TRANSPORT

Alternative Fuel Vehicles

Alternative fuel vehicles are vehicles which use fuels other than petrol and diesel. Because of a combination of factors, such as environmental concerns, high oil prices and the potential for peak oil, development of cleaner alternative fuels and advanced power systems for vehicles has become a high priority for many governments and vehicle manufacturers around the world. As of July 2010 more than 40 million alternative fuel and advanced technology vehicles have been sold worldwide, compared to around 1 billion cars and light trucks in use in the world in 2010.

It is believed that major advantages of alternative fuels are two: one is to reduce reliance on petroleum, and two is to improve air quality by lowering the emission of CO, CO2, hydrocarbons and NOx. There are many alternative fuels around the world, some commonly found include

• liquefied petroleum gas (LPG)
• natural gas
• biodiesel
• battery-powered electric
• hybrid electric

LPG

Liquefied petroleum gas (LPG) is a by-product of natural gas processing and crude oil refining. LPG generally produces fewer vehicular emissions than petrol or diesel owing to its chemical nature. For Hong Kong, LPG is a good choice as alternative fuel because the import, storage, and road transport infrastructure are alreadythere. Almost all licensed taxis in Hong Kong are LPG-fuelled. Right now, about 60% of the registered public light buses are LPG.

Natural gas

Natural gas mainly composes of methane (usually 60% or above). Combustion of methane produces the least amount of CO2 of all fossil fuels. Compared to diesel, natural gas vehicles emit less nitrogen oxides emission and particulate emissions would be almost eliminated.

For vehicles, natural gas can be stored in tanks as compressed natural gas (CNG) or as liquefied natural gas (LNG).

Natural gas vehicles are popular in regions or countries where natural gas is abundant, such as Italy, Russia, Pakistan and United States. At the present moment, natural gas in Hong Kong is used solely for electricity generation, and has not yet entered the retail fuel market. Converting vehicle fleets to using natural gas before formation of natural gas retail market will require significant up-front investment on import and storage infrastructure.

Biodiesel

Biodiesel is a form of diesel fuel manufactured from vegetable oils, animal fats, or recycled restaurant greases. It is biodegradable and produces less air pollutants than petroleum-based diesel. Pure biodiesel or biodiesel blended with petroleum diesel can be used to fuel diesel vehicles, providing another fuel alternative with less emission of gaseous pollutants.

Biodiesel is often considered as a renewable energy because it can (at least partly) recovered from other abundant sources such as food waste. Replacing fossil diesel by biodiesel can help reduce global greenhouse gas level. In respect of exhaust emissions, its overall emission performance is roughly on a par with ultra-low sulphur diesel, particularly when blended with ultra-low sulphur diesel in small concentration.

In January 2010, the Legislative Council of Hong Kong approved the Air Pollution Control (Motor Vehicle Fuel) (Amendment) Regulation 2009. The Amendment Regulation provides for the statutory control on the specifications of motor vehicle biodiesel and the labelling requirement on selling of motor vehicle biodiesel with biodiesel content over 5%. The Amendment Regulation came into operation from 1 July 2010.

Battery-powered electric

Battery-powered Electric Vehicles (EVs) are vehicles whose energy source is in the chemical energy of batteries. The biggest advantage of battery-powered electric vehicles is the zero emission. Energy is stored in batteries and is used to drive electric motors.

New advanced batteries and motors have allowed EVs to appear as a clean alternative to internal combustion vehicles. They are non-polluting and very energy efficient. Whereas 75% or more of the energy from a battery reaches the wheels of an EV, only about 20% of the chemical energy in petrol gets converted into useful work at the wheels of an internal combustion vehicle.

Electric motors can provide power at almost any engine speed. Internal combustion engines must operate at high rotating speeds to achieve maximum power, but in contrast electric motors give nearly peak power output even at low speeds. This gives electric vehicles good acceleration performance from a stop.

The major obstacles that have hindered the wider adoption of EVs include the relatively long time required to charge up the batteries as compared to that required to fill up a fuel tank, the expensive charging infrastructure, and the limited travel range for each full charge of the battery.

One of the local power suppliers had introduced Hong Kong’s first EV Quick Charger for technical trials in February 2010, which marking a new milestone in promoting a wider adoption of EVs in Hong Kong. This charger claimed that it would take only 15 minutes to charge up an EV, with energy sufficient to run for sixty kilometres. Until November of 2010, there are 21 EV charging station in Hong Kong built by this power provider.

Hybrid vehicles

Hybrid electric vehicles (HEVs) are primarily powered by an internal combustion engine. However, they use the electric motor as a generator to convert energy wasted during coasting and braking into electricity, which is stored in a battery. The electric motor is used to provide extra power for accelerating or hill climbing and in low-speed driving conditions where internal combustion engines are less efficient. Because the internal combustion engine only operates for a fraction of the time, hybrid vehicles have lower emissions and better fuel efficiency than cars running on petrol/diesel. There have been reports of fuel saving of up 40 - 50% for hybrid electric vehicles currently available in the market when compared with a petrol vehicle of similar specifications. A major advantage of hybrid electric vehicles over the pure electric vehicles is that the hybrid electric vehicles require no external charging of the battery so there is no need to build up expensive charging infrastructure.

Fuel-cell electric

In fuel-cell, an electrochemical reaction takes place when hydrogen and oxygen are combined to produce electricity. The electricity generated is then used to drive motors in fuel-cell vehicles.

Fuel cells often requires oxygen and hydrogen to generate electricity with heat and water as side-products. Fuel-cell vehicles are envisaged as vehicles of the future, and in many countries a great deal of research effort has been devoted to the development of fuel-cell technology for automotive applications. Because fuel cell vehicles operate with electric motors which have very few moving parts (only those pumps and fans needed to provide fuel and coolant), vehicle vibrations and noise will be significantly reduced and routine maintenance (oil changes, spark plug replacement) will be less.

Ethanol and methanol

Ethanol is an alcohol-based fuel produced by fermentation and distillation of starch crops. Ethanol can also be produced from trees and grasses - known as "bioethanol", which is most commonly blended with petrol to increase octane and improve the quality of the emissions. In some places, ethanol is blended with petrol in a minor proportion (e.g. 10% ethanol and 90% petrol). In other places, ethanol is used in much higher concentrations (e.g. 95%).

Similarly, methanol (also known as wood alcohol) has been used as an alternative fuel. It can be blended with petrol (e.g. 85% methanol and 15% gasoline) like ethanol, or used as raw materials to produce hydrogen for fuel-cell.

Solar

Solar energy is harnessed by using photovoltaic cells to produce electricity to drive motors. Solar-powered vehicles appear mainly in competitions and demonstration projects. Solar vehicles are not commercially available due to its many limitations.