S2 Science Physics Energy Matters Name: Experiences and Outcomes SCN 3-04a - I can use use my knowledge of different ways in which heat is transferred to improve the energy efficiency of systems. SCN 3-04b/4-04a By contributing to investigations, I can discuss the benefits and potential risks of renewable energy sources. Learning Intentions I can name the eight forms of energy and give sources of each. I can identify the main energy change happening in a system. I can explain the difference between renewable and nonrenewable energy sources. I can identify an energy source as renewable or non-renewable. I can describe the benefits and risks of using renewable energy sources I can state that efficiency is an indication of how well a system converts energy. I can perform calculations involving efficiency. I can describe methods to improve the efficiency of a system. I can describe heat as a form of energy which moves from hot areas to cold areas. I can state that temperature is a measure of how hot or cold a substance is. I can describe how heat is transferred by conduction, convection and radiation. I can describe ways to reduce heat losses around the home. 1
Energy: Energy allows a body, machine or system to do work. There are eight forms of energy. Write the eight in the space below and include an example of where the energy can be found. 1. Electrical solar cell, battery, mains socket 2. Chemical food, fossil fuels, petrol 3. Sound musical instrument, voice, loudspeaker 4. Light the Sun, a lamp, TV screen 5. Heat Burning match, fire, radiator, the Sun 6. Kinetic any moving object, 7. Nuclear Nuclear power stations_ 8. Potential Stretched spring/elastic band Energy Converters An energy converter changes energy from one form into another. List four energy converters and the energy changes taking place. You must include the arrow in your answer. The arrow is important because _the arrow shows the direction of the energy change.. 1. Loudspeaker, electrical to sound 2. Lamp, electrical to light 3. Burning match, chemical to light and heat 4. Violin, kinetic to sound Energy Source: Renewable/Non-Renewable (delete as appropriate) Examples: Coal, crude oil, natural gas, nuclear fuels Definition: An energy source which cannot be (easily) replaced. Energy Source: Renewable/Non-Renewable (delete as appropriate) Examples: Solar, wind, wave, tidal, biofuels, geothermal, hydroelectric Definition: A source of energy which can be used more than once. 2
Renewable Energy Sources The diagram shows a wind turbine. Describe how a wind turbine generates electrical energy. (You need to include the energy conversion in your description). The wind turns the blades which turn the generator. The generator produces electrical energy, which goes to the National Grid. The energy change is kinetic to electrical. The diagram shows a hydroelectric power station. Describe how this station produces electrical energy (You need to include the energy conversion in your description). Water flows down from the dam (or mountains) and turns the turbine in the power plant. The turbine turns the generator, which produces electrical energy. The energy change is potential to electrical. 2
Risks and Benefits of Renewable Energy Energy Source Benefits Potential Risks Wind No greenhouse gases produced. Even a small windfarm can power a lot of houses. Ruins the look of the landscape. Can only be used below certain wind speeds. Wave No greenhouse gases produced. Can be moored out at sea to limit impact on landscape. Disruption of animal habitats. Can be damaged in strorms Solar During the hours of daylight, there is always some solar energy input. In some areas, quite a lot. Not ideal for Scotland! No power at night. Ultra-violet radiation is harmful. Tidal Geothermal Biomass Hydroelectric In a funnel-shaped estuary, lots of power is available by building a barrier and allowing the tide to flow through turbines. Caused by radioactivity in rocks. Available everywhere (if you drill deep enough) but best in areas with volcanic activity (e.g.; Iceland) Discarded plant material (from agriculture and households) is plentiful and cheap. It can be decayed to produce methane, a good fuel. Lots of dammable streams and lochs in Scotland. Plentiful. Well understood old-ish technology. A tidal barrier disrupts shipping and fishing not suitable for the Forth. Also the Clyde is the wrong shape. Volcanic areas threaten human life and livelihood. Icelanders don t seem to mind Methane and CO2 produced by burning it are greenhouse gases linked to climate change. Same disadvantage as fossil fuels. Disrupts fish migration (salmon, etc.). Can cause flooding. 3
Efficiency Efficiency is a measure of _how much energy of one type is converted to energy_(of another type). Efficiency is usually recorded as a _percentage. In the boxes below, write in two efficiency calculations that you have got correct. % efficiency = useful energy output Energy input = 700 1400 = 50% % efficiency = useful energy output Energy input = 135 675 = 20% Improving Efficiency Give examples of improving efficiency in the following areas At home Draught excluders keep heat in a room. Turn off lights when leaving a room unoccupied. In transport Car-share or use public transport. Driving close to the optimum speed (55 mph) and anticipating braking by lifting foot off the accelerator to avoid wasting energy. 4
Heat Heat is a form of energy, while temperature is a measure of how hot or cold an object is. Heat always moves from hotter areas to colder areas. Conduction Conduction is the transfer of heat by the vibration of particles. This is how heat transfers through solids. Metals are good conductors of heat, while non-metals are poorer conductors of heat. Good Conductors of Heat Copper Poor Conductors of Heat Wood Aluminium Brass Iron Polythene Paper Air Convection Heat is transferred through liquids and gases by convection. The particles do not vibrate, but move/flow upwards. They move from hot areas to cold areas. Room Heat Source Radiation Infrared or heat/thermal waves transfer heat energy. This process is called radiation. Black objects radiate heat well, but shiny objects are poor radiators of heat. The sun transmits heat to Earth through radiation. This proves that radiation does not need particles/substance/medium to transfer heat energy. 5