The electric vehicle
A purely electric vehicle uses a large amount of batteries, combined with a electric motor. They emit no exhaust fumes whatsoever and are thus very useful in certain situations (ie use in enclosed spaces).
Downsides of the electric vehicles
Amount of battery capacity required
Purely electric vehicles require a great amount of battery (or rather electric energy) capacity, and thus a huge amount of batteries. At present, lithium ion batteriesW are mostly used (sulpheric acid-lead batteries can be used too, but are generally not used anymore due to their low power/weight ratio). Lithium-ion batteries have a major environmental impact (the production of these batteries atleast, not their use).[verification needed]
Other battery types can also be used (some battery types lowers this impact greatly), but all generally still have a negative environmental effect, and weighten down the vehicle and reduce range (compared to fuel, batteries -regardless of the type- have very low power/weight ratio's.[1]
The hybrid vehicle as a solution to remove a lot of battery capacity
One solution to reducing the amount of battery capacity is to swap the battery with a (ultra)capacitor and a range extender (ie microturbine, IC (gasoline) engine, IC (diesel) engine or Stirling engine) fitted to a dynamo or alternator to recharge the ultracapacitor. This is known as a series hybrid.
Especially Stirling engines (which are 10% more efficient than IC (gasoline) engines, ie regarding incineration) are very useful in vehicles, as they are very light, and (as any range extender) allow to use of the energy dense fuels (more energy can be taken along compared to batteries).
The capacitor can be used as a buffer (so storing say energy to drive a few hundred meters upto 1 km, rather than storing energy for say 100 - 500 km).
Advantages of the hybrid electric to purely electric vehicles
Besides the main advantage of the descreased weight/increased range, and the advantage of eliminating a lot of battery capacity (which is useful as the production of the batteries are environmentally unfriendly), there are additional advantages:
- Unlike Stirling-only vehicles, Stirling-electric hybrid vehicles can be immediatelly driven after starting. Stirling engines require a "warm-up time", yet due to the capacitor, the vehicle can use the energy still present in the capacitor to immediatelly drive off. The capacitor is then continuously recharged underway.
- Stirling engines extract more energy and can use other environmentally friendly fuels (ie plant oils) than IC (gasoline) engines.
- It also still function as a hybrid (allowing to switch to the electric motor within densely populated areas). Electric motors are more efficient here than a heat engine since the heat engine (ie microturbine, IC engine or Stirling engine) would need to operate on a speed/load that is not optimal for it
- In the specific case of parallell hybrid electric vehicles fitted with a Diesel engine (not a gasoline engine as the latter are more efficient on operating on almost any speed/load ratio):
- Diesel engines can not oxygenate their fuel optimally beyond a certain speed/load[2] (it works fine for low speeds/loads though). This results in a lesser energy conversion and thus power loss. The electricity generator (dynamo or alternator) too works more efficient[3] at a specific speed and load. As with series hybrids it's possible to keep the speed/load of both the diesel engine and the electricity generator at a constant rate, near their optimal speed/load range, the efficiency is kept very high during the entire trajectory the vehicle needs to cover.
Additional improvements to electric vehicles
Plug-in hybrids
Plug-in hybridsW are series or parallell hybrids equipped with a power plug. They have the option of recharging the batteries from the mains electricity grid.
Criticisms
=Costs of private electric vehicles (cars)
Although the cost of electricity to has been estimated as less than one fourth the cost of gasoline (in California in 2007), the lifetime cost of electric and hybrid-electric cars is much higher than IC-powered cars.[4] This is partly a result of the huge amount of battery capacity installed on these cars, aswell as other parameters (ie car weight, non-essential systems, safety precautions, ...).
Another issue is the use of rare earth elements in some electric or hybrid-electric vehicles. especially lanthanum and some 3 other elements seems often used in these vehicles. In some cases, their use can not be avoided, in other cases, they can be avoided.[5][6]
Notes
External links
- ↑ climate scientist Graeme Pearman's comments to Chriswaterguy (after his Lowy Institute talk, 18 Apr 2007) that he had helped to built a hybrid (15 years ago?) which did not use lithium ion batteries. (He confirmed my query as to whether this was the "Eco-Commodore," which I assume is actually the Holden ECOmmodore, but the ECOmmodore was much later, unveiled in 2000... was it just ignored for the intervening ~8 years? --Chriswaterguy)
- ↑ See wikipedia article on "Diesel engine"
- ↑ This difference can be quite high, ie brushed types can show a difference of 40% !
- ↑ [http://www.team-fate.net/phev.html "What are Plug-In Hybrids?"
- ↑ Rare earth elements used in electric and hybrid electric cars
- ↑ Lithium not being a rare earth element