Source: Energie & Management Powernews , December 12 2022
The award "CHP of the Year", awarded by E&M and the B.KWK, goes this year to Lemgo.
The Stadtwerke Lemgo had won the iKWK December 2019 tender. The system must combine flexible CHP plants with an annual use of 30 percent renewable heat from heat pumps and/or solar thermal and a PtH plant. Implementation of the plant concept, which relies on two renewable heat sources at once, began in 2020 with the dismantling of the 1980 gas turbine plant and the old chimney. According to its own climate protection concept, the Hanseatic city of Lemgo aims to be climate neutral in 2035, and a transformation plan for district heating has already been drawn up for this purpose, which includes the iKWK system and the use of waste and residual biomethane in the CHP plant.
The experience gained at Stadtwerke Lemgo from a combined CHP-heat pump project, which was realized even before the legislature invented the term "iKWK", and which combined an existing CHP of 2 MW with a heat pump and the first wastewater treatment plant effluent heat pump in Germany, is testimony to the innovative strength of the Lemgo-based company. Together with Eugen Rejek from Beratende Ingenieure Rejek in Düsseldorf, the municipal utilities broke new technical ground and had the courage to go further. Without years of good cooperation and mutual trust, the new iKWK system would never have come into being.
In Lemgo in 2020, various conventional CHP plants with an installed capacity of 35.286 MW and an overall efficiency of 84.6 percent at 3.526 full utilization hours per CHP plant in operation. The iKWK plant, which was named CHP of the Year 2022, has provided 26 percent renewable supply to the district heating network since it began operation in March 2022. The existing power-to-heat plant with 5 MW and a large heat storage volume could be credited for the investment.
In the future, district heating will be predominantly CO2-neutral from April to September. The CHP units in Lemgo will be operated in a way that is optimized for the electricity market because they are decoupled from the heat supply requirement thanks to the large heat storage facilities. The elasticity of 85 to 100 degrees Celsius in the flow of the district heating system means that it is also possible to vary between summer and winter operation.
The investment of 11 million euros for the iKWK system can save an enormous amount of natural gas despite the expansion and densification of the district heating network.
Future investments in Lemgo are a photovoltaic area plant, another large-scale heat storage with integrated PtH plant and own wind power plant (wind heat). In addition, a wind power plant for electrolysis with hydrogen storage in the existing gas storage up to 100 bar including reverse power CHP and a wood chip heating plant plus wood gasifier CHP for residual and waste wood from cascade use to achieve the goal of climate neutrality.
- The excellent combination of new and existing plant technology with the existing district heating system and the integration of several renewable energy sources at once leads to an all-round convincing result.
- About the solar thermal large-scale plant are produced annually more than 3.3 million kWh of heat and thus saved about 1,500 tons of CO2.
- From the Bega River is taken via an intake a part of the flow of 100 cubic meters of river water without separating heat exchanger, but with filter. The cooling difference is normal 6 and minimum 3 Kelvin at a minimum source temperature of 5 degrees Celsius.
- The overall plant concept with the flexible, electricity market-led operation of the iKWK plant allows decarbonization of district heating and leads to a significant reduction in greenhouse gas emissions.
- The energy supply concept selected here has a model effect for other operators and shows in particular for municipal utilities of medium-sized cities, how decarbonization can succeed through a successful interaction of renewable energy sources, storage and existing infrastructures and local conditions.
Jury Criteria
The election of the cogeneration plant of the year by the Federal Association of Combined Heat and Power (B.KWK) looks back on a long tradition. As in the years before it was a question also with this choice of appreciating under the many good examples for CHP concepts a completely particularly trend-setting one
Was looked for a CHP, which fulfills with all technical refinement also a completely serving use for humans and environment. In this respect, the choice this year is a little different than in previous years, because it has rarely had such political relevance. At a time like this, cogeneration stands like no other technology for the claim to provide secure energy for people's lives through the combined generation of heat and electricity, and at the same time to protect the environment through the resource-conserving use of fuels. It filled the jury with pride to be allowed to distinguish again a BHKW, which exactly fulfills this requirement.
It made its decision between eleven BHKW plants, which were presented in the months January to November 2022 in E&M as "BHKW of the month". Convincing and forward-looking CHP solutions for very different tasks were found.
The following criteria tipped the scales:
- Solution concepts of the plant combination
- the partners involved
- the planning
- technical execution
- operation of the investments
This year, a variety of CHP concepts with natural gas and biogas-fueled engine block heat and power plants between 16 kW and 3.5 MW of electrical power were available for selection. Among them a combination of CHP and absorption refrigeration plant with 25 kW cooling capacity, in addition, various CHP systems in combination with photovoltaics or solar thermal, as well as with power-to-heat and gas and wood chip boilers. Battery storage and dynamic load management for E-mobile charging stations complement projects in the object, neighborhood and district heating supply.
Integrated into the overall systems are hot and warm water storage tanks for decoupling electricity production from heat demand. Electricity storage and CHP units provide a secure power and heat supply as well as emergency supply in several projects. They are heat-led and often operated according to the electricity market. The plants presented monthly by E&M are used for self-supply of the operators or also for the supply of residential and commercial properties, local and district heating systems.
High system efficiencies and primary energy savings
In the plants, high system efficiencies and primary energy savings are achieved. The reduction of CO2 emissions by CHP plants is up to 5,000 tons per year for the operating companies. Through the use of biomethane and the displacement of gray power by green power, the balance sheet emissions (calculated according to FW 309) approach zero.
The decision was not easy for the jury this year, because it showed that in addition to classic CHP plants with outstanding parameters, increasingly innovative solutions with flexible plants and combination solutions with renewable energy technologies and storage are finding application in practice.
After intensive consideration of the eleven projects and detailed discussion the experts came to a unanimous vote in favor of the CHP of the month of July 2022. It concerns with the distinguished project of the public utilities Lemgo an innovative CHP system with two BHKW of Zeppelin power of system (each 2,5 MW), a solar thermal plant with vacuum tube collectors of the manufacturer Viessmann and with a river water heat pump of the Kulmbacher manufacturer AGO (1 MW heat achievement). Through various feed points, the heat is fed all year round into the existing district heating network.
The jury of the B.KWK
Gebhard Gentner (Stadtwerke Schwäbisch Hall), Karl Meyer (BTB Berlin), Marek Preißner (Infracon Service GmbH Leipzig), Prof. Dr. Bernd Thomas (Reutlingen Research Institute RRI), Claus-Heinrich Stahl (B.KWK)
Author: Heidi Roider
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