A burning issue

“Since when can weathermen predict the weather, let alone the future?”1 Evaluating alternative energy options and infrastructure challenges, René Meuleman shares Schneider-Electric’s approach to moving the glass industry forwards and helping to establish the next generation of furnace technology. The full version of this article appears in the March/April 2023 issue that has been mailed globally and is also now available free of charge in the digital archive*.

A burning issue

The correlation between greenhouse gases and global warming was recognised by [Irish physicist] John Tyndall back in 1859. He wrote: “Thus the atmosphere admits of the entrance of the solar heat but checks its exit, and the result is a tendency to accumulate heat at the surface of the planet”.2 Or perhaps it was Eunice Foote who demonstrated the ability of carbon dioxide to absorb heat from the sun in 1856?3 Despite [these warnings], it took humanity a long time to understand that burning fossil fuels and releasing carbon dioxide into the atmosphere would cause humanity major issues.

Focusing on these facts today, there seems to be only one way forward. Move away from fossil fuels and towards green solar and wind energy, fuelled by the only real green source, the sun. You may say, why not use biofuels? Biofuels come from capturing CO2 out of the atmosphere and are converted into biomass, by sunlight. [This is] well known as photosynthesis: 12H2O + 6CO2 → C6H12O6 + 6H2O + 6O2 [the process by which] all kinds of wood and biomass and organic waste can be gasified when bacteria digest the organic matter in the absence of oxygen.

Unfortunately, these process cycles are very slow and leave us with the question of whether it makes sense to grow a tree in 20 years to burn it in a steam boiler in two minutes. Of course, it makes sense to decompose and convert residue coming from cattle and water treatment into biofuels. However, questions remain as to whether there will be sufficient biogas or fuel available for the glass industry, keeping in mind that there is still at least 35% of CO2, H2O, NH3, H2S in biogas that would need to be separated before use. It’s fair to say that there have been successful trials with biofuels but the ones we know all question its future availability and price.

We can of course take natural gas and take out the hydrogen by steam reforming CH4 + H2O → CO + 3H2 → CO + H2O → CO2 + H2. Using the hydrogen and putting the CO2 into where the natural gas came from: the wells. It sounds like a good idea but comes very close to being a landfill. In fact, it comes close to trying to get rid of nuclear waste by putting it underground. Next to that, burning hydrogen is not very energy efficient, that’s why hydrogen cars have fuel cells, so why would the glass industry go down that route if it only needs heat and not specifically hydrogen?

That brings us to another argument against the use of hydrogen in glass manufacturing. Other industries such as aerospace and automotive cannot do without hydrogen gas, and as a result, are willing to pay more for it. Of course, the ability to store hydrogen could become an important argument but compressing it up to 600 bar or cooling it down to -253°C is a challenge and comes with additional energy losses.

Storing sufficient hydrogen on site is therefore not very likely, simply because it is not easy to store large amounts of hydrogen under these circumstances (yet). Getting more than 30% of the initial green energy put into the processes of electrolysing, compressing, cooling down, storing, transporting, and finally burning it in a glass furnace is [also] not very likely. And again there is the argument that hydrogen can be stored and electricity not, at least not in the amount we need for glass-making processes. Most probably and in case hydrogen becomes a commercially viable solution, the industry [would need to] depend on off-site large-scale storage, raising concerns about transportation or available infrastructure.

However, let’s keep in mind that glass manufacturers are luckily in a better position compared to the steel or cement industries. Glass manufacturing only needs process heat, and not a reactant like the steel or cement industry. Perhaps for some glass types and colours, and for the sake of flexible furnace operations, the furnace could do with some top heat coming from a combustion system, fed by hydrogen or perhaps some kind of a syntactic fuel. Overall, it seems that in commodity glass manufacturing, such as container and float glass, future furnaces will move towards hybrid designs where most of the energy will come from electrical power.

Today, there are already some furnace designs fit for the future but ramping up electrical power and feeding it into a glass-melting furnace sounds easy?

Being an old and established technology, electrical melting comes with unexplored technologies and scaling up (to higher pull-rate related-) problems that need to be solved. As there is a limited amount of power, a boosting electrode is [required to preclude] running into unwanted, short maintenance intervals. Nor can we keep on increasing the number of electrodes due to the – although low – risk of losing an electrode or its holder during operations. The more electrical energy that needs to be fed into a furnace by an increasing number of electrodes could eventually lead to less time for maintenance of electrodes. Can we move up to bigger electrodes, investigate the cathodic protection of electrodes and start applying it, perhaps even looking at higher power frequencies?

We still have several design options to improve systems, but many would need more research. From an operational point of view, data collection and analytics, AI, and predictive maintenance strategies can help to keep maintenance interruptions to a minimum, maintaining an acceptable level of glass quality.

What should not be forgotten is the engineering legacy and the huge installed base of regenerative furnaces. Massive energy efficiency improvements have been achieved in fossil fuel-based systems, and existing sites were designed to fit the traditional type of furnaces. Interestingly, promising new glass melting systems will arrive but they must fit in existing real estate – these could become the new standard for future greenfield builds. The bottom line and the downside are that eventually the industry must let fossil fuels loose and refocus on renewable energy and a different way of approaching the energy efficiency of new heating systems. It requires a shift of focus, as well as a shift of competencies on the shop floor. Sooner or later a completely new furnace design will enter, forcing operational staff to learn to fly again with a new set of ‘wings’. That is where digitisation, AI and advanced control will help. The industry needs to keep its OpEx acceptable to stay competitive, keeping an eye on the social license to operate, which means operations need to move faster at higher yields and stay flexible. In that respect, we need to use all the flexibility available in manufacturing to be matched to the ongoing fluctuation of energy pricing and the demands of the market. Use more energy when it is cheap and use less when expensive by making sure that future furnace designs can cope with higher energy fluctuation, without impacting glass quality or manufacturing flexibility.

Energy infrastructure

There are already solutions available, or at least under development, for most of what has been discussed. This brings us to perhaps the biggest problem: energy infrastructure. Internally, the electrical energy demand will quadruple. In most new situations, medium-voltage power systems will have to step up to become high-voltage systems. Power control will increase from low to medium voltage. That is manageable but getting the increased amount of power from utilities into factories on time remains, in most cases, questionable. Which green energy sources come out on top depends on availability and a decent, stable supply. Today, most existing glass factories do not have sufficient mega Watts available on-site, nor the supply of sufficient hydrogen, biogas, or syntactic fuels. As a result of these infrastructural and availability issues, the glass industry depends heavily on governments and utilities.

Future outlook 

So, how can we help you to move the industry forward in the most cost-efficient and pragmatic way?

  • By helping to get the best possible and realistic outlook of what kind of renewable energies will become available and what they will cost.
  • Providing an overview of today’s and tomorrow’s available electrical power and infrastructure at or close to your sites.
  • Helping to get a good overview of your installed base by making an inventory of all electrical equipment on site, keeping an eye out for opportunities to re-use what is available and only add what’s needed.
  • Designing an overall from ‘grid to glass’ system layout, having the most energy-efficient locations and types of power supply equipment: re-use where possible; add what is needed.
  • Assisting you and your furnace suppliers to get the most CapEx and OpEx efficient energy supply systems around your future furnaces.
  • Integrating available furnace mathematical models into process automation and using them to streamline the glass manufacturing processes, assist, and train operators to find safe ways to adapt furnace flexibility to support glass quality and energy consumption.

We at Schneider Electric try to answer all those questions, knowing that they, in some way will interact with each other and not all in the same direction. Changing one will have an impact on the other and knowing that alone, without all the other yet unknown question marks related to new ways of glass melting, will not make our lives easier. Moving away from fossil fuels towards renewable energy is a big step change – perhaps the biggest since the introduction of the regenerative furnace 160 years ago.

It is now that we define new ways of glass manufacturing and most probably will fix the next generation of furnace technology, similar to what was done 160 years ago. Finding the right, unbiased answers and ruling out as many risks as possible is key and will potentially contribute to the success of your projects. We at Schneider-Electric are well equipped to help you to find those answers, solve your problems and execute your electrification, decarbonisation and digitisation projects. l


1. Quote from the 1985 film Back to the Future

2. Excerpt from John Tyndall’s 1859 paper “On the Transmission of Heat of different qualities through Gases of different kinds.”

3. Eunice Foote, “Circumstances Affecting the Heat of Sun’s Rays”, American Journal of Art and Science, 2nd Series, v. XXII/no. LXVI, November 1856.

4. https://www.envchemgroup.com/john-tyndallrsquos-discovery-of-the-lsquogr...

5. https://www.glindco.com/blog/will-hydrogen-be-the-new-energy-carrier-for...

6. https://www.researchgate.net/figure/Carbon-footprint-of-the-production-o...4



Figure 1: The first ratio spectrophotometer, assembled by John Tyndall.2

Figure 2: Energy efficiency of H2 in glass melting.4

Figure 3: Position of glass against other energy-intensive industries.5

About the Author: 

René Meuleman is Senior Solution Architect ‘green’ glass at Schneider-Electric

Further Information: 

Schneider-Electric, Baarn, the Netherlands
tel: +31 6268 79952
email: rene.meuleman@se.com
web: www.se.com

* The full version of this article appears in the March/April issue that has been mailed globally. The digital version of this issue can also currently be read free of charge in its entirety in the Digital Archive (sponsored by FIC) of over 60 issues of Glass Worldwide at https://www.glassworldwide.co.uk/Digital-Issues. To receive the paper copy, all future issues and a free copy of the Who’s Who / Annual Review yearbook, subscribe now at https://www.glassworldwide.co.uk/subscription-choice