With new efficiency

In the bidding for the local supply of Darmstadt Technical University with electricity, heat and cooling, STEAG New Energies and ENTEGA convinced the customer with a concept which, along with being economical, surpassed the energy efficiency and ecology requirements. What is different about this concept?

TU Darmstadt is one of the leading German technical universities. Currently around 30,000 students and employees learn and do research at the campuses Stadtmitte (City) and Lichtwiese. TU Darmstadt concentrates on selected technology-related subject areas that are of great relevance to the sustainable development of society and economy. Accordingly, it sets ambitious standards also for its energy supply – making it all the more significant that STEAG New Energies and the local Darmstadt energy utility ENTEGA succeeded in winning the contract in response to a Europe-wide tender. Since 1 January 2016 the newly formed company ENTEGA STEAG Wärme GmbH supplies electricity, heat and cooling to TU Darmstadt. A long-term distributed supply concept will drastically reduce climate-damaging CO2 and pollutant emissions yet again starting in 2018. ENTEGA STEAG Wärme GmbH will invest a total of 17 million euros in the construction of a new, high-efficiency central energy plant with combined power, heat and cold generation and a cooling network, and in the modernization of two existing combined heat and power units. The contracting agreement signed in December 2015, which runs until the end of 2030, is a big success for the team of project manager Ralf Cavelius – and the result of two years of intensive work. "We produce energy on the Lichtwiese campus very efficiently and in an ecologically exemplary way – and we are even capable of meeting more stringent legal requirements in future," says a very pleased Ralf Cavelius.

„We produce energy on the Lichtwiese campus very efficiently and in an ecologically exemplary way – and we are even capable of meeting more stringent legal requirements in future.“

Ralf Cavelius

Primary energy factor
The primary energy factor tells us how much primary energy (energy that comes from natural, as yet unprocessed sources, for example petroleum, natural gas and coal) must be used to produce a certain quantity of usable final energy: the lower the factor, the more efficient and environment-friendly the energy input.

Distributed energy supply
Distributed energy supply means the energy is produced near the point where it is consumed. The simultaneous generation of electricity and heat, and cold as well (combined power and heat generation or combined power, heat and cold generation), enables attaining high energy utilization rates of as much as 90 percent. In addition, transmission losses caused by the transport of energy are reduced. Distributed energy supply additionally relieves the load on the interregional power grids. STEAG operates more than 200 such installations across Germany.

Expectations surpassed
It all began in autumn 2013 with first exploratory talks between STEAG New Energies and ENTEGA following the EU-wide invitation to tender from TU Darmstadt. STEAG New Energies had installed the three natural gas CHP units on the Lichtwiese campus some 15 years earlier. It has since then operated them and has become known as a reliable partner. In order to tap further synergies and efficiency potentials, the two companies decided to participate in the tendering procedure as a consortium. Together they developed a concept that went well beyond the stated requirements and convinced TU Darmstadt in every single phase from prequalification to the ultimate conclusion of the contract. Specified in the call for tender was the construction of a new central energy plant with combined power, heat and cold generation and the construction of a new cooling network in order to meet the increased requirements for cooling energy in future with an efficient generation and distribution concept. In addition, the consortium offered to modernize two existing CHP units – and as a unique selling proposition, to connect the district heating system of TU Darmstadt to the Darmstadt-Nord district heating network operated by ENTEGA. The particular advantage of this setup: the heat for the ENTEGA network comes mostly from Darmstadt's refuse-fired cogeneration plant and features an extremely low primary energy factor (see explanation on the left). With the new supply concept, worked out under the direction of technical project manager Dr. Jürgen Schöler and Mike Barthel, TU Darmstadt will achieve overall a very low primary energy factor for its energy supply in future. This not only benefits the environment, but also pays off in economic terms for TU Darmstadt: in the event of future new-build projects and energy-saving rehabilitation measures to existing buildings of TU Darmstadt, as much as ten percent of the construction costs can be saved. Background: For every building the German Energy Saving Ordinance specifies a maximum permissible annual primary energy requirement – and the specified values constantly are being tightened. If the primary energy factor of a building's energy supply is low, requirements are eased for energy-saving measures to be applied to building shell and building management systems. "This unique concept only was made possible by the good interdisciplinary cooperation both within the STEAG New Energies team and in the cooperation with ENTEGA," Ralf Cavelius explains.

About STEAG New Energies
STEAG New Energies GmbH specializes in the development of local customized energy solutions based on efficient and sustainable concepts. Customers are local authorities and public utilities, industry and large properties.

About ENTEGA
The ENTEGA Group is a leading German energy and infrastructure service provider and one of the largest suppliers of green electricity and climate-neutral natural gas. The company pursues a consistent sustainability strategy for which it received the renowned German Sustainability Award in 2013. Through HEAG Holding AG, ENTEGA AG is majority-owned by the City of Darmstadt.

Growing campus
In the 150 buildings of TU Darmstadt, which have a total net floor space of about 530,000 square meters, around 54,000 MWh electricity, 62,000 MWh heat and 5,000 MWh cooling energy are consumed annually. Its energy requirements thus are equivalent to the requirements of a small town – and are trending up. The campus is scheduled for further expansion in the next few years. Accordingly, the new supply concept of ENTEGA STEAG Wärme GmbH makes allowance for growing energy needs.

Current and future supply
At the Lichtwiese cogeneration plant, operated by a five-member team from ENTEGA STEAG Wärme GmbH headed by plant manager Michael Stapf, currently three CHP units with a thermal capacity of 2 MW each and an electric capacity of 1.95 MW each are installed. For peak heating requirements, six hot-water boilers with a capacity of 9.3 MW each are available. The electricity produced by the CHP units is fed into the Darmstadt University grid and currently covers about 60 percent of the total requirements. The district heating network of TU Darmstadt has a length of about 20 kilometers and, in addition to the university's properties, supplies state properties like the Justice Center, the Hessian State Museum and the Darmstadt tax office, along with third-party customers of ENTEGA STEAG Wärme GmbH. For the purpose of extending and modernizing the energy supply system, starting in spring 2017 in a first step ENTEGA STEAG Wärme GmbH will build a completely new central energy plant on the Lichtwiese campus: it will comprise a CHP unit with a thermal capacity of 2.6 MW and an electric capacity of 2.7 MW as well as an absorption refrigerator with a cooling capacity of 1 MW. It generates cold from heat with particular efficiency, instead of from electricity. In addition, a two-kilometer-long cooling network will be constructed to provide energy-efficient cooling, for instance for the Lichtenberg High Performance Computer of TU Darmstadt, but also for other facilities. Commissioning is scheduled for the second quarter of 2018.

As early as the first quarter of 2018 the district heating networks will be hooked up. Owing to the increased thermal capacity provided by combined heat and power operation and to the delivery of environment-friendly heat from the Darmstadt-Nord district heating network, considerably less additional boiler heat then will be needed during peak demand periods; moreover, further customers can be connected with the network. Through the connected networks, in future ENTEGA STEAG Wärme GmbH will provide around 60,000 MWh of district heating to TU Darmstadt and another 10,000 MWh to external customers. In addition, the coupling of the networks enables the further expansion of district heating supply in Darmstadt by ENTEGA STEAG Wärme GmbH. In 2019 two of the three existing CHP units then will be modernized and furnished with highly-efficient new engines with capacities of 1.8 MW thermal and 2 MW electric. When all measures have been completed, the new system will produce a total of 40,000 MWh of electricity annually through combined power, heat and cold generation. As a result, in future 75 percent of requirements will be covered by local production – a clear-cut increase compared to today's 60 percent. Positive effect on climate and environment of all these measures: compared to the present, annual CO2 emissions will be cut by a total of 18,000 tons.

Supplier, consultant, partner
However, the role of ENTEGA STEAG Wärme GmbH involves far more than pure energy supply. The company is assisting TU Darmstadt to create an energy management system as a basis for further efficiency improvements – a tremendous task, seeing as all electricity, heat and cold meters in all buildings must be covered by the system. On top of that, ENTEGA STEAG Wärme GmbH will be an important partner in the "EnEff:Stadt Campus Lichtwiese" project, which is being sponsored by the German federal government under its Sixth Energy Research Program: the sustainable energy supply concept of TU Darmstadt and ENTEGA STEAG Wärme GmbH is an integral part of this project and will be further developed and optimized on the dynamically changing university campus in order to meet the targets of the year 2050 for the transition to sustainable energy at neighborhood level already in the year 2030. And so ENTEGA STEAG Wärme GmbH can invest all its skills – from the planning, construction and operation of distributed installations to continuous consultation – in the long-term cooperation with TU Darmstadt.