geothermal, solar, wind 1% hydropower 2% energy · 2016-03-15 · energy unit 5 renewable resources • renewable • solar • wind • hydroelectric • wood • geothermal •

energyunit 5

renewable resources• renewable

• solar• wind• hydroelectric• wood• geothermal

• non-renewable• fossil fuels

• oil, coal, natural gas• nuclear? (uranium)

nonrenewable87%

renewable13%

hydropower2%

geothermal, solar, wind1%

nuclear power6%

natural gas21%

coal26%

oil34%

biomass10%

Worldwide commercial energy mix, 2010

net energy• net energy yield

• each energy production process involves energy investment

• gross energy production - investment = net energy yield• more steps involved in

finding and using energy source, lower net energy yield

source net energy yield

reducing waste high

gasoline medium

natural gas medium

ethanol (sugarcane) medium

diesel medium

gasoline from heavy shale oil low

gasoline from tar sands oil low

ethanol (corn) low

biodiesel low

hydrogen negative

transportation energy sources

direct solar• solar cooking

• solar cookers and ovens• passive solar heating

• absorbs and stores heat during the day

• active solar heating• radiators

• solar thermal system• mirrors collect and focus sunlight • low net energy yield• Ivanpah (5 mi2)

• solar cells

hydro• hydroelectric power

• dams and reservoirs• tidal?

biomass• solid biomass

• wood, crop residues, animal waste• wood is most used renewable energy source

• biofuel• biodiesel• ethanol

geothermal• geothermal energy

• geothermal heat pump system• hydrothermal reservoirs

wind power• wind farms

• high net yield• turbines generate electricity• power lines carry electricity• clusters of windmills capture

favorable winds

wind power• trends in wind power

• lots of growth• 35% average 2007-2011

• calls for smart grid• could distribute energy

efficiently to eliminate regional effects of wind energy production

nuclear?• not renewable• low net energy yield

• high cost, efficiency loss in mining / processing

• inefficient power plants• waste?• safety issues?

portable energy• transportation

• hybrid cars• PHEV• HEV

• hydrogen• solar• biodiesel

hydrogen• hydrogen gas, H2

• can be produced by running electrical current through water -- electrolysis

• can be removed from methane (CH4)• negative net energy yield• no emissions other than water

what about oil• crude oil production

• peak production• proven oil reserves• heavy oil

• shale oil• tar sands

• low net energy yield• harmful environmental

impacts

improving efficiency• energy efficiency

• cheapest, fastest, safest way to reduce consumption• industry

• cogeneration• can double the efficiency of an power plant

• recycling• replacing lightbulbs

• transportation• increase efficiency standards• hybrids• less reliance on cars

• houses, buildings

discussion questions• what energy sources do you think people will be using 50

years into the future?• nuclear?

• what do you do that wastes energy? • are you willing to change?

• should we stop developing energy resources with low or negative net energy yield?• tar sands• hydrogen?

• what is the most promising / best energy source, all things considered?