- Written by Ben Morris
- Business Technology Editor
image source, Stölzle Froconage
Glass bottle manufacturing is an energy-intensive business
I was handed an elegant pear-shaped bottle with an intricate leaf pattern that reached up to my neck.
It’s empty but heavy.
Ask for the price of the bottle. “About 270 pounds,” I said. I carefully return the bottle.
Designed for rare whiskies, this bottle is one of the creations of Stoelzle Flaconnage, based in Nottingley, West Yorkshire. Glassware has been made here since 1871.
In 1994, the factory was taken over by the Austrian Stölzle Grass Group and has focused on producing bottles for the spirits industry.
You can do everything from design, bottle production, and decoration on one site.
Demand is strong, supported by a boom in gin production in Asia and demand for whisky. When I visited, the factory was busy, with chunks of molten glass falling into dozens of molds, the glass still glowing orange from the heat of the furnace.
To stand out in a crowded market, customers are looking for distinctive bottles with patterned and sometimes colored glass, elaborate labels and artwork.
“Our clients want their products to be showcased in a distinctive and sometimes symbolic way,” says Thomas Riss, CEO of Stoelzle Flaconnage.
To make glass, raw materials must be heated to 1,500℃
While business is booming, Stolzle Fraconage and other glass manufacturers are having to make big decisions about how they make glass containers.
The European Union is cracking down on packaging waste. The company hopes to make packaging lighter to reduce the materials needed and the fuel needed for transportation.
The company is working on the Packaging and Packaging Waste Regulations (PPWR) and is in the final stages of approval.
Under this regulation, Member States will be required to reduce packaging weight and introduce measures to achieve the target.
There are concerns in the glass packaging industry that glass is an unfair target because it is relatively heavy compared to plastic and aluminum.
“Light does not mean sustainable,” says Vanessa Chesnot of FEVE, an industry group representing European glass container manufacturers.
“Glass is 100% infinitely recyclable, which means you can recycle a bottle of whiskey into another bottle, basically forever.”
While it’s true that glass recycling is a well-established process, glass production is energy-intensive, even when recycled materials are used.
Most glass manufacturing involves burning natural gas to heat the raw material in a furnace to 1,500°C. CO2 is produced when gas is burned or raw materials are heated.
Thomas Riss plans to open an electric furnace at its Stoelzle factory in Knottingley in 2026
The furnace I saw in action at Stoelzle Flaconnage uses approximately 191,000 kWh of energy per day. This is enough to power the average UK household for 12 years.
This is considered a relatively small furnace, with larger plants having furnaces twice the size.
Additionally, it takes 12 days for the glass furnace to reach operating temperature, so the glass furnace will never turn off. Basically, the furnace runs all day every day for the duration of its life, which is typically 10 to 12 years.
Therefore, the glass industry is considering switching from gas furnaces to electric furnaces.
When electricity comes from sustainable sources, it reduces carbon emissions and could go a long way toward helping glass companies reach their goal of becoming net-zero by 2050.
Until recently, it was considered too expensive to run a furnace with electricity. However, as electricity rates have become more competitive, glass manufacturers are considering switching to electricity rates.
Stoelzle Flaconnage plans to have an electric furnace up and running in Knottingley by 2026.
“Five years ago, when I talked to engineers, no one had the idea of an electric furnace because the math didn’t make sense. But now things have changed,” Lis says.
However, for companies that produce large quantities of containers such as beer bottles, electric furnaces may not be an option. Even if you can make your electric furnace large enough, the extra electricity bill is unpleasant.
“For now, that is [electric furnace tech] is primarily developed for niche markets and small reactors producing high-value-added products,” says Fabrice Rivet, Director of Environment, Health and Safety at FEVE.
A further challenge with electric glass furnaces is connecting the plug. Connections to the power grid often need to be upgraded to accommodate additional power supplies.
But the glass industry is trying to overcome some of these hurdles.
Ardagh Glass Packaging produces glass in Europe’s first hybrid furnace
The world’s most advanced hybrid glass furnace is being tested at Alder Glass Packaging (AGP) in Obernkirchen in northern Germany.
Manufactured by the German company Sorg with part-funding from the German government and the European Union, the furnace is a large furnace with a capacity of 350 tonnes, enough to produce around 1 million beer bottles a day.
Once fully operational, it will run on 80% sustainable electricity and 20% gas, saving 45,000 tonnes of CO2 per year, AGP says.
AGP engineers put their furnaces to the ultimate test. Producing amber glass involves tricky chemical reactions that are more difficult to control than producing clear glass.
“There has never been a successful demonstration of the production of full-scale amber glass by complete electromelting. And if you want to combine maximum reduction of carbon footprint with high tint levels and amber glass, hybrid is the logical choice,” he says. Joris Goossens, Research and Development Project Manager at AGP, said:
If the hybrid reactor’s performance is proven, the next step could be to replace natural gas with hydrogen, AGP said.
Even if the industry switches to electric or hybrid furnaces, there are still other issues to solve.
The raw materials needed to make glass, such as sand, soda ash, and limestone, emit CO2 during heating. These account for approximately 20% of the carbon emissions of the glass manufacturing process.
The industry hopes that using more recycled glass in the manufacturing process will reduce these emissions, but getting enough unwanted glass is difficult.
One academic who studies the packaging industry says the answer may simply be to use less glass.
Alice Block, a postdoctoral researcher at the University of Southampton, said in a paper published in 2020: We compared the impact on the environment A study of glass, plastic, and aluminum containers found that glass has the most negative impact on the environment.
“Even recycled glass has incredibly high energy demands,” she points out.
“The hierarchy of waste is reduce, reuse, recycle. We need to reduce the number of packaging, reuse packaging, or recycle where appropriate,” she says.
