Energy Efficiency and Renewable Energy Chapter 16 16

Energy Efficiency and Renewable Energy Chapter 16

16 -1 Why Is Energy Efficiency an Important Energy Resource? § Concept 16 -1 We could save as much as 43% of all the energy we use by improving energy efficiency.

We Waste Huge Amounts of Energy § Energy conservation • A decrease in energy use as a result of a decrease in the amount of wasted energy – “Use less” § Energy efficiency • The measure of work we can get out of a unit of energy we use – “Use it better” § Four widely used devices waste large amounts of energy: • Incandescent light bulb: 95% lost as heat • Internal combustion engine: 94% of the energy from fuel wasted • Nuclear power plant: 92% of energy is wasted through nuclear fuel and energy needed for waste management • Coal-burning power plant: 75 -80% of the energy released by burning coal is lost

Flow of Commercial Energy through the U. S. Economy § 84% of all commercial energy used in the U. S. is wasted. § 41% wasted due to the 2 nd law of thermodynamics. § Only 9% of the total energy put into the U. S. economy results in useful energy.

Advantages of Reducing Unnecessary Energy Waste

16 -2 How Can We Cut Energy Waste? § Concept 16 -2 We have a variety of technologies for sharply increasing the energy efficiency of industrial operations, motor vehicles, and buildings.

We Can Save Energy and Money in Industry § Industry accounts for 38% of U. S. energy consumption. It can save energy and money by: • Produce both heat and electricity from one energy source (cogeneration or combined heat and power, CHP) • Use more energy-efficient electric motors • Recycle materials • Switch from low-efficiency incandescent lighting to higherefficiency compact fluorescent (CFL) and LED lighting • Update the old/wasteful electrical grid system (how electricity is transmitted from the power plant to the consumer) • Utility companies promote use of energy • Instead, should promote conservation

We Can Save Energy and Money in Transportation § Transportation accounts for 2/3 of U. S. oil demand is a major source of air pollution. § We can save energy in transportation by increasing fuel efficiency and making vehicles from lighter and stronger materials. § Corporate Average Fuel Economy (CAFE) standards • The average fuel economy, in miles per gallon (mpg), of a manufacturer’s fleet of passenger cars and/or light trucks § Fuel-efficient cars are on the market § Tax breaks for buying fuel-efficient cars

Average Fuel Economy of New Vehicles Sold in the U. S. and Other Countries § CAFE standards did not increased from 1985 to 2009. § In 2009, the Obama administration increased the standards to 35. 5 MPG by 2016. § In 2012, the Obama administration increased the standards again to 54. 5 by 2025. • This represents the doubling of the original CAFE standards

More Energy-Efficient Vehicles Are on the Way § Hybrid vehicles have two types of engines working together to achieve higher gas mileage (15 -70% more) and lower engine exhaust emissions: • A standard gas powered engine • An electric motor assist powered by a rechargeable nickel-metal hydride (Ni. MH) battery pack § Gasoline-electric hybrid car • Mostly gas…some electric § Plug-in hybrid electric vehicle • Mostly electric…some gas § Electric vehicle (EV’s) • ALL electric

Solutions: A Hybrid-Gasoline-Electric Engine Car and a Plug-in Hybrid Car

More Energy-Efficient Vehicles Are on the Way § Hybrid cars accounted for 3. 5% cars on the road in 2012. • Up from than 1% in 2007 § Typically cost $3 -4, 000 more than non-hybrid models. § Plug-in hybrids can get twice the mileage of gasolineelectric hybrid cars, but… • How is the electricity generated? • Electricity from coal or nuclear power plants = JUST AS BAD • Electricity produced by wind or solar energy = GOOD § Analysts estimate that hybrid cars could make up as much as 20% of the car market by the year 2020. • The boost in sales will be pushed by consumer demands and possible government regulations on CO 2 emissions.

Science Focus: The Search for Better Batteries § Current obstacles to hybrid or electric vehicles: • Storage capacity of battery • Currently about 100 mile range • Charging time • 8 hours for a Nissan Leaf (available NOW) • 3 hours for a Ford Focus EV (available in 2013) • Use of rare earth metals for battery construction

We Can Design Buildings That Save Energy and Money § Green architecture • Makes use of passive solar heating, natural lighting, natural ventilation, rain water collection, cogeneration of heat/electricity, geothermal heat pumps, and recycled building materials § Living or green roofs § Superinsulation § U. S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) Graded on 100 possible points: Certified - 40 - 49 points Silver - 50 - 59 points Gold - 60 - 79 points Platinum - 80 points up

We Can Save Energy and Money in Existing Buildings § § § § Insulate and plug leaks Use energy-efficient windows Stop other heating and cooling losses Heat houses more efficiently Heat water more efficiently Use energy-efficient appliances Use energy-efficient lighting § About 1/3 of the heated air in typical U. S. homes and buildings escapes through closed windows, holes, and cracks.

Individuals Matter: Ways in Which You Can Save Money Where You Live

Why Are We Still Wasting So Much Energy? § Low-priced fossil fuels and few government tax breaks or other financial incentives for saving energy promote energy waste.

We Can Use Renewable Energy in Place of Nonrenewable Energy Sources § A variety of renewable-energy resources are available but their use has been hindered by a lack of government support (subsides) compared to nonrenewable fossil fuels and nuclear power. • • Direct solar Moving water Wind Geothermal

16 -3 What Are the Advantages and Disadvantages of Solar Energy? § Concept 16 -3 Passive and active solar heating systems can heat water and buildings effectively, and the costs of using direct sunlight to produce high-temperature heat and electricity are coming down.

Solar Power

We Can Heat Buildings and Water with Solar Energy § Passive solar heating system • Absorbs/stores heat from the sun within a structure without the need for pumps to distribute the heat. • Lots of windows on the south side of house

We Can Heat Buildings and Water with Solar Energy § Active solar heating system • Pumping a liquid such as water or an oil through rooftop collectors • Can also be used to provide hot water

Trade-Offs: Passive or Active Solar Heating

We Can Use Sunlight to Produce High. Temperature Heat and Electricity § Solar thermal systems • Sunlight is directed towards a central tower where and oil absorbs the heat and is used to create high temperature steam to turn a turbine. § Large arrays of solar collectors in sunny deserts § Costs are high and energy yield is low.

Solutions: Woman in India Uses a Solar Cooker § Solution to the “fuel wood crisis”?

We Can Use Solar Cells to Produce Electricity § Photovoltaic (PV) cells (solar cells) • Convert solar energy to electric energy • Can be made in all shapes and sizes and can be included in the building design and construction.

We Can Use Solar Cells to Produce Electricity § Solar cells can be used in rural villages with ample sunlight who are not connected to an electrical grid. • Mostly for pumping water

We Can Use Solar Cells to Produce Electricity Gigawatts of solar generation § Solar cells currently account for less than 1% of the world’s electricity § Solar power has the largest POTENTIAL for supplying electrical power to the world. Projected growth of solar generation

Trade-Offs: Solar Cells, Advantages and Disadvantages § Photovoltaic cells costs are high but are quickly falling as a result of mass production, new designs, and nanotechnology.

16 -4 Advantages and Disadvantages of Producing Electricity from the Water Cycle § Concept 16 -4 Water flowing over dams, tidal flows, and ocean waves can be used to generate electricity, but environmental concerns and limited availability of suitable sites may limit the use of these energy resources.

Hydropower

We Can Produce Electricity from Falling and Flowing Water § Hydropower • Build a high dam across a large river • Water builds up into a reservoir • Let water flow through large pipes and turn turbines to produce electricity § World’s leading renewable energy source used to produce electricity • 16% of the world’s electricity • 99% in Norway, only 7% in the U. S.

We Can Produce Electricity from Falling and Flowing Water

Trade-Offs: Large-Scale Hydropower, Advantages and Disadvantages

Tides and Waves Can Be Used to Produce Electricity § Ocean tides and waves and temperature differences between surface and bottom waters in tropical waters are not expected to provide much of the world’s electrical needs. • Few suitable sites • High costs • Equipment corrosion § Only two large tidal energy dams are currently operating: one in La Rance, France and Nova Scotia’s Bay of Fundy (where the tidal difference can be as high as 63 feet).