Heat recovery in the Rozzano power plant
As a rule, some of the heat generated in combined heat and power (CHP) plants is lost to the atmosphere as waste heat. This not only represents a loss of energy but also impacts the environment unnecessarily.
In order to solve this problem, we are using waste heat recovered from CHP plants alongside other heat sources in modernizing the district heating system in Rozzano, Italy. The timing is ideal. This socially disadvantaged district close to Milan is currently being refurbished and equipped with innovative technologies. Aspects of the project are the optimized use of the CHP plant, use of the surplus electricity output and use (recovery) of the process heat from other production plants in the area.
The pipelines of the district heating system have been extended to these plants to transport their waste heat to the system via local heat exchangers and water pumping stations rather than releasing it to the atmosphere.
This makes it possible to utilize the output of the CHP plants – 1,200 kWe of electricity, 613 kWt of steam and 630 kWt of hot water. The CO2 reduction achieved in the first step will be increased to approx. 905 tCO2 per year in the future when the Rozzano district is connected and supplied with surplus heat. As a result of these reductions, heating can be supplied at lower cost to the socially disadvantaged residents of Rozzano.
Innovation mix for Raunheim
From year to year, the residents of the Ringstrasse district in Raunheim, Germany, had become increasingly dissatisfied. The reason for this was that the district, built in the 1960s, was outdated in terms of both technology and appearance. That is why, in 2001, the district was included in the State of Hesse’s Social City (Soziale Stadt) program. A district manager was appointed to improve the quality of life for residents. One of the measures implemented by the new district management team was an improved energy supply to deliver an efficient, sustainable and affordable energy mix. GETEC developed a modern concept for the some 1,500 residential units with a heat requirement of up to 24,000 MWh – and was awarded the contract. The micro combined heat and power plants and power-to-heat module began operation in February 2022. With the start-up of the heat pump in 2023, the entire iCHP plant came on stream fully. The idea underlying the innovative combined heat and power concept was to equip the existing district heating network – two gas boilers (5.8 MW) and one pellet boiler (4 KW) – with a more sustainable heat generation technology (see graphic at right). In this way, more renewable energy can be used in generating heat and, at the same time, electricity. This was achieved by installing two electric micro combined heat and power plants (2.3 MW each), which convert gas into heat AND electricity. The waste heat is used to heat the district, while the electricity is routed to the grid and sold. The second module is an air-to-water heat pump (1.9 MW), which requires electricity but uses this very efficiently thanks to the clever way it works. In the best-case scenario, it produces three to four kilowatts of heat for every kilowatt of electricity used. On warm summer days, the heat can be stored for use in the evening when residents need warm water. The heat pump has a positive impact on the carbon footprint because it is so environmentally friendly. The third component of the system is the power-to-heat module (1.6 MW), which functions in much the same way as an electric-powered instantaneous water heater. In the best case, any surplus electricity in the grid can be used by the module to generate a large amount of heat on an ad hoc basis. However, it is not particularly efficient, generating one kilowatt of heat for each kilowatt of electricity used. Nevertheless, regulations require the installation of this module because it can be used at any time in almost any conditions. Two buffer storage units (80 m3 and 250 m3) complete the concept. The old pellet boiler is now no longer needed and has been removed. The various modules have their advantages and disadvantages. Which one is chosen depends on the current market price of the energy needed/purchased and climate conditions. That is why the plants are not operated simultaneously but alternately as required. They are controlled via a schedule that queries the prices on the respective energy exchanges at short intervals. The least expensive energy source at the time of the query is then selected. This process is largely automated and has been tried-and-tested in many cases. As a result, the plant is sustainable both ecologically and economically. In respect of the 1,500 residents of the Ringstrasse district, it is important to GETEC – and the customer – to always achieve the right balance between clean and affordable energy. This is the way to achieve the energy transformation in the medium term. As far as the residents are concerned, two things are important: affordable prices and clean energy.
The biomass boiler in Emmen
Everyone knows that sawing wood produces wood chips, but not everyone knows that these can be used to generate electricity and heat. In the Netherlands, BeGreen Refinery B.V. and GETEC’s Platform Netherlands are among those that do. The two companies have started an innovative collaboration aimed at providing customers with market-ready biodust applications to generate heat. The joint project is not only interesting from a technological perspective but, in light of rising prices and declining reliability in the supply of fossil fuels such as gas, the innovative biocoal technology represents a sustainable component of the future fuel mix.
Burning dust is not a new technology but most of the dust used at present derives from fossil fuels. However, further development of the technology means that GETEC’s boilers are now also able to burn biocoal dust produced from forestry waste and other biomass fuels.
The principle is simple. Local forestry companies supply their waste. The wood chips are treated in a steam explosion process to break down the fiber structure of the wood and remove some of the volatile components, thus increasing the carbon content. The resulting wood-based biomass is then pressed into black pellets. Compared with untreated biomass, these pellets have similar characteristics to coal – a higher energy density, grindability and better transport and storage properties. The production process also yields biochemicals such as furfural, methanol and acetic acid, which raises the biomass value chain to an even higher level.
The pellets are then ground and burned in the biomass boiler that came on stream in 2023, thus generating electricity. The dust burning technology deployed at GETEC PARK.EMMEN can produce up to 18 t/h with a steam output of 30 bar.
Given the many advantages of using biocoal, other sites are now being analyzed. There is a particular focus on converting existing plants which are less suitable for other green concepts because of storage restrictions or a lack of biomass availability. However, biocoal could also be an efficient and sustainable fuel for new-build plants.
Carbon capture in Switzerland
One of the biggest challenges created by climate change is the high level of CO2 in our atmosphere. That is why reducing carbon emissions is a main focus of climate protection efforts. To achieve this, there are a number of innovative processes known by the acronym CCUS – carbon capture, utilization and storage. In these processes, CO2 is removed either directly from the air (direct air capturing – DAC) or from highly concentrated CO2 streams (point-source capture – PSC) and then reused or stored permanently. GETEC’s Platform Switzerland has introduced a number of initiatives in this key field based on different approaches. One of the most interesting projects resulted from a collaboration with the University of Applied Sciences and Arts Northwestern Switzerland (FHNW) in which
GETEC is working with young experts to develop a proprietary solution for its industrial park customers. Launched in February 2023, the initiative involving master’s students is already well advanced. The first task was a plausibility study for using the CO2 separator on a smaller incinerator (point-source capture). This was the basis for developing a specific solution what is now being put through implementation testing. In a single process, the CO2 is not only separated and stored but also transformed into a marketable substance. The process results in methanol, which can be used in the chemical and transport industries. Project management opted for the methanol value stream because it is difficult to sell CO2 from an industrial park to the food industry and the amounts of CO2 captured from the smaller incinerator exceed the CO2 requirements of the other industries. All the stakeholders are pleased with the outcome: clean air (society), a new value stream (GETEC) and a lower CO2 value (customer). “Our customers in Switzerland are extremely interested in carbon capture because everyone knows that the regulations for CO2 emissions will become stricter over the next ten years. That is why we aim to be at the forefront of this development. In order to drive things forward, we need a demonstration plant now. We are working on achieving this as quickly as possible,” says project sponsor Arthur Gebhardt.