Energy II: Renewable Energy THE GOOD NEWS

Energy Resources Renewable (Alternative) Energy: Nonrenewable Energy: Alternative energy sources that are more or less continuously made available in a time framework useful to humans Nonrenewable Energy: Energy sources that are dependent upon fuels or a resource that that may be used up much faster than it is replaced by natural processes

Current Sources of Energy

Current Costs of Energy

Types of Renewable Energy Solar Water Wind Biomass burning conversion to liquid fuels Geothermal Solar-Hydrogen

Solar Energy Used to Heat houses and buildings Heat water Create high temperature heat Create electricity

Passive Solar Building Heating Architectural Design exposure direction, windows, building materials, eaves Requires no energy to use

Active Solar Building Heating Uses mechanical power and pumps to circulate air A heat absorbing fluid is heated in the sun and then transported into the structure

Water Heating Flat-plate collectors - flat box with glass on top, black on the bottom, water tubes in middle hot water coming out of tubes is placed in top of tank cooler water from bottom of tank is returned to collector

High Temperature Heating Solar towers many solar panels are used to focus solar energy for immediate, or later use Solar cookers metal lined box and mirrors focus solar energy to cook food

Solar electricity Photovoltaic cells or solar cells When photons from sunlight hit a thin wafer of metal, a small electric current is produced many cells must be linked together to produce usable energy are mostly used in remote areas, calculators, watches

Locations in U.S. with good solar potential

Water Power Methods of creating electricity dams tides waves solar ponds OTEC

Hydroelectric Power: Dams High dam is built across a river to make a reservoir water is allowed through dam, past turbines spinning turbines produce electricity 20% of world’s energy

Problems with hydroelectric power Damming floods areas above dam, ruining biologically, agriculturally or culturally important areas migration of fish is disrupted (ex. salmon) change of cold water stream to warm water lake - increases humidity and temps (new pests?) Downstream areas are affected because of lack of floods, unpredictable water levels, cold water from bottom of dam

Tides In places in the world where there are extreme tides, electricity can be generated from tides Water can be held back, and let through turbines like in dams If turbines work in both directions, energy can be generated 2 times a day

Waves In some locations in the world, waves are consistent and strong In these places, electricity can be generated from waves probably not going to be a major source of global electricity

Solar Ponds In inland saline seas, heat accumulates in the saltier bottom layer. As it heats up, this layer is pumped out and used for heating or electricity. In fresh water ponds, holes are dug and lined with black. The water heats up, but the heat is prevented from escaping Both of these are cheap and do not pollute. They don’t require expensive storage. Some energy.

OTEC: Ocean thermal energy conversion In tropical waters there is a large difference between the surface and bottom temperature The heat at the surface is used to vaporize a low boiling point liquid The pressure is used to run turbogenerators Liquid is condensed using bottom water Not very useful

Wind Power Wind power is created by wind turbines Wind Farms - location of high wind where many turbines are concentrated (ex. Palm Springs) Problem : requires expensive storage during non-windy periods, hurt birds

Biomass - burning Burning of organic material examples: wood, reeds, animal dung, etc. Potentially renewable resource - but biomass must not be removed faster than it can be replaced used primarily in developing countries trash can also be burned can be quite efficient when harvested locally burning dung takes nutrients from fields

Biomass - burning

Biomass- conversion to liquid biofuels Methane Animal dung can be digested by bacteria and converted to methane Burning methane provides more energy than burning dung Currently practiced on a small scale/has potential Ethanol and methanol excess grain stocks can be fermented by bacteria to produce these fuels which can then be burned as fuel Burning both of these fuels still produces CO2

Geothermal Energy In some places on the Earth’s surface, the hot magma beneath the surface produces hot springs and geysers At these locations, hot pressurized steam can be brought to the surface to turn turbines The steam is then condensed and returned to the earth

Solar-Hydrogen Energy- Theory Hydrogen gas can be used for energy in two ways: burned directly - since no carbon, it burns cleanly, producing water combined with oxygen gas to produce water (fuel cells)

Solar-Hydrogen Energy Problem: Hydrogen gas is very rare in the environment H2 gas is costly to make through chemical reactions Solution H2 and O2 can be produced easily by running a current through water - electrolysis Solar cells can be used to create electricity to fuel electrolysis H2 gas

The Negawatt Revolution In the past, electrical companies have increased their profits by increasing demand, and building more plants Now it is cheaper for them to encourage users to lower their own energy needs to reduce the need for expensive plants So energy companies now give incentives to people who employ energy saving strategies

Energy Deregulation California is currently in the process of energy deregulation Impacts on rates Impact of energy sources used Will it work?

All you wanted to know about these energy sources and their benefits and drawbacks Miller p456-457