Transcript Slide 1
Lesson 5 Canadians are some of the highest consumers of energy in the world. Currently, 89% of energy resources used in Canada are nonrenewable. As the world’s population grows we need to find more efficient energy-transforming technologies. Original sources of energy are called energy resources. A raw material, obtained from nature, that can be used to do work; also called an energy source. Renewable Resource An energy resource the renews itself in a normal human lifetime Non-Renewable An energy resource that does not renew itself in a normal human lifetime. Fossil fuels are convenient and for the time being readily available but there are many disadvantages. It is costly to remove from the ground and to deliver to the user. When burned the products produce pollutants that contribute to climate change. Unspent fuel also contaminates the environment when it is leaked or spilled. Of the natural gasses, Natural gas burns the cleanest and has the least amount of environmental impact. 1. 2. 3. 4. the fuel is burned to boil water to make steam the steam makes a turbine spin the spinning turbine turns a generator which produces electricity the electricity goes to the transformers to produce the correct voltage Nuclear reactors use uranium in a process called nuclear fission. The nucleus of an atom is split and energy is released. If enough nuclei are split water can be heated to produce steam, this generates electricity in a very similar manner to that of fossil fuels. CANDU reactors are Canadian built and designed reactors that are much safer than other reactors as it is almost impossible for them to have a melt-down. Nuclear power is very expensive to set up and the nuclear waste is also a major problem. However, they produce very little emissions and can be built where they are needed as long as there is a water source. In a nuclear reactor, atoms of a heavy element, usually uranium, are split in a chain reaction. This splitting, called nuclear fission, releases an enormous amount of energy. The nuclear fission of just 1 kg of uranium is equivalent to burning about 50 000 kg of coal. Solar energy from the sun (radiant), can be used in solar cells, or photovoltaic cells. These devices transform light energy directly into electrical energy. Solar energy can also be used to heat buildings directly. takes advantage of the Sun’s energy at all times of the year. This includes eaves that overhang the windows to block sunlight in the summer and allow light in, in the winter. uses solar collectors to absorb the Sun’s energy and converts it into thermal energy that can be used elsewhere in the structure. This is much more expensive than the passive method. Solar energy is abundant, non-polluting, and available almost anywhere. The set up can be expensive but they usually require little maintenance. One of the world’s largest solar energy projects includes solar farms in Sarnia and Sault Ste. Marie and aims to produce enough electricity for about 9000 homes Hydraulic energy uses gravitational potential energy generated by water to turn turbines connected to generators. This is an indirect source of the Sun’s radiant energy as the water cycle is powered by the sun. This is an indirect source of the Sun’s radiant energy as the water cycle is powered by the sun. This method electricity generation does not produce pollution but it does affect the ecology of the river where it is dammed. The electricity must also normally be transmitted long distances which reduces its efficiency. SIDE NOTE: 60 % of Canada’s electricity is generated by hydroelectric Wind energy is also generated indirectly by the Sun’s radiant energy. The kinetic wind energy is used to turn rotors on turbines attached to generators. Wind mills require large amounts steady wind all year long. They do not produce any pollution but the power generation is dependent on if there is wind and the turbines are noisy and known to kill migrating birds. Wind energy currently provides about 1 percent of Ontario’s electricity, but it is one of the fastest-growing energy sources in the world. Tidal energy is a potential energy in regions that are affected by ocean tides. Tides are produced by the gravitational pull of the moon. To harness the energy a dam must be built across the mouth of a river that enters the ocean. When the tide comes in gates are opened and the water pours in and turns turbines When the tides goes out the gates are opened again and once again the turbines are used to produce electrical energy. This method does not produce pollution but the energy generation is dependent on the tides, the dams can affect the ecology and because the turbines must be able to spin two ways they require a different turbine technology. Biomass energy is a chemical energy stored in plants and animal waste. This energy comes indirectly from the sun to grow the plants. This energy source can be as simple as a wood stove to a methane capturing facility which then burns the fuel in the same manner as a fossil fuel power plant. Although this method can be renewable if trees are replanted and it also reuses materials but it does produce pollution. Examples of biomass include wood, peat, straw, nut shells, sewage, and corn husks Organic waste decomposes to produce a gas called methane. The methane gas can be burned to boil water to make steam. The most common biomass material used today is wood waste from lumber and from pulp and paper industries. Geothermal energy is thermal energy or heat taken from the beneath the Earth’s surface. The source of this heat is radioactive decay. On average every 1km in depth results in a 25 ° C increase in temperature. Obviously volcanic areas are more suitable for this method of energy generation. Nuclear fusion is the process in which the nuclei of the atoms of light elements join together at extremely high temperatures and densities to become larger nuclei. This is the energy source at in the Sun and stars. Since hydrogen is one of the most abundant atoms we have a limitless fuel source that produces much less nuclear waste than nuclear fission. The problem is that temperatures of a few million degrees are needed to start the reaction and then the pressure must be extreme in order for the reaction to continue. This makes this energy source a very distant possibility. In a fuel cell, the chemical potential energy of the fuel, is changed directly into electrical energy. The hydrogen combines chemically with oxygen in the presence of a catalyst. The result is the production of water and electric current. The fuel cell is very efficient because it transforms the energy directly from chemical energy into electrical energy. It also operates at a relatively low temperature, thus emitting very few pollutants. I t is also quiet and easy to maintain. The major problem is that energy is needed to obtain the hydrogen from water. Write the energy transformation equation for each of the following resources used to produce electrical energy. Which is the most efficient? Each transformation will lose some energy to heat. A) Hydraulic, B) The Sun, C) Biomass, D) Nuclear fission, E) Wind, F) Geothermal, G) Fossil Fuels. Source Advantages Disadvantages Fossil - Fossil fuel generating - The burning of fossil stations can quickly fuels releases Fuels adjust to changes in demand - The technology for using these fuels is already in place pollutants into the atmosphere and directly contributes to global warming. - Mining coal is hazardous to the workings and damages the environment Source Advantages Nuclear - Nuclear power is inexpensive to produce - Produces enormous amounts of energy from very little fuel. Disadvantages - Waste is poisonous and radioactive and needs to be stored very carefully for hundreds or thousands of years - Nuclear plants are very costly to construct and maintain. Source Advantages Hydroel - Large generating stations produce electricity ectric - - Disadvantages - inexpensively Reservoirs may be used for flood control, irrigation, drinking water, and recreation Small scale hydroelectric plants using the local rivers can be practical for some communities - There is a huge environmental impact when the dam is constructed, including flooding large areas of land, disruption or destruction of wildlife and fish habitat and migration routes, and displacement of Aboriginal communities. Hydroelectric stations are very expensive to build Source Advantages Sunlight - Solar cell energy is a convenient source of energy for small appliances, such as calculator’s Solar energy is useful in remote areas. Disadvantages - Solar cell efficiency is low, so many photoelectric cells have to be used, which takes up large areas of land. - Solar energy is the most expensive energy source at present. Source Tides Advantages Disadvantages - Once tidal generating - The environmental stations are built, tidal impact of marine life energy is very in area can be inexpensive. significant, due to - Tides are more changes in water level predictable than wind and water quality. or sunlight - Tidal energy is suitable for few areas as it requires very high tides. Source Wind Advantages - - Wind energy production does not produce greenhouse gases that contribute to global warming. Farming and grazing can continue on land where wind turbines are located. Disadvantages - The wind does not always blow or remain constant. Wind turbines can present barriers to bird movement, cause bird fatalities due to collisions with turbine blades, and can disturb breeding, wintering, and staging sites.