Connected To The Land 04-2018-Fall-718-PM96 - Page 18

ALTERNATIVE GOES MAINSTREAM RENEWABLE ENERGY A BIG PART OF ELECTRICITY SUPPLIES Story by Helen McMenamin. About 19 percent of Canada’s primary energy – that includes oil and gas and heating buildings and transport – comes from renewable resources that can be replaced as fast as they are used. Moving water is the main renewable source of electricity supplying almost 60 percent of Canada’s power needs. Biomass – burning wood, composting waste from farms or cities – is the second most-used source, then wind with 3.5 percent. Solar systems are rapidly increasing as their costs drop and efficiency increases. Water and wind generate electricity in much the same way as windmills and waterwheels that powered grain mills, sawmills and other industry a century ago. The water or wind drives a wheel or a turbine connected to a generator. Burning wood and other waste can be used to produce steam that drives a turbine, and composting farm waste or sewage can be used to produce methane, which is burned to produce steam that drives a turbine. Photovoltaic cells use certain materials with a special character. Sunlight moves electrons away from their atoms and produces electricity in a process called the photoelectric effect. It was discovered in 1839, but it was just a curiosity until the 1960s when space 18 programs used the technology for power aboard spacecraft. Ongoing research has led to much more efficient, lower cost and more versatile photovoltaic cells, the units that make up solar panels. For example, photovoltaic cells have been incorporated into sidewalks and are to be tested on stretches of US highway Route 66 next year. Chinese companies expect to produce photovoltaic cells for as little as 37 cents per watt in the next few years. Mass-produced ready-to-connect solar energy panels allow consumers to power remote locations or produce electricity from their own solar system. The mix of electricity sources in power supply depends on local resources and the demand for power. The southern prairies, especially the west, have abundant wind (some would say the wind is their major feature). Ontario’s big lakes have winds that can drive wind turbines. Quebec and BC have rivers with sharp inclines for hydro-electric power generation. Tidal resources are greatest on the east coast where the difference between high and low tide is huge and vast volumes of water move rapidly, changing direction every 6 hours. Geothermal resources are believed to be most abundant in BC, North Western Territory and Alberta. Sun, wind and biological materials are distributed across Canada and around the world. As a result, many scientists and engineers have focused on these and made the technologies more efficient and power plant design simpler. Geothermal energy – using the extreme heat of the earth’s core to produce steam to drive a turbine – has considerable technical challenges, but a project underway in BC is believed to have a capacity of 200MW. In-ground heat pump systems are often called geothermal. They use the constant temperature of the earth below the frost line by pumping air from that depth to a heat exchanger to heat or cool a building. The air pump and other equipment need electricity to run, so the system may not be truly renewable. WHY MOVE TO RENEWABLES? The push to change to renewables is partly economic – the constant push for lower costs. Coal has been the most widely used energy source for electricity generation because it is relatively cheap and abundant, but it has huge environmental costs. Historically, miners and communities near power plants suffered from the social and often fatal health effects of coal dust and smoke. Then there was acid rain – sulfur compounds released from burning coal combines with water to make lakes uninhabitable for fish, even killed vegetation. Engineering improvements – taller smokestacks, scrubbing systems and more efficient burners were installed so that modern GHG EMISSION RANGES FOR VARIOUS TECHNOLOGIES 1,400 W e use more and more electricity every year and we’re not likely to slow down. Whether it’s industry, or air conditioning in our homes, or people wanting fridges and lights in the developing world, we all want more of the appliances that make our lives easier and more comfortable. And almost every business and modern home needs electricity to function. 1,200 1,000 800 600 400 200 0 Wind Wind Wind Reservoir Reservoir Run- CF 0-15% CF 16-25% CF 26-35% hydro inc. hydro excl. of-river gross emissions hydro emissions from from flooded flooded land land PV Nuclear Newly flooded boreal reservoirs (Eastmain 1) Natural Diesel and gas heavy oil Coal Connected to the Land