The International Energy Agency will release research later this year showing that solar panels can be landfilled safely, amid growing concern over the disposal of renewable energy components.

Solar panels have a range of recycling options, but none of them are perfect. The challenges for wind turbine blades are even greater.

The IEA study will show that disposing of solar panels in landfills is unlikely to have an adverse impact on human health, according to co-author Garvin Heath, a senior scientist in the U.S. National Renewable Energy Laboratory’s resources and sustainability group.

The study, which is due to be released within a couple of months as part of the IEA’s Task 12 sustainability research activities, looked at the potential for human health impacts under a worst-case scenario involving unlined landfill sites with water seepage affecting crushed modules.

The research was limited to the primary pollutant in each of the three biggest classes of solar panels today: crystalline silicon, cadmium telluride (CdTe) and copper indium gallium selenide (CIGS). The pollutants studied were lead, cadmium and selenium, respectively.

“When we examined those, under the worst-case conditions, none of them exceeded health-screening thresholds, meaning they’re not deemed to potentially have significant enough risk that you’d want to do a more detailed health risk assessment,” Heath said.

He stressed that the study had yet to complete its peer-review process and that it did not cover all the potentially toxic materials in each type of module.

But given that real-life disposal options are likely to be safer than those modeled in the study (all modern landfills have a lining, for example), the research bodes well as the renewables industry takes stock of what to do with a growing mountain of waste from end-of-life assets.

Solar’s recycling options

As it stands, sending old panels to landfills is one of several options for disposal. Panels that are substandard but still operational can potentially be sold on secondary markets.

Those that are broken or so old as to no longer be functional can potentially be recycled, but in the U.S. at least, the recycling options for solar traditionally have been limited.

First Solar, uniquely, has a longstanding recycling scheme that recovers up to 90 percent of its cadmium telluride thin-film modules. For the most part, though, the more common crystalline-silicon modules have been handled by mainstream glass, metal or electronic waste recycling facilities.

“The challenge with that is it’s not their main product line, [and] to date there’s not been a lot of PV modules to recycle, so they end up having to store them for a while until they can run them in a batch,” said Heath.

“That works, but it’s not a fully integrated or high-value recycling process that can extract all the trace materials.”

Work is underway to improve matters, though.

Last September, the Brussels, Belgium-based waste management nonprofit PV Cycle unveiled a partnership with a U.S. company called Recycle PV Solar “to quickly ramp up nationwide management of…discarded solar panels,” a press release stated.

Recycle PV Solar launched its recycling service in 2018, at which point an estimated 90 percent of decommissioned U.S. solar panels was going to landfill, the company said.

Elsewhere, the U.S. Solar Energy Industries Association has a program that aims to cut the cost of recycling panels, inverters and other solar equipment by aggregating waste collection and channeling old or damaged products to a select group of recyclers to achieve economies of scale.

And Phoenix, Arizona-based We Recycle Solar is one of what looks set to become a growing group of companies specializing in solar industry recycling.

The company has operations in the U.S., Belgium, Japan and South Korea and a global processing capacity of 100,000 pounds of equipment a day.

Furthermore, said Alex Hobson, vice president of communications at the American Council of Renewable Energy (ACORE): “At the state level, Washington, New York and California have programs in place to help incentivize and regulate photovoltaic panel recycling.”

Europe’s big idea, small volumes

With all this, the U.S. still lags behind Europe on solar recycling. In the European Union, the setup and financing of take-back and recycling schemes for solar modules and inverters is mandatory under the Waste Electrical and Electronic Equipment (WEEE) Directive of 2012.

“Under the WEEE Directive, PV modules are in a category of electronic waste with an 85 percent recovery target, 80 percent of which consists of reuse and recycling,” said Kristina Thoring, communications director at the industry body SolarPower Europe.

Even with this regulatory pressure, cost-effective solar recycling remains a challenge in Europe, as in the U.S., because most PV panels are still in use.

Modules entering the market today are expected to last 30 years, and since hardly any solar was installed in Europe before 2000, there is still only a trickle of end-of-life panels for recycling.

Collected modules awaiting recycling. Europe only has one dedicated PV recycling plant so far. (Credit: PV Cycle)

Furthermore, European solar markets didn’t really take off until 2008, so most of the PV equipment being used in Europe today won’t enter the waste stream until around 2040, Thoring noted. Nevertheless, PV Cycle has been working to improve European solar recycling since 2007.

Over the last decade, the body has organized the collection and treatment of more than 33,000 tons of PV panel waste, equivalent to roughly half a gigawatt of solar capacity, said Thoring.

Europe’s solar recycling capacity was given a boost in 2018 with the opening of a dedicated facility operated by the French waste management company Veolia.

The crystalline silicon panel recycling plant claims a 95 percent recovery rate for materials and is ultimately expected to handle more than 4,000 tons a year.

Until more such plants come online, the case for solar panel recycling is helped by the fact that old panels are between 85 to 90 percent glass and aluminum by weight. This means they can be recycled relatively easily, albeit at a cost, within traditional recycling facilities.

Solving wind power’s blade problem

The same cannot be said for fiberglass-based wind turbine blades, though. And although the blades, like solar panels, are not expected to pose a health hazard, their size is seen as a challenge when it comes to disposal.

In February, a Bloomberg report claimed U.S. wind operators were sending 8,000 blades a year to landfills. While 85 percent of wind turbine components can be recycled or reused, fiberglass blades remain difficult to dispose of, the report said.

Eric Goetz, chief technology officer at Goetz Composites, thinks he has an answer. As a board member of the Rhode Island Marine Trades Association, he has been looking at how to dispose of the fiberglass- and epoxy-resin-based hulls of association members’ old boats.

As a result, in 2016 the association embarked on what Goetz said was the first pilot project in the U.S. to turn fiberglass hulls into cement. The silica in fiberglass is used to create an aggregate while the epoxy resin is burned, helping offset the energy required for the process.

Last year 18 tons of hulls were processed in the scheme, said Goetz. He believes the same process could be used to recycle U.S. wind turbine blades, which are made of similar materials.

“I think it is an emerging solution, although it’s obviously something we need to dive into,” he told GTM.

Turning wind blades into cement

The idea of turning blades into cement comes from Germany, where the multinational building materials giant LafargeHolcim has been recycling the wind turbine components since the mid-2000s through a business unit called Geocycle. 

Last July, the concept also gained the backing of WindEurope, the European Chemical Industry Council, Cefic, and the European Composites Industry Association. The bodies joined forces to help recycle the 2.5 million tons of composite material tied up in European wind turbine blades.

“Composite materials are being recycled today at commercial scale through cement co-processing, where the cement raw materials are being partially replaced by the glass fibers and fillers in the composite, and the organic fraction replaces coal as a fuel,” states a Cefic press note.

Nor is cement production the only recycling option for end-of-life blades.

In January of last year, Bothell, Washington-based Global Fiberglass Solutions announced the opening of a recycling plant in Sweetwater, Texas to turn turbine blades into thermoplastic fiberglass pellets for use in injection molding and extrusion manufacturing processes. 

Additionally, said Hobson at ACORE: “You have leading companies like Vestas that have come out with plans to eliminate non-recyclable waste from the manufacturing, operation and decommissioning of their wind turbines by 2040.”

A review of blade disposal options last June, carried out by Hamburg, Germany-based civil engineer Francesco Miceli, also includes incineration and breaking down by heat, solvents or mechanical processes.

Although cement-making has been touted as most viable of all of these, “I would say that there is no absolute best solution,” said Miceli.

And the problem for renewables is that landfill disposal, where allowed, is still the cheapest way of getting rid of old components. At least it’s not a health hazard — and as recycling volumes grow, soon it may not even be the most cost-effective option.