Emissions-free energy system saves heat from the summer sun for winter

October 03, 2018

A research group from Chalmers University of Technology, Sweden, has made great, rapid strides towards the development of a specially designed molecule which can store solar energy for later use. These advances have been presented in four scientific articles this year, with the most recent being published in the highly ranked journal Energy & Environmental Science.

Around a year ago, the research team presented a molecule that was capable of storing solar energy. The molecule, made from carbon, hydrogen and nitrogen, has the unique property that when it is hit by sunlight, it is transformed into an energy-rich isomer - a molecule which consists of the same atoms, but bound together in a different way.

This isomer can then be stored for use when that energy is later needed - for example, at night or in winter. It is in a liquid form and is adapted for use in a solar energy system, which the researchers have named MOST (Molecular Solar Thermal Energy Storage). In just the last year, the research team have made great advances in the development of MOST.

"The energy in this isomer can now be stored for up to 18 years. And when we come to extract the energy and use it, we get a warmth increase which is greater than we dared hope for," says the leader of the research team, Kasper Moth-Poulsen, Professor at the Department of Chemistry and Chemical Engineering.

The research group have developed a catalyst for controlling the release of the stored energy. The catalyst acts as a filter, through which the liquid flows, creating a reaction which warms the liquid by 63 degrees Celsius. If the liquid has a temperature of 20C when it pumps through the filter, it comes out the other side at 83C. At the same time, it returns the molecule to its original form, so that it can be then reused in the warming system.

During the same period, the researchers also learned to improve the design of the molecule to increase its storage abilities so that the isomer can store energy for up to 18 years. This was a crucial improvement, as the focus of the project is primarily chemical energy storage.

Furthermore, the system was previously reliant on the liquid being partly composed of the flammable chemical toluene. But now the researchers have found a way to remove the potentially dangerous toluene and instead use just the energy storing molecule.

Taken together, the advances mean that the energy system MOST now works in a circular manner. First, the liquid captures energy from sunlight, in a solar thermal collector on the roof of a building. Then it is stored at room temperature, leading to minimal energy losses. When the energy is needed, it can be drawn through the catalyst so that the liquid heats up. It is envisioned that this warmth can then be utilised in, for example, domestic heating systems, after which the liquid can be sent back up to the roof to collect more energy - all completely free of emissions, and without damaging the molecule.

"We have made many crucial advances recently, and today we have an emissions-free energy system which works all year around," says Kasper Moth-Poulsen.

The solar thermal collector is a concave reflector with a pipe in the centre. It tracks the sun's path across the sky and works in the same way as a satellite dish, focusing the sun's rays to a point where the liquid leads through the pipe. It is even possible to add on an additional pipe with normal water to combine the system with conventional water heating.

The next steps for the researchers are to combine everything together into a coherent system.

"There is a lot left to do. We have just got the system to work. Now we need to ensure everything is optimally designed," says Kasper Moth-Poulsen.

The group is satisfied with the storage capabilities, but more energy could be extracted, Kasper believes. He hopes that the research group will shortly achieve a temperature increase of at least 110 degrees Celsius and thinks the technology could be in commercial use within 10 years.
The research is funded by the Knut and Alice Wallenberg Foundation and the Swedish Foundation for Strategic Research.

Chalmers University of Technology

Related Energy Articles from Brightsurf:

Energy System 2050: solutions for the energy transition
To contribute to global climate protection, Germany has to rapidly and comprehensively minimize the use of fossil energy sources and to transform the energy system accordingly.

Cellular energy audit reveals energy producers and consumers
Researchers at Gladstone Institutes have performed a massive and detailed cellular energy audit; they analyzed every gene in the human genome to identify those that drive energy production or energy consumption.

First measurement of electron energy distributions, could enable sustainable energy technologies
To answer a question crucial to technologies such as energy conversion, a team of researchers at the University of Michigan, Purdue University and the University of Liverpool in the UK have figured out a way to measure how many 'hot charge carriers' -- for example, electrons with extra energy -- are present in a metal nanostructure.

Mandatory building energy audits alone do not overcome barriers to energy efficiency
A pioneering law may be insufficient to incentivize significant energy use reductions in residential and office buildings, a new study finds.

Scientists: Estonia has the most energy efficient new nearly zero energy buildings
A recent study carried out by an international group of building scientists showed that Estonia is among the countries with the most energy efficient buildings in Europe.

Mapping the energy transport mechanism of chalcogenide perovskite for solar energy use
Researchers from Lehigh University have, for the first time, revealed first-hand knowledge about the fundamental energy carrier properties of chalcogenide perovskite CaZrSe3, important for potential solar energy use.

Harvesting energy from walking human body Lightweight smart materials-based energy harvester develop
A research team led by Professor Wei-Hsin Liao from the Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong (CUHK) has developed a lightweight smart materials-based energy harvester for scavenging energy from human motion, generating inexhaustible and sustainable power supply just from walking.

How much energy do we really need?
Two fundamental goals of humanity are to eradicate poverty and reduce climate change, and it is critical that the world knows whether achieving these goals will involve trade-offs.

New discipline proposed: Macro-energy systems -- the science of the energy transition
In a perspective published in Joule on Aug. 14, a group of researchers led by Stanford University propose a new academic discipline, 'macro-energy systems,' as the science of the energy transition.

How much energy storage costs must fall to reach renewable energy's full potential
The cost of energy storage will be critical in determining how much renewable energy can contribute to the decarbonization of electricity.

Read More: Energy News and Energy Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.