Carbon Emissions of Electric vs Gas Melting Furnaces: Electrification Is the Direction

The Paris Agreement was reached in late 2015 and entered into force in November 2016, and China also set out its international commitment to control carbon emission intensity. For the energy-intensive glass industry, melting accounts for the largest share of a line's energy consumption and emissions, so whether furnaces should run more on electricity is an unavoidable question for any low-carbon technology route. Amid discussion of green power certification and emissions trading, furnace electrification has been listed as an important reserve option in several low-carbon technology roadmaps. This article compares the carbon emission logic of electric melting furnaces and gas-fired furnaces across three dimensions.

Direct emissions: electric melting furnaces have almost no combustion source

Gas-fired furnaces rely on fuel combustion for heat, and the flue gas directly emits carbon dioxide, nitrogen oxides and sulfur compounds, putting a heavy burden on end-of-pipe treatment. In an electric melting furnace, current is fed through molybdenum electrodes into the high-resistance glass melt, heat is generated inside the melt, and there is almost no combustion flue gas at the furnace site. Electricity may still come from thermal power, but emission control at large power plants is far better than that of dispersed industrial furnaces, so the electric melting route still comes out ahead on a full-scope accounting basis. At the same time, electric boosting reduces the combustion volume and furnace pressure of flame furnaces, with clear accompanying cuts in nitrogen oxides and sulfur dioxide.

Thermal efficiency: electric melting furnaces come close to doubling it

Key indicators for the two furnace types compare as follows:

The inspection and acceptance basis for the indicators above: electrode products are controlled under YS/T 1312-2019, Molybdenum Electrodes; molybdenum rods follow ASTM B387 / GB/T 17792; molybdenum plate and discs follow ASTM B386 / GB/T 3876; a quality certificate accompanies every shipment, and batches are traceable.

The reason electric melting furnaces achieve such high thermal efficiency is that heat is generated inside the melt and little of it is carried away in flue gas; this advantage shows up especially clearly in small and medium furnace types.

Process fit: electric melting better supports high-quality melting

• Specialty glass, glass microspheres and other small-capacity, high-value products suit all-electric furnaces with side-entry molybdenum electrodes;
• Large-tonnage general-purpose glass uses flame primary melting plus deep electric boosting with molybdenum electrodes to cut gas consumption and stabilize furnace temperature;
• Using off-peak or clean-energy electricity further amplifies the emission reductions of electric melting furnaces;
• Combined with regenerative furnace operation: peak shaving and valley filling widen both the emission reduction and the economic return of electric melting.

Of course, electric melting conversions are also constrained by capital intensity and power supply reliability, and must be advanced product by product and scenario by scenario. On this path, the corrosion resistance and current-carrying capacity of the electrode set the upper limit of electrification; for existing flame furnaces, adding electrodes for boosting is a more realistic entry point, since the furnace body itself needs no major changes. The WeiBeam.com technical team's analysis is that whatever direction carbon policy instruments take, the trend of a rising electricity share in the melting step is clear, and the electrode industry that supports it will gain long-term structural growth room.