Can we safely burn waste to make fuel like they do in Denmark? Well, it’s complicated

The Amager Bakke power plant in Copenhagen, Denmark.

Thomas Cole-Hunter, Queensland University of Technology; Ana Porta Cubas, University of Sydney; Christina Magill, GNS Science, and Christine Cowie, UNSW

When it comes to handling the waste crisis in Australia, options are limited: we either export our waste or bury it. But to achieve current national targets, policy-makers are increasingly asking if we can instead safely burn waste as fuel.

Proposals for waste incinerators are being considered in the Greater Sydney region, but these have been lambasted by the Greens and independent members of the NSW parliament, who cite public health concerns.

Meanwhile, the ACT government has recently put a blanket ban on these facilities.

Read more:
China’s garbage ban upends US recycling – is it time to reconsider incineration?

But are their concerns based on evidence? In our systematic review of the scientific literature, we could identify only 19 papers among 269 relevant studies — less than 10% — that could help address our question on whether waste-to-energy incinerators could harm our health.

This means the answer remains unclear, and we therefore call for a cautious approach to waste-to-energy technology.

One person, one year, 500 kilograms of waste

Australia’s waste crisis began in 2018 when China greatly reduced how much waste it imported. China’s waste market was handling about half of the world’s recyclable materials, including Australia’s.

On average, Australia produces roughly 500 kilograms of municipal (residential and commercial) waste each year. This aligns with the OECD average.

New Zealand in comparison, despite its strong environmental stance, is among the worst offenders for producing waste in any OECD country. It produces almost 800 kilograms per person per year.

Now, most recyclable or reusable waste in Australia goes to landfill. This poses a potential risk to both climate and health with the emission of potent greenhouse gases such as methane and the leaching of heavy metals such as lead into the groundwater. As a result, local governments may want to seek alternative options.

Burning waste in Denmark

“Waste-to-energy” incineration is when solid waste is sorted and burned as “refuse-derived” fuel to generate electricity. This can replace fossil fuel such as coal.

Read more:
The recycling crisis in Australia: easy solutions to a hard problem

The technology is on the rise among OECD countries. Denmark and Japan, for example, rely on waste-to-energy incineration to reduce their dependency on landfills and reach carbon neutrality.

In fact, Denmark’s waste-to-energy incinerator, Amager Bakke, is so well known it has become a tourist attraction, and is celebrated as one of the world’s cleanest waste-to-energy incinerators.

Amager Bakke provides electricity to around 680,000 people.

Every day, around 300 trucks filled with non-recyclable municipal solid waste are sent to Amager Bakke.

This fuels a furnace that runs at 1,000℃, turning water into steam. And this steam provides electricity and heat to around 100,000 households. Generally, people in Denmark warmly welcome it.

So what’s the problem?

In Australia and the US, community reception towards the building of new incinerators has been cold.

The big concern is burning waste may release chemicals that can harm our health, such as nitrogen oxide and dioxin. Exposure to high levels of dioxin can lead to skin lesions, an impaired immune system and reproductive issues.

However, control measures, such as the technologically advanced filters used in Amager Bakke, can bring the amount of dioxin released to near zero.

Another concern is that implementing waste-to-energy incineration may go against recycling schemes, due to the potential for an increased demand for non-recyclable plastics as fuel.

A truck dumping waste to get incinerated
Burning waste may release substances that can harm our health, such as nitrogen oxide and dioxin.

Supply of this plastic could come from the waning fossil fuel industry. This would work against the goal of establishing a “circular economy” that reuses and recycles goods where possible.

An analysis from 2019 found that to meet European Union circular economy goals, Nordic countries would need to increase their recycling, and significantly shift away from incineration.

This concern is understandable given incinerators operate cleanest when fuelled at full capacity. This is because a higher temperature means a more complete combustion — a bit like less ash and smoke coming off of a well-built campfire.

A lack of evidence

As with many policy solutions, determining the safety of burning waste is complicated.

Our review found a lack of evidence to fully reject well-designed and operated facilities. However, based on the limited number of health studies we found, we support a precautionary planning approach to waste-to-energy proposals.

Read more:
Garbage in, garbage out: Incinerating trash is not an effective way to protect the climate or reduce waste

This means we need appropriate health risk assessment and life cycle analyses built into the approval process for each and every incinerator proposed in the near-future.

The studies we found were all performed in the last 20 years. None were from the Nordic countries, however, where waste-to-energy incineration has been in use for many decades.

The reasons for the Nordic embrace of this technology are speculative. One reason may be that their level of economic development allows large capital investment for safe, state-of-the-art design and operation.

Mechanical claw grabbing a huge pile of mixed waste.
Waste incineration goes against the goals of a circular economy.

Where to from here?

If councils are determined to pursue waste-to-energy incineration, we suggest they prioritise specific applications.

For example, we found the process with the most favourable life-cycle assessment (the most beneficial to health compared to traditional fossil fuel use) was the “co-incineration” of refuse-derived fuel for industrial cement.

Read more:
South African study highlights growing number of landfill sites, and health risks

Currently, cement kilns are mostly fuelled by burning coal, and it’s difficult to reach the high temperatures required with traditional renewables. This means substituting coal for refuse-derived fuel could reduce the industry’s dependency on coal, when renewables aren’t an option.

Another solution is to focus instead on the waste hierarchy. This means first minimising waste production, maximising energy efficiency and maximising recycling and reuse of waste materials.

So, while we wait for more knowledge on how waste-to-energy incineration may affect our health, let’s focus on improving our waste hierarchy, rather than exporting our waste to feed a global crisis.The Conversation

Thomas Cole-Hunter, Research fellow, Queensland University of Technology; Ana Porta Cubas, Knowledge and Translation Broker- Centre for Air pollution, energy and health Research (CAR), University of Sydney; Christina Magill, Senior Natural Hazards Risk Scientist, GNS Science, and Christine Cowie, Senior Research Fellow, Centre for Air Quality & Health Research and Evaluation, Woolcock Institute of Medical Research, University of Sydney; Senior Research Fellow, South West Sydney Clinical School, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia has failed miserably on energy efficiency – and government figures hide the truth

Dave Hunt/AAP

Hugh Saddler, Australian National University

Amid the urgent need to slow climate change by cutting greenhouse gas emissions, energy efficiency makes sense. But as Australia’s chief scientist Alan Finkel last week warned, we’re not “anywhere close to having that nailed”.

Energy efficiency means using less energy to achieve the same outcomes. It’s the cheapest way to cut greenhouse gas emissions and achieve our climate goals. Improving energy efficiency is also vital to achieving so-called “energy productivity” – getting more economic output, using the same or less energy.

But Australia’s national energy productivity plan, agreed by the nation’s energy ministers in 2015, has gone nowhere.

It set a goal of a 40% improvement in energy productivity by 2030. But my analysis, based on the most recent official data, shows that in the three years to 2017-18, energy productivity increased by a mere 1.1%.

Clearly, there is much work to do. So let’s take a look at the problem and the potential solutions.

Energy efficiency reduces power bills for consumers.
Julian Smith/AAP

Energy efficiency: a low-hanging fruit

Better energy efficiency lowers electricity bills, makes businesses more competitive and helps manage energy demand. Of course, it also means less greenhouse gas emissions, because fewer fossil fuels are burnt for energy.

Business, unions and green groups recognise the benefits. Last month they joined forces to call for a sustainable COVID-19 economic recovery, with energy efficiency at the core, saying:

In Australia, a major drive to improve the energy efficiency of buildings and industry could deliver over 120,000 job-years of employment […] Useful upgrades could be made across Australia’s private and public housing; commercial, community and government buildings; and industrial facilities.

The group said improvements could include:

  • more efficient and controllable appliances and equipment, especially for heating and cooling
  • improved shading and thermal envelopes (improving the way a building’s walls, ceiling and floors prevent heat transfer)
  • smart meters to measure energy use
  • distributed energy generation and storage, such as wind and solar backed by batteries
  • fuel switching (replacing inefficient fuels with cleaner and economical alternatives)
  • equipment, training and advice for better energy management.

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The International Energy Agency (IEA) has suggested other measures for industry and manufacturing, such as:

  • installing more efficient electric motors
  • switching from gas to electric heat pumps
  • more waste and material recycling.

And in transport, the IEA suggests incentives to get older, less efficient cars off the roads and encourage the uptake of electric vehicles.

Residential buildings offer big opportunities for energy efficiency improvements.
Brendan Esposito/AAP

Governments’ sleight of hand

In 2018 the IEA observed:

the power sector will be at the heart of Australia’s energy system
transformation […] International best practice suggests that both energy efficiency and renewable energy are key drivers of the energy transition.

Since then, renewable energy’s share of the electricity mix has increased. But energy productivity has stalled.

To understand how, we must define a few key terms.

Primary energy refers to energy extracted from the environment, such as coal, crude oil, and electrical energy collected by a wind turbine or solar panel.

Final energy is the energy supplied to a consumer, such as electricity delivered to homes or fuel pumped at a petrol station.

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A lot of energy is lost in the process of turning extracted primary fuels into ready-to-use fuels for consumers. For example at coal-fired power stations, on average, one-third of the energy supplied by burning coal is converted to electricity. The remainder is lost as waste heat.

Until 2015, Australia and most other countries used final energy as a measure of how rapidly energy efficiency was improving. But the national productivity plan instead set goals around primary energy productivity – aiming to increase it by 40% between 2015 and 2030.

This has made it possible for governments to hide how badly Australia is travelling on improving energy efficiency. I analysed national accounts figures and energy statistics, to produce the below table. It reveals the governments’ sleight of hand.

Over the three years from 2014-15 to 2017-18, final energy productivity increased by only 1.1%, whereas primary energy productivity increased by 3.5%.

The reduced primary energy consumption is mostly due to a large increase in wind and solar generation. The efficiency of energy used by final consumers has scarcely changed.

A sustainable future

The lack of progress on energy productivity is not surprising, given governments have shown very little interest in the issue.

As Finkel noted in his address, Australia’s energy productivity plan is absent from the list of national climate and energy policies. The plan’s 2019 annual report has not been released. And those released since 2015 have not monitored progress in energy productivity.

What’s more, the plan makes no mention of previous similar agreements, in 2004 and 2009, to accelerate energy efficiency with regulation and financial incentives. Since 2013, almost all Commonwealth programs supporting those agreements have been de-funded or abolished, and many state programs have also been cut back.

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The IEA’s sustainable recovery plan, released last week, outlined what a sustainable global economic recovery might look like. In particular, it said better energy efficiency and switching to more efficient electric technologies will deliver triple benefits: increased employment, a more productive economy and lower greenhouse gas emissions.

In this carbon-constrained world, relatively easy and cheap opportunities such as energy efficiency must be seized. And as Australia spends to get its post-pandemic economy back on track, now is the time to act.The Conversation

Hugh Saddler, Honorary Associate Professor, Centre for Climate Economics and Policy, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Really Australia, it’s not that hard: 10 reasons why renewable energy is the future

Lucy Nicholson/Reuters

Andrew Blakers, Australian National University

Australia’s latest greenhouse gas figures released today show national emissions fell slightly last year. This was by no means an economy-wide effort – solar and wind energy did most of the heavy lifting.

Emissions fell 0.9% last year compared to 2018. The rapid deployment of solar and wind is slashing emissions in the electricity sector, offsetting increases from all other sectors combined.

Read more:
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Renewables (solar, wind and hydro) now comprise 26% of the mix in the National Electricity Market. In 2023, renewables will likely pass black coal to become the largest electricity source.

In an ideal world, all sectors of the economy – transport, agriculture, manufacturing and others – would pull in the same direction to cut emissions. But hearteningly, these figures show the huge potential for renewables.

Here are 10 reasons why renewable energy makes perfect sense for Australia.

Australia leads the world in rooftop solar installations.
David Mariuz/AAP

1. It can readily eliminate fossil fuels

About 15 gigawatts of solar and wind farms will probably start operating over 2018-2021. That’s on top of more than 2 gigawatts of rooftop solar to be added each year.

It averages out at about 6 gigawatts of additional solar and wind power annually. Research from the Australian National University, which is under review, shows the rate only has to double to about 12 gigawatts to eliminate fossil fuels by 2050, including from electricity, transport, heating and industry.

Fossil fuel mining and use causes 85% of total national emissions – and doubling the renewables deployment rate would eliminate this.

The task becomes more than achievable when you consider the continual fall in renewables prices, which helped treble solar and wind deployment between 2017 and 2020.

2. Solar is already king

Solar is the top global energy technology in terms of new generation capacity added each year, with wind energy in second spot. Solar and wind energy are already huge industries globally, and employ 27,000 people in Australia – a doubling in just three years.

3. Solar and wind are getting cheaper

Solar and wind electricity in Australia already costs less than it would from new coal and gas plants.

The price is headed for A$30 per megawatt hour in 2030. This undercuts most existing gas and coal stations and competes with gas for industrial heating.

Renewable electricity is becoming cheaper than coal-fired power.
Petr Josek/Reuters

4. Stable renewable electricity is not hard

Balancing renewables is a straightforward exercise using existing technology. The current high voltage transmission network must be strengthened so projects in regional areas can deliver renewable electricity into cities. And if wind and sun is not plentiful in one region, a stronger transmission network can deliver electricity from elsewhere. Electricity storage such as pumped hydro and batteries can also smooth out supplies.

5. There’s enough land

To eliminate all fossil fuel use, Australia would need about 60 square metres of solar panel per person, and one wind turbine per 2,000 people. Panels on rooftops take up no land, and wind turbines use very little. If global energy consumption per person increased drastically to reach Australian levels, solar farms on just 0.1% of Earth’s surface could meet this demand.

6. Raw materials won’t run out

A solar panel needs silicon, a glass cover, plastic, an aluminium panel frame, copper and aluminium electrical conductors and small amounts of other common materials. These materials are what our world is made of. Recycling panel materials at the end of their life adds only slightly to larger existing recycling streams.

Solar panel materials are relatively easy to obtain.
Tim Winbourne/Reuters

7. Nearly every country has good sun or wind

Three-quarters of the global population lives in the planet’s sunbelt (lower than 35 degrees of latitude). This includes most developing countries, where most of the growth in energy consumption and greenhouse emissions is occurring.

8. We will never go to war over sunshine

Solar and wind power make energy systems much more robust in the face of a pandemic, disasters or war. They are difficult to misuse in any significant way for military, terrorist or criminal activities. And it is hard to destroy billions of solar panels spread over millions of square kilometres.

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9. Solar accidents and pollution are small

Solar panel accidents pale in comparison to spilled radioactive material (like Fukushima or Chernobyl), an oil disaster (like BP’s Deepwater Horizon), or a coal mine fire (like Hazelwood in Victoria). Wind and solar electricity eliminates oil imports, oil-related warfare, fracking for gas, strip mining for coal, smokestacks, car exhausts and smog.

10. Payback time is short

For a sunny country like Australia, the time required to recover the energy invested in panel manufacture is less than two years, compared with a panel lifetime of 30 years. And when the world is solar powered, the energy required to produce more panels is non-polluting.

Renewable energy can do they heavy lifting on emissions reduction.
Vincent West/Reuters

The future is bright

While COVID-19 triggered a significant fall in global emissions so far this year, they may bounce back. But if solar and wind deployment stay at current levels, Australia is tracking towards meeting its Paris target.

The Reserve Bank of Australia says investment in renewables may moderate in the near term, but “over the longer term, the transition towards renewable energy generation is expected to continue”.

But there are hurdles. In the short term, more transmission infrastructure is needed. Electrifying transport (with electric vehicles) and urban heating (with electric heat pumps) is straightforward. More difficult is eliminating fossil fuels from industries such as steel and fertilisers. This is a task for the 2030s.

But it’s clear that to get to net-zero carbon emissions by mid century, solar and wind are far and away Australia’s best option.

Read more:
Australia is the runaway global leader in building new renewable energy

The Conversation

Andrew Blakers, Professor of Engineering, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate explained: seven reasons to be wary of waste-to-energy proposals

Many developed countries already have significant waste-to-energy operations and therefore less material going to landfill.

Jeff Seadon, Auckland University of Technology


Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to

I was in Switzerland recently and discovered that they haven’t had any landfill since the early 2000s, because all of their waste is either recycled or incinerated to produce electricity. How “green” is it to incinerate waste in order to produce electricity? Is it something New Zealand should consider, so that 1) we have no more landfill, and 2) we can replace our fossil-fuel power stations with power stations that incinerate waste?

Burning rubbish to generate electricity or heat sounds great: you get rid of all your waste and also get seemingly “sustainable” energy. What could be better?

Many developed countries already have significant “waste-to-energy” incineration plants and therefore less material going to landfill (although the ash has to be landfilled). These plants often have recycling industries attached to them, so that only non-recyclables end up in the furnace. If it is this good, why the opposition?

Here are seven reasons why caution is needed when considering waste-to-energy incineration plants.

Read more:
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Stifling innovation and waste reduction

  1. Waste-to-energy plants require a high-volume, guaranteed waste stream for about 25 years to make them economically viable. If waste-to-energy companies divert large amounts of waste away from landfills, they need to somehow get more waste to maintain their expensive plants. For example, Sweden imports its waste from the UK to feed its “beasts”.

  2. The waste materials that are easiest to source and have buyers for recycling – like paper and plastic – also produce most energy when burned.

  3. Waste-to-energy destroys innovation in the waste sector. As a result of China not accepting our mixed plastics, people are now combining plastics with asphalt to make roads last longer and are making fence posts that could be replacing treated pine posts (which emit copper, chrome and arsenic into the ground). If a convenient waste-to-energy plant had been available, none of this would have happened.

  4. Waste-to-energy reduces jobs. Every job created in the incineration industry removes six jobs in landfill, 36 jobs in recycling and 296 jobs in the reuse industry.

  5. Waste-to-energy works against a circular economy, which tries to keep goods in circulation. Instead, it perpetuates our current make-use-dispose mentality.

  6. Waste-to-energy only makes marginal sense in economies that produce coal-fired electricity – and then only as a stop-gap measure until cleaner energy is available. New Zealand has a green electricity generation system, with about 86% already coming from renewable sources and a target of 100% renewable by 2035, so waste-to-energy would make it a less renewable energy economy.

  7. Lastly, burning waste and contaminated plastics creates a greater environmental impact than burning the equivalent oil they are made from. These impacts include the release of harmful substances like dioxins and vinyl chloride as well as mixtures of many other harmful substances used in making plastics, which are not present in oil.

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Landfills as mines of the future

European countries were driven to waste-to-energy as a result of a 2007 directive that imposed heavy penalties for countries that did not divert waste from landfills. The easiest way for those countries to comply was to install waste-to-energy plants, which meant their landfill waste dropped dramatically.

New Zealand does not have these sorts of directives and is in a better position to work towards reducing, reusing and recycling end-of-life materials, rather than sending them to an incinerator to recover some of the energy used to make them.

Is New Zealand significantly worse than Europe in managing waste? About a decade ago, a delegation from Switzerland visited New Zealand Ministry for the Environment officials to compare progress in each of the waste streams. Both parties were surprised to learn that they had managed to divert roughly the same amount of waste from landfill through different routes.

This shows that it is important New Zealand doesn’t blindly follow the route other countries have used and hope for the same results. Such is the case for waste-to-energy.

There is also an argument to be made for current landfills. Modern, sanitary landfills seal hazardous materials and waste stored over the last 50 years presents future possibilities of landfill mining.

Many landfills have higher concentrations of precious metals, particularly gold, than mines and some are being mined for those metals. As resources become scarcer and prices increase, our landfills may become the mines of the future.The Conversation

Jeff Seadon, Senior Lecturer, Auckland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia’s energy exports increase global greenhouse emissions, not decrease them

Frank Jotzo, Crawford School of Public Policy, Australian National University and Salim Mazouz, Australian National University

When unveiling government data revealing Australia’s rising greenhouse emissions, federal energy minister Angus Taylor sought to temper the news by pointing out that much of the increase is due to liquefied natural gas (LNG) exports, and claiming that these exports help cut emissions elsewhere.

LNG exports, Taylor argued, help to reduce global emissions by replacing the burning of coal overseas, which has a higher emissions factor than gas. In reality, Australian gas displaces a mix of energy sources, including gas from other exporters. Whether and to what extent Australian gas exports reduce emissions therefore remains unclear. Meanwhile, Australia’s coal exports clearly do increase global emissions.

The way Australia can help clean up world energy systems in the future is through large-scale production and export of renewable energy.

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In a statement accompanying the latest quarterly emissions figures, the Department of Environment and Energy stated:

Australia’s total LNG exports are estimated to have the potential to lower emissions in importing countries by around 148Mt CO₂-e [million tonnes of carbon dioxide equivalent] in 2018, if they displace coal consumption in those countries.

In truth, the assumption that every unit of Australia’s exported gas displaces coal is silly. The claim of a 148Mt saving is wrong and unfounded. The real number would be much smaller, and there could even be an increase in emissions as a result of LNG exports.

For the most part, exported gas probably displaces natural gas that would otherwise be produced elsewhere, leaving overall emissions roughly the same. Some smaller share may displace coal. But it could just as easily displace renewable or nuclear energy, in which case Australian gas exports would increase global emissions, not reduce them.

How much might gas exports really cut emissions?

Serious analysis would be needed to establish the true amount of emissions displaced by Australian gas. It depends on the specific requirements that importers have, their alternatives for domestic energy production and other imports, changes in relative prices, resulting changes in energy balances in third-country markets, trajectories for investments in energy demand and supply infrastructure, and so forth. No such analysis seems available.

But for illustration, let’s make an optimistic assumption that gas displaces twice as much coal as it does renewable or nuclear energy. Specifically, let’s assume – purely for illustration – that each energy unit of Australian exported LNG replaces 0.7 units of gas from elsewhere, 0.2 units of coal, and 0.1 units of renewables or nuclear.

Australia exported 70 million tonnes of LNG in 2018. A Department of Environment and Energy source told Guardian Australia that this amount of gas would emit 197 million tonnes of CO₂ when burned. We calculate a similar number, on the basis of official emissions factors and export statistics.

Under the optimistic and illustrative set of assumptions outlined above, we calculate that Australia’s LNG exports would have reduced emissions in importing countries by about 10 million tonnes of CO₂ per year. (See the end of the article for a summary of our calculations.)

They might equally have reduced emissions by less, or they might in fact have increased these countries’ emissions, if more renewables or nuclear was displaced than coal. But whatever the the actual number, it’s certainly a long way short of the 148 million tonnes of emissions reduction claimed by the government.

We also should consider the emissions within Australia of producing LNG. The national emissions accounting shows that the increase in national emissions of 3.5 million tonnes of CO₂-e compared with the year before is mostly because of a 22% increase in LNG exports. This means that LNG production in Australia overall may be responsible for 16 million tonnes of CO₂ emissions per year.

A full analysis of global effects would also need to factor in the emissions that would be incurred from the production of alternative energy sources displaced by Australia’s LNG.

Read more:
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Coal exports unambiguously raise emissions

The picture is more clear-cut for coal. If there was no Australian thermal coal (the type used in power stations) in world markets, much of this would be replaced by more coal mined elsewhere. The remainder would be replaced by gas, renewables or nuclear. As for the case of gas, the precise substitution effects are a matter of complex interactions.

The crucial point is that all alternative fuels are less emissions-intensive than coal. In the substitution of Australian-mined coal for coal from other sources, there could be some substitution towards coal with higher emissions factors, but this is highly unlikely to outweigh the emissions savings from the substitution to nuclear, renewables and gas.

So, removing Australian coal from the world market would reduce global emissions. Conversely, adding Australian coal to the world market would increase global emissions.

Australia exported 208 million tonnes of thermal coal in 2018, which according to the official emissions factors would release 506 million tonnes of CO₂ when burned. On top of this, Australia also exported 178 million tonnes of coking coal for steel production.

If a similar “replacement mix” assumed above for gas is also applied to coal – that is, every unit of coal is replaced by 0.7 units of coal from elsewhere, 0.2 units of gas, and 0.1 units of renewables or nuclear – then adding that thermal coal to the international market would increase emissions by about 19% of the embodied emissions in that coal. As in the case of LNG, this is purely an illustrative assumption.

So, in this illustrative case, Australia’s thermal coal exports would increase net greenhouse emissions in importing countries by about 96 million tonnes per year.

This figure does not consider the coking coal exports, nor the emissions from mining the coal in Australia and transporting it.

The real opportunity is in export of renewable energy

Thankfully, there actually is a way for Australia to help the world cut emissions, and in a big way. That is by producing large amounts of renewable energy for export, in the form of hydrogen, ammonia, and other fuels produced using wind and solar power and shipped to other countries that are less blessed with abundant renewable energy resources.

Even emissions-free production of energy-intensive goods like aluminium and steel could become cost-competitive in Australia, given the ever-falling costs of renewable energy and the almost unlimited potential to produce renewable energy in the outback. Australia really could be a renewable energy superpower.

Such exports will then unambiguously reduce global emissions, because they will in part displace the use of coal, gas and oil.

Once we have a large-scale renewable energy industry in operation, the relevant minister in office then will be right to point out Australia’s contribution to solving the global challenge through our energy exports. In the meantime, our energy exports are clearly a net addition to global emissions.

Summary of data and calculations

LNG emissions and displacement – illustrative scenario

Emissions inherent in Australia’s LNG exports of 69.5 million tonnes (in calendar year 2018) are 197 million tonnes (Mt) of carbon dioxide, based on emissions factors published by the Australian government.

If the same amount of energy was served using coal, emissions would be:

197Mt CO₂ + 148Mt CO₂ = 345Mt CO₂

Emissions under the mix assumed for illustration here would be:

0.7 x 197 (LNG) + 0.2 x 345 (coal) + 0.1 x 0 (renewables/nuclear) = 207Mt CO₂

That is 10Mt higher than without Australian LNG.

Coal emissions and displacement – illustrative scenario

Australia’s thermal coal exports were 208Mt in calendar year 2018. Emissions when burning this coal were 506Mt CO₂, based on government emissions factors.

Assuming typical emissions factors for fuel use in electricity generation of 0.9 tonnes of CO₂ per megawatt-hour (MWh) from black coal and 0.5 tonnes of CO₂ per MWh from gas, the emissions intensity of electricity generation under the mix assumed for illustration here would be:

0.7 x 0.9 (coal) + 0.2 x 0.5 (gas) + 0.1 x 0 (renewables/nuclear) = 0.73 tonnes CO₂ per MWh

This is 19% lower than the emissions intensity of purely coal-fired electricity, of 0.9 tonnes CO₂ per MWh.

19% of 506Mt CO₂ is 96Mt CO₂.The Conversation

Frank Jotzo, Director, Centre for Climate Economics and Policy, Crawford School of Public Policy, Australian National University and Salim Mazouz, Research Manager, Crawford School of Public Policy; and Director at EcoPerspectives, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Computing faces an energy crunch unless new technologies are found

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The tools on our smartphones are enabled by a huge network of mobile phone towers, Wi-Fi networks and server farms.

Daisy Wang, UNSW and Jared Cole, RMIT University

There’s little doubt the information technology revolution has improved our lives. But unless we find a new form of electronic technology that uses less energy, computing will become limited by an “energy crunch” within decades.

Even the most common events in our daily life – making a phone call, sending a text message or checking an email – use computing power. Some tasks, such as watching videos, require a lot of processing, and so consume a lot of energy.

Because of the energy required to power the massive, factory-sized data centres and networks that connect the internet, computing already consumes 5% of global electricity. And that electricity load is doubling every decade.

Fortunately, there are new areas of physics that offer promise for massively reduced energy use.

Read more:
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The end of Moore’s Law

Humans have an insatiable demand for computing power.

Smartphones, for example, have become one of the most important devices of our lives. We use them to access weather forecasts, plot the best route through traffic, and watch the latest season of our favourite series.

And we expect our smartphones to become even more powerful in the future. We want them to translate language in real time, transport us to new locations via virtual reality, and connect us to the “Internet of Things”.

The computing required to make these features a reality doesn’t actually happen in our phones. Rather it’s enabled by a huge network of mobile phone towers, Wi-Fi networks and massive, factory-sized data centres known as “server farms”.

For the past five decades, our increasing need for computing was largely satisfied by incremental improvements in conventional, silicon-based computing technology: ever-smaller, ever-faster, ever-more efficient chips. We refer to this constant shrinking of silicon components as “Moore’s Law”.

Moore’s law is named after Intel co-founder Gordon Moore, who observed that:

the number of transistors on a chip doubles every year while the costs are halved.

But as we hit limits of basic physics and economy, Moore’s law is winding down. We could see the end of efficiency gains using current, silicon-based technology as soon as 2020.

Our growing demand for computing capacity must be met with gains in computing efficiency, otherwise the information revolution will slow down from power hunger.

Achieving this sustainably means finding a new technology that uses less energy in computation. This is referred to as a “beyond CMOS” solution, in that it requires a radical shift from the silicon-based CMOS (complementary metal–oxide–semiconductor) technology that has been the backbone of computing for the last five decades.

Read more:
Moore’s Law is 50 years old but will it continue?

Why does computing consume energy at all?

Processing of information takes energy. When using an electronic device to watch TV, listen to music, model the weather or any other task that requires information to be processed, there are millions and millions of binary calculations going on in the background. There are zeros and ones being flipped, added, multiplied and divided at incredible speeds.

The fact that a microprocessor can perform these calculations billions of times a second is exactly why computers have revolutionised our lives.

But information processing doesn’t come for free. Physics tells us that every time we perform an operation – for example, adding two numbers together – we must pay an energy cost.

And the cost of doing calculations isn’t the only energy cost of running a computer. In fact, anyone who has ever used a laptop balanced on their legs will attest that most of the energy gets converted to heat. This heat comes from the resistance that electricity meets when it flows through a material.

It is this wasted energy due to electrical resistance that researchers are hoping to minimise.

Recent advances point to solutions

Running a computer will always consume some energy, but we are a long way (several orders of magnitude) away from computers that are as efficient as the laws of physics allow. Several recent advances give us hope for entirely new solutions to this problem via new materials and new concepts.

Very thin materials

One recent step forward in physics and materials science is being able to build and control materials that are only one or a few atoms thick. When a material forms such a thin layer, and the movement of electrons is confined to this sheet, it is possible for electricity to flow without resistance.

There are a range of different materials that show this property (or might show it). Our research at the ARC Centre for Future Low-Energy Electronics Technologies (FLEET) is focused on studying these materials.

The study of shapes

There is also an exciting conceptual leap that helps us understand this property of electricity flow without resistance.

This idea comes from a branch of mathematics called “topology”. Topology tells us how to compare shapes: what makes them the same and what makes them different.

Image a coffee cup made from soft clay. You could slowly squish and squeeze this shape until it looks like a donut. The hole in the handle of the cup becomes the hole in the donut, and the rest of the cup gets squished to form part of the donut.

Topology tells us that donuts and coffee cups are equivalent because we can deform one into the other without cutting it, poking holes in it, or joining pieces together.

It turns out that the strange rules that govern how electricity flows in thin layers can be understood in terms of topology. This insight was the focus of the 2016 Nobel Prize, and it’s driving an enormous amount of current research in physics and engineering.

Read more:
Physicists explore exotic states of matter inspired by Nobel-winning research

We want to take advantage of these new materials and insights to develop the next generation of low-energy electronics devices, which will be based on topological science to allow electricity to flow with minimal resistance.

This work creates the possibility of a sustainable continuation of the IT revolution – without the huge energy cost.The Conversation

Daisy Wang, Postdoctoral Fellow, UNSW School of Physics, UNSW and Jared Cole, Professor of Physics, RMIT University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Labor’s policy can smooth the energy transition, but much more will be needed to tackle emissions

Frank Jotzo, Crawford School of Public Policy, Australian National University

The Labor party’s energy policy platform, released last week, is politically clever and would likely be effective. It includes plans to underwrite renewable energy and storage, and other elements that would help the energy transition along. Its approach to the transition away from coal-fired power is likely to need more work, and it will need to be accompanied by good policy in other sectors of the economy where greenhouse emissions are still climbing.

The politics is quite simple for Labor: support the transition to renewable electricity which is already underway and which a large majority of Australians support, and minimise the risk that its proposed policy instruments will come under effective attack in the lead-up to the 2019 election.

Read more:
Grattan on Friday: Labor’s energy policy is savvy – now is it scare-proof?

By aiming for 50% renewables at 2030, the party has claimed the high ground. That goal and perhaps a lot more is achievable, given that the large investment pipeline in electricity consists almost entirely of wind and solar projects, and that new renewables are now typically the cheapest options to produce energy with new plants.

The question then is what policy instruments Labor would use to facilitate the transition from coal to renewables.

NEG games

The government’s abandoned National Energy Guarantee (NEG) policy is now a political asset for Labor. If the Coalition were to support it under a Labor government, the policy would effectively be immune to political attack. If the Coalition were to block it, Labor could blame many future problems in electricity on the Coalition’s refusal to endorse a policy that it originally devised.

The NEG has many warts. Some of the compromises in its design were necessary to get it through the Coalition party room. That no longer matters, and so it should be possible to make improvements. One such improvement would be to allow for an explicit carbon price in electricity under the NEG, by creating an emissions intensity obligation for electricity generators with traded certificates. This is better than the opaque model of contract obligations on electricity retailers under the original version.

Underwriting renewables

But the real action under a Labor government might well come from a more direct policy approach to push the deployment of renewables. In his energy policy speech last week, Shorten foreshadowed that Labor would “invest in projects and underwrite contracts for clean power generation, as well as firming technologies like storage and gas”.

As interventionist as this sounds, it has some clear advantages over more indirect support mechanisms. First, it brings the costs of new projects down further by making cheap finance available – a tried and tested method in state-based renewables schemes. Second, it allows for a more targeted approach, supporting renewable energy generation where it makes most sense given demand and transmission lines, and prioritising storage where and when it is needed. Third, it channels government support only to new installations, rather than giving free money to wind farms and solar plants that are already in operation.

Managing coal exit

Where renewables rise, coal will fall. Labor’s approach to this issue centres on the affected workers and communities. A “just transition authority” would be created as a statutory authority, to administer redundancies, worker training, and economic diversification.

This is a good approach if it can work effectively and efficiently. But it may not be enough to manage the large and potentially rapid shifts in Australia’s power sector.

Contract prices for new wind farms and solar plants now are similar to or lower than the operating costs of many existing coal plants. The economics of existing coal plants are deteriorating, and many of Australia’s ageing coal power plants may shut down sooner than anticipated.

All that Labor’s policy says on the issue is that all large power plants would be required to provide three years’ notice of closure, as the Finkel Review recommended. But in practice this is unlikely to work.

Without any guiding framework, coal power plants could close very suddenly. If a major piece of equipment fails and repair is uneconomic, then the plant is out, and operators may find it opportune to run the plant right until that point. It’s like driving an old car – it runs sort of OK until the gearbox goes, and it’s off to the wreckers right then. It is unclear how a three-year rule could be enforced.

This is effectively what happened with the Hazelwood plant in Victoria. That closure caused a temporary rise in wholesale power prices, as new supply capacity gradually fills the gap.

One way to deal with this would be to draw up and implement some form of specific exit timetable for coal power plants. This would give notice to local communities, provide time to prepare investment in alternative economic activities, and allow replacement generation capacity to be brought online. Such a timetable would need a mechanism to implement it, probably a system of carrots and sticks.

Batteries, energy efficiency and the CEFC

Most public attention was given to a relatively small part of Labor’s energy policy platform: the promise to subsidise home batteries. Batteries can help reduce peak demand, and cut electricity bills for those who also have solar panels. But it is not clear whether home batteries are good value for money in the system overall. And the program would tend to benefit mostly upper middle-income earners.

Read more:
Labor’s battery plan – good policy, or just good politics?

Labor’s platform also foreshadows a renewed emphasis on energy efficiency, which is economically sensible.

Finally, Labor promises to double the Clean Energy Finance Corporation’s endowment with another A$10 billion, to be used for revolving loans. The CEFC is already the world’s biggest “green bank”, co-financing projects that cut emissions and deliver financial returns. Another A$5 billion is promised as a fund for upgrading transmission and distribution infrastructure. These are big numbers, and justifiably so – building our future energy system will need massive investments, and some of these will be best made by government.

Big plans for electricity, but what about the rest?

Overall, Labor’s plan is a solid blueprint to support the electricity transition, with strong ambition made possible by the tremendous technological developments of recent years.

But really it is only the start. Electricity accounts for one-third of national greenhouse emissions. Emissions from the power sector will continue to fall, but emissions from other sectors have been rising. That poses a huge challenge for the economy-wide emissions reductions that are needed not only to achieve the 2030 emissions targets, but the much deeper reductions needed in coming decades.

A national low-carbon strategy will need to look at how to get industry to shift to zero-emission electricity, how to convert road transport to electricity or hydrogen, and how to tackle the difficult question of agricultural emissions. More pre-election announcements are to come. It will be interesting to see how far Labor will be willing to go in the direction of putting a price on carbon, which remains the economically sensible but most politically charged policy option.

As difficult as electricity policy may seem based on the tumultuous politics that have surrounded it, more seismic shifts are waiting in the wings.The Conversation

Frank Jotzo, Director, Centre for Climate Economics and Policy, Crawford School of Public Policy, Australian National University

This article is republished from The Conversation under a Creative Commons license. 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.

Semitransparent solar cells: a window to the future?

File 20180215 124886 1cij0t2.jpg?ixlib=rb 1.1
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.