Reducing the vast quantities of energy used for heating and cooling buildings is a fundamental pillar of decarbonisation. But the manufacture of insulation materials like mineral wool is highly energy intensive putting pressure on companies in the insulation material business to make huge investments in emissions reduction. Denmark’s Rockwool, the largest company in the business, is discovering that market specific innovations are the way to go

GEOGRAPHIC BARRIERS
Electrification of energy-hungry industrial processes only makes sense in countries with high penetrations of renewable energy in their supply mix. Elsewhere, extraordinary innovation is needed to decarbonise heavy industry and that requires extraordinary investment

LEANING ON GAS
The use of natural gas as a stepping stone to full decarbonisation using biofuels and renewable electricity is a route chosen by some companies, but it is an unsustainable path in the long term

KEY QUOTE
The CO₂ embedded in building materials must go down, so that within the next ten years we can see that for every square metre of construction, far less CO₂ is emitted than today

Extracting fibres from raw molten rock and spinning them into building insulation material is an extremely energy intensive process. It takes temperatures of 1500°C to melt volcanic rock into a hot mass from which to spin fibres into mineral wool. While interwoven layers of stone wool material make for effective building insulation, reducing the energy used for space heating and cooling, its manufacturing process must be decarbonised to make it a truly green solution. Decarbonisation requires eliminating the burning of fossil fuels for heat, or the problematic and expensive removal and storage of the carbon emitted during combustion. The world’s largest manufacturer of insulation material from rock fibres, Danish company Rockwool, is working on the problem. It has developed new technology that uses electricity from renewable energy to create the temperatures needed to melt rock. At the company’s factory in Moss, Norway—one of 47 Rockwool production facilities in 22 countries—Rockwool has adapted its operations to electrify the production process and in this way reduce its carbon footprint. The company declines to reveal specific technical details of the commercially sensitive innovation, but the new process reduces direct CO₂ emissions in stone wool production at the site by up to 80%. It further cuts waste headed for landfill by 95% compared to its pre-electrification upgrade, Rockwool says. The site was previously powered by coke.

HYDRO POWER

Electricity for the Moss site comes from Norwegian hydropower secured through the purchase of certified renewable energy certificates and the project was supported by the Norwegian government’s clean energy funding unit Enova, which provided €9.71 million of the total €32.54 million investment. The technology is “an important step” towards decarbonisation, says Anthony Abbotts from Rockwool. “It is promising and currently the largest project as such in our industry, but it is still a pilot project. We need further development and tests to be able to scale it to our other facilities.” The next steps in scaling are not yet public. Aside from the Norwegian factory, Rockwool still relies heavily on fossil energy sources for its manufacturing and made no dent in its global carbon emissions from 2017 to 2019. It is the fifth largest emitter of carbon among companies in Denmark. But with rising political ambitions for decarbonisation and consumer trends in low carbon purchasing, innovative technologies that meet those needs are in high demand.

GROWTH WITHOUT CARBON

Rockwool is just one example from heavy industry of a company reliant on energy intensive production technologies that are proving notoriously difficult to decarbonise. Even in Denmark, a country where light industry dominates, emissions from heavy industry are projected to increase by 20% from 2017-2030 unless decarbonisation solutions are introduced. “As is the case with many energy intensive manufacturing companies, Rockwool needs to find solutions and technologies that can help it grow without increasing its footprint—and it needs to do it now,” says Peter Maagøe Petersen, of Danish advisory company, Viegand and Maagøe. Michael Nielsen of the Danish Construction Association agrees. The organisation took part in a climate partnership on buildings orchestrated by the government. In early 2020, the partnership presented recommendations for emissions reduction in the Danish construction industry. “The CO₂ embedded in building materials must go down, so that within the next ten years we can see that for every square metre of construction, far less CO₂ is emitted than today. It requires companies to find more energy efficient ways to produce,” he says. Maagøe Petersen agrees that Rockwool’s results with the electrification of its manufacturing processes is promising, but probably only makes economic sense in Norway and for that reason is not “a silver bullet” solution. In many other countries, there is currently no business case for electrification. “In Denmark, electrification would be much more expensive now than using natural gas and four to five times more expensive than using coke or coal for these processes,” he says. For Rockwool to succeed in cutting large volumes of its global emissions it will need to explore various instruments and technologies, Maagøe Petersen says. Rockwool concurs. “We do not put all our eggs in one basket. We need to apply different strategies and technologies to different facilities, depending in part on the energy mix in a given location,” says Abbotts.

Companies need to decrease their own carbon footprint by an average of over 4% each year in order to live up to the 1.5°C target. We need companies to achieve absolute decarbonisation

FUEL FLEXIBLE

In Denmark, Rockwool has developed a so-called fuel-flexible technology, which enables it to use different energy sources, such as coal, natural gas and biogas to reach the high furnace temperatures its manufacturing processes require. In a trumpeting announcement of the technology in autumn 2020, Rockwool claimed it would reduce emissions at its two Danish factories by 70% already in 2021, with 1990 as a baseline—coincidentally exactly the same percentage the government has in its sights for decarbonisation of the entire country’s economy by 2030. Rockwool says its Danish carbon emissions will halve from 90,000 tonnes a year today to 45,000 tonnes in 2021, down from 132,000 tonnes in 1990. The intention is for Rockwool to roll-out its fuel-flexible technology to facilities in other countries. “Our fuel-flexible technology enables us to transition from coal to natural gas and, in the case of Denmark, biogas owing to its availability. That will not always be the case in every market. By transitioning from coal to natural gas in countries such as the United States and Poland we will reduce factory CO₂ emissions by approximately 25-30%,” says Abbotts. Relying on natural gas raises some red flags. Burning natural gas emits less carbon than burning coal, but it is not a renewable energy. Denmark is phasing out gas central heating of buildings in pursuit of the 2030 target. Biogas is named as a solution “to processes that can not be electrified” by the Danish government’s climate partnerships initiative, with potential to reduce emissions from heavy industry in Denmark by 20% but barriers to making the switch to biogas remain. The decarbonisation potential of biogas depends on its origin and how it is produced plus it is still significantly more expensive than coal or natural gas. Rockwool declines to comment on the impact using biogas would have on the price of its end product. But the firm assures it uses “certified carbon-neutral biogas” from agricultural and food industry waste products, says Abbotts. Rockwool declines to disclose its manufacturing cost comparison between switching from fossil fuel to green electrification, biogas or natural gas. Energy cost varies depending on factory location and the availability of energy sources, it stresses. “This is why we work with multiple melting technologies,” says Abbotts.

ALTERNATIVE MATERIALS

Other insulation materials can be made using far less energy than the production of stone wool, such as paper, linen, hemp, straw or wood fibre. Additionally, these materials absorb and store CO₂ while growing. But Rockwool is not planning to diversify from mineral wool, arguing its product is superior in various ways. The company says stone wool will not burn or release toxic gases or smoke if exposed to high heat. Rockwall wants to focus instead on increasing the proportion of recycled materials used in its manufacturing. In 2019 the proportion was around 26% and there is potential for more that the new electrified process at Moss can also support. Critics challenge Rockwool’s claim to a superior product. An analysis by the Danish Heat Insulation Association (VIF) points to a range of insulation materials that meet the same building requirements and insulation performance as stone wool.

MOUNTING PRESSURE

Rockwool will likely have to move much further and faster with its programme of innovations under mounting economic pressure to decarbonise. Along with 41 other companies in Denmark with significant carbon emissions it is excused from full compliance with caps on those emissions under the EU’s carbon Emissions Trading System (ETS) and is granted free emissions allowances. Europe’s heavy industry has for some years successfully argued that being forced to buy ETS allowances at competitive market prices to offset emissions would make it uncompetitive on global markets. In Denmark, a cross-party parliamentary agreement on green tax reform is part of the strategy for achieving the 70% carbon reduction target by 2030. The package includes a carbon tax to make sure all Danish companies pay the cost of their impact on the climate. In autumn 2020, the details were still being worked out, but the independent Danish Climate Council has suggested that a tonne of CO₂ should cost approximately €200 by 2030, considerably more than the ETS trading price of around €20/tonne at the time. Piling on the pressure for Rockwool to accelerate its decarbonisation efforts is the likelihood of tougher EU carbon reduction ambitions. The EU Commission is to present legislative proposals to that end in June 2021. A focus on increasing energy efficiency and more climate friendly industrial processes seems inevitable.

LEGITIMACY ISSUE

Rockwool is also facing a legitimacy issue in expounding the environmental benefits of using its products to save energy in buildings when the manufacture of them is a major source of carbon emissions. Buildings account for over 40% of the EU’s total energy bill and 36% of Europe’s CO₂ emissions. Better insulation could slash their total energy demand by 50% by 2050 according to the European Mineral Wool Manufacturers Association. “Rockwool has so far not been showing climate leadership. Talking about avoided emissions is not enough and does not excuse it from cutting its own emissions,” says Maxfield Weiss from the European office of the Carbon Disclosure Project (CDP). CDP gives Rockwool a “B” grade in its 2019 climate score. Weiss argues that to reduce its emissions in line with climate science, Rockwool’s initiatives should lead to absolute emissions reductions as the company grows its business, not just emissions measured per unit of production: “Companies need to decrease their own carbon footprint by an average of over 4% each year in order to live up to the 1.5°C target. We need companies to achieve absolute decarbonisation,” he says, stressing the need for focusing on the “lifecycle perspective” of company footprints. Rockwool is confident of growing demand in Denmark and the Nordic region for low-carbon building materials, says Abbotts. “We see similar demand in other markets especially in the EU,” he adds. The firm is reviewing its carbon reduction ambitions. It has also engaged with the business-focused Science Based Targets Initiative (SBT). In late 2020, Rockwool’s global climate ambitions are aimed at a 20% reduction in energy intensity (energy per unit of production) by 2030. The indication is that the scale of emissions reductions required by heavy industry will not be reached for several years, says Maagøe Petersen. He wants to see much more investment in research and demonstration projects to drive the innovation needed. Without it, energy intensive processes will continue to be major sources of climate destruction.

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TEXT Anna Fenger