Microwave rock drill

Tunnelling through soft ground is rela­tively easy. Set a drilling machine to work in hard rock such as granite or ba­salt, the rate of progress drops dramati­cally because of slow cutting speed and the increased rate at which drill bits wear

out. One way to speed up drilling would be to heat up the rock ahead, causing it to crack. Engineers have attempted to do this using gas jets, lasers and even electric heaters, but with little success.

Jacques Ouelett, a mining engineer at McGill University in Montreal, Canada, suggests fitting a drilling head with a low energy microwave generator to heat rock just ahead of the drill bit. This fractures the rock efficiently making it much easier to cut.