Potential of demand response for chlor-alkali electrolysis processes

Chlor-alkali electrolysis indicates significant demand response potential, accounting for over 2% of Germany’s total elec-tricity demand. To fully analyze this potential, digital models or digital twins are necessary. In this study, we use the IRPopt modeling framework to develop a digital model of an electrolysis process and examine the cost-optimal load shifting application in the day-ahead spot and balancing reserve market for various price scenarios (2019, 2030, 2040). We also investigate the associated CO2 emissions. Combined optimization at both markets results in greater and more robust cost savings of 16.1% but cannibalizes the savings that are possible through optimization separately at each market. In future scenarios, the shares of savings from spot and reserve market could potentially reverse. CO2 savings between 2.5% and 9.2% appear only through optimization at the spot market and could even turn negative if optimized solely at the reserve market

A two-stage stochastic optimisation methodology for the operation of a chlor-alkali electrolyser under variable DAM and FCR market prices

The increased penetration of renewable energy sources in the electrical grid raises the need for more power system flexibility. One of the high potential groups to provide such flexibility is the industry. Incentives to do so are provided by variable pricing and remuneration of supplied ancillary services. The operational flexibility of a chlor-alkali electrolysis process shows opportunities in the current energy and ancillary services markets. A co-optimisation of operating the chlor-alkali process under an hourly variable priced electricity sourcing strategy and the delivery of Frequency Containment Reserve (FCR) is the core of this work. A short term price prediction for the Day-Ahead Market (DAM) and FCR market as input for a deterministic optimisation shows good results under standard DAM price patterns, but leaves room for improvement in case of price fluctuations, e.g., as caused by Renewable Energy Sources (RES). A two-stage stochastic optimisation is considered to cope with the uncertainties introduced by the exogenous parameters. An improvement of the stochastic solution over the deterministic Expected Value (EV) solution is shown

Towards demand-side management of the chlor-alkali electrolysis: Dynamic, pressure-driven modeling and model validation of the 1,2-dichloroethane synthesis

A promising application of demand-side management is the chlor-alkali electrolysis. However, storing the produced chlorine for flexibility should be avoided whenever possible. If PVC is produced from chlorine, storing the intermediate 1,2-dichloroethane resulting from direct chlorination of ethene is a better alternative as it is less toxic than chlorine and can be easily stored. Currently, no dynamic process models to study the process behavior or to develop optimal trajectories for the 1,2-dichloroethane production under different demand response scenarios are available. Hence, we formulate and solve a dynamic, pressure-driven model of the synthesis of 1,2-dichloroethane and validate it with real process data in this contribution. As part of this dynamic model, differentiable formulations for weeping and the flow over a weir of a distillation tray are presented, which are also valid whenever certain trays run dry.BMWi, 0350013A, Verbundvorhaben: ChemEFlex - Umsetzbarkeitsanalyse zur Lastflexibilisierung elektrochemischer Verfahren in der Industrie; Teilvorhaben: Modellierung der Chlor-Alkali-Elektrolyse sowie anderer Prozesse und deren Bewertung hinsichtlich Wirtschaftlichkeit und möglicher Hemmniss

Flexible and economical operation of chlor‐alkali process with subsequent polyvinyl chloride production

Demand response (DR) can compensate for imbalances in variable renewable energy supplies. This possibility is particularly interesting for electrochemical processes, due to their high energy intensity. To determine the technical feasibility and economic viability of DR, we chose the chlor‐alkali process with subsequent polyvinyl chloride production, including intermediate storage for ethylene dichloride. We estimate the maximum possible cost savings of implementing load flexibility measures. A process model is set up to determine the system characteristic. Subsequent optimizations result in the facility's best possible dispatch depending on additional and minimum power load, storage volume, and cost of a load change. Real plant data are used to specify model parameters and validate the system characteristic and the plant dispatch. An economic evaluation reveals the economic advantages of efficiency and flexibility. The approach can be used to analyze the DR potential of other chlorine value chains or facilities with high electricity demand in general.BMWi, 0350013A, Verbundvorhaben: ChemEFlex - Umsetzbarkeitsanalyse zur Lastflexibilisierung elektrochemischer Verfahren in der Industrie; Teilvorhaben: Modellierung der Chlor-Alkali-Elektrolyse sowie anderer Prozesse und deren Bewertung hinsichtlich Wirtschaftlichkeit und möglicher Hemmniss

Flexibility of Epichlorohydrin Production—Increasing Profitability by Demand Response for Electricity and Balancing Market

The increasing share of variable renewable energies in the power grid is an incentive to explore demand response strategies. Chlor-alkali processes are high potential candidates, according to previous publications. Within Germany’s chemical industry, chlorine production accounts for approximately 20% of electricity use and could play a significant role in power grid stabilisation on the consumer end. This study focuses on the feasibility of load flexibilisation in epichlorohydrin plants, with the second biggest estimated demand response potential for chlorine-based products in Germany. A plant model with allyl chloride storage was created based on real data and literature values. Results from this model, spot market and balancing power prices, and future electricity market scenarios were used in a mixed-integer linear optimisation. We find that benefits from demand response can be generated as soon as additional power and storage volume is provided. The composition of provided types of balancing power bids follows the price trend on the market. Additionally, the computation time could be lowered significantly by running the scenarios in parallel. The results encourage a practical validation of the flexibility of epichlorohydrin production.BMWK,0350013A, Verbundvorhaben: ChemEFlex - Umsetzbarkeitsanalyse zur Lastflexibilisierung elektrochemischer Verfahren in der Industrie; Teilvorhaben: Modellierung der Chlor-Alkali-Elektrolyse sowie anderer Prozesse und deren Bewertung hinsichtlich Wirtschaftlichkeit und möglicher Hemmniss

Optimization of Electric Ethylene Production:Exploring the Role of Cracker Flexibility, Batteries, and Renewable Energy Integration

The electrification of naphtha cracking for ethylene production could reduce the associated CO2 emissions but would require significantly larger electricity consumption. Within this context, the flexible operation of electric crackers opens opportunities for improved integration with the future electricity system. In this work, we developed a computationally efficient mixed-integer linear programming model to investigate flexibility in electric crackers, exploring the effect of operational parameters, such as operating envelope, ramping time, and start-up/shut-down time, on costs and emissions. We optimized three electric cracker systems: two with grid electricity consumption (with/without batteries) and one with electricity supply from dedicated renewable technologies. We find that the operating envelope of the cracker has the strongest impact on cost savings, enabling up to 5.5% reduction when using flexible electricity from the grid and 58% for systems with direct coupling to renewables. Moreover, the flexible operation of electric crackers relying on the electricity grid enhances the CO2 emission savings, achieving a 90.4% emission reduction against 54.6% of the constant operation case. Finally, we find that for direct coupling with renewables, electric crackers need to be flexible to avoid suboptimal oversizing of renewable technologies and especially unrealistic battery capacities.</p

Life Cycle Sustainability Assessment of the Hydrogen Fuel Cell Buses in the European Context. Evaluation of relevant measures to support low-carbon mobility in the public transport sector

Goal and Background. Transport represents 27% of Europe's Greenhouse Gas (GHG) emissions and is the main cause of air pollution in cities. With the global shift towards a low-carbon economy, the EU set forth a lowemission mobility strategy with the aim of reducing the overall emissions in the transport sector. The High V.LO.-City project is part of this overarching strategy and addresses the integration of hydrogen fuel cell (H2FC) buses in the public transport. Methods. In this thesis, the environmental assessment of one H2FC bus and the related refuelling station is carried out using the Life Cycle Assessment (LCA) methodology, taking into account the following phases: (1) bus production, (2) hydrogen production pathways (water electrolysis, chlor-alkali electrolysis, and steam methane reforming), (3) hydrogen consumption during bus operation, and (4) the vehicles' end of life. The potential impacts are evaluated for magnitude and signi cance in the life cycle impact assessment (LCIA) phase, using Environmental Footprint (EF) method which is part of the Product Environmental Footprint (PEF) method, established by the European Union (EU) in 2013. The calculated fuel economy is around 10.54 KgH2/100Km and the energy demand of a refuelling infrastructure may vary between 6 and 9 KWh/KgH2. Results. The results show that H2FC buses have the potential to reduce emissions during the use phase if renewables resources are used. The expected Global Warming Potential (GWP) bene t is about 85% in comparison to a diesel bus. Additionally, the emissions of the selected patterns of hydrogen production depend on how electricity is produced and on the chemical-based or fossil-based feedstocks used to drive the production process. Conclusions and Outlook. The improvement of the environmental pro le of hydrogen production requires to promote clean electricity sources to supply a low-carbon hydrogen and to sharpen policy focus with regard to life cycle management, and to counter potential setbacks, in particular those related to problem-shifting and to grid improvement

Optimization of Electric Ethylene Production: Exploring the Role of Cracker Flexibility, Batteries, and Renewable Energy Integration

The electrification of naphtha cracking for ethylene production could reduce the associated CO2 emissions but would require significantly larger electricity consumption. Within this context, the flexible operation of electric crackers opens opportunities for improved integration with the future electricity system. In this work, we developed a computationally efficient mixed-integer linear programming model to investigate flexibility in electric crackers, exploring the effect of operational parameters, such as operating envelope, ramping time, and start-up/shut-down time, on costs and emissions. We optimized three electric cracker systems: two with grid electricity consumption (with/without batteries) and one with electricity supply from dedicated renewable technologies. We find that the operating envelope of the cracker has the strongest impact on cost savings, enabling up to 5.5% reduction when using flexible electricity from the grid and 58% for systems with direct coupling to renewables. Moreover, the flexible operation of electric crackers relying on the electricity grid enhances the CO2 emission savings, achieving a 90.4% emission reduction against 54.6% of the constant operation case. Finally, we find that for direct coupling with renewables, electric crackers need to be flexible to avoid suboptimal oversizing of renewable technologies and especially unrealistic battery capacities

A review of energy management strategies for renewable hybrid energy systems with hydrogen backup

Hybrid systems are presented as a viable, safe and effective solution to minimize the associated problems of the dependence on renewable energies with the environmental resources. In this way different renewable systems such as photovoltaic, wind, hydrogen and so on, can work together to configure hybrid renewable systems. However, to make them work properly in a holistic way by creating synergies among them is not an easy task. Recently hydrogen technology has appeared as a promising technology to hybridize renewable energy systems, since it allows the generation (by electrolyzers) and storage of hydrogen when there is a surplus of energy in the system, and at a later time (e.g. when there are insufficient renewable resources available) using the stored hydrogen to generate electrical energy by fuel cells. The choice of a correct energy management strategy should guarantee an optimum performance of the whole hybrid renewable system; therefore, it is necessary to know the most important criteria in order to define a management strategy that ensures the best solution from a technical and economic point of view. This paper presents a critical review and analysis of different energy management strategies for hybrid renewable systems based on hydrogen backup. In the same way, a review is also presented of the most important technical and economic optimization criteria, as well as problems and solutions studied in the scientific literature