1. Hybrid Vehicles

Hybrid vehicles are called hybrids because they use both a small internal combustion engine (ICE) and an electric motor to obtain maximum power and fuel economy with minimum emissions. How they do this varies from one model to another, with varying success.

What all hybrids have in common is the ability to generate electric current, store it in a large battery, and use that current to help drive the car. Hybrids capture electrical energy produced by a regenerative braking system, and their engines can power a generator, too. Hybrids can also conserve energy by shutting down the ICE when the vehicle is in Park, idling at a light, or stopped in traffic, or when the electric motor’s energy is sufficient to drive the vehicle without assistance from the ICE.

Hybrids have regenerative braking systems that generate electric power to help keep the batteries charged. When the driver applies the brakes, the electric motor turns into a generator, and the magnetic drag slows the vehicle down. For safety, however, there is also a normal hydraulic braking system that can stop the car when regenerative braking isn’t sufficient. There’s no difference in maintenance or repair except that the brake pads tend to last much longer because they don’t get used as much. In fact, if you drive a hybrid in a moderate manner, you almost never actually use the disc brakes on the wheels and may be able to go the life of the car without changing pads. The big difference is that regenerative brakes capture energy and turn it into electricity to charge the battery that provides power to an electric motor.

2. Plug-in hybrids

Because plug-in hybrids feature larger batteries that can be charged at any ordinary 110-volt electrical socket, they have the capacity to extend the ability of the electric motor to drive the car farther without the need for starting the ICE and therefore substantially increase the vehicle’s fuel efficiency. Estimates have ranged as high as 100 mpg!

Some technologically savvy individuals have adapted their hybrid vehicles into plug-in hybrids, and automakers are in the process of developing and producing them (sometimes in cooperation with major utility companies). The development of new, smaller, high-capacity lithium-ion batteries that can be recharged many times is the key to making plug-in hybrids available to the general public. Estimates are that plug-in hybrids equipped with these more powerful batteries will have a range of as much as 125 miles before the charge is depleted and the vehicle reverts to standard hybrid mode.

The main environmental problem with plug-in hybrids is that the electric current they draw is usually generated by utility companies powered by fossil fuels. The good news is that some major chains have committed to establishing charging stations powered by solar panels or wind energy, and many hybrid owners are willing to install solar panels to recharge these vehicles at home. Plug-in hybrids charged by commercial sources of electricity or solar panels will be less dependent on the ICE, but will still need it for long trips, climbing hills, and so on. Future hybrids may use a small fuel cell to make electricity from hydrogen, which would mean the ICE would have to run even less frequently.

3. Two-mode hybrids

Two-mode hybrids may be the key to a competitive place for the U.S. in the hybrid market. Instead of the large storage battery found on conventional hybrids, two-mode hybrids use smaller batteries and two electric motors located inside an automatic transmission with two sets of gears — one for the ICE and the other to amplify the power of the electric motors. The transmission can function as a continuously variable transmission, as well. In one mode, at lower speeds, the vehicle can run with one or both electric motors, with or without the ICE, or on the ICE alone. At higher speeds, the second mode kicks in, and the ICE runs continuously in its higher gear ratios.

A hybrid vehicle uses two or more distinct types of power, such as internal combustion engine to drive an electric generator that powers an electric motor, e.g. in diesel-electric trains using diesel engines to drive an electric generator that powers an electric motor, and submarines that use diesels when surfaced and batteries when submerged. Other means to store energy include pressurized fluid in hydraulic hybrids.

The basic principle with hybrid vehicles is that the different motors work better at different speeds; the electric motor is more efficient at producing torque, or turning power, and the combustion engine is better for maintaining high speed (better than typical electric motor). Switching from one to the other at the proper time while speeding up yields a win-win in terms of energy efficiency, as such that translates into greater fuel efficiency,

Vehicle type

Two-wheeled and cycle-type vehicles

Mopeds, electric bicycles, and even electric kick scooters are a simple form of a hybrid, powered by an internal combustion engine or electric motor and the rider’s muscles. Early prototype motorcycles in the late 19th century used the same principle.

1. In a parallel hybrid bicycle human and motor torques are mechanically coupled at the pedal or one of the wheels, e.g. using a hub motor, a roller pressing onto a tire, or a connection to a wheel using a transmission element. Most motorized bicycles, mopeds are of this type.
2. In a series hybrid bicycle (SHB) (a kind of chainless bicycle) the user pedals a generator, charging a battery or feeding the motor, which delivers all of the torque required. They are commercially available, being simple in theory and manufacturing.

The first published prototype of an SHB is by Augustus Kinzel (US Patent 3’884’317) in 1975. In 1994 Bernie Macdonalds conceived the Electrilite SHB with power electronics allowing regenerative braking and pedaling while stationary. In 1995 Thomas Muller designed and built a “Fahrrad mit elektromagnetischem Antrieb” for his 1995 diploma thesis. In 1996 Jürg Blatter and Andreas Fuchs of Berne University of Applied Sciences built an SHB and in 1998 modified a Leitra tricycle (European patent EP 1165188). Until 2005 they built several prototype SH tricycles and quadricycles.  In 1999 Harald Kutzke described an “active bicycle”: the aim is to approach the ideal bicycle weighing nothing and having no drag by electronic compensation.

1. A series hybrid electric-petroleum bicycle (SHEPB) is powered by pedals, batteries, a petrol generator, or plug-in charger – providing flexibility and range enhancements over electric-only bicycles.

A SHEPB prototype made by David Kitson in Australia in 2014 used a lightweight brushless DC electric motor from an aerial drone and small hand-tool sized internal combustion engine, and a 3D printed drive system and lightweight housing, altogether weighing less than 4.5 kg. Active cooling keeps plastic parts from softening. The prototype uses a regular electric bicycle charge port.

5. Engine type

Hybrid electric-petroleum vehicles

Hybrid New Flyer Metrobus

Hybrid Operate Solo

When the term hybrid vehicle is used, it most often refers to a Hybrid electric vehicle. These encompass such vehicles as the Saturn Vue, Toyota Prius, Toyota Yaris, Toyota Camry Hybrid, Ford Escape Hybrid, Toyota Highlander Hybrid, Honda Insight, Honda Civic Hybrid, Lexus RX 400h and 450h, Hyundai Ioniq and others. A petroleum-electric hybrid most commonly uses internal combustion engines (using a variety of fuels, generally gasoline or Diesel engines) and electric motors to power the vehicle. The energy is stored in the fuel of the internal combustion engine and an electric battery set. There are many types of petroleum-electric hybrid drivetrains, from Full hybrid to Mild hybrid, which offer varying advantages and disadvantages.

William H. Patton filed a patent application for a gasoline-electric hybrid rail-car propulsion system in early 1889, and for a similar hybrid boat propulsion system in mid 1889.There is no evidence that his hybrid boat met with any success, but he built a prototype hybrid tram and sold a small hybrid locomotive.

In 1899, Henri Pieper developed the world’s first petro-electric hybrid automobile. In 1900, Ferdinand Porsche developed a series-hybrid using two motor-in-wheel-hub arrangements with an internal combustion generator set providing the electric power; Porsche’s hybrid set two speed records.^{[citation needed]} While liquid fuel/electric hybrids date back to the late 19th century, the braking regenerative hybrid was invented by David Arthurs, an electrical engineer from Springdale, Arkansas in 1978–79. His home-converted Opel GT was reported to return as much as 75 mpg with plans still sold to this original design, and the “Mother Earth News” modified version on their website.

The plug-in-electric-vehicle (PEV) is becoming more and more common. It has the range needed in locations where there are wide gaps with no services. The batteries can be plugged into house (mains) electricity for charging, as well being charged while the engine is running.

Continuously outboard recharged electric vehicle (COREV)

Some battery electric vehicles (BEVs) can be recharged while the user drives. Such a vehicle establishes contact with an electrified rail, plate or overhead wires on the highway via an attached conducting wheel or other similar mechanism (see Conduit current collection). The BEV’s batteries are recharged by this process—on the highway—and can then be used normally on other roads until the battery is discharged. For example, some of the battery-electric locomotives used for maintenance trains on the London Underground are capable of this mode of operation.

Developing a BEV infrastructure would provide the advantage of virtually unrestricted highway range. Since many destinations are within 100 km of a major highway, BEV technology could reduce the need for expensive battery systems. Unfortunately, private use of the existing electrical system is almost universally prohibited. Besides, the technology for such electrical infrastructure is largely outdated and, outside some cities, not widely distributed (see Conduit current collection, trams, electric rail, trolleys, third rail). Updating the required electrical and infrastructure costs could perhaps be funded by toll revenue or by dedicated transportation taxes.

6. Hybrid fuel

In addition to vehicles that use two or more different devices for propulsion, some also consider vehicles that use distinct energy sources or input types (“fuels”) using the same engine to be hybrids, although to avoid confusion with hybrids as described above and to use correctly the terms, these are perhaps more correctly described as dual mode vehicles:

1. Some electric trolleybuses can switch between an on-board diesel engine and overhead electrical power depending on conditions (see dual mode bus). In principle, this could be combined with a battery subsystem to create a true plug-in hybrid trolleybus, although as of 2006, no such design seems to have been announced.
2. Flexible-fuel vehicles can use a mixture of input fuels mixed in one tank — typically gasoline and ethanol, methanol, or biobutanol.
3. Bi-fuel vehicle: Liquified petroleum gas and natural gas are very different from petroleum or diesel and cannot be used in the same tanks, so it would be impossible to build an (LPG or NG) flexible fuel system. Instead vehicles are built with two, parallel, fuel systems feeding one engine. For example, some Chevrolet Silverado 2500 HDs can effortlessly switch between petroleum and natural gas, offering a range of over 1000 km (650 miles).^[33] While the duplicated tanks cost space in some applications, the increased range, decreased cost of fuel, and flexibility where LPG or CNG infrastructure is incomplete may be a significant incentive to purchase. While the US Natural gas infrastructure is partially incomplete, it is increasing at a fast pace, and already has 2600 CNG stations in place.^[34] With a growing fueling station infrastructure, a large scale adoption of these bi-fuel vehicles could be seen in the near future. Rising gas prices may also push consumers to purchase these vehicles. When gas prices trade around $4.00, the price per MMBTU of gasoline is $28.00, compared to natural gas’s $4.00 per MMBTU. On a per unit of energy comparative basis, this makes natural gas much cheaper than gasoline. All of these factors are making CNG-Gasoline bi-fuel vehicles very attractive.

4. Some vehicles have been modified to use another fuel source if it is available, such as cars modified to run on autogas (LPG)and diesels modified to run on waste vegetable oil that has not been processed into biodiesel.
5. Power-assist mechanisms for bicyclesand other human-powered vehicles are also included (see Motorized bicycle).

7. Fluid power hybrid

Chrysler minivan, petro-hydraulic hybrid

Hydraulic hybrid and pneumatic hybrid vehicles use an engine to charge a pressure accumulator to drive the wheels via hydraulic (liquid) or pneumatic (compressed air) drive units. In most cases the engine is detached from the drivetrain, serving solely to charge the energy accumulator. The transmission is seamless. Regenerative braking can be used to recover some of the supplied drive energy back into the accumulator.

Petro-air hybrid

A French company, MDI, has designed and has running models of a petro-air hybrid engine car. The system does not use air motors to drive the vehicle, being directly driven by a hybrid engine. The engine uses a mixture of compressed air and gasoline injected into the cylinders. A key aspect of the hybrid engine is the “active chamber”, which is a compartment heating air via fuel doubling the energy output. Tata Motors of India assessed the design phase towards full production for the Indian market and moved into “completing detailed development of the compressed air engine into specific vehicle and stationary applications”.

Conventional Vehicles

Conventional vehicles are those that use an internal combustion engine (ICE) for propulsion, without assistance from an electric motor or other mechanism. The vast majority of South Australian vehicles – across all classes – are conventional vehicles. However, they operate on a variety of fuels, use a variety of supporting technologies and, as a result, vary in efficiency and emissions levels.

Internal Combustion Engines (ICE’s)

An internal combustion engine harnesses repeated combustion (explosion) of a fuel/air mix to drive a set of pistons down a corresponding set of cylinders. These, in turn, deliver rotating mechanical power through an attached crankshaft. The two most common types of internal combustion engines used in road transport are compression ignition engines and spark ignition engines.

Compression Ignition Engines

Compression ignition engines use fuels such as mineral diesel and biodiesel.  Gaseous fuels are sometimes used in a mixture with a diesel product. Compression ignition engines draw in air, compress it (thereby heating it), then draw in the fuel. The hot, compressed air mixes with the fuel and the mixture ignites. A glow plug (electrical resistance heating) may be used to ensure sufficient temperatures for ignition are reached.

Spark Ignition Engines

Spark ignition engines are fuelled by petrol, ethanol blends, LPG or natural gas. These engines use a spark plug to ignite the premixed fuel and air at the correct time. In spark ignition engines that have high compression ratios, and require premium (ignition resistant) fuel, the use of regular fuel can induce early combustion under similar principles as diesel combustion; this can lead to a loss of efficiency and increase engine wear.

Engine Efficiency and Emissions

For the most part, ICE engine efficiencies are now about refinements to the conventional combustion process. Smart engine management systems (EMS) and components have helped optimise this process. More complete combustion and exhaust treatments have reduced air toxic emissions markedly (by orders of magnitude in some cases) and, with incremental efficiency improvements, greenhouse gas emissions are trending downwards as well. Turbochargers are an important addition, packing more fuel and air into the cylinders, increasing ICE power and efficiency.

Still, internal combustion engines face fundamental efficiency limits.

Vehicle Efficiency

A range of approaches are being used to improve vehicle efficiency, beyond improving the engine’s efficiency, such as:

1. Vehicle light-weighting
2. Improved aerodynamics
3. Anti-idle technologies and electric motors (see Emerging Fuels and Technologies)
4. Efficient accessories and lights, and innovative electrical systems
5. Low rolling resistance tyres

ICE Vehicles: What to Consider

Conventional vehicles are well accepted, deliver good utility and, for most fuels, the refuelling network is comprehensive.

• Specify and select the right size and type of vehicle.
• Consider which fuel(s) you will use. Some fuels are cheaper and/or cleaner than others. Vehicles capable of operating on multiple fuel types offer a hedge against fuel price increases and may offer low-cost emission abatement opportunities.
• Compare efficiency and emissions of vehicles with the Green Vehicle Guide or Fuel Consumption Guide Database (light vehicles), or the Truck Buyer’s Guide (heavy vehicles).
• You can get more from your vehicle and fuel by ecodriving.

What issues are there?

• Conventional ICE vehicles can have significant air toxic emissions and greenhouse gas emissions – consider fuel and vehicle options to minimise these.
• Conventional fuel prices are quite likely to continue to rise in real terms.