Mechanical Energy Storage Created by Nick Stroud Three

Mechanical Energy Storage Created by Nick Stroud

Three Types of Storage • Pumped hydroelectric storage (PHS) • Compressed air energy storage (CAES) • Flywheels

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

Pumped Hydroelectric Storage (PHS) • 70 -85% of electrical energy is recovered • Energy 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 water • Never used in portable technology • 1000 kg at 100 ft =. 272 k. Wh

Pumps: On the Grid • The Us has 19. 5 gigawatts capacity • 2. 5% of baseload • Technology is in use world wide • Hundreds of plants around the world • Man made reservoirs as well as natural reservoirs

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

Compressed air energy storage (CAES) • Large tank is buried underground • During times of low demand electricity compresses air • During times of peak demand compressed air is heated and released http: //www. sandia. gov/media/News. Rel/NR 2001/norton. htm

Types Of CAES • Adiabatic storage • Heat from compression is captured and stored in a solid or liquid • Hot Oil 3000 C • Molten Salt 6000 C • Heat is reincorporated during release • Close to 100% efficiency • No utility scale plants • Diabatic storage • Heat is lost through cooling • Natural gas is burned to reheat compressed air • Very inefficient 38 -68% • Uses 1/2 gas of an all gas plant

More about CAES • Can use sandstone layer to hold compressed air • USA has good ground for this type of storage • Can be used to level load from wind and solar • 200 -300 MW Plants

Compressed air in Cars • Zero pollution Motors • Stores air at around 300 atm • Under 35 mph it is zero emissions • Over 35 mph uses combustion engine to compress air • Runs on many different types of fuel • 1 air tank + 8 gal gas= 848 miles

Fueling/Refueling • Flex engine runs off of gas, diesel, alcohol, possibly even vegetable oil • Refueling air tank at refuel station about 3 minutes • Home refuel unit takes 4 hours, electrical cost $2 • 3 cents per mile

Flow. Air • After 35 mph only 1/2 the CO 2 emissions of Prius • Takes advantage of light engine and light frame to be efficient • Uses fiberglass frame filled with foam • May lose efficiency in cold weather

Future of Air Vehicles • Flowair- release in 2010 • First needs to pass US safety ratings • 6 seats • 106 mpg • 800 -1000 mile range • Top speed 96 mph • $17500

Flywheels • Captures energy in a rotating Mass • Flywheel is charged using electric motor • Electric generator extracts energy http: //en. wikipedia. org/wiki/Image: G 2_front 2. jpg#filehistory

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

Bearings • Mechanical bearings not practical • Friction is directly proportional to speed • Magnetic bearings used to minimize friction • Rotor is suspendedstate of levitation • Operates in a Vacuum

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

Flywheels Vs. Batteries Pros • Not effected by temperature changes • No Memory Effect • Made more environmentally friendly • Easy energy content identification Cons • Shattering due to overload • Safety devices add lots of mass • Gyroscope (duel FES systems)

Energy Stats Composite Flywheel Li-ion Battery Cycles 100, 000 to 10 million Around 1200 Energy Density 130 Wh/kg 160 Wh/kg Capacity Range from 3 k. Wh to Max of 133 KWh Equal to 13, 825 18650 Li-ion Over 4 times what is used to power the Tesla Charge Time 15 min Several Hours Self discharge time “ 0 run down time”- Years 10 -20 months Energy Exchange Limited by generator Limited by chemical process

• Flywheels have High volumetric density

Flywheel Projects • Gyrobuses- used in 1950 s in Switzerland • Buses run off of Flywheels • Never gained economic foothold • Low fuel costs compared to electricity

Flywheel Projects • Flywheels 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

Sources • • • http: //photo. proaktiva. eu/digest/2008_gyrobus. html http: //eco-energy. info/asp/index. asp? uc=&k=3165 http: //www 1. eere. energy. gov/femp/pdfs/fta_flywheel. pdf http: //www. vyconenergy. com/pages/flywheeltech. htm http: //www. isepa. com/about_isep. asp http: //finance. yahoo. com/family-home/article/106040/Air-Cars: A-New-Wind-for-America's-Roads • http: //gas 2. org/2008/07/15/an-air-car-you-could-see-in-2009 zpms-106 -mpg-compressed-air-hybrid/ • http: //zeropollutionmotors. us/