As fossil fuel levels are exhausted, building a more sustainable world is an issue that is coming to the fore as a crucial consideration in the development of new technology. The energy needs of the planet's population are immense, and an environmentally friendly source of energy is desperately needed. Energy harvesting from renewable sources is not a new concept - windmills have been around since the first century - but the desire to harness renewable energy has intensified. Energy harvesting technology is the term given to technology used for collecting unused energy from the surrounding environment and converting it into electrical power. Solar, wind and hydroelectric power are perhaps the best-known of these technologies. However, there are many other forms of energy that are under developed and hold much potential for powering the future. These include vibration, pressure, heat and temperature difference. While large-scale power generation cannot be realised using these sources due to their low levels, devices with low power demands may be able to harness such energy sources, potentially eliminating the need for an external power source. Dr Haruichi Kanaya at Kyushu University is leading a team investigating wireless technology.