Technology

Ever wanted to know how a hybrid engine works, or what a fuel cell is? Don’t know your catalytic converter from your combined cycles or your E85 from your electric vehicles. This section answers all your green car questions with simplified technical information on what’s what.

Glossary of Green Terms

Active Fuel Management
A trademark name from General Motors which describes automobile variable displacement technology, formerly known as displacement on demand. This allows the engine to turn off cylinders during light loads therefore having the advantage of a small engine at low speeds which minimises fuel efficiency and economy.

All Petroleum Internal Combustion Engine Vehicle (APICEV)
An internal combustion engine is engine that houses an exothermic combustion reaction using a fuel substance in the presence of an oxidiser. With APICEVs the fuel is either petrol or diesel using air as the oxidiser. The expanding hot gases at combustion directly cause movement of the engine.

Auto Stop-Start
When the car becomes stationary and is taken out of gear the engine will automatically stop. When ready to move, the clutch is depressed to put the car in gear and the engine automatically starts. First employed by BMW EfficientDynamics, this technology utilises the modern efficient engines and saves fuel and cuts emissions.

Bio-diesel
A non-petroleum based fuel from biological origin which is made from short chain alkyl esters made by the transesterification of vegetable oil. It can be used in unmodified diesel engines.

Bio-ethanol
An increasingly common alternative fuel to petroleum based fuels. Ethanol is produced using common crops that have high sugar content such as sugar beets and maize but scientists have recently developed the use of algae. Crops are fermented to produce ethanol which has can be used in modified cars as fuel.

BlueMotion
A trade name of the Volkswagen featuring a range of cars aiming to reduce carbon emissions and improve fuel economy using existing technologies.

Bluetec
A trade name of Daimler AG which aims to reduce nitrogen oxides and pollutant emissions from their vehicles.

Carbon Footprint
A measure of human impact on the environment in terms of greenhouse gases emitted using CO2 as a measurement units. Carbon footprint is a buzzword useful to encourage people to reduce or offset their impact on the world.

Climate Change
A significant change in the average weather for example a change in temperature, rainfall or wind. The average weather is measured during a year and is compared against a similar time point in a previous year.

Compressed Natural Gas (CNG)
A more environmentally friendly alternative to petroleum based fuels and propane. By compressing the natural gas methane (CH4) to less than 1% of its normal atmospheric volume it is becoming a useful, clean alternative.

CO2
The chemical abbreviation for Carbon dioxide, CO2 is a naturally occurring gas constituting around 21% of our atmosphere. Essential to life, this is the carbon source that plants fix during photosynthesis to make glucose.

CO2 Emissions
Carbon has been locked away over millions of years due to plants and animals being buried without decay underground. Now in the form of fossil fuels CO2 is released as a product of combustion to create energy. CO2 is a greenhouse gas because although visible it strongly absorbs the infrared and near infrared parts of the spectrum.

CO2 Air Conditioning
Previous air conditioning units used a fluorocarbon based liquid know as R134a which is 1,300 times more harmful to the environment that CO2. From 2011 all air conditioning units will use CO2 based refrigeration instead.

DiesOtto Engines
A new type of experimental engine developed by Mercedes-Benz is said to incorporate the benefits of diesel whilst using regular unleaded. It features Homogenous Charge Compression Ignition, direct fuel injection and variable valve timing, geometry turbo-charging and compression ratio.

Direct Injection
Fuel is injected into the combustion chamber at high pressure of each cylinder. The fuel can burn more effectively resulting in better fuel economy, lower emissions and particulates.

E85
An alcohol-petroleum fuel mixture which can be used in Flexible Fuel Vehicles. The alcohol, ethanol, is mixed with a petroleum derivative either petrol or diesel in a ratio of 85% to 15% respectively. E85 is popular in Brazil and Sweden and is growing in popularity in the corn growing states of America which is used to make the bio-ethanol.

ECOnetic
A trademark of Ford which denotes a new range of environmentally friendly green cars. Using existing technologies and improvements on design they have reduced carbon emissions and increased fuel efficiency

EfficientDynamics
A trademark of BMW which describes the new technologies being developed to combat climate change. Their new designs make for faster, more powerful cars that also are more economical and produce less carbon emissions. Lightweight engineering, EPS, auto stop-start, brake energy regeneration are just some of the features they have developed into their new cars.

Electric Vehicles
An Electric Vehicle (EV) is a vehicle powered by an electric motor. The energy used to propel the vehicle comes from a battery, fuel cell or generator opposed to the petroleum fuels used in combustion engines. An electric motor produces no carbon emissions and can have an extremely small carbon footprint if powered using renewable energy.

End of Life Vehicle (ELV)
End of Life Vehicles (ELVs) are cars that have reached the end of their useable life span. With more and more cars being produced what happens to cars after their use is an important environmental concern.

Emissions
The human introduction of chemicals, biological materials and particulate matter into the atmosphere that can cause a detrimental effect to the ecosystem.

Electronically Powered Steering (EPS)
Designed for the BMW EfficientDynamics range this is use if lightweight electrical motors to power the steering. They only use power when the wheel is turned opposed to the hydraulic systems that require constant management.

European Emissions Standards
A set of requirements to define the acceptable limits of vehicle exhaust emissions from new vehicles. Using nitrogen oxides, carbon monoxide, hydrocarbons and particulate matter as key emissions to monitor.

Flexible Fuel Vehicles
An alternative fuel vehicle capable of using a combination of fuels either mixed in the same tank or from different tanks. Often called dual fuel these vehicles often use varying mixes of bioethanol and gasoline i.e. E85

Fossil Fuels
A hydrocarbon fuel source found in the earths crust; ranging from volatile gases such as methane, through viscose liquids of petroleum and tar, all the way through to solid anthracite coal. Formed from fossilised remains of plants and animals over millions of years of compression in the earths crust.

Fuel Cells
An electrochemical conversion device which produces electricity from fuel and an oxidant which react in the presence of an electrolyte. They are different from a battery as they consume a reactant in a flow through system whereas batteries are a closed system. An example of a reactant is hydrogen oxidised in the presence of air which are incredible clean and powerful, but storage of hydrogen is dangerous.

Grams/Kilometre (CO2)
A cars green status is measured in the amount of CO2 they produce in grams per kilometre driven.

Green Car
A green car is generally considered one which produces less than 150 g/km CO2 but individual aspects of cars can be designed with green incentives. In addition the design should consider what is going to happen to the vehicle after its use when it becomes and ELV.

Greenhouse Effect
Normally when light energy hits the earth from the sun it penetrates the atmosphere and reflects off the earth’s surface and back out to space. The greenhouse effect is when certain gases known as ‘greenhouse gases’ prevent the energy reflecting back out the space which increases the temperature of our planet.

Greenhouse Gases<br /> These are gases that act to increase the greenhouse effect on the earth’s atmosphere. One gas in particular is CO2 which although it doesn’t absorb the visible part of the light spectrum absorbs infra red and near infra red. This acts to trap heat into the atmosphere like the glass does in a greenhouse.

Gas to Liquid (GTL)
A refinery process to convert natural gases such as methane into longer chain hydrocarbons. These longer chain hydrocarbons can then be transported and/or mixed with diesel fuel.

Homogenous Charge Compression Ignition
A form of internal combustion engine where a well mixed fuel and oxidiser combination are compressed to the point of auto-ignition.

Hybrids
A combination of an electric vehicle and internal combustion engine. The two work in tandem with one another to maximise fuel efficiency. During low energy demands the electrical motor will power the vehicle using energy stored in a battery, when power is needed to increase the petroleum motor engages and drives the vehicle. Meanwhile the battery is recharged using excess kinetic energy.

Hydrocarbons
An organic compound containing hydrogen and carbon molecules which form chains. In the pure form they would contain only these two molecules; however the name hydrocarbon is often used for impure molecules containing additional functional groups on the chain. Crude oil contains a multitude of hydrocarbons at varying lengths. Short chains such as methane (CH4) and propane (C3H8) are gases at atmospheric pressure whereas longer chains like petroleum are more viscose.

Hydrogen Fuels
Hydrogen can be used as a fuel source in fuel cells. It is extremely combustible and generates a lot of energy. It is also very clean as the only product of oxidation is water and oxygen. Unfortunately hydrogen is extremely explosive and is dangerous to store.

Lithium Ion Batteries
These batteries are used commonly in consumer electronics as they offer the best energy to weight ratio, no memory effect and no slow loss of charge. Because of these features researchers are using them to store energy for electric and hybrid vehicles.

Low Friction Fluids
Ford ECOnectic and BMW EfficientDynamics have both developed new engine oils and lubricants that decrease engine wear and friction in order to maximise the efficiency from their engines.

Liquid Petroleum Gas (LPG)
An alternative fuel source created from liquefied propane and butane gas mixed with petrol. It reduces CO2, nitrogen oxides, methane and particulate emissions.

Mild Hybrid
Similar to the conventional hybrid but the electric motor can not provide enough energy to solely propel the vehicle. This claims to provide many of the benefits of a normal hybrid but at much lower cost. This term is also used to describe cars with auto stop-start facilities.

Miles Per Gallon
Fuel economy is measured in these units. As fuel economy depends on how and where you drive in the EU cars are measured on three tests know as urban cycle, extra urban cycle and combined cycle. These should give consumers fair indications of what they can expect to achieve.

Methane
The shortest hydrocarbon chain with just on carbon molecule. This natural gas is harmful to the environment as it is a strong greenhouse gas. It can be used as a fuel source due to its flammable nature.

Nitrogen Oxides
Nitrogen oxides are often abbreviated to NOx with x indicating the variable number of nitrogens and oxygens involved. Nitric Oxide (NO), Nitrogen Dioxide (NO2) and Nitrous Oxide (N2O) are common in addition to a range of di-nitrogen compounds, which are often found in exhaust emissions.

OPEC
The Organisation of Petroleum Exporting Countries (OPEC) is a group set up to protect the interests of selected petroleum producing countries. They control the production in order to provide a continuous balance of supply and demand.

Particulates
Tiny particles of solids or liquids suspended in gas usually found in exhaust emissions from burning fossil fuels. These particulates are thought to cause health problems to humans and effect the entire ecosystem.

Parts Per Million
Standard unit of measurement for gases.

Plug-in Hybrids
Plug in Hybrid Electrical Vehicles (PHEV) combine are similar to standard hybrid vehicles except they can be plugged in to electrical mains to charge their batteries. With an internal combustion engine onboard the electric motor is not the only source of power but this differs in the fact it has a large battery to be plugged into the mains.

Regenerative Braking
A mechanism that uses the kinetic energy created during braking, which is usually lost as heat, into electricity which is stored in batteries. In hybrid vehicles this is used to power the electric motors however in designs such as, BMW EfficientDynamics, it is used to power electrical features such as headlights and stereos etc...

Renewable Transport Fuel Obligation (RTFO)
A government directive that states that by 2010 at least 5% of the UK’s fuel will be from renewable biofuel sources, it is expected to cut the country’s transport emissions by 2-3%.

Super Caps
A super capacitor (super caps) which gives an additional injection of power to an electric motor in a similar way a turbo charge does to an internal combustion engine.

Turbo Charger
Formerly used in high performance engines this technology is now used to maximise the efficiency of fuel as it enters the combustion chamber. A pressurised mix of fuel and air are fired into the chamber to ensure efficient combustion of all the fuel. This can be used to get improve fuel economy and performance without increasing the engine.

Well-to-wheel
Similar to air miles when describing food products. This phrase describes the total environmental impact incurred from extraction of the oil from the source to its end point use by the driver. This is a concern for companies who are researching ways to improve their extraction, refinement and transportation of fuels to the customer.