Electric Powered Cars - Renewable Energy (PV System)

WHY SHOULD CARS BURN GASOLINE? WAKE UP KENYA!

The Tesla Roadster isn't just fun to drive - it provides exhilarating electric miles with technology more efficient than any other sports car. An engine dependent on combustion will never attain the efficiency of the Tesla electric powertrain. The driving efficiency of a Roadster is 88% compared to 20-25% for traditional gas-powered cars. The experience of beating an equivalent gas-guzzling sports car off the line is exhilarating - and using less energy to do it makes the Tesla grin that much bigger. While hybrid (including plug-in hybrids with "range extenders") technologies increase the efficiency of internal combustion, they are still less efficient than an electric vehicle like the Tesla Roadster.

Tesla vehicles are the only cars that get more efficient from the moment they're first driven. The Roadster charges with electricity from the grid - whether the grid is dominated by natural gas or coal, or increasingly by solar and wind energy. And as the grid shifts to increasingly efficient technologies, Tesla vehicles reap the efficiency benefits. The opposite is true of a gasoline-burning car, which gets less and less efficient as it ages. Plus, a Tesla can be charged with electricity created from 100% renewable energy - no other sports car can say the same.

For all the energy required to propel a vehicle, not all of it makes it to the wheels. Some of it is lost to friction and heat. Vehicle inefficiency can be classified into two categories of losses: road-load and energy conversion. At Tesla, careful attention is given to both to achieve the maximum range. The Tesla Roadster leverages both an incredible electric powertrain and an engineer’s obsession with efficiency to be the most efficient production sports car on the market today.

ROAD-LOAD

All vehicle types, regardless of what powertrain they use, need to overcome road-load. It includes wind resistance, mechanical friction (bearings, hubs, driveshaft, etc.), and tire rolling resistance. Road-load affects all vehicles.  As a car speeds up, wind resistance increases; there is more air for the car to “push” out of the way. Therefore, road-load is greater at higher speeds and is dependent on the aerodynamics of the vehicle. Tesla engineers are focused on decreasing aerodynamic losses while achieving beautiful styling. Road-load can be minimized by designing brakes, bearings and other rotating components with less friction. It is also important to use tires that have low rolling resistance and make the vehicle as light as possible. Energy saved by decreasing road-load can have a significantly positive impact on range. The Model S will be one of the most aerodynamic sedans ever built with all components tuned to minimize friction and achieve the highest possible range.

ENERGY CONVERSION LOSSES

Two theoretical cars with identical road-load could have very different overall efficiency based on how effectively they convert energy before it turns to the wheels. Electric vehicles have the lowest overall energy conversion losses.

ELECTRIC VEHICLE EFFICIENCY

In an electric vehicle, chemical energy is stored in a battery. Lithium-ion batteries are used in Tesla vehicles because of high energy density. Converting the chemical energy to free electrons (electrical energy) can be greater than 90% efficient – some energy is lost to heat in cells and other battery pack components such as current conductors and fuses. The remaining components of the Tesla powertrain – the drive inverter and motor – are also extremely efficient. Overall, drive efficiency of the Tesla Roadster is 88% - almost three times more efficient than an internal combustion powered vehicle.

INTERNAL COMBUSTION VEHICLE EFFICIENCY

Chemical energy is stored as gasoline in a conventional car. Combustion is used to convert the chemical energy into thermal energy. Pistons convert the thermal energy to the mechanical work that turns the wheels. The conversion process is, at best, 35% efficient. The majority of the energy stored in the gasoline is lost as heat.

HYBRIDS AND PLUG-IN HYBRID VEHICLE EFFICIENCY

The energy conversion process in a hybrid is a combination of the process in an internal combustion vehicle and battery electric vehicle. Overall efficiency for a hybrid is a bit higher than a conventional vehicle because it can recapture some road load energy, but is still much lower than an electric vehicle. When Hybrids operate in all-electric mode – overall efficiency can be quite high. However, once the gasoline engine kicks in, the overall powertrain efficiency includes losses due to both the ICE conversion process and the battery. A world of 100% hybrid vehicles is still 100% dependent on oil.

WELL-TO-WHEEL EFFICIENCY

Comparing an example of each technology reveals that Tesla electric technology uses energy most efficiently. As utility companies build more efficient power plants and bring more renewables online, the well-to-station efficiency will significantly increase. In turn, the overall vehicle efficiency increases to levels never to be recognized by internal combustion or hybrid technologies.