Climate

How solving solar’s aluminium problem is key to keeping its climate credentials

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The rapid rise of low-cost solar power has provided a key solution to lowering energy costs and emissions, but a looming problem with the aluminium required to support solar could undermine its climate credentials, Australian researchers have warned.

An analysis published by researchers at the University of New South Wales, in the journal Nature Sustainability, has raised concerns about the potential impacts of surging demand for the materials used in the construction of solar panels – particularly aluminium – which could cause their own climate pressures.

The study, which was partially funded by the Australian Renewable Energy Agency, cites predictions for solar power uptake that could see global installed solar capacity grow to more than 85-times its current levels by 2050, under roadmaps consistent with keeping global warming to within safe levels.

This massive expansion of global solar production will have flow-on impacts for the components and materials used in solar panel manufacturing and their installation, the researchers say, including energy-intensive aluminium that is commonly used in solar panel frames and mounting, as well as solar inverter devices.

“It is also heavily used by many other clean energy technologies (for example, batteries, wind turbines and associated power systems). However, despite its desirable attributes, its primary production comes at a high cost in terms of energy and associated greenhouse gas emissions through both direct and indirect emissions,” the research paper says.

The researchers cited the very high emissions footprint of aluminium produced in China, the world’s largest manufacturer of both solar panels and aluminium, where production can occur with embodied emissions as high as 14.5 tonnes of carbon dioxide for each tonne of aluminium produced.

The researchers say that solar panel production could require the equivalent of 40 per cent of current global aluminium production, leading to a substantial emissions footprint.

If the expected surge in solar uptake occurs without making substantial improvements to the emissions footprint of aluminium production, it could lead to the addition of almost four gigatonnes of carbon dioxide emissions by 2050, under a “worst-case” scenario, the researchers say.

this raises potential concerns around the environmental and climate change consequences, with aluminium being a particularly energy-intensive material given the large amounts of electricity used in its production.

From aluminium production alone, such emissions would deplete around 1 per cent of the global carbon budget, consistent with keeping warming to within 1.5 degrees.

The researchers modelled several alternative scenarios, where improvements in aluminium production techniques and the increased adoption of zero emissions supplies of electricity help achieve reductions in the embodied emissions of aluminium.

The group also considered the potential for an increased proportion of recycled aluminium used in solar panel production, stressing that the aluminium sector cannot rely on the decarbonisation of the electricity system, but needed to find additional ways of reducing the sector’s overall emissions.

Aluminium has the ability to be recycled effectively indefinitely, and its reprocessing results in secondary-use aluminium with a significantly reduced emissions footprint. Recycled aluminium can be produced with embodied emissions of as little as 0.5 tonnes of carbon dioxide per tonne of aluminium – a dramatic reduction from “primary” production.

The researchers say that efforts to cut the embodied emissions of aluminium need to occur within the next ten years to provide the best opportunity of keeping associated emissions to below one gigatonne by 2050.

In considering potential alternatives to aluminium as part of their analysis, the researchers concluded that the most promising approach would be to focus on the opportunities to reduce the amount of embodied carbon in aluminium rather than searching for alternative materials.

“Although decreasing aluminium usage in PV systems can reduce the expected demand and its associated [global warming potential], this strategy may only be effective if alternative materials used to replace the aluminium do not contribute additional emissions and do not diminish the product’s longer-term value in terms of a circular economy,” the paper says.

“For example, replacing aluminium with steel in PV module frames can reduce PV module resistance to corrosion, and make modules heavier and more costly to transport.”

Even with the potential to reduce the embodied emissions of solar panels, solar technologies still produce electricity with a substantially lower carbon footprint than fossil fuel technologies.

The US-based National Renewable Energy Laboratory estimates that the life-cycle emissions intensity of solar power is 40 kilograms of carbon dioxide per megawatt-hour.

This compares to the life-cycle emissions intensity of black coal power, which can often exceed 1,000 kilograms of carbon dioxide per megawatt-hour.

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