Solar Energy: Solar/Electric Cars

Good List of Internet Resources on Electric Cars

Currently there is a big Marketing Problem with Electric Vehicles. Consumers simply won't buy them. Here are some attempted marketing strategies:

• Reduced range of electric cars is irrelevant since most people drive less than 40 miles per day. --> This is true and electric cars are certainly practical for "getting around town".

• Fossil fuel use in internal combustion engines is the single largest environmental problem on the planet. --> This is debatable but certainly there are direct health hazards as well as global warming

• Conversion of gas powered cars to electric cars is a good form of consumer recycling --> true but we don't have noble consumers and conversion costs at least $9,000

• Electric cars are more efficient per dollar and yield better air quality --> this is mostly true; decreased fuel costs for EVs make them more cost-effective in the long run

• An electric car bought today, will only get better over time. WIthin the next 3 years, batteries will be available which will double and triple your per-charge-range. --> one can hope this is the case!

  Basic Idea:

  Array of solar collectors on the car's surface delivers electricity to batteries which then power the car and can be recharged.
  • Tradeoff between Range and Power
  • Battery storage technology is the key

  Example

  A practical motor vehicle needs about 30 KWH of deliverable energy for a range of 100 miles.

  For reasonable performance about 20 hp must be delivered to the drive train.

  Efficiency of energy delivery from batteries to drive train is about 40%

  • Delivered energy = 40% of stored energy
  • So you need 30 KWH/0.4 = 75 KWH of stored energy
  • Energy storage density of lead-acid batteries is .04 KWH per kilograms
  • So you need 75/.04 = 1875 = 4125 pounds of lead-acid batteries

  • Power: 20 hp/0.4 = 37.3 KW
  • Power density of lead-acid batteris is .07 W/kg
  • So you need 37.3/.07 = 533 = 1172 pounds

  So the range requirements are more severe than the power requirements.

  Improvements in battery Technology are definitely required.

  Other types of batteries:

  Material	Energy Density (W-hrs/kg)	Power Density (W/kg)	Comments
  Lead Acid	40	70	Long Cycle Life
  Nickel Iron	55	100	Very Long Cycle Life
  Sodium Sulfur	90	100	300-350 C operating temp
  Lithium-Iron sulfide	100	> 100	400-450 C
  Nickel-Zinc	75	120	low cycle life

  Driving Habits and Requirements

  • Long distances - Interstate --> 75 mph and 400 miles range
  • Daily Commute --> 55 mph and 35 miles range
  • Puttering around town --> 35 mph and 20 miles range

  It is very unlikely that electric cars will ever have prodution line performance that satisfies the Interstate requirement.

  Most practical application is for in town commutting/shopping and this would then eliminate a major source of air pollution

  The Key of course is marketing --> people have to buy the product

  • Performance --> people need to change their driving habits
  • Range --> not a problem for in town use. City ordinance to make city limits and internal combustion free zone would clearly help
  • Price --> Probably needs to come down to 10K before people would seriously consider this "glorified golf cart"
  • Safety --> Lightweight materials --> carbon fiber. High tensile strength but not a Farady Cage (thunderstorm problem!). Also braking is a concern.

  California Mandate:

  • 1998: 2% of all vehicles offered for sale must be zero emission vehicles (meaning electric cars)
  • 2003: 10% must be zero emission
  • As of Fall 1995 the Mandate has been rolled back (see also this release )

    Some Prototypes:

  • Ford Ecostar two-passenger electric mini-van used by Post-Office and UPS --> sodium-sulfur batteries
  • Chrysler TEVan --> nickel-iron batteries
  • $500,000 given to Yosemite to replace diesel buses with electric buses
  • $500,000 given to General Motors to loan 50 vehicles to 1000 people nationwide for test drive results

  EV Fact Sheet

  Batteries and Fuel Cells for EVs

  Advanced Battery Technology

  Components of Government Program

  Next Page

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  The Electronic Universe Project
  e-mail: nuts@moo.uoregon.edu