Is It Time Again For Big Engineering?

The ancient Greek philosophers thought the physical world was made of four elements: earth, air, water and fire. In this issue we celebrate the benefits to engineering of one of those elements –terra firma. Welcome to magazine’s first special issue on geothermal systems.

Most of the articles are about ground source heat pumps, or geoexchange systems (see p. 18 ff.). Today these systems are used for heating and cooling homes, offices, small factories, schools, and even institutional buildings as large as hospitals. They circulate thermal energy from the ground immediately near or below the building, thus offering environmental benefits by reducing the building’s reliance on the grid and traditional carbon-based combustion.

Geoexchange technology has had its problems in the past, but most people agree that the industry has matured. The key for designers is to balance the inputs and outputs of energy so that temperatures in the ground loop don’t become lopsided. There are some ecological considerations as well. Research is going on at universities such as the University of Ontario Institute of Technology to measure the slightest temperature changes in the ground over the long term. The results will be used by ecologists to determine impacts at the microbial level.

At a dramatic and exciting scale we could be tapping energy sources deep within the earth’s core. Brian Brunskill and Laurence Vigrass’ article on page 36 suggests that Saskatchewan might be a good location to try deep geothermal technology, which would involve drilling down to aquifers more than two kilometres below the earth’s surface where temperatures are 60 degrees Celsius.

Indeed, with the pressure to find new energy sources, we’re seeing a resurgence of Big Engineering ideas. Riverbank Power of Toronto, for example, is doing tests for something called an “Aquabank.” It involves installing turbines 600 metres down an underground shaft. Water is sent down the shaft from a river or surface source to drive four 250-MW turbines, then recycled back up to the surface at night (see page 10).

Another Big Engineering idea that is not related to geothermal systems, but is so audacious I can’t resist mentioning it, is the brainchild of Rod Tennyson, professor emeritus at the University of Toronto Institute for Aerospace Studies. He has proposed building a massive pipeline across Africa that would supply not oil, but another of the Ancients’ vital elements — water. The 2-metre diameter reinforced concrete pipe would run from Mauritania on the Atlantic Ocean to Djibouti on the Indian Ocean, carrying a billion litres a day of desalinated sea water into a network of branches. The pipe could provide water for up to 20 million people. “It’s a megaproject, but it’s doable,” Tennyson said in UofT Magazine. He says that the $24- billion project can use existing technology and only needs the political and economic backing to move ahead.

In recent decades Big Engineering ideas have fallen somewhat into disrepute. Perhaps it’s time to revive them.