Turning the 'tides'

CLIMATE CHANGE SERIES

- KRISHNA GUPTA

While solar and wind power have become the dominant renewable energy sources, there are other sources such as wave and tidal energy, which can be exploited in coastal areas. While wave and tidal energy have been used in some form or another since hundreds of years, the modern applications can be traced back to the 1960s. In particular, the Japanese Naval Commander Yoshio Masuda may be regarded as the father of modern wave energy. In 1947, he invented the Oscillating Water Column (OWC), which is basically a navigation buoy fitted with a small air turbine. As a wave or a tide pushes water into the OWC, air is displaced and pushed through the air turbine, which creates electricity.

Wave and tidal power can also be tapped by Tapchans (or Tapered Channels), which raise the wave length of waves by tapering a channel, which feeds into a reservoir) and pendular devices (which is a rectangular box, with one end open to the sea with a flap attached. The waves create a pendular motion in the flap which powers a hydraulic pump and a generator).

Wave and tidal power devices can be onshore and offshore. Among the offshore devices, these could be either floating devices or fixed devices (fixed to the ocean floor with a chord or rope). These devices are collectively known as wave energy converters or tidal energy converters.