Glass furnaces operate 24/7, 365 days a year for up to 20 years, at temperatures around 1500C.
If a furnace loses temperature and the glass freezes due to shortage of fuel, they cannot return to be operational again and will need to be rebuilt, costing tens of millions and many months to rebuild, meaning the need to find long-term, sustainable energy solutions for the industry is critical.
The sector continues to develop new ways to continue the improvements in sustainability, with research and development identifying clear options for manufacturers to secure their long-term futures and achieve net-zero emissions targets.
Facing the challenges ahead
At present, there are clearly challenges for all energy-intensive industries to achieve net-zero targets, due to global supply chain disruption and increasing energy costs. Most of the glass manufacturing sector still relies predominantly on the combustion of natural gas, with up to 75% of energy consumption in glass production coming from the operation of furnaces. During the energy crisis, glass manufacturers saw wholesale energy costs increase by 700% over the last 12 months leading to spiraling energy bills across every sector.
By no means is the industry standing still on sustainability initiatives because of these challenges, if anything, this ongoing situation has highlighted the need to lessen the reliance on a single source of energy.
Biofuel has recently been trialed in the UK in the production of packaging glass and flat architectural glass. Biofuel offers a supplementary fuel option but is it not the long-term solution, as the long-term solution is likely to be mixed of energy such as renewable electricity, hydrogen and biofuel, depending on availability, sustainability and cost of the energy.
One of the ways glass manufacturers will be able to reduce emissions whilst maintaining output is by incorporating hybrid melting. This process uses renewable electricity to make up around 60-80% of energy input at furnace, with additional energy coming from hydrogen generated from renewable electricity, known as green hydrogen. This blended approach provides flexibility to manufacturers, enabling them to alter proportional energy inputs depending on the availability, sustainability, and price of energy sources, whilst still maintaining stable furnace temperatures.
Single source green hydrogen energy is also a feasible solution within glass manufacturing, with furnaces using this technology able to reach the required temperatures for production. There are currently a number of projects in place with glass manufacturers throughout the UK and Europe that are transitioning furnaces to utilise green hydrogen, as well as hydrogen blended with natural gas.
Waste not, want not
Another key tool already employed and that is being continually developed by glass manufacturers to increase their sustainability is waste heat recovery technology. With furnaces operating at such extreme temperatures, leakage is an unavoidable inevitability. Capturing and redirecting this excess waste heat can be incredibly beneficial for glass manufacturers from a sustainability and financial perspective.
Firstly, there is the option of heat recovery, which is utilised by all UK glass manufacturers, when hot gas coming off the furnace is captured by regenerators and used to preheat the combustion air. After the waste gases have passed through the abatement equipment to remove particulates and pollutants, the waste gas can be used to generate electricity or used for local heating of homes and offices.
There is the option to use waste heat to preheat raw materials and recycled glass (cullet) for glass production before it is put into the furnace. Pre-heating in this way is an effective option, as pre-heated raw materials and recycled glass generally result in a 10-15% energy saving throughout the overall glass production process.
As we prepare for the future, we are confident that technology will be available to action net-zero strategies and that there is a sustainable and long-term future to UK glass manufacturing. This will include the use of renewable electricity and hydrogen produced from renewable electricity to replace natural gas.
Significant advancements have been made in electric and hydrogen solutions, however the cost of implanting this technology still remains high and infrastructure challenges persist.
As well as requiring large amounts of energy, glass furnaces represent the largest capital investment for manufacturers, costing tens of millions and lasting for around 20 years. In this context, it is understandable that manufactures are seeking clarity on the availability and cost of electricity and hydrogen and other energy sources before making large investments. However, the appetite is clearly shared in the glass manufacturing industry to secure the long-term future for the production of one of the oldest materials in the world in new and innovative ways.
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