Mechanical Energy StorageCreated by Nick Stroud

Three Types of StoragePumped hydroelectric storage (PHS)

Compressed air energy storage (CAES)

Flywheels

Pumped Hydroelectric Storage (PHS)Used for load balancing of energyWater is pumped up in elevation during time of low demand Water flows back down during times of high demandTurbines recapture the energy.

Pumped Hydroelectric Storage (PHS)70-85% of electrical energy is recoveredEnergy loss due to evaporation and Pump/generator inefficiency Currently the most cost effective way to store large amounts of electricity Low energy density calls for large bodies of waterNever used in portable technology1000 kg at 100 ft = .272 kWh

Pumps: On the GridThe Us has 19.5 gigawatts capacity2.5% of baseloadTechnology is in use world wideHundreds of plants around the worldMan made reservoirs as well as natural reservoirs

Future Of PHS This energy storage can be used to level the grid for renewable energyWind power and solar power are not constantly onUsing salt mines to increase energy density

Compressed air energy storage (CAES)Large tank is buried undergroundDuring times of low demand electricity compresses air During times of peak demand compressed air is heated and releasedhttp://www.sandia.gov/media/NewsRel/NR2001/norton.htm

Types Of CAES Adiabatic storageHeat from compression is captured and stored in a solid or liquidHot Oil 3000CMolten Salt 6000CHeat is reincorporated during releaseClose to 100% efficiencyNo utility scale plantsDiabatic storageHeat is lost through coolingNatural gas is burned to reheat compressed airVery inefficient 38-68%Uses 1/2 gas of an all gas plant

More about CAES Can use sandstone layer to hold compressed airUSA has good ground for this type of storageCan be used to level load from wind and solar200-300 MW Plants

Compressed air in CarsZero pollution Motors Stores air at around 300atmUnder 35 mph it is zero emissionsOver 35 mph uses combustion engine to compress airRuns on many different types of fuel1 air tank + 8 gal gas= 848 miles

Fueling/RefuelingFlex engine runs off of gas, diesel, alcohol, possibly even vegetable oil Refueling air tank at refuel station about 3 minutesHome refuel unit takes 4 hours, electrical cost $23 cents per mile

FlowAir After 35 mph only 1/2 the CO2 emissions of PriusTakes advantage of light engine and light frame to be efficientUses fiberglass frame filled with foamMay lose efficiency in cold weather

Future of Air VehiclesFlowair- release in 2010 First needs to pass US safety ratings6 seats106 mpg800-1000 mile rangeTop speed 96 mph$17500

FlywheelsCaptures energy in a rotating MassFlywheel is charged using electric motorElectric generator extracts energy

http://en.wikipedia.org/wiki/Image:G2_front2.jpg#filehistory

Operation Of FlywheelEnergy held in Spinning Rotor (Steel or Carbon composite)Steel rotors can spin at several thousand rpmCarbon composite spin up to 60k rpmKinetic Energy 1/2mv2http://www.aretepower.us/images/Composite%20Flywheel%20Rotor.jpg

BearingsMechanical bearings not practicalFriction is directly proportional to speedMagnetic bearings used to minimize frictionRotor is suspended- state of levitationOperates in a Vacuum

SuperconductorsNew technology uses high temperature superconductors (HTSC)HTSC operate at -1960C or -3210FDiamagnetism- creates a field of opposition to a magnetic field Hybrid systems use conventional magnets to levitate and superconductors to stabilize

Flywheels Vs. BatteriesNot effected by temperature changesNo Memory EffectMade more environmentally friendlyEasy energy content identification Shattering due to overloadSafety devices add lots of massGyroscope (duel FES systems)ProsCons

Energy Stats

Composite FlywheelLi-ion Battery

Cycles100,000 to 10 millionAround 1200Energy Density130 Wh/kg160 Wh/kgCapacityRange from 3 kWh to Max of 133 KWhEqual to 13,825 18650 Li-ionOver 4 times what is used to power the TeslaCharge Time15 minSeveral HoursSelf discharge time0 run down time- Years10-20 monthsEnergy ExchangeLimited by generatorLimited by chemical process

Flywheels have High volumetric density

Flywheel ProjectsGyrobuses- used in 1950s in Switzerland Buses run off of FlywheelsNever gained economic footholdLow fuel costs compared to electricity

Flywheel ProjectsFlywheels used in electric trains to carry over gaps and regenerative breaking Some car models tried (Rosen Motors)Formula 1 competition Used on systems that need Uninterrupted power supply. (maintenance 1/2 cost of battery)Testing of fuses

Sourceshttp://photo.proaktiva.eu/digest/2008_gyrobus.htmlhttp://eco-energy.info/asp/index.asp?uc=&k=3165http://www1.eere.energy.gov/femp/pdfs/fta_flywheel.pdfhttp://www.vyconenergy.com/pages/flywheeltech.htmhttp://www.isepa.com/about_isep.asphttp://finance.yahoo.com/family-home/article/106040/Air-Cars:-A-New-Wind-for-America's-Roadshttp://gas2.org/2008/07/15/an-air-car-you-could-see-in-2009-zpms-106-mpg-compressed-air-hybrid/ http://zeropollutionmotors.us/

Nick I like this topic very much. I think you could possibly choose all three, with a brief overview of each, comparison of advantages and disadvantages between them, and I think the most course-relevant part which a comparison with electrochemical storage (battery, capacitor, fuel cell). Go for it.