Other Energy Sources
Since the opening of the Sir Adam Beck hydroelectric plant at Niagara falls, Canada has had a love affair with hydroelectricity. Hydro provides a large scale clean source of energy to Canadians, giving us an incredible energy advantage over most other nations. Currently hydroelectric energy provides 62% of Canada’s electricity, and there are numerous small and large scale projects that could still be developed. Hydroelectric generators create energy by converting the flow of water under gravity into electricity. Hydro power represents a perpetual resource, as the water that flows through the turbines returns to the sea, is evaporated by the sun, and then falls in the mountains again as rain.
Two variables affect the generating power of a hydro installation; the height the water falls, and the volume of water falling. Thus bigger rivers with steeper drops have the best potential for hydro. The needed drop can be created by constructing a dam, or, as in the case at Niagara falls, installing run-of-river turbines to utilize natural drops. At Niagara water is diverted into tunnels that bypass the famous landmark. Though this cuts the volume of water going over the falls, this is in some ways desirable because it slows the erosion of the fall rim, helping to preserve the region’s most famous tourist attraction.
Hydro’s advantage over the other renewable sources is that it provides steady electrical production. A hydroelectric plant can respond immediately to fluctuations in power demand through diverting water flow into and out of the turbines. Hydro plants can thus counter the intermittency of solar and wind installations. The disadvantages of hydro involve profound effects on the local ecology. Dam construction interrupts species movement in the river, changes water flow due to increased evaporation, and changes water temperature. Dams also impede sediment flow. For these reasons there is a growing interest in small hydro projects and less disruptive run-of-river installations.
Though Conventional oil supplies are dwindling, there remain fairly significant non-conventional oil sources. The best known of these are oil sands. The Alberta Oil Sands represent the last great oil reserve on Earth, rivaling the conventional deposits of Saudi Arabia. Oil sands formed when conventional oil and bacterial mingled in sand to form bitumen, a dense tar-like hydrocarbon. It is important to note that bitumen is not oil, but can be processed into crude oil. In the densest deposits near Athabasca, the bitumen makes up from one to twenty percent of total material volume, and is relatively close to the surface, allowing for open pit mining.
People have tried to harness bitumen for over a century, but it was only recently that processing of this material became profitable. Most of the mining occurs in giant pits, and then the raw material is mixed with hot water to form a slurry. The sand and water are then separated out to produce concentrated bitumen. Where the oil sands are too deep to mine, researchers are experimenting with injecting steam into the ground to soften the bitumen, a process that requires large amounts of energy and water.
Once the bitumen is mined, it must be processed. Bitumen molecules are more complex than oil and it is rich in carbon and poor in hydrogen. Bitumen must undergo a four step process that involves removing carbon and physically breaking the molecules, distilling the molecules by size, catalytically converting the fragments into molecules of the right size, and finally adding hydrogen and removing nitrogen and sulphur. The end result is synthetic crude oil.
As can be imagined, the above process is very energy intensive. It also requires large amounts of water and hydrogen, currently generated from natural gas. The net energy gain from synthetic oil production is much smaller than the gain from conventional oil production.
Solar energy can be broken down into active and passive applications. Active solar energy involves the direct conversion of sunlight into electricity through cells utilizing the photoelectric effect. In such cells, semiconducting materials absorb sunlight and release electrons, an effect first explained by Albert Einstein. Banks of such panels are connected together and exposed to the sun. They traditionally came in the form of flat plates, but recent advances in thin film technology have allowed them to be shaped into roofing tiles and other applications. As the thin films use much less semiconductor per area, they are much cheaper.
Solar cells currently convert about fifteen percent of ambient sunlight into electricity, but this efficiency continues to rise. The cost of solar panels continues to fall, though it is still a large barrier in all but the sunniest climates. Photovoltaic panels could provide significant energy though, and could take advantage of the roughly 33% of urban area that is blank roof space. Solar electricity suffers from intermittency, as the sun isn’t always available. In stand alone applications solar power is paired with battery storage, an expensive way to store energy.
There are also many passive applications of solar power involving capturing the heat from the sun and putting it to use. Solar heating systems can be as simple as heavy stone walls that act as a heat sink during the day and release heat at night. Solar energy can also be used for lighting, and can be reflected deep into buildings to limit conventional lighting needs. Solar energy can also be use to heat water. Solar water heaters capture the sun’s energy in a collector system, which can be as simple as coils of black pipe. The water is then pumped to a storage tank. Swimming pools, which normally consume large amounts of energy, can be heated quite well by solar energy. In this case the storage tank is the pool itself. Proper use of passive solar energy could greatly drop conventional energy needs.
The large scale burning of coal is a major contributor to the global increase in greenhouse gasses. However coal is so abundant that is valid to wonder if one could harness this energy source without polluting the atmosphere. There is enough coal to supply our energy needs for hundreds of years, and these supplies are widely geographically dispersed, limiting the need for elaborate transportation or energy transmission schemes.
Coal can be superheated under pressure to yield energy without pollution. The coal is gasified by the heat, breaking into its component parts. Pollutants such as Sulphur and Mercury can be screened out, leaving a pure flow of hydrogen and carbon dioxide. The hydrogen can be burned to create electricity, and the carbon dioxide can be sequestered.
Many long term carbon storage technologies are being explored, including injection into old oil wells and deep into the ocean. The hydrogen can also be used to power vehicles.
Nuclear energy currently accounts for fifteen percent of Canada’s energy production and elicits a very polarized and emotion response from many members of the public. North American policy makers have expressed a renewed interest in nuclear power as the technology produces large amounts of power with no greenhouse gas emissions, and relies on a readily available domestic fuel source.
Nuclear power is produced through neutron bombardment of Uranium 235, which makes up about 0.75% of natural uranium. The uranium atom then splits into daughter atoms, but the mass of these daughter atoms is not quite equal to the mass of the parents. The “lost mass” is turned into energy, creating a great amount of heat that can be used to produce electricity. The core of the reactor consists of the uranium, a moderator which controls the flow of neutrons, and a coolant. In Canada the moderator used is heavy water, and the coolant is regular water.
Once the pariah of the Green Movement, nuclear energy is enjoying a bit of a theoretical renaissance, and has been endorsed by environmentally concerned people such as James Lovelock, co-creator of the Gaia theory, Geoffrey Ballard, founder of Ballard Power, and Patrick Moore, co-founder of Greenpeace. They see nuclear power as a way to mitigate climate change damage. However nuclear power has its downsides; it has proven to be a very expensive energy option here in Canada, and storage of the spent fuel is still a contentious issue. The spent fuel rods will remain dangerous for thousands of years. Mismanagement of nuclear energy can be dangerous and deadly, and ultimately the supply of Uranium is limited, though spent fuel recycling could greatly increase reactor lifetime.
Wind energy is the fastest growing energy alternative. Wind turbines transform the kinetic energy of the wind into electricity. The wind turn a rotor blade mounted on a tower, and this blade turns an axel connected to a generator. Usually the entire generation unit is mounted on the tower in such a way that it can turn to maximize electricity production no matter what the wind direction. The average turbine is now much larger than windmills of old, and can generate one megawatt of power, enough for the consumption of about three hundred households. The amount of energy produced depends on the blade size, and rises with the cube of the wind speed. Windy sites are therefore much better than less windy sites. Turbines are often grouped into wind farms in order to take full advantage of the best locations.
Wind Energy has several advantages over other technologies. The technology is very simple and thus is seldom off line for repairs. The footprint is very small, and thus turbines are compatible with farming and grazing. Electricity generated in this manner is emissions free, and uses no water, a concern that is often overlooked. Some energy production techniques are very water intensive, particularly coal, which must be washed before burning, and reservoir hydro, where great quantities of water are lost to evaporation. Wind is also the cheapest energy alternative. Prices are close to those for conventional sources, and if subsidies were removed and economics of scale utilized fully, wind might be the cheapest energy source of all.
Wind has one major drawback: intermittency. The wind doesn’t blow all of the time, so one cannot count on a steady supply of electricity. Utilities must have enough electricity to meet demand. About ten percent of a grid’s input sources can be intermittent without destabilizing the grid, and with careful planning and use of wind forecasting twenty percent of a grid’s energy supply can be intermittent as long as extra supply exists that can be brought on line quickly. As wind currently makes up only a tiny percentage of North American energy production, we don’t have to worry about grid limits yet.
Wind power has a few very local environmental negatives. Turbines can throw ice and snow, they create a small amount of noise, and they interfere with television signals and radar. They can also kill birds and bats, though studies suggest that dropping a domestic housecat into an area is likely almost one hundred times more damaging to bird life than a wind turbine.