What is the role of flexible combined heat and power plants in the decentralized energy system?
Looking ahead to EnergyDecentral 2024, the exhibition for renewable energy relevant to agriculture, it is evident that modern combined heat and power plants have become more than just “flexibility champions” for short-term power supply. Flexible combined heat and power plants have become indispensable on the way to the hydrogen economy. From 12 to 15 November, 2024, the leading trade fair for decentralized energy supply, which takes place at alongside EuroTier in Hanover, will be presenting an array of combined heat and power generation in practice which points to its prospects as part of the energy transition.
In Germany by 2030, at least 80 percent of the electricity demand should come from renewable energy sources. In order for the supply to be secure and stable, controllable output such as that offered by combined heat and power generation is required. “If we no longer to wish to rely on fossil fuel power plants in the future, we need flexible power generation for exactly those times when the wind isn't blowing and the sun isn't shining,” says Marcus Vagt, Project Manager for EnergyDecentral, DLG. Flexible combined heat and power plants are a key element for the success of the energy transition. Thanks to combined heat and power (CHP), they use 80 to 90 percent of the energy in the fuel. Vagt: “Their environmental footprint looks even better if they are operated with biogas - because then they are not only highly energy-efficient, but also climate-friendly.”
Electricity and heat from biogases and special gases: This is the trend. In addition to the use of special gases such as biogas and sewage gas, a lesser-known technology, wood gasification, has recently come back into focus. Here, too, the companies exhibiting in Hanover are serving a steadily growing market with high-performance gas engines. Many of the engines on show in Hanover are also approved for the use of synthetic fuels in accordance with the EN15940 standard and therefore for sustainable HVO (Hydrotreated Vegetable Oil). The use of HVO can reduce CO2 emissions by up to 90 percent compared to fossil diesel, depending on the production process and source material.
Sustainable fuels for the future
“Internal combustion engines are an essential building block for a reliable energy supply in the energy transition. With sustainable fuels, we are making them climate-friendly,” says Dr. Jörg Stratmann, CEO of Rolls-Royce Power Systems. From November 12 to 15, EnergyDecentral 2024 will provide the answers to two of the most important questions: What engine is suitable for combined heat and power generation? And how do the mode of operation and fuel affect the CHP plant?
Especially when running on green hydrogen, the engines make a significant contribution to decarbonization. With the latest generation of hydrogen engines, the technology providers are aiming for performance classes similar to those of the tried-and-tested natural gas engines. “In principle, we are improving our existing natural gas engine by converting it into a hydrogen engine. Powered by green hydrogen, it produces 100 percent CO2-neutral electricity and heat,” says Werner Kübler, Head of Engineering MAN Engines. Another advantage: the strict EU emission limits, such as nitrogen oxide, can be complied with without any exhaust gas aftertreatment. “Smaller, decentralized gas engine systems in particular can flexibly compensate for the fluctuating feed-in of wind and solar power into the grid, depending on the weather conditions,” explains Dr Daniel Chatterjee, Head of Corporate Sustainability (ESG) at Rolls-Royce Power Systems. And: “With our gas engines, which are now H2-ready certified, we can make a contribution to the energy transition.” H2-ready means that the engines are prepared for future use with hydrogen and can be converted accordingly.
On-demand supply at the touch of a button
“The value of providing renewable energy on demand at the touch of a button will continue to increase in the coming years,” confirms Jörg Lösing, Head of Sales at 2G Energy AG. In addition to increasing the absolute system output, the reliability and efficiency of the gensets is of great importance. Lösing: “The systems must be available without restriction at maximum efficiency during the hours when they are needed. This is precisely the direction in which we have developed our systems.” The recently presented avus 1000plus CHP unit is a good example of this. In biogas mode, the module has an electrical output of 1,000 kilowatts (945 kilowatts thermal) and is aimed at plant operators who want to exploit further revenue potential on the electricity market by making their own plant more flexible.
Modern biogas gensets for power and heat generation, such as those presented at the trade fair in Hanover, set standards in terms of efficiency, power density and life cycle costs. The containerized design of the combined heat and power units makes the entire system mobile; individual modules can be installed wherever they can provide their capacity to the grid in order to ensure maximum resilience. CHP units are the ideal solution for decentralized energy supply on farms using gas from agricultural waste - especially liquid manure - or sewage sludge. In addition to agriculture, the units are also in demand for use in sewage treatment plants (sewage gas), landfill sites (landfill gas) and in food processing. Rolls-Royce, for example, is currently installing a twelve-cylinder mtu biogas CHP unit from its new Series 4000 L64 FB at starch producer Tongjit in Thailand. It will be used to supply electricity and superheated steam. The company already has a 20-cylinder system of the predecessor model in operation and will now be able to supply its entire factory with electricity itself, saving the equivalent of 600,000 euros per year.
Self-sufficient energy supply with microgrids
The examples show: While combustion technologies formed the basis of the electricity system in the past, today they are increasingly becoming a bridging technology that closes the gaps between demand and renewable energy generation and paves the way to the hydrogen economy. Combined heat and power plants play a central role as the backbone in all future energy supply scenarios. They are generally integrated into the low or medium voltage level, i.e. where the majority of fluctuating renewable energies are connected to the electricity grid.
However, flexible CHP units also offer a number of other potentials for the energy transition: The systems with outputs of between 30 kilowatts and three megawatts can be installed directly on site and used to supply microgrids - small energy networks that provide a self-sufficient energy supply. They can be connected to the public power grid, but can easily be disconnected from it and operated independently if required. Base load-capable energy sources cushion the natural fluctuations of sun and wind and thus ensure the supply of electricity and heat at all times. By integrating combined heat and power plants, battery storage and advanced control systems, microgrids offer a reliable and cost-effective option not only for farms, but also for municipal and industrial applications.
Decentralization is the word of the hour
“Microgrids are among the solutions that are driving the energy transition. They therefore have to deal with global megatrends and challenges, including decentralization, digitalization and decarbonization,” says Robert Autengruber, Senior Product Manager for the INNIO Group's Jenbacher product line. Microgrids of this kind become particularly sustainable when one or more renewable energy sources are included in the energy mix, for example in the form of photovoltaic systems or wind turbines. Thanks to their flexible approach, microgrids unfold their full potential and contribute to the resilience of the entire energy system. How this can look in practice will be discussed in Hanover as part of the “Expert Stage EnergyDecentral”.
As important as the generation and storage technologies are, microgrids cannot do without digital measurement technology. An energy management system is crucial in order not to jeopardize the reliability of the integration of renewable energies. It enables the continuous exchange between generation, storage and consumption in order to control the optimal use of the individual components, which enables an efficient and secure energy supply. An advanced all-in-one microgrid control system, for example, includes functions such as load management, regulation of power input and output, grid and tie switch control as well as interfaces for additional services or auxiliary units. It is also designed for a wide range of distributed energy resources or inverter-based technologies. Looking ahead to EnergyDecentral 2024, it is clear that the old system of energy generation and distribution is undergoing radical change. Decentralized approaches are coming to the fore, with microgrids and combined heat and power plants enabling direct energy consumption at the point of generation.