Sao Paulo Special
BBC World Service
This week BBC World Service Digital Planet programme is in Brazil. Here the show looks at efforts to use solar power to get more people online.
Digital Planet's Gareth Mitchell tests out "green" wi-fi in Sao Paulo
While many net users in developed nations can get online pretty much anywhere thanks to reliable electricity and telecoms networks, the same is not true in developing nations where power sockets and fixed line links can be few and far between.
A project at the University of Sao Paulo aims to overcome one of these hurdles by using the sun to power a self-contained wi-fi access point.
The creators of the access-point-in-a-box hope that it will help many poor communities get free access to the net.
The project is the creation of Professor Marcelo Zuffo, Interactive Electronics Coordinator at the University of Sao Paulo, and prototypes are being tested on lamp posts dotted around the institution's campus.
"It was designed to work in an open environment, like a forest, a park or a low-income neighbourhood," he told BBC Digital Planet presenter Gareth Mitchell.
The low cost, solar-powered access point is ready as soon as it is unpacked and needs neither maintenance nor a power socket to get going.
"It is a completely autonomous wi-fi hotspot, it doesn't need any internet or energy connection," said Prof Zuffo.
Green wi-fi tries not to disturb the natural world that lives beside it, like bird's nests
"Everything comes from the sun and we have plenty of that in Brazil," he said.
Prof Zuffo believes the self-contained unit will prove popular with schools that lack a reliable electricity source to power access points or computers that students can use to surf the web.
"One of the original motivations of this project was a high school where we deployed the internet and they do not have power plugs in their classrooms," said Prof Zuffo.
"We came up with the idea of taking energy that is most plentiful and cheap, ie the sun, and try and transform this in bits," he said.
"We have a solar panel, a cheap motorcycle battery and a circuit that is responsible for energy management.
The internet comes from a mesh, from different buildings," said Professor Zuffo.
Rather than rely on dedicated connections to make a link back to the core of the net, the self-contained units form an ad hoc network and pass data between each other to connect to the larger internet.
Each unit effectively becomes a relay station for all the boxes scattered across a neighbourhood or campus.
"We can have up to two days of full internet coverage and our goal is to increase that to 10 days - so that in the rainy season and the winter - you can have the internet for free," said Prof Zuffo.
"The natural plan is to miniaturise the system so that we can save on costs.
"So by the end you can imagine these wi-fi solar mesh devices being the size of a cellphone or playing card," said Prof Zuffo.