Lecture12EnergyEfficiencyRenewableEnergyResources.pdf

    E N E R G Y E F F I C I E N C Y & R E N E W A B L E E N E R G Y

    R E S O U R C E SL E C T U R E 1 2

    W H Y D O W E N E E D A N E W E N E R G Y T R A N S I T I O N ?

    • World is in early stages of a transition– Move from fossil fuels to energy

    efficiency and renewable energy

    • Cost of generating energy with solar energy fell by 82% between 2009 and 2015

    – Wind costs fell 61%

    • Costa Rica gets more than 90% of its energy from renewable resources

    W H Y I S I M P R O V I N G E N E R G Y E F F I C I E N C Y A N D R E D U C I N G E N E R G Y W A S T E A N I M P O R TA N T E N E R G Y R E S O U R C E ?

    • Improvements in energy efficiency and reductions in energy waste

    – Could save at least one-third of the energy used in the world

    • Up to 43% of energy used in the United States

    • Many technologies exist for increasing energy efficiency of industry, vehicles, appliances, and buildings

    W E WA S T E A LO T O F E N E R G Y A N D M O N E Y

    • Energy efficiency – How much useful work we get from

    each unit energy

    • Energy conservation– Reducing or eliminating unnecessary

    energy waste

    W E WA S T E A LO T O F E N E R G Y A N D M O N E Y

    • Some sources of waste

    – Poorly insulated buildings

    – Reliance on cars for getting around

    – Huge data centers filled with electronic servers

    • Use only 10% of energy they consume

    – Motor vehicles with internal combustion engines (25% efficiency)

    – Nuclear, coal, and natural gas power plants (1/3rd

    electricity)

    I M P R O V I N G E N E R G Y E F F I C I E N C Y I N I N D U S T R I E S A N D U T I L I T I E S

    • Cogeneration– Combined heat and power

    – Two forms of energy from same fuel source

    • Replace energy-wasting electric motors (consume 60% of electricity used)

    • Recycle materials (75% less high quality energy; 40% less CO2)

    • Use energy-efficient LED lighting• Smart meter to monitor energy use• Shut down unused computers and lights

    BUILDING A SMARTER AND MORE ENERGY-EFFICIENT ELECTRICAL GRID• Current electrical grid system–outdated and

    wasteful

    • Smart grid– Ultra-high-voltage

    – Super-efficient transmission lines

    – Digitally controlled

    – Responds to local changes in demand and supply

    – Easier to buy renewable energy

    M A K I N G T R A N S P O R TAT I O N M O R E E N E R G Y – E F F I C I E N T

    • Hidden costs in gasoline

    – Government subsidies and tax breaks for oil companies

    – All hidden costs add up to $12 per gallon

    • Build or expand mass transit and high speed rail

    • Carry more freight by rail instead of trucks

    • Encourage biking by building bike lanes

    S W I T C H I N G T O E N E R G Y -E F F I C I E N T V E H I C L E S

    • Gasoline-electric hybrid car• Plug-in hybrid electric vehicle• Electric vehicle with a hydrogen fuel

    cell

    • Car bodies made of light, composite materials

    D E S I G N I N G B U I L D I N G S T H AT S AV E E N E R G Y A N D M O N E Y

    • Green architecture• Living or green roofs

    – Specially formulated soil and vegetation

    • Superinsulation– No need for heating system

    • U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED)

    – Standards

    WHY ARE WE WASTING SO MUCH ENERGY AND MONEY?• Energy remains artificially cheap

    – Government subsidies

    – Tax breaks

    – Prices don’t include true cost

    • Few large and long-lasting incentives for improving energy efficiency and reducing waste

    • Rebound effect (using more energy when they buy energy efficient devices)

    R E LY I N G M O R E O N R E N E WA B L E E N E R G Y

    • Reasons renewable energy use is not more prevalent

    – Inaccurate perceptions that solar and wind energy are unreliable and intermittent

    – Government subsidies and tax breaks lower for renewable energy than for fossil fuels

    – Prices for nonrenewable energy do not include harmful environmental impacts

    – Energy shift takes many decades

    H E AT I N G B U I L D I N G S A N D W AT E R W I T H S O L A R E N E R G Y

    • Passive solar heating system– Absorbs and stores heat from the

    sun directly within a well-insulated structure

    • Active solar heating system – Captures energy from the sun in a

    heat-absorbing fluid

    C O O L I N G B U I L D I N G S N AT U R A L LY

    • Methods to keep a building cool– Open windows when cooler outside

    – Use fans

    – Superinsulation and high-efficiency windows

    – Shade trees, overhangs, or window awnings

    – Light-colored roof

    – Geothermal heat pumps bring cool air from underground

    C O N C E N T R AT I N G S U N L I G H T T O P R O D U C E H I G H – T E M P E R AT U R E H E AT A N D E L E C T R I C I T Y• Solar thermal systems

    – Collect sunlight to boil water and produce steam to generate electricity

    – Used in deserts and open areas with ample sunlight

    – Require large volumes of cooling water for condensing steam and cleaning mirrors

    • Low net energy yields

    SOL AR COOKERS

    • Solar cookers can replace wood and charcoal fires

    USING SOL AR CELLS TO PRODUCE ELECTRICIT Y• Photovoltaic (PV) cells

    – Convert solar energy to electric energy

    • Design of solar cells– Sunlight hits cells and produces flow of electrons

    – Systems can be connected to existing electrical grids or to batteries

    USING SOL AR CELLS TO PRODUCE ELECTRICIT Y

    • Solar cells made of paper-thin, rigid, or flexible sheets

    – Enabled by nanotechnology and other emerging technologies

    • Rural use of solar– Rooftop solar panels power LED lamps

    – Solar powered microgrids

    U S I N G W I N D T O P R O D U C E E L E C T R I C I T Y

    • Tall, long-blade turbines can extract more energy from the wind

    • Rapidly growing power source– The United States, China, and Germany

    • Future is offshore wind farms• Wind power has potential to produce 40

    times the world’s current electricity used

    U S I N G W I N D T O P R O D U C E E L E C T R I C I T Y

    • Wind is abundant, widely distributed, and inexhaustible

    – Mostly carbon-free and pollution-free

    • High net energy yield• Largest potential areas are usually rural

    – Smart grid needed to connect

    • Backup power source may be needed– Alternative: large number of wind farms in

    different areas connected to smart grid

    TA P P I N G I N T O T H E E A R T H ’ S I N T E R N A L H E AT

    • Geothermal energy– Heat stored in soil, underground rocks, and

    fluids in the earth’s mantle

    • Geothermal heat pump system– Uses temperature difference between the

    earth’s surface and underground

    – Fluid carried through a closed loop

    – Can heat a building in winter and cool it in summer

    TA P P I N G I N T O T H E E A R T H ’ S I N T E R N A L H E AT

    • Hydrothermal reservoirs – Drill wells and extract dry steam, wet

    steam, or hot water

    – The United States is the world’s largest producer

    – Drilling geothermal wells is expensive

    • 2015: 134 new geothermal power plants under construction or development in the United States

    P R O D U C I N G E N E R G Y B Y B U R N I N G S O L I D B I O M A S S

    • Biomass– Plant materials and agricultural waste

    that can be burned for fuel

    • Biomass plantations– Fast growing trees and shrubs for

    repeated harvest

    – Wood pellet production degrades forests

    • Burning wood and other forms of biomass produces CO2 and pollutants

    USING LIQUID BIOFUELS TO POWER VEHICLES• Ethanol

    – Ethyl alcohol produced from plants

    • Biodiesel– Produced from vegetable oils

    • Advantages– Crops can be grown throughout the world

    – No net increase in CO2 emissions under certain circumstances

    – Easy to store and transport

    U S I N G L I Q U I D B I O F U E L S T O P O W E R V E H I C L E S

    • Brazil makes ethanol from sugarcane residue– Medium net energy

    • 2014: 43% of the corn produced in the United States was used to make ethanol

    – Corn-based ethanol has a low net energy

    – Producing and burning corn-based ethanol adds 20% more greenhouse gases than burning gasoline

    U S I N G L I Q U I D B I O F U E L S T O P O W E R V E H I C L E S

    • Growing corn requires much water• Ethanol distilleries produce large

    volumes of wastewater

    • Cellulosic ethanol– Alternative made of inedible cellulose

    – Can be made from grasses that do not require fertilizer or replanting (perennials)

    • Algae can produce biofuel

    P R O D U C I N G E L E C T R I C I T Y F R O M FA L L I N G A N D F L O W I N G W AT E R

    • Hydropower– Uses kinetic energy of moving water

    – Indirect form of solar energy

    – World’s leading renewable energy source

    • Top three producers– China, Canada, and Brazil

    • Hydropower supplies half the electricity used on the West Coast

    U S I N G T I D E S A N D W AV E S T O P R O D U C E E L E C T R I C I T Y

    • Produce electricity from flowing water– Coastal bays and estuaries

    • Tidal energy dams– France, Nova Scotia, and South Korea

    • Challenges– Few suitable sites

    – High costs

    – Equipment damage from storms and saltwater corrosion

    WILL HYDROGEN SAVE US?• Advantages of hydrogen as a fuel

    – Eliminates most outdoor air pollution from burning fossil fuels

    – Would greatly slow climate change and ocean acidification

    WILL HYDROGEN SAVE US?• Some challenges

    – Hydrogen chemically locked in water and organic compounds

    – Negative net energy

    • Serious limitation

    – Fuel cells are costly

    – CO2 emissions depend on method of hydrogen production

    SHIFTING TO A NEW ENERGY ECONOMY

    • China and the United States– Key players in making the shift to a new set of

    energy resources

    – Each country uses about 20% of the world’s energy

    • Important actions to enable energy shift– Use full-cost pricing

    – Tax carbon emissions

    SHIFTING TO A NEW ENERGY ECONOMY• Important actions (cont’d.)

    – Decrease and eliminate government subsidies for fossil fuel industries

    – Establish a national feed-in-tariff system

    – Mandate that a certain percentage of electricity generated by utility companies be from renewable resources

    – Increase government fuel efficiency standards

    • Energy Efficiency & Renewable Energy Resources
    • Why Do We Need a New Energy Transition?
    • Why Is Improving Energy Efficiency and Reducing Energy Waste an Important Energy Resource?
    • We Waste a Lot of Energy and Money
    • We Waste a Lot of Energy and Money
    • Improving Energy Efficiency in Industries and Utilities
    • Building a Smarter and More Energy-Efficient Electrical Grid
    • Making Transportation More Energy-Efficient
    • Switching to Energy-Efficient Vehicles
    • Designing Buildings That Save Energy and Money
    • Why Are We Wasting So Much Energy and Money?
    • Relying More on Renewable Energy
    • Heating Buildings and Water with Solar Energy
    • Cooling Buildings Naturally
    • Concentrating Sunlight to Produce High-Temperature Heat and Electricity
    • Solar Cookers
    • Using Solar Cells to Produce Electricity
    • Using Solar Cells to Produce Electricity
    • Using Wind to Produce Electricity
    • Using Wind to Produce Electricity
    • Tapping into the Earth’s Internal Heat
    • Tapping into the Earth’s Internal Heat
    • Producing Energy by Burning Solid Biomass
    • Using Liquid Biofuels to Power Vehicles
    • Using Liquid Biofuels to Power Vehicles
    • Using Liquid Biofuels to Power Vehicles
    • Producing Electricity from Falling and Flowing Water
    • Using Tides and Waves to Produce Electricity
    • Will Hydrogen Save Us?
    • Will Hydrogen Save Us?
    • Shifting to a New Energy Economy
    • Shifting to a New Energy Economy

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