The projects should help to increase the energy efficiency of both fossil fuels and renewables

Waste energy from tower blocks and power lines harvested

A new system is being developed that promises to harness waste heat from tower blocks and industrial complexes and convert it into electricity.

A team from the University of Navarre in South Spain is trialling a thermoelectrical generation system that could make heat generation in large buildings significantly less wasteful.

Currently, just 35 to 40 per cent of the heat energy produced in these locations is used for its intended purpose with the rest being released into the atmosphere and lost.

PHD student Patricia Aranguren has been testing thermoelectric devices based on the ‘Seebeck’ effect to reuse the lost energy.

The Seebeck effect is a method for creating electricity from the temperature difference between two dissimilar electrical conductors or semiconductors to produce a voltage.

The system requires only minimal maintenance and has a long service life because no moving parts are used.

Commenting on a trial system that she is currently testing, Aranguren said: “The generator was fitted to the flue outlet of a boiler used to heat water. It comprises 48 thermoelectric modules, two heat exchange systems and other devices. The net optimum generation of electricity amounts to an output of 100 W/m2.

“Net maximum electrical power of 136.77 MWh/year was obtained and is the equivalent of the energy used every year by 40 homes.”

The system is thought to be particularly suited to the waste energy produced by tower blocks and industrial facilities because it is able to recover relatively low temperature waste heat.

Aranguren described her system as "intelligent" and said it was a far more effective use of fossil fuels that traditional heating systems.

Thermoelectricity has already been successfully applied across a range of sectors, including automotives and space technology, for example in the NASA rover Curiosity sent to Mars.

Meanwhile, researchers across a number of European universities are looking at ways to extend the length at which electricity can be transported via power lines in order to boost renewables.

Currently, European consumers tend to pay more for energy from renewables than for energy from conventional resources because the power generating facilities themselves are often located further away from densely populated areas.

The act of transmission across traditional power lines incurs an efficiency hit with additional energy lost the further it has to travel. This is typically the case with wind farms, many of which are located on offshore or remote sites.

However, teams from Germany, Moldova and Romania are currently trialling different materials and components to lower the energy lost in order to improve the viability of renewables.

“Using innovative materials and geometries for pylons, conductors and insulators helps to keep within the space already used, while allowing for a higher electrical capacity,” said Vanessa Gombert with 50Hertz, a power transmission operator in Germany.

To boost efficiency, the existing alternating current (AC) transmission lines must be upgraded or new lines built.

Insulated cross-arms can reduce the pylon widths and high-temperature low sag conductors can transmit higher electrical capacity without having to increase pylon height.

”For example we use aluminium conductors and add steel in the middle of the conductor for mechanical reasons,” said Nicolae Golovanov at the Polytechnic University of Bucharest in Romania.

Further improvements can be made with improved weather forecasting for electricity generation.

Gombert’s team is also currently developing low-cost sensors that can assess the current ambient conditions at power generating sites in order to help plan the feed-in to the grid.

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