Energy Flexibility in the German Glass Industry

Motivation

The reason for the study is the planned expiry of the so-called ‘band load regulation’ on 1 January 2026, which represents a reduction in grid fees for electricity-intensive end consumers. A transition period until 31 December 2028 applies to end consumers. The ‘band load regulation’ encourages end consumers to consume electricity as consistently as possible. With an annual electricity consumption of over 10 GWh and at the same time over 7,000 full-load hours (FLH), a discount of up to 80 % on grid fees is applied. A planned revision of grid fee privileges, among other things to integrate fluctuating renewable electricity generation into the energy system, is intended to activate energy flexibility potential and incentivize flexible, grid-friendly electricity consumption.

Project Objectives & Methodology

To answer the question of whether and to what extent the glass industry can provide such energy flexibility potential, this study examines the processes of glass production in the status quo and provides an outlook on future developments, taking into account possible transformation paths. To this end, interviews and on-site visits with container glass manufacturers and glass producers are being conducted.

Conclusion & Key Findings

Glass production is characterized by continuous, energy-intensive and temperature-sensitive processes. The thermal equilibrium of the glass melts is essential for product quality. Adjustments to the process parameters usually lead to production rejects, which severely limits the energy flexibility potential. The foreseeable decarbonization of the industry will primarily take place through electrification using fully electric or hybrid melting tanks. These significantly increase electricity demand without creating any new relevant flexibility potential. Hybrid furnaces theoretically offer scope for varying the electricity-gas ratio, but these adjustments are technically complex, time-consuming and only feasible in the long term, as well as associated with risks to efficiency and service life. Energy storage systems such as battery systems could enable flexibility outside the core process, but they are challenging in terms of economics and infrastructure.

Regulatory incentives to activate an energy flexibility potential can only be effective if they take into account the technical limitations of glass production. Continuous, efficient, high-quality and economically viable production remains the top priority. The individual location- and product-specific requirements of manufacturers must be taken into account in the design of network fee systems.

Key Findings of the Study

1. Diversity in Glass Manufacturing 
   Each location and each product in the glass industry has its own highly individual requirements and conditions for achieving the desired product quality. It is particularly important to distinguish between the individual sub-sectors of flat glass, hollow/container glass and speciality glass.
2. Technical Reasons: Low Energy Flexibility Potential in the Manufacturing Process
   All glass production processes must run continuously in order to maintain the set thermal equilibrium in the process and thus the desired product quality. Changes to the process have a direct impact on product quality and usually lead to production rejects. Due to the thermal inertia in the process and the sometimes long dwell times in the melt, it takes several days to weeks to adjust operating points and obtain a usable product that meets quality requirements.
3. Decarbonization: Rising Electricity Consumption, Consistently Low Energy Flexibility Potential
   The decarbonization of the glass industry is based primarily on increased electrification, either through fully electric or hybrid melting tanks. Both technologies significantly increase the electricity consumption of production sites. However, the processes must continue to be operated continuously and without significant energy flexibility potential in order to maintain product quality. The elimination of band load privileges makes electricity procurement considerably more expensive and, especially in the case of hybrid melting tanks, means that the use of fossil natural gas is the more economical option. The goal of decarbonization should be prioritized and supported by appropriate incentives, including in the grid fee system.
   
4. Flexibility vs. Efficiency, Service Life and Economic Utilization
   Adjustments to the operating points of the melting tank usually take hours to days, and in some cases weeks. Each adjustment is associated with product waste and reduces the service life of the melting tanks and, in some cases, the transformers. In order to operate a melting tank economically, it must be continuously utilized under full load for as long as possible. Any adjustment of the operating point also reduces the energy efficiency of the melting tank. Hybrid melting tanks in particular are designed for maximum efficiency, both in terms of their tank size for the planned number of electrodes and in terms of the size of the top furnace for the associated gas flame, in accordance with an optimum operating point.
5. Costs and Economic Risks in Electricity Procurement
   The costs incurred by the elimination of baseload privileges cannot be offset by alternative revenue opportunities, such as conceivable marketing on the control energy market. The technically feasible energy flexibility potential for providing the corresponding power is too low for this. In addition, baseload supply is often secured several years in advance through long-term electricity purchases, depending on the risk appetite of glass producers, in order to hedge against price risks, with only a small portion being procured at short notice via the spot market. In order to be able to react to price signals, electricity procurement would have to be more strongly oriented towards the spot market, which would lead to a greater risk of dependence on short-term price fluctuations. Since the processes must be operated continuously and do not offer any relevant energy flexibility potential, electricity would then also have to be purchased even if prices were high in the short term.

Project Partner

Bundesverband Glasindustrie e. V. 

Further Information

• Study on the Homepage of the BV Glas: Energieflexibilität in der Glasindustrie