Chris Lefteri takes a look at new and smart technologies that can collect ‘waste’ energy, from boiling kettles to the footfall of marathon runners. Lefteri is a designer and has written seven books about new materials and their application

Chris Lefteri takes a look at new and smart technologies that can collect 'waste' energy, from boiling kettles to the footfall of marathon runners. Lefteri is a designer and has written seven books about new materials and their application

In our search to squeeze every last drop of usefulness from our manufactured world, waste is becoming an increasingly valuable resource, to a point where even the heat from the outside of your kettle or the vibration from a vacuum cleaner can have value.

Regeneration of waste has become a buzz word and a commodity, and rightly so. Without doubt the term 'waste' is predominantly focused on material waste, but the harvesting of latent energy is emerging as one of the new areas of research into sustainability. The Romans understood that excess heat generated from heating water could serve many functions in a building, but research in modern contemporary technologies is taking another look at waste heat from a completely different source, exploiting our increasing dependency on electronics.

Tiles harvest the energy of footsteps

In 2011, Cisco predicted that by 2020 there will 50 billion devices connected to the internet (the population estimate for 2020 is 7.6 billion people). As you will know if you use a mobile, laptop or desktop computer for a long period of time, they generate heat. Research is looking at how to harvest this and other waste energy, not just from electronics but also but household products and industry.

Technically referred to as thermoelectric technology, solid-state devices belong to a family of energy-harvesting technologies. Overall these are focused on the powering of electronic devices by scavenging small amounts of energy that would be normally lost as 'wasted' energy from a variety of sources: heat gradients and sunlight, and even pressure and movement are converted into usable electrical energy. The advantage of these technologies are long-term fuel savings and replacing primary batteries in low-power applications.

Energy harvesting is also an area of materials and technology that the UK government's Technology Strategy Board believes is untapped by the design community. To generate a consumer demand for these technologies the board commissioned an ideation project to explore different household-appliance. Looking at 'horizontal issues' for energy harvesting, designs were developed that could address the use of new materials to harvest energy in technology used at home. It looked at elements including size, available power levels and extending the life of a battery -- the most likely energy sources for harvesting energy being solar, thermal or vibrational -- as well as the energy harvester as storage structure.

Ideas from this project included the use of piezoelectric ceramics (PZT), that's been around a while -- the clicking on a gas hob is a piezo crystal being hit to generate a spark. But here piezo electric fibres are used to harvest movement vibrations from vacuum cleaners and washing machines to charge electronic items.

Piezoelectric ceramic materials have a crystalline structure that produces an electric current when mechanical pressure is applied. In terms of the design versatility of PZTs, they can be formed into almost any shape and combined into composite structures with polymers.

From the same project, another thermoelectric technology exploited the temperature change from boiling a kettle to power a milk frother. In this application, based on a product called Powerfelt, a felt is wrapped around the kettle and when boiling produces a temperature difference between the inner and outer surface of the felt a charge is produced. Researchers at Wake Forest University in North Carolina who developed the technology are carrying out further development for initial concepts for mobile phone covers and smart clothing. The material can charge 15 per cent of 2000 mA batteries for more than eight hours at the temperature differences of 10 degrees. This means it would even work with just your body temperature.

Outside the domestic arena, UK company Pavegen is also harvesting people power with paving stones that capture the energy from footsteps. Installed outside sports stadiums, stations and airports, the tiles are inserted into the existing pattern of street paving stones. When installed in the path of 37,000 marathon runners, nearly 5kwh of energy was generated. In addition to producing energy the tiles can also collect footfall data.

These few case studies illustrate how increasingly useful waste is going to become as a valuable commodity and naturally, as these energy harvesting technologies grow, so they will become more affordable and widespread.