Sector coupling: Everything in flux

Not all areas of society can be electrified at the drop of a hat – think of the process industry or aviation, for example. The provision of heat is also still based to a large extent on fossil fuels. In the all-electric society, the solution to this will be the coupling of sectors that currently often operate in their own separate domains. These sectors include the main areas of the energy economy – electricity, heat and transport – and the consumer groups of industry, commerce, trade and services, as well as private households. They all need to be interconnected so that renewable electrical energy can be universally used as the primary energy source. 

In addition, coupling sectors in this way would provide for the necessary flexibility. At the end of the day, power generation using wind and solar energy is subject to considerable fluctuations over time and depending on the weather. It therefore makes sense to use excess electricity in times with considerable wind and sun for heat or transport, or to preserve it in storage units. Sector coupling will therefore form the foundation of the all-electric society.

A range of different technologies are available to serve as links between sectors, and none is more important than the power-to-X processes. This refers to all processes that convert green electricity into chemical energy carriers for power storage, electricity-based fuels for mobility or raw materials for the chemical industry. Electromobility is an excellent example of how sector coupling has already begun at the lowest level. The various sectors come together in individual buildings, or in cellular structures such as urban districts. This is where bridges can be built – for instance, by charging your EV with electricity from your household photovoltaic system. 

Integrating so many stakeholders requires highly intelligent

To drive the sector coupling forward at the municipal level, the Agency for Renewable Energies (AEE) and Environmental Action Germany (DUH) launched the three-year project Forum Synergiewende in January as part of the National Climate Protection Initiative and with funding from the Federal Ministry for Economic Affairs and Climate Action. The focus is on supporting municipalities that want to implement their own projects in the area of sector coupling, says Barbara Metz, federal managing director of the DUH. Metz explains that alone, these communities would lack the necessary experience and knowledge.

One example of how sector coupling can work is provided by the Heidelberg Energy Cooperative (HEG), which has implemented the direct supply of solar electricity in a residential district in the southern part of Heidelberg from the area’s roofs. An electricity storage unit and a charging point have also been integrated. The photovoltaic system, which offers peak output of 67 kWp, is installed on two buildings and supplies about 130 people with electricity.

Another district-level example demonstrates how digitalization plays a crucial role in sector coupling. The Smartes Quartier Karlsruhe Durlach ("Smart District Karlsruhe Durlach") project involves a building complex with 175 apartments whose conventional supply system was replaced with a new energy system consisting of heat pumps, photovoltaics and cogeneration units. For the development of the energy system, the Fraunhofer Institute for Solar Energy Systems (ISE) simulated the district with all its generators and consumers. A concept emerged that is based on an intelligent energy management system. With the help of artificial intelligence, the heat generators for the five linked buildings are controlled centrally. Energy loads, for example, can be predicted on the basis of weather forecasts using algorithms. In this way, the system can maintain the intelligent operation of the heat pumps, which are to run when the photovoltaic system or the cogeneration units are producing electricity.

Algorithms also ensure that the system detects any deviations from standard operations. Should an anomaly occur, the possible error at hand is reported. As a self-teaching system, the process is also improving constantly over time.

The service provided by the energy management system in this example will be a general requirement in the energy system of the future. Sector coupling ensures that more and more stakeholders are being integrated into the system, including wind power systems, charging points and private photovoltaic systems. These need to communicate with each other and be controlled intelligently. Data also needs to flow alongside the energy being provided.

A smart grid – a topic that has been debated rather than implemented for many years – is now actually needed. In the meantime, though, there has been a change of mentality according to Johannes Stein, senior principal expert at the DKE. He says that specific concepts for smart grids are now being drawn up, with a focus on the integration of 100-percent renewable energies. Stein also reports that the consumer perspective is being taken into account much more than before, and that consumers now include the industrial realm along with residential buildings. “It’s quite clear that a smart grid is an important component of the all-electric society,” he states.

Security in an ever-growing data stream

A series of projects are testing out the power grid of the future, and one of them is Smart Grid Lab Hesse. For this project, a network was set up in a laboratory along with all the associated equipment, such as inverters, load resistors, storage units, photovoltaic systems and charging points. On this basis, all the aspects of operating a smart grid, including energy producers and energy consumers, can be simulated. The smart grid collects energy data, analyzes it and then decides autonomously how to distribute its electrical energy most efficiently. Another part of the process is flexibility, which can be represented by active grid elements such as voltage regulators, or by different load behavior on the part of customers.
The project is focusing on data security, as well. “Grid management is becoming more and more demanding because of the ever-growing data streams generated by smart components and the extreme complexity of the power grid,” says project leader Prof. Ingo Jeromin. “It is hugely important to guarantee the highest possible level of security for all the processes and sensitive data. Data security and resilience are key.” In Jeromin’s opinion, one of the major challenges lies in the communication among the various pieces of equipment. “We’re pleased that we succeeded in linking the various components with each other,” he reports. The problem is that the various devices all use their own data protocols, so the systems don't understand each other by default. That makes setting up a smart grid a particularly complex affair.

Systems that are meant to work together need a common language

The project in Hesse therefore demonstrates one of the biggest hurdles that remains in sector coupling. “Each of the various sectors has its own data models, its own semantics,” says DKE expert Johannes Stein. Within the sectors, there are standards that regulate work, such as the Common Information Model (CIM) for electricity grids. However, the exchange of data among the sectors is the problem.
One approach from industry could offer a solution. Under the banner of buzzwords like “Industry 4.0” or “smart manufacturing”, production companies are beginning to set about digitalizing their production. In this context, machines, IT systems and sensors with different data models have to be interconnected. To solve this problem, the national initiative Plattform Industrie 4.0 has developed an asset administration shell as part of a reference architecture model. This shell represents a manufacturer-independent standard for providing information and communicating in a standardized language. In specific terms, that means that every asset – such as a component, a device or a piece of software – has its own asset administration shell, which represents a sort of digital product passport. It consists of various submodels, which in turn provide characteristics, abilities and instructions about the respective asset in defined, standardized semantics. These submodels, including any and all modifications made to them, are stored for the entire life cycle of the asset. The IEC 63278 standard represents the first international norm for asset administration shells.
All along their value-creation and supply chains, the companies involved will compare notes on a shared data space that is to be implemented by the Manufacturing-X initiative – according to the plans of Plattform Industrie 4.0. There, all the participating companies should be able to make common use of the data collected. The data space will be based on the standards of the International Data Spaces initiative, which are designed to guarantee the sharing of information while safeguarding data sovereignty.

According to Stein, this concept – that is, an asset administration shell combined with a shared data space – could also be used for communications in sector coupling. The model and the initial standardization of the asset administration shell have been created so openly that they could quickly be used as a framework for other sectors outside the industry. Every component in the energy grid of the future would then also have its own digital product passport. “This concept has been very well received within the DKE because it’s very generic,” says Stein, who adds that the concept is very easy to transfer to other areas even though it originally came from industry. “You don’t have to look at the tiniest details of the individual data models to enable overarching communications,” he points out. “It’s enough to agree on a specific set of data in order to develop standardized semantics.”
According to Stein, the experts at the DKE are now working on how to implement an asset administration shell and a data space across several sectors. The feasibility will then be tested in individual use cases.

Combining individual standards to form a functioning overall

A key factor will again be the interoperability of the standards, because they also play an extremely important role in sector coupling. Standards are already ensuring uniformity within every individual sector. In the case of fuel cells, for instance, DIN EN 50465 stipulates the requirements relevant systems must meet. In the electromobility sector, DIN EN IEC 62196 ensures that vehicle owners in Europe can charge their EVs using the standardized CCS 2 connector system. Similar developments are happening in the area of bidirectional charging, as former DKE president Roland Bent reports.

However, it’s now a question of taking the next step. “What we need in standardization is to merge several individual solutions into an overall concept,” Bent asserts. Standardization needs to create the architectural framework for sector coupling in terms of both information technology and the organization of energy flows.

In the future, the relevant standards should be available as machine-readable content. In that way, the relevant semantic information can be provided via an asset administration shell. If sectors are coupled, however, it may be necessary to harmonize different semantics for the use cases at hand. The DKE and DIN are now working on concepts for machine-readable or Smart Standards with a group of standard users in the Digital Standards initiative. The data and standards stored in an asset administration shell for two components – an energy storage unit and a distribution network, for instance – could then negotiate with each other about how they should interact. Intelligence is therefore also key to the energy system of the future – in the form of smart standards and smart grids.

Markus Strehlitz is a freelance journalist and editor for VDE dialog.