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BUILDING A SMARTER AND MORE ENERGY-EFFICIENT ELECTRICAL GRID• Current electrical grid system–outdated and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