Photovoltaic panels on almost every roof, large wind farms at sea and on land, millions of heat pumps and battery storage systems, electric and fuel cell vehicles on every road, powerfuels produced by offshore wind farms in the North Sea or by solar farms in North Africa – the energy landscape of a climate-neutral Germany in 2050 is extremely diverse. Renewable electricity is the main source of energy, either consumed directly or used indirectly to produce liquid and gaseous energy carriers or to supply district heating networks.
Making this vision a reality will require an efficient infrastructure that includes and coordinates all levels – the electricity grids, gas grids, heating networks, pipelines, storage systems, filling stations and charging stations. Today’s existing infrastructure needs to be used to optimal capacity, linked up, improved, and strategically expanded where necessary. As well as helping to achieve climate targets and guarantee security of supply, this will also optimise costs on the road to a climateneutral future. “An integrated energy transition, in which a wide variety of energy carriers are used, also requires an integrated infrastructure and a comprehensive view of that infrastructure,” says Hannes Seidl, Head of Division for Energy Systems and Energy Services at dena.
This type of holistic approach could, for instance, help to reduce the need for curtailing coastal wind turbines in response to bottlenecks in the transmission system that carries the electricity to southern Germany. Using electrolysis to convert wind electricity into hydrogen or green gas that is then stored in the existing gas network or used in industry or transportation would have multiple benefits. It would allow more renewable electricity to be used, which would be good for the climate. Converting electricity into gaseous energy carriers would also make it possible to store renewable energies and better manage the seasonal fluctuations in the amount of electricity they produce. Not least, it would ease the burden on electricity transmission lines and reduce the costs associated with intervening in the grid; in the first quarter of 2019 alone, wind electricity curtailment reached a record level of more than three billion kilowatt-hours.
Integrated infrastructure increases flexibility
To avoid this situation, the electricity grids must be expanded across all voltage levels and interlinked with other energy infrastructures. This will increase flexibility and make the entire system significantly more efficient. Germany is still quite far from achieving this kind of holistic approach to its energy infrastructure, and a look back at its history explains why. For many decades, the various infrastructures were planned, built and operated in isolation from each other. As well as focusing on high safety requirements, each infrastructure system concentrated on its own optimisation and expansion. The same applied when the European energy markets began opening in the late 1990s – a process that was about expanding beyond former territories and national borders.
Requirements only shifted with the expansion of renewable energies and the remodelling and increasing decentralisation of the generation structure. This has created the need for a new approach. A few years ago, Germany introduced a new procedure for establishing the level of expansion required in the medium term: since 2012, the country’s electricity transmission system operators have been engaged in a multi-stage process for developing the Grid Development Plan Power; the gas transmission system operators are doing the same for the Grid Development Plan Gas. The plans separately show the need for expansion in the national transmission grids over the next 10 to 15 years. They are updated every two years. Similar processes are happening at the European level, and this is where the first threads are coming together: the EU has been using jointly agreed scenario frameworks for electricity and gas transmission system planning since 2018.
“If we are going to take an integrated energy transition that covers all the energy sectors seriously, we have to make sure that the infrastructures are much better coordinated and connected than they are right now.”
Converting wind into gas and heat
Where and how is this already happening? Which solutions are being tested? And what requirements need to be met? One example involves using electrolysers to connect the electricity and gas grids. Electrolysers produce hydrogen and synthetic gas from renewable electricity. Several dozen pilot projects are underway in Germany. One of the first is located at a wind farm in Prenzlau in the state of Brandenburg. The company Enertrag has been running a 0.5-megawatt (MW) electrolyser there for several years now. When the three 2.3-MW wind turbines are turning at full speed, some of the electricity produces hydrogen that can be stored to cover the next slump in output, or fed via a short stub pipeline into the gas grid run by the transmission system operator Ontras. This mixture of natural gas and hydrogen is marketed as “windgas” via a surcharge model through Greenpeace Energy. Enertrag also invested in a filling unit in 2016, partly to supply backup power systems. The hydrogen is sold throughout Germany and can be used to fuel busses and recreational craft, for industrial processes or for electricity production. “Our first customer for the green hydrogen was Total, which wanted it for its filling stations,” says Simon Müller, Head of Energy Systems at Enertrag. Now Enertrag is planning another hydrogen hub close to a wind farm in Bahnsdorf, Lusatia. This one will be much bigger, though: the idea is to install an electrolyser with a capacity of up to 100 MW at the new site.
Connecting electricity and heating systems at a municipal level is essentially nothing new. Combined heat and power systems, which generate electricity and heat simultaneously, have already produced many clever solutions. However, with more electricity being generated from renewable energies, and with electricity becoming more important overall, new approaches are now needed. Public utilities and other energy suppliers are involved in countless projects where, at times when feed-in levels are high, green electricity is used to generate district heating and thereby relieve the electricity grid. This process is known as power-to-heat.
Another approach is on show in Krummhörn, East Frisia. The town is home to a compressor station that is part of the transmission system that brings Norwegian natural gas into Germany’s pipelines. To keep the pressure in the transmission system balanced, the gas has to be compressed every 150 to 200 kilometres. In Krummhörn, this is achieved with an electric compressor. The station operator, Open Grid Europe, says that it primarily runs on electricity from renewable sources. “Our new compressor relieves the pressure on the regional electricity grids, particularly when a lot of wind electricity is being produced that can’t be transported to southern Germany,” explains Thomas Hüwener, Technical Director at Open Grid Europe. The station has been undergoing testing since October 2019. It is part of the “enera” project that is being funded by the Federal Ministry for Economic Affairs and Energy (BMWi) as part of its SINTEG programme.
Driving with battery power and overhead lines
Connecting energy infrastructure with mobility offers particularly great potential. This is true whether the energy is used directly via batteries, or indirectly via synthetic fuels produced using electricity. At every level, existing or new infrastructure must be connected with intelligent data management.
The number of public charging stations for electric vehicles is steadily growing. Figures from the Federal Network Agency show that there were around 21,100 public charging points in Germany in August 2019.
If renewable electricity is to be used directly, the most efficient solution is battery-electric technology. Around 5.6 million electric vehicles were on the roads worldwide at the start of 2019, with 142,000 of them in Germany. The number of charging points, a new infrastructure that links electricity and mobility, passed the 21,000- mark in Germany in autumn 2019.
Electromobility is particularly attractive when the vehicles are used to cover relatively short distances and regularly return to the same place. Things become more difficult with long-distance travel and with usage that requires a lot of energy, such as heavy-duty road transport; the batteries needed for these vehicles would be simply too big and too heavy. A variety of alternative approaches are currently being developed and tested. In addition to replacing fossil fuels with biofuels or powerfuels, tests are also being carried out on something that has long been the norm for trains and trams: individual overhead lines.
Trials on the first eHighway, located in the Greater Frankfurt area, began in May 2019. Hybrid trucks travelling on the A5 Autobahn can dock onto newly installed overhead cables that stretch for five kilometres in both directions. The trucks are powered by the electricity, which also charges a small battery. If the battery runs out of power after the truck has left the eHighway, the diesel engine will take over. “The dena Study Integrated Energy Transition showed that this kind of system could be a costefficient solution for very busy routes in future,” says Stefan Siegemund, Director of Mobility at dena. However, he also notes that a few other conditions will need to be in place, such as a Europe-wide solution: “We can only achieve a positive overall effect if foreign trucks can also use the overhead lines in Germany.”
Linking electricity and mobility can be especially efficient if drivers of electric vehicles mostly charge their batteries with solar electricity from panels on the roof of their garage or home, thereby reducing their use of the public electricity grid. An intelligent energy management system can help here – as shown by the Fellbach Zero Plus field trial led by the Fraunhofer Institute for Solar Energy Systems ISE. Residents of five passive houses were able to enter their charging needs for their electric cars at home or using their smartphone. In conjunction with forecasts of how much electricity the photovoltaic system would produce and the household would use, charging timetables were then developed and monitored. “The energy management system can significantly increase self-sufficiency,” says Christof Wittwer, Head of Department for Intersectoral Energy Systems and Grid Integration at Fraunhofer ISE. “On a sunny day the intelligent, forward-looking management system meant that the photovoltaic panels supplied 86 percent of the charging current. Without the charging algorithm, it would have been just 46 percent.”
Natural gas grid
According to the Federal Network Agency, Germany’s natural gas grid (excluding service lines) is 536,000 kilometres long – around 13 times the Earth’s circumference. Roughly 171,000 of those kilometres are low-pressure pipelines, 243,000 are medium-pressure pipelines, and 122,000 are high-pressure pipelines. With 50 underground storage facilities that can accommodate roughly 280 terawatt-hours of natural gas, Germany has by far the largest storage capacity in Europe. This is because Germany’s geographic location makes it an important country for transferring gas. About 42 percent of all the gas in Germany’s grid in 2017 was forwarded on to other European countries.
Accelerating integration with digital solutions
This brings us to another important type of infrastructure: digital solutions, including the use of artificial intelligence, are crucial for connecting existing physical cable and pipeline systems. They can act as a bridge between different networks or help to optimise a physical connection. TransnetBW and Netze BW, both electricity-grid operators in the state of BadenWürttemberg, launched the DA/RE (DAta exchange / REdispatch) initiative in June 2018. Its aim is to coordinate grid-stabilisation measures across all voltage levels using a digital platform. This would make it possible to use more plants for redispatching (which involves adjusting feed-in when the grid is overloaded) and would increase grid security. The digital approach provides a quicker overview of the redispatch capacity available at a given moment, for instance at generation plants, in storage systems or with bulk buyers who can adjust their consumption. Ultimately, this results in more redispatch capacity being available in total and means that plant deployment can be coordinated across the entire system. The platform is due to start operating in 2021.
Contribution of artificial intelligence (AI)
Artificial intelligence could also help achieve an integrated energy system with an integrated infrastructure. Examples here include using optimised consumption and load forecasts with neuronal networks, self-learning sensors in distribution grids, and smart electricity meters. In order to manage the increasing complexity of grid operations, software developer PSI collaborated closely with transmission system operator TenneT to develop an autopilot for grid management. The PSIsaso system (“saso” stands for security assessment and system optimization) independently assesses the status of the electricity grid using real-time data and algorithms. It is designed to simplify grid management for employees by assessing and visualising the current stability status, which will make it possible to identify critical situations at an early stage. The system also independently analyses which measures could return the grid to a stable condition.
Obstacles to integration
Yet these highly promising approaches frequently face problems: a lack of price signals often prevents them from being economically viable, or regulatory requirements create obstacles for new business models. This is because technologies such as electrolysers are only in their infancy and still very expensive, and because the current system of duties and fees makes electricity extremely expensive and therefore prevents it from being used flexibly for new areas of application. Then there are the technical challenges. These include retrofitting compressors in natural gas grids in order to accommodate blends containing more hydrogen, and producing durable electrolysers and batteries. Another major issue is the need to improve the efficiency of the various steps involved in converting electricity to hydrogen and synthetic fuels. Currently, less than 15 percent of the initial energy remains after electricity has been turned into liquid fuel.
Hydrogen pipeline system
Data from the German Hydrogen and Fuel Cell Association (DWV) show that the country’s hydrogen pipeline system is just 340 kilometres long. By early 2020, Germany will have more than 100 hydrogen filling stations. By comparison, around 14,500 filling stations supply petrol and diesel across the country.
However, solutions are beginning to emerge. One of them is the German government’s decision to adopt carbon pricing and reduce duties on electricity. Another is the discussion, happening at the EU level, to allow grid operators to run electrolysers and battery storage systems if the market fails. A further sign of new, integrated approaches are the plans drawn up by large consortia, in which electricity and gas grid operators often work together, for building electrolysers in the three-digit megawatt range. Finally, transmission system operators TenneT, Amprion and TransnetBW are working on deploying powerful battery storage systems (known as grid boosters) to support higher grid loads.
From grid planning to system development planning
These are all measures that work with existing infrastructures, seeking to link them, supplement them and optimise them. But are there also any signs of efforts to establish integrated planning for new energy infrastructures? And what might this look like?
Brussels has led the way with a good example. Since 2018, electricity and gas transmission system operators have been using a shared scenario framework for European grid development planning (the Ten-Year Network Development Plan). Yet electricity and gas grid operators in Germany are also seeking new approaches. For instance, the gas transmission system operators are now including hydrogen, synthetic methane and biomethane in their planning for updating the Grid Development Plan Gas up to 2030. In addition, North Rhine-Westphalia wants to be the first state in Germany to introduce a joint grid development plan for both electricity and gas.
Within the scope of its third Grid Study, which began in 2019, dena is developing a new approach for integrated planning at the national level. The aim is to design a process for a system development plan. It is unlikely that integrated planning will mean that electricity and gas networks are planned from a single source. “We will continue to have separate processes for electricity and gas infrastructures. For us, it’s primarily about optimising interfaces in both systems, such as gas-fired power plants or power-to-X systems, and ensuring that the plans are based on the same initial premises and are better coordinated,” says Stefan Mischinger, a team leader at dena. The system development plan is therefore intended to be a process that exists upstream of the grid development plan and provides a holistic view of the system as a whole. This new integrated approach could also be expanded to include hydrogen infrastructure: “The trend is pointing to a paradigm shift – away from pure grid planning and towards a holistic system approach,” says dena’s Hannes Seidl.
Through broad public participation, which will include translating the specific issues into plain language, the system development plan should also provide politicians with a better basis for making decisions and should simplify basic future decisions about the energy transition. “There’s also a need to focus more closely on the future market design. Market structures are fundamental to the way in which a future energy system can and should function,” says Carolin Schenuit, also a team leader at dena. The first results of Grid Study III are expected in late 2021.
Bringing energy planning into urban planning
“System-wide planning for the heating supply in urban energy systems will become increasingly important in the future”
Cities are a major starting point for integrated solutions. Nowhere else are the infrastructures for generating, transporting and consuming energy situated so closely together. This provides numerous opportunities to link the systems – particularly the electricity grids and heating networks. Cities often have a larger scope for using waste heat or incorporating power-to-heat solutions that can offset fluctuating electricity feed-in from renewable energies. “System-wide planning for the heating supply in urban energy systems will become increasingly important in the future,” says Susanne Schmelcher, a dena expert for the urban energy transition. She believes that energy infrastructure planning overall must be better established as an integral component of urban planning. Future supply concepts should, for instance, aim to optimise infrastructures for energy, mobility and information technologies in an integrated way.
Achieving this will also require better coordination between the various actors. Structures in cities are more complex. The way in which planners, city and district authorities, energy suppliers, housing companies, transport operators, water utilities and other participants interact needs to be optimised. “We need new processes in which local actors can contribute their expertise and jointly develop infrastructures suited to their area,” says Schmelcher. The starting point at the local level is more or less the same as at the national level: more consistent efforts are needed to develop integrated solutions for the energy transition. Many things are already technologically possible.
Copyright header image: shutterstock.de / Scharfsinn