Electric Cars

Electric cars were developed before the internal combustion engine. In later years there was ruthless competition.

  • 1859 French physicist Gaston Plantéthe invented the lead-acid battery.
  • 1884 First practical car built by Thomas Parker in UK
  • 1888 German Flocken Elektrowagen.
  • 1897 Electric taxi fleets in London and New York

In 1900 in US the traffic was nearly all horse drawn and there were very few cars.

  • 38% of the cars were electric,  some had a range of 70 miles
  • 40% were  steam,
  • 22% by petrol /  gasoline.
  • Most cities had electric tramway systems

In the 1930s, National City Lines, which was a partnership of General Motors, Firestone, and Standard Oil of California purchased many electric tram networks across USA to dismantle them and replace them with GM buses. The partnership was convicted of conspiring to monopolize the sale of equipment and supplies to their subsidiary companies.

Electric car, built by Thomas Parker in UK 1884

EV

EV, or electric vehicle, should include rail, air, water, space, or land, but has become shorthand for electric road vehicles.

They are powered by an electric motor with the electricity coming from any source.

  • Battery, capacitor
  • fuel cell - Hydrogen, ammonia, methane, ethanol, etc
  • generator - powered by diesel, gas turbine, nuclear, flywheel, compressed air, etc.
  • PV - solar car
  • mains - trolley bus, tram, train

Hybrid

A hybrid vehicle has both battery and another energy source such as an internal or external combustion engine. 

Diesel Electric

A diesel electric vehicle such as mine haul trucks, locomotives, submarines, or ships have a diesel motor driving a generator, that in turn drives and electric motor. They have no battery. The advantage is the high torque when the vehicle is starting and the elimination of expensive gear boxes. It is cheaper and more flexible than gears, especially for multiple wheels. Some ships use gas turbines to drive the generator. It is a good way of converting high revs to turn a slow propeller.

Electric Motors

The electric motor can be AC or DC.

The power is usually measured in kW.  1 KW = 1.34 HP

Usually the DC output from a battery is changed to 3 phase AC to give better control of the motor speed. Some motors are universal which can use DC or AC.

A single electric motor can simply replace the normal petrol motor in your car.

The rear wheel drive Tesla has an electric motor for the two rear wheels.

The all-wheel drive models have another motor for the front two wheels.

Cars can be converted to electric by replacing the wheels or disk brakes with ones with electric motors in them.

 

Lola B09/60 (Drayson Racing)

Diesel electric hummer (using biodiesel to be environmental). Bit of fun, but too high to use on sloping ground. Source

Gearbox

An electric car does not have a gearbox. A petrol car has a differential ratio of 3:1. However as an electric motor is usually spinning faster than a petrol engine, it needs a lower gear. An electric car has a diff ratio of 5:1 or 10:1.

In a conversion from a petrol engine, it is often simplest to leave the gearbox in place and drive in 2nd or third gear. This way there is no need to change the diff gears.

If an electric motor is used at low revs, then the fan may be slow, and the motor may need extra cooling. The motor may not be as efficient at low revs. The gearbox also has a reverse gear which simplifies the electric controls.

 

 

Five components of an electric car

Electric hubs

An Australian company, Evans Electric, has developed a  linear induction motor that can replace most sets of disk brakes. Each motor can supply 100 HP.

Wikipedia   protean.

 

 

Evans in-hub motor

Mitsubishi have developed a similar in-wheel electric motor.

 

Batteries

Lead acid

The first and still the cheapest are lead acid. But they are heavy and dangerous as they produce hydrogen and oxygen which can explode. EVs use deep cycle batteries that are expensive. They are 70-75% eficient. They must be replaced every 3 years.

Nickel metal hydride

Used in hybrids because they have a long life and the technology is regarded as mature. However the patent was owned by a consortium of US auto industry companies with the aim of stifling development of the electric car. This company only permitted the sale of small batteries for use in hybrid cars that still had a petrol motor. Ref

BASF now owns the patent.

Molten salt 

Molten sodium and sulfur, Molten Lithium and sulfur, and molten potassium. The  "zebra" battery uses a molten sodium chloroaluminate  (NaAlCl4) as the electrolyte. They have high power densities/Kg, and can take thousands of rechrge cycles. They must be kept hot when operating.  Ref.

Lithium ion

Lithium ion batteries are not yet a mature technology so have further improvement possible.  They are prone to fire if not charged properly. Their lifetime is relatively short with hundreds to a few thousand charge cycles.

Lion batteries use a lithium cobalt oxide cathode and a graphite anode.

The newer Lithium iron phosphate batteries are expected to last for at least 10+ years and 7000+ charge cycles.

Lithium-manganese spinel batteries from LG Chem are expected to last up to 40 years.

Lithium vanadium oxide are used in Subaru prototype G4e, doubling energy density.

Silicon nanowires, silicon nanoparticles,and tin nanoparticles promise several times the energy density in the anode, while composite and superlattice cathodes also promise significant density improvements. Wikipedia

The Mars opportunity Rover generates 140 watts from it PV cells and store the electricity in its lithium ion battery.

 

 

Charging (polymers of sulfur form at the cathode):
Li2S → Li2S2 → Li2S3 → Li2S4 → Li2S6 → Li2S8 → S8

Discharging
S8 → Li2S8 → Li2S6 → Li2S4 → Li2S3

Regenerative braking

Motors can also act in reverse by generating electricity when the wheel drive the motor as in slowing down or braking. They can charge the battery thus recovering energy making EVs more efficient.

 

How many KM per kWh?

One kilowatt-hour of storage offers sufficient energy to travel approximately 4 km in a 1.5 T electric car, or 120 km on an electric bicycle.

Using coal fired mains power, electric vehicles produce about 50% less COcompared to petrol or diesel vehicles.

This will decrease to near zero if you use clean energy.

The Tesla S with a 60 kWh battery can drive 320 KM, with a 85 kWh battery, 510 KM

Source

Roo​ftop PV

The average car drives 38 KM/day  (14,000 KM/y). This would use 9 kWh/day.

A 1 KW PV cell generates about 4 KWh/day.

So a car would need a 2.25kWh rooftop PV to produce 9 kWh/d  (3,000 kWh/y).
Each average house has about 2 adults and uses about 12 kWh/D - or 6 kWh/D/driver.

In a house with 2 cars, 2 car owners uses 18 kWh/day for cars, and 15 kWh/D for the house. Total = 33 kWh/D. (12,000 kWh/y)

So to generate enough for the house and the 2 cars you need 33 kWh per day. So without losses, you would need an 8 KW PV system.

 

Microgrid - car plugged into home

The standard Tesla has a battery capacity of 60 kWh. 

With normal driving we use about 10 kWh during the day and return home with 50 kWh in the battery. For the evening we will need about 5 kWh to run the home.

We can easily run the house with this during the most expensive part of the day, then recharge during the night when power is cheap.

If there were 2 electric cars in a household, they could run the house and transport for 3.5 days.

The difficult part is charging the car with the PV cells during the day. Batteries are expensive.

EV and the grid

If everyone had an electric car, then our electricity consumption would be about double. If trucks and busses etc were electric also, our consumption would be more than double.

If most buildings generated and used their own electricity, then there would be no need to increase the size of our grid. It is probably about the right size now.

The average Australian car drives 14,000 KM/y and that will need about 3,000 kWh/y.

When battery prices drop, it will be possible to generate much of this with rooftop solar. Some work places, parking lots, etc. will install rooftop solar for charging cars during the day.

With so many variables, it is very difficult for power companies or governments to predict the power and grid requirements in the future.

Wind turbines

The average wind turbine has a power capacity of 3 MW. A wind turbine will produce about 20 MWh per day (3 MW x 24 hours x 30% capacity)  7,200 MWh/y.

Enough for  900 car owners, including their  household usage.

For 13 million private cars and homes we would need 14,500  3MW turbines.

At 0.1 Ha per turbine, the total land required for wind turbines would be 1,400 Ha

TYPICAL ELECTRICITY USE

Households with 1-2 residents use about 5,600 kWh/y

Households with 3-4 residents use about 8,400 kWh/Y
Households with 5 or more residents use at least 10,800 kWh/Y.

Further, residents of freestanding houses tend to use more electricity than residents of semi-detached dwellings and flats, .

  Source: IPART

 

Cost of energy for electric vehicles for 10,000 KM

Cost of EV   kWh/ kWh/ Weight kWh/ kWh/ Cost  Cost  Cost  Cost  Cost  Cost  Cost 
    100 100   100 KM/ 10,000  $ 0.10  $  0.15  $  0.20  $    0.25  $    0.30  $    0.35  $    0.40
Model Y Miles KM KG tonne KM $/kWh $/kWh $/kWh $/kWh $/kWh $/kWh $/kWh
BMW active 2011 33 21 1815 11 2063  $    206  $   309  $   413  $     516  $     619  $     722  $     825
BMW i3 2014 27 17 1300 13 1688  $    169  $   253  $   338  $     422  $     506  $     591  $     675
BYD e6 2012 54 34 2380 14 3375  $    338  $   506  $   675  $     844  $  1,013  $  1,181  $  1,350
Coda 2013 46 29 1682 17 2875  $    288  $   431  $   575  $     719  $     863  $  1,006  $  1,150
Fiat 500e 2013 29 18 1355 13 1813  $    181  $   272  $   363  $     453  $     544  $     634  $     725
Ford Focus Electric 2013 32 20 1360 15 2000  $       200  $   300  $   400  $     500  $     600  $     700  $     800
Honda Fit EV 2013 29 18 1475 12 1813  $       181  $   272  $   363  $     453  $     544  $     634  $     725
Kia Soul EV 2015 32 20 1542 13 2000  $       200  $   300  $   400  $     500  $     600  $     700  $     800
Mercedes B-class Elec 2014 40 25 1784 14 2500  $       250  $   375  $   500  $     625  $     750  $     875  $  1,000
Misubishi i 2013 30 19 1070 18 1875  $       188  $   281  $   375  $     469  $     563  $     656  $     750
Nisan Leaf 2015 30 19 1475 13 1875  $       188  $   281  $   375  $     469  $     563  $     656  $     750
Smart electric drive 2013 32 20 840 24 2000  $       200  $   300  $   400  $     500  $     600  $     700  $     800
Tesla Model S 2013 35 22 2107 10 2188  $       219  $   328  $   438  $     547  $     656  $     766  $     875
Toyota RAV4 EV 2012 44 28 1838 15 2750  $       275  $   413  $   550  $     688  $     825  $     963  $  1,100
Toyota Scion iQ EV 2013 28 18 965 18 1750  $       175  $   263  $   350  $     438  $     525  $     613  $     700
VW e-Golf 2015 29 18 1538 12 1813  $       181  $   272  $   363  $     453  $     544  $     634  $     725

Mileage Data: UDSOE

Efficiency of electric vs petrol / gasoline

Electric vehicles convert about 59%–62% of the electrical energy from the grid to power at the wheels

Petrol / gasoline vehicles only convert about 17%–21% of the energy stored in gasoline to power at the wheels.

So electric vehicle are bout 3 times more efficient.

Cost  of petrol vehicles 10,000 KM

Consumption Cost of petrol
Litres/100 KM  $1.40/litre
5  $                     700
6  $                     840
7  $                     980
8  $                  1,120
9  $                  1,260
10  $                  1,400
11  $                  1,540
12  $                  1,680
13  $                  1,820
14  $                  1,960
15  $                  2,100