Building has been taking place for several weeks behind the HCL chemistry building on the Science City Campus, but downwards for once, not upwards. The first two ground heat storage fields for a sustainable heat supply network on the campus are currently being constructed here and under the new Life Science Platform (HPL) building in the north-eastern part of the campus.
There are 100 ground probes – plastic pipes 200 metres long – at the HPL and 130 behind the HCI. The pipes are sunk into the ground at five metre intervals, then connected to the building’s supply network. The plan is for 800 of these pipes to be located underneath and alongside the Science City buildings by 2020, which, together with other structural measures, will enable energy to be managed on the campus with almost no CO2 emissions, as stipulated by the ETH Zurich Energy Concept.
Like a big heat-exchanger
Via circulating water system, the waste heat is put into storage in the cool ground, whose temperature ranges from 8 to 18°C. In winter the heat is pumped up again through the same circulation system and used to heat the building. Since the temperature range of 8 to 18°C is insufficient for this, the heat is “upgraded” to 30 to 35°C using several electrically-driven heat pumps. The system is decentralised: each building is equipped with a computer that controls precisely how much heat is needed to heat it.
Heat can be tapped off via the water circulation system from each of the storage units, nine of which will be installed by 2020. The target is for only one twelfth of the total energy for heating and cooling to be generated by electricity, i.e. high-value energy (exergy). The remainder will be extracted from the managed ground. The potential is enormous: although the ground’s heat capacity, around 1.0 kJ/kgK, is about one quarter of that of water, the gigantic volume of the ground storage compensates for this disadvantage. The engineers want to make four million cubic metres of ground usable on the Hönggerberg Campus. A density of 2500 kilograms per cubic metre and a 5 Kelvin temperature difference between charging and discharging yields a total capacity of 13 to 15 gigawatt-hours, corresponding to the energy content of around 1500 tons of petroleum.
Networking more important than insulation
The possibility of heat storage in the subsoil has far-reaching consequences for building design and running costs. Project Manager Thomas Gautschi from engineering consultants Amstein and Walthert Engineering describes it in a nutshell: “Don’t insulate like idiots, network well instead.” At Science City the main emphasis is no longer on ensuring the thickest possible insulation against heat losses, as in building standards such as Minergie P for example. Instead about the focus is on delaying the flow of heat and making the excess heat in summer usable for heating in winter.
With enough ground probes, high-efficiency insulation is unnecessary, and may even be a counter-productive. In fact, the ground storage can only absorb waste heat in summer if it is “emptied” during the winter; i.e. the earth is cooled back down to its original temperature. This opens up new prospects for building developers, especially for renovations: by networking buildings they gain more freedom in dealing with the existing building shells. Areas with numerous single buildings in particular, such as the Science City Campus, harbour a far higher potential for efficiency as a total networked system than as the sum of the individual structures.
Easy and economical
The ground storage system is also financially attractive. Hansjürg Leibundgut is Professor of Building Services at ETH Zurich and adviser to the project. He is convinced that “It will be very beneficial to ETH Zurich.” A façade renovation of a medium-sized building on the campus would cost about 15 million Swiss francs, a simpler re-glazing for lower heat losses five million. On the other hand, the ground storage currently installed under the HPL costs only 1.5 million Swiss francs. Moreover, upgrading the stored waste heat through a heat pump is cheaper than heating oil, and ground storage can hedge against fluctuations in the price of petroleum and, to a certain extent, electricity as well.
“There are many benefits, the system is relatively simple – it is surprising no-one thought of it sooner,” says Gautschi. The fact that there is still a lack of years of experience in dealing with ground probe boreholes is certainly one reason. They first came into existence in Switzerland 25 years ago. However, Leibundgut is convinced that ground storage will become accepted in Switzerland on a large scale in the future: “One day we will use the whole of Switzerland as a big heat store. A connection to a heat supply through the ground will then be taken for granted just like a connection to the drains or access to transport.”
Onto the network in 2011
First of all, however, the system must prove itself. There are, as yet, no reference projects. The plan is for the two heat storages at the HPL and behind the HCI to be connected to the network in mid-2011, followed by all nine storage units with a total of 800 probes by 2020. By then, however, ETH Zurich will probably no longer be the only site relying on heat storage in the ground. In fact, Gautschi is already planning comparable network systems for other clients in Zurich.
Claudia Naegeli | idw
Energy hybrid: Battery meets super capacitor
01.12.2016 | Technische Universität Graz
Tailor-Made Membranes for the Environment
30.11.2016 | Forschungszentrum Jülich
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy