Glass plants across Europe, Asia, and North America are feeling the pressure. Rising natural gas prices, tighter carbon regulations, and aging furnace infrastructure have pushed glass manufacturers into survival mode. The energy crisis that first intensified in 2021 and continued rippling through 2023–2025 didn't spare heavy industry — and glass production, one of the most energy-intensive industrial processes on earth, has taken a particularly hard hit.

But within this crisis, a proven technology is gaining serious momentum: oxy-fuel combustion. For plant operators and energy managers looking to cut fuel consumption, lower carbon dioxide emissions, and keep production competitive, oxy-fuel furnaces are no longer just an option — they're becoming a strategic necessity.

This article breaks down exactly what's happening in the glass industry, why energy costs are threatening plant viability, and how oxy-fuel technology works as a practical, scalable solution.

Why Energy Costs Are Breaking Glass Plants

Glass manufacturing is inherently fuel-hungry. A single float glass furnace or container glass furnace can consume between 4 and 8 gigajoules of energy per tonne of molten glass produced. Across a full production year, that's an enormous natural gas bill — one that became nearly unbearable when wholesale gas prices spiked to record highs.

In Europe, the energy crisis driven by geopolitical disruptions in natural gas supply forced many glass plants to curtail output or temporarily shut furnaces altogether. Smaller specialty glass producers faced the harshest choices: absorb the losses, pass costs to customers, or close lines. Even large multinational players like Owens-Illinois, Saint-Gobain, and Ardagh Group were forced to restructure operations and accelerate their decarbonization roadmaps — not just for sustainability optics, but for raw financial survival.

The core problem is structural. Traditional air-fuel furnaces — the dominant technology in glass plants for over a century — burn natural gas mixed with atmospheric air. Since air is roughly 79% nitrogen, a massive portion of heat energy goes straight into heating that nitrogen rather than melting glass. That's inherent thermal inefficiency baked into the combustion process itself.

When energy was cheap, inefficiency was manageable. When gas prices doubled or tripled, it became a crisis.

What Is Oxy-Fuel Combustion?

Oxy-fuel combustion replaces atmospheric air with high-purity oxygen — typically 90% to 99.5% pure — as the oxidant in the burner system. Eliminating nitrogen from the combustion equation changes everything.

When pure oxygen burns with natural gas (or other hydrocarbon fuels), the flame temperature is significantly higher, the combustion is more complete, and heat transfer to the glass melt is dramatically more efficient. Because there's no nitrogen to heat and exhaust, flue gas volumes drop by roughly 70% compared to conventional air-fuel furnaces.

That reduction in flue gas volume translates directly into:

• Lower fuel consumption — typically 20% to 50% less natural gas per tonne of glass produced

• Reduced NOx emissions — nitrogen oxides form when nitrogen and oxygen react at high temperatures; remove the nitrogen and NOx collapses

• Lower CO2 output per tonne — because you're burning less fuel to produce the same amount of glass

• Smaller furnace footprint — reduced gas volumes mean smaller regenerator or recuperator systems are needed, freeing up capital and plant space

For glass plants under pressure from both energy costs and carbon compliance obligations, this combination is compelling.

How Oxy-Fuel Furnaces Work in Glass Plants

In a conventional regenerative glass furnace, hot exhaust gases pass through brick checkerwork called regenerators, preheating the incoming combustion air to around 1,000–1,200°C. This preheating recovers some heat, but the system is still moving enormous volumes of nitrogen-laden air.

An oxy-fuel furnace bypasses regenerators entirely. Oxygen is delivered from either an on-site air separation unit (ASU) or liquid oxygen storage, then mixed with fuel at the burner. The combustion products — primarily carbon dioxide and water vapor — are exhausted directly, often after passing through a heat recovery system or waste heat boiler.

The glass melting process itself benefits from the higher flame luminosity and improved radiative heat transfer that oxy-fuel flames provide. Molten glass absorbs radiant heat more effectively than convective heat, so the direct, luminous flames of oxy-fuel burners heat the glass bath more uniformly and efficiently.

Several furnace configurations are used in practice:

Full oxy-fuel conversion replaces all air-fuel burners with oxy-fuel burners. This delivers maximum energy savings and emissions reductions but requires upfront capital investment.

Oxygen-enrichment or oxy-boost adds supplemental oxygen to an existing air-fuel system, improving combustion without full conversion. This is a lower-cost entry point for plants not ready for complete retrofits.

Batch and cullet preheating combined with oxy-fuel further improves efficiency by using exhaust heat to preheat raw materials before they enter the furnace.

Real-World Impact: Energy and Emissions Numbers

The efficiency gains from oxy-fuel aren't theoretical — they've been demonstrated across decades of commercial operation in container glass, flat glass, specialty glass, and fiberglass production.

Typical reported results from oxy-fuel conversions in the glass industry include:

• Fuel savings of 25–45% per tonne of glass melted

• NOx emission reductions of 70–90% compared to air-fuel regenerative furnaces

• CO2 emission reductions of 20–40% per tonne of glass, depending on baseline furnace efficiency and oxygen production method

• Improved glass quality due to more uniform temperature distribution in the melt

Companies supplying oxy-fuel burner systems and engineering services to the glass industry — including Air Products, Linde, Air Liquide, and Messer Group — have documented these results across hundreds of furnace installations globally.

The Oxygen Supply Question

One common concern plant operators raise is the cost and complexity of oxygen supply. High-purity oxygen doesn't come free — it's produced by cryogenic air separation or, for smaller volumes, pressure swing adsorption (PSA) systems.

For large glass furnaces, on-site cryogenic ASUs are typically the most cost-effective option, particularly when electricity costs are manageable. For medium-sized operations, long-term liquid oxygen supply contracts with industrial gas suppliers offer a viable alternative without major capital outlay.

The economic equation is straightforward: if the cost of oxygen is less than the value of natural gas saved — which in high-gas-price environments it often is — oxy-fuel pays for itself. During the worst of the energy crisis, many plants found the math increasingly favorable.

Carbon Compliance and the Oxy-Fuel Advantage

Beyond direct cost savings, glass manufacturers operating in the European Union face obligations under the EU Emissions Trading System (EU ETS). Carbon allowance prices have climbed steadily, adding another cost burden to high-emitting air-fuel furnaces.

Oxy-fuel conversion reduces verified CO2 output per tonne of production, directly lowering a plant's compliance costs under cap-and-trade frameworks. As carbon prices continue their long-term upward trend under EU climate policy, this regulatory advantage compounds the direct fuel savings.

For glass plants planning furnace rebuilds or major repairs — which happen on 10-to-15-year cycles — oxy-fuel is increasingly the default choice for new builds, not just a retrofit option.

Read more: How to Stay Compliant With Your Equipment

Practical Considerations for Glass Plant Operators

Transitioning to oxy-fuel is not without challenges. Plants need to consider:

Furnace crown and refractory materials — oxy-fuel atmospheres are hotter and have different chemical compositions, requiring compatible refractory systems to avoid accelerated wear.

Batch chemistry adjustments — higher concentrations of water vapor in oxy-fuel combustion gases can affect volatile species in the glass batch, particularly for borosilicate and specialty glasses.

Electrical integration — some plants combine oxy-fuel with electric boosting (electrode systems submerged in the glass melt) for additional flexibility and efficiency.

Capital planning — full oxy-fuel conversion during a furnace rebuild is significantly more cost-effective than retrofitting a running furnace mid-campaign.

Working with experienced combustion engineering partners and industrial gas suppliers during the feasibility and design phase is critical to achieving projected savings.