The light of the Future – Renewable Energy Resources Chapter 18

Solar Energy Heating Systems Heating houses with solar energy can occur in two ways – passive and active. A passive solar heating system absorbs and stores heat from the sun directly within a structure An active solar heating system absorbs energy from the sun by pumping a heat-absorbing fluid through a special collector mounted on a roof facing the sun

Benefits of Passive Solar heating It is not something new – for generations people have been using materials to build their houses to absorb heat from the sun. By building new houses to face the sun and using energy efficient windows people are thinking about sustainability. In a life cycle, super-insulated houses may add 5-10% to your housing costs but reduce your cost of operation by 30-40%!!!

Benefits of Active Solar Heating Absorbs the heat in a fluid on a panel that has a black surface (usually) and then has a coil that winds through containing the fluid. The heat is collected and can be used immediately or is stored for later use in containers found under a house. They can also provide hot water for a home.

Advantages to both Energy is FREE!!!!!!!! NO BETTER KIND Net energy is moderate (active) to high (passive) No CO2 emissions Very low air and water pollution Very low land disturbances Moderate costs

Disadvantages For both you need to have access to the sun for 60% of the day Trees and design of old houses does not allow for modern technology to be added. You need a heat storage system (if building an active heating system) Active heating systems need maintenance and repair They can be unattractive (big deal!)

Solar Cells Solar energy can be converted to electrical energy by photovoltaic (PV) cells also known as solar cells. Solar cells typically consist of a semiconductor material that is energized by sunlight and creates a flow of electrons generating electricity. These cells have no moving parts Require very little maintenance Produce no pollution And last as long as conventional fossil fuel or nuclear power plants! http://www.youtube.com/watch?v=AmWrGPKcMNM

Advantages of Solar Cells You have a fairly high net energy Work on cloudy days Quick installation Easily expand by adding more or can be easily moved No CO2 emissions Low environmental impact Last for 20-40 years Low land use (if built on a roof) Reduces dependence on fossil fuels

Disadvantages of Solar Cells Needs access to sun Low efficiency Need electricity storage for backup High land use (when a power plant) which can disrupt a desert area High costs (but may be competitive in 5-15 years) DC current must be converted to AC

Producing Electricity from the Water Cycle Water that flows from high elevations to low elevations in rivers and streams can be controlled by dams and reservoirs and used to produce electricity. This indirect form of renewable solar energy is called hydropower. http://www.youtube.com/watch?v=cEL7yc8R42k

Three methods to produce electricity Large scale hydropower: A high dam is built across a large river to create a reservoir. The water flows through and spins turbines to produce electricity Small scale hydropower: A low dam with no reservoir is built on a small stream and the water currents spin the turbine and produce electricity without disrupting the movement of fish. Pumped-storage hydropower: Uses surplus of water from a lake and pumps to another lake or reservoir at a higher elevation As it flows back down it spins turbines and generates electricity.

Advantages of Large-Scale Hydropower Moderate to high net energy High efficiency Large untapped potential Low-cost electricity Long life span No CO2 emissions May provide flood control below a dam Provides water year round for irrigation of cropland Reservoir is useful for fishing and recreation

Disadvantages of large-scale Hydropower High construction costs High environmental impacts from flooding land to form a reservoir High CO2 emissions from biomass decay in shallow waters Floods natural areas behind dams Converts land habitat to lake habitat Uproots people Decreases fish harvest below the dam Decreases flow of natural fertilizer (silt) to land below dam.

Producing electricity from Wind This indirect form of solar energy can be captured by wind turbines and converted into electricity. It is a resource that still remains untapped by most of the world. http://www.youtube.com/watch?v=tsZITSeQFR0

Advantages of wind power Moderate to high net energy High efficiency Moderate capital cost Low electricity cost (and still falling) Very low environmental impact No CO2 emissions Quick construction Easily expanded Can be located at sea Land below turbines can be used to grow crops or graze livestock

Disadvantages of wind power Steady wind needed Backup energy source when wind is low High land use for wind farm Visual pollution Noise when located near populated areas May interfere in flights of migratory bird and kill birds of prey

Producing energy from Biomass Biomass consists of plant materials and animals wastes that can be burned directly as solid fuel or converted into gaseous or liquid biofuels. Most biomass is burned directly to spin turbines to generate electricity. The burning of wood and manure actually provides about 10% of the world’s energy and about 30% of the energy is used in developing countries.

Biomass plantations One way to produce biomass is to plant, harvest, and burn large numbers of fast growing trees. Crop residues and animal manure can be collected and burned to produce heat for cooking in many poorer nations. Some ecologists believe it is better to leave the animal manure as a fertilizer and the crop residue to feedstock or prevent soil erosion. Not doing so may reduce the production of food supplies in that given area.

Plantation – (also a wind farm!)

Worksheet!

Geothermal Energy Systems http://www.youtube.com/watch?v=uVDBRQvBVs o&feature=related

How Geothermal Works Geothermal heat pumps use a pipe and duct system to make use of heat stored in underground rocks and fluids. The Earth is used as a heat source in winter and a heat sink in summer.

Geothermal Exchange Geothermal exchange, or geoexchange, uses buried pipes filled with fluid to move heat in or out of the ground for heating or cooling needs. Wells can be used to withdraw wet and dry steam, as well as hot water, for heat, or to produce electricity. Many energy experts say that geothermal exchange is the most-energy-efficient, cost- effective, and environmentally clean way to heat or cool a building.

Geothermal in Canada There are many sources of hot water here. The amount of geothermal energy available is much greater than that stored in Alberta’s oil and gas reserves.

Major Issues There are two problems with goethermal energy. It is too expensive to tap, except for the most concentrated and accessible sources. It may be depleted if heat is removed faster than it is renewed.

A Sustainable Energy Strategy A combination of subsidies, tax breaks, and taxes can be used by government to promote or discourage the use of various energy alternatives. To encourage the shift to sustainable energy use, economic and political strategies can be employed. Keep energy prices artificially low to encourage use of selected energy resources. Our current system actually encourages energy waste. Keep energy prices artificially high to discourage use of a resource. Increase taxes on fossil fuels to reduce air and water pollution, slow greenhouse gas emissions, and encourage improvements in energy efficiency with greater use of renewable energy resources.

Continued… To develop a more sustainable energy future, we must increase energy efficiency, use more renewable energy, and reduce adverse environmental effects from the use of fossil fuels and nuclear energy. The U.S. is described as a first world nation with a third world electrical grid system. Implementing policies described in Figure 18-38 over the next several decades would save money, create a net gain in jobs, reduce greenhouse emissions, and sharply reduce air and water pollution. They might also increase national security by: reducing the dependence on imported oil, and decreasing dependence on large, centralized coal and nuclear power plants.

Various Ways to Transition to Sustainable Energy

The Sustainable Star http://www.youtube.com/watch?v=_ikDjh8tDx8

Assessment 1.What is the major energy source for heating your living space?  2. What is the major energy source for providing electricity to your living space? 3. How do you feel toward different energy sources? 4. What would be the best alternative energy source in your area? 5. Do you feel a responsibility to use energy wisely? What steps are you willing to take to reduce your energy consumption? 6. How do you feel toward decentralization of the power grid? 7. Do you favour policies that encourage energy conservation and more development of renewable and perpetual energy sources?