can help to develop increased energy independence, build resilience and save money.

My biogas experiment

In the spirit of scientific research, I installed one of the few home biogas systems currently available, at a cost of just over A$1,000 delivered, and have been impressed by its ease and functionality. (Please note that I have no affiliation, commercial or otherwise, with the manufacturer.)

In practical terms, I put in about 2kg of food waste each day and so far I have had enough gas to cook with, sometimes twice a day. If I ever needed more gas, I could put in more organic matter. I will continue to monitor the system as part of my research and will publish updates in due course. If interested, watch this space.

My personal motivation to explore biogas (related to my research) arises primarily from a desire to decarbonise my household’s energy use. So far, so good. We have disconnected from the conventional gas grid and now have more money to spend on projects such as expanding our solar array.

Given the alarming levels of food waste in Australia, I also like the idea of turning this waste into green energy. My neighbours kindly donate their organic matter to supplement our own inputs, increasing community engagement. When necessary I cycle to my local vegetable market and enthusiastically jump into their large food waste bin to take what I need, with permission.

They think I’m mad. But, then, I think using fossil fuels is mad.

Hurdles and hopes

Home biogas is widely produced in developing regions of the world. The World Bank and the United Nations actively encourage its use as a cheap, clean energy source. China has 27 million biogas plants.

But developed regions, including Australia, have been slow to exploit this vast potential. Given that Australia is one of the most carbon-intensive countries on Earth, this is unfortunate.

The failure to embrace home biogas is partly due to a lack of clear regulations about its use. Where is the Home Biogas Act? Almost every Australian backyard has an independent gas bottle to power the ubiquitous barbecue, so clearly storing gas in the backyard is not a problem. My biogas system came with robust safety certificates, warranties and insurance, and these systems do not feature high-pressure gas pipes.

Read more: Capturing the true wealth of Australia’s waste

Home biogas production is unusual. But I believe that state governments should draw up legislation to accommodate it, and that local councils should offer advice and assistance to householders who are interested in taking it up. Hoping for progress in this regard, I recently made a submission to the Victorian government as part of its Waste to Energy consultations.

The ConversationMy own carefully managed experiment demonstrates how home biogas can be used safely and successfully. Nevertheless, biogas is a combustible fuel and needs to be filtered for poisonous hydrogen sulfide. Like any fuel, it should be respected and used responsibly. But biogas need not be feared. Fossil gas is far more dangerous anyway.

Samuel Alexander, Research fellow, Melbourne Sustainable Society Institute, University of Melbourne

This article was originally published on The Conversation. Read the original article.


Sydney’s closer to being a zero-carbon city than you think

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The potential clean energy sources are all around Sydney, just waiting to be harnessed.
Author provided

Rob Roggema, University of Technology Sydney

You live in one of the sunniest countries in the world. You might want to use that solar advantage and harvest all this free energy. Knowing that solar panels are rapidly becoming cheaper and have become feasible even in less sunny places like the UK, this should be a no-brainer.

Despite this, the Australian government has taken a step backwards at a time when we should be thinking 30 years ahead.

Further reading: Will the national energy guarantee hit pause on renewables?

Can we do it differently? Yes, we can! My ongoing research on sustainable urbanism makes it clear that if we use the available renewable resources in the Sydney region we do not need any fossil resource any more. We can become zero-carbon. (With Louisa King and Andy Van den Dobbelsteen, I have prepared a forthcoming paper, Towards Zero-Carbon Metropolitan Regions: The Example of
Sydney, in the journal SASBE.)

Enough solar power for every household

Abundant solar energy is available in the Sydney metropolitan area. If 25% of the houses each installed 35 square metres of solar panels, this could deliver all the energy for the city’s households.

We conservatively estimate a total yield of 195kWh/m2 of PV panel placed on roofs or other horizontal surfaces. The potential area of all Sydney council precincts suited for PV is estimated at around 385km2 – a quarter of the entire roof surface.

We calculate the potential total solar yield at 75.1TWh, which is more than current domestic household energy use (65.3TWh, according to the Jemena energy company).

Further reading: What’s the net cost of using renewables to hit Australia’s climate target?

Wind turbines to drive a whole city

If we install small wind turbines on land and larger turbines offshore we can harvest enough energy to fuel our electric vehicle fleet. Onshore wind turbines of 1-5MW generating capacity can be positioned to capture the prevailing southwest and northeast winds.

The turbines are placed on top of ridges, making use of the funnel effect to increase their output. We estimate around 840km of ridge lines in the Sydney metropolitan area can be used for wind turbines, enabling a total of 1,400 turbines. The total potential generation from onshore wind turbines is 6.13TWh.

Offshore turbines could in principle be placed everywhere, as the wind strength is enough to create an efficient yield. The turbines are larger than the ones on shore, capturing 5-7.5MW each, and can be placed up to 30km offshore. With these boundary conditions, an offshore wind park 45km long and 6km wide is possible. The total offshore potential then is 5.18TWh.

Altogether, then, we estimate the Sydney wind energy potential at 11.3TWh.

Around 840km of ridge lines (marked in yellow and red) in the Sydney metropolitan area can be used for wind turbines.
Author provided

Further reading: FactCheck Q&A: is coal still cheaper than renewables as an energy source?

Turning waste into biofuels

We can turn our household waste and green waste from forests, parks and public green spaces into biogas. We can then use the existing gas network to provide heating and cooling for the majority of offices.

Biomass from domestic and green waste will be processed through anaerobic fermentation in old power plants to generate biogas. Gas reserves are created, stored and delivered through the existing power plants and gas grid.

Further reading: Biogas: smells like a solution to our energy and waste problems

Algae has enormous potential for generating bio-energy. Algae can purify wastewater and at the same be harvested and processed to generate biofuels (biodiesel and biokerosene).

Specific locations to grow algae are Botany Bay and Badgerys Creek. It’s noteworthy that both are close to airports, as algae could be important in providing a sustainable fuel resource for planes.

Using algae arrays to treat the waste water of new precincts, roughly a million new households as currently planned in Western Sydney, enables the production of great quantities of biofuel. Experimental test fields show yields can be high. A minimum of 20,000 litres of biodiesel per hectare of algae ponds is possible if organic wastewater is added. This quantity is realisable in Botany Bay and in western Sydney.

Biomass fermentation of household and green waste and wastewater treatment using algae arrays can generate biogas, biodiesel and biokerosene.
Author provided

Further reading: Biofuel breakthroughs bring ‘negative emissions’ a step closer

Extracting heat from beneath the city

Shallow geothermal heat can be tapped through heat pumps and establishing closed loops in the soil. This can occur in large expanses of urban developments within the metropolitan area, which rests predominantly on deposits of Wianamatta shale in the west underlying Parramatta, Liverpool and Penrith.

Where large water surfaces are available, such as in Botany Bay or the Prospect Reservoir, heat can also be harvested from the water body.

The layers of the underlying Hawkesbury sandstone, the bedrock for much of the region, can yield deep geothermal heat. This is done by pumping water into these layers and harvesting the steam as heat, hot water or converted electricity.

Sydney’s geology offers sources of both shallow and deep theothermal heat.
Author provided

Further reading: Explainer: what is geothermal energy?

Hydropower from multiple sources

The potential sources of energy from hydro generation are diverse. Tidal energy can be harvested at the entrances of Sydney Harbour Bay and Botany Bay, where tidal differences are expected to be highest.

Port Jackson, the Sydney Harbour bay and all of its estuaries have a total area of 55km2. With a tidal difference of two metres, the total maximum energy potential of a tidal plant would be 446TWh. If Sydney could harvest 20% of this, that would be more than twice the yield of solar panels on residential roofs.

If we use the tide to generate electricity, we can also create a surge barrier connecting Middle and South Head. Given the climatic changes occurring and still ahead of us, we need to plan how to protect the city from the threats of future cyclones, storm surges and flooding.

I have written here about the potential benefits of artificially creating a Sydney Barrier Reef. The reef, 30km at most out at sea, would provide Sydney with protection from storms.

At openings along the reef, wave power generators can be placed. Like tidal power, wave power can be calculated: mass displacement times gravity. If around 10km of the Sydney shoreline had wave power vessels, the maximum energy potential would be 3.2TWh.

In the mouths of the estuaries of Sydney Harbour and Botany Bay, freshwater meets saltwater. These places have a large potential to generate “blue energy” through reverse osmosis membrane technology.

To combine protective structures with tidal generating power, an open closure barrier is proposed for the mouth of Sydney Harbour. The large central gates need to be able to accommodate the entrance of large cruise ships and to close in times of a storm surge. At the same time, a tidal plant system operates at the sides of the barrier.

An artist’s impression of the Sydney Harbour surge barrier and tidal plant.
Drawing: Andy van den Dobbelsteen, Author provided

Further reading: Catching the waves: it’s time for Australia to embrace ocean renewable energy

Master plan for a zero-carbon city

All these potential energy sources are integrated into our Master Plan for a Zero-Carbon Sydney. Each has led to design propositions that together can create a zero-carbon city.

The Zero-Carbon Sydney Master Plan maps out how the city can be fossil-free.
Author provided

The ConversationThe research shows there is enough, more than enough, potential reliable renewable energy to supply every household and industry in the region. What is needed is an awareness that Australia could be a global frontrunner in innovative energy policy, instead of a laggard.

Rob Roggema, Professor of Sustainable Urban Environments, University of Technology Sydney

This article was originally published on The Conversation. Read the original article.