Throughout the ancient Greek and Roman civilisations, oil lamps were used to cast light over camps and keep thieves and unwanted visitors at bay. In 1726, clergyman and scientist Stephen Hales developed a street lighting system using piped coal gas, calling it the "spirit" of gas. After more than 150 years of dominance, Thomas Edison fought off the objections of the gas suppliers to dig up the streets of London to install underground electric lines and turn the Holborn Viaduct into the home of the world’s first electric street lights.
From New York’s public lighting system to Tamworth, Australia being coined the ‘First City of Light’, electricity spread light across the world at rapid pace and continues to grow today. However, while street lights will continue to be powered by electricity, the way they generate it and their impact on local electricity grids is starting to change.
With the growth in renewable energy sources, from solar panels to biomass, engineers, scientists and manufacturers are turning their attention to taking street lights off the grid and into the era of sustainability.
Wind and solar to light up Spanish streets
Combining the technology of solar panels and wind turbines, the Department of Electrical Engineering at the Barcelona College of Industrial Engineering has developed the world’s first autonomous industrialised public lighting system.
Designed in collaboration with energy company Eolgreen over a period of four years, the 10m-high street light draws its power from a small wind turbine capable of running at 200 revolutions per minute and producing 400w of electricity, with further power coming from solar panels.
Scientists working on an international collaboration to mimic the process of photosynthesis have reached a significant milestone.
"It takes very little wind to produce energy. The generator that has been developed can start working at a wind speed of only 1.7m per second, whereas current wind turbines need more than 2.5m per second," said Ramon Bargallo, who led the development. "This low intensity can provide six nights of electricity without wind or sun."
Planning to build 700 units of the light system in 2015 for use in the town of Girona and across the Andalusia region, Eolgreen expects it to be widely adopted on inter-urban roads, motorways, urban parks and a range of public spaces. Central to its appeal is its cost at 20% lower than conventional street light systems.
A clean energy lamp that stays clean
Turning convention on its side, the Scotia Monopole street light integrates its solar cells into the column of the light rather than on top – a design solution its developers claim reduces the need for cleaning and maintenance, and improves operation. Manufacturer Scotia explains that, "less dirt can stick on the panels", "snow will fall off completely" and "less cleaning is required".
In addition, any maintenance or cleaning of the solar panels can be done without needing to get to the top of the fixture. Powered entirely by solar panels, and compatible with the grid in order to feed excess power generated, the Monopole is capable of making money from its operation, rather than costing it.
Smartening up big city lights
Leading the charge from big industry in the street lighting space, Philips has developed a broad range of products that spreads across energy-efficient LED light poles and lamps and software to control their operation across a city. Through its CityTouch LightWave solution, which has been rolled out in Buenos Aries, Madrid, and is currently being installed in Los Angeles, public bodies are gaining new degrees of control to maximise the efficiency of street lighting.
The installation of the system in Madrid saw the Spanish capital’s entire street lighting infrastructure upgraded to LED bulbs and brought under central control, with expected savings of 44% offering the opportunity for the system to be made to pay for itself. Speaking at the time of its launch, Madrid mayor Ana Botella said: "This will be the biggest technological renewal ever seen in Madrid City. A change that will allow achieving some important goals. Namely, reducing the city’s energy consumption thanks to energy efficient luminaires, extending the lifespan of the city lighting and controlling light pollution by enabling the regulation of the intensity of light when and where it’s needed."
Taking in smog and giving out light
While it has yet to be rolled out commercially, research into dual purpose applications that clean air and light public spaces is continuing to develop. Conceived by Hungarian industrial designer Peter Horvath, the Biolamp is a dual function application that serves as both a street light and a smog processing plant. Containing a solution of alga and water at its core, the light sucks in smog from urban streets through a ventilator and processes it through the solution to clean away the carbon, separate the biofuel and pump it to a nearby processing plant for use as a power source.
"The tubes lead the biomass to the closest filler station. Here, biofuel is made for use in environmentally friendly cars. After this, the street lamps should be refuelled with alga," said Horvath. Similar products are also being developed by French company Fermentalg, which was founded by biochemist Pierre Calleja to exploit the carbon harvesting potential of microalgae. The overriding challenge for the concept is for the technology to exist to also power the street light through microalgal photosynthesis, but with a variety of major research currently making advances in the area, the solution may well become a reality.
Building a bridge between highway lighting
When the Chinese city of PingQuan decided that it was time to illuminate a stretch of highway that had previously had no lighting solution it stated that it wanted to make an aesthetic statement but not at extra expense, opting for 105 street lights from UGE equipped with a HoYi! Wind turbine and two 280W solar panels. Having successfully generated all the power required since installed, the lights have borne out no extra costs. "We haven’t had a single issue since they were installed, and people ask about the project all the time," said the procurement manager for PingQuan.
Away from China, the UGE streetlights have been installed to light a play area in Virginia, US, an architecturally renowned bridge in Busan, South Korea, and a customer car park at a Brooklyn, NY, branch of Whole Foods, which claims to be roughly 60% more energy efficient than any grocery store in the US.
The future’s bright for streetlights
From start-ups within universities developing novel conceptual applications for streetlights to the world’s industrial giants updating large-scale public lighting networks city by city, the technology and power base behind streetlights is undergoing significant change.
Alone, the potential to take streetlights off grid and in some cases turn them into net power contributors is of strong appeal to city planners, politicians and businesses with global operations. But there is further appeal from the simple fact that lighting systems in the developed world are outdated and in need of replacement and, in much of the developing world, still being installed for the first time. The day of grid connected systems will endure for the foreseeable future, but its dominance is certainly starting to dim.