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Other Comments: 0 Feb 19, 2016

More than a century fossil fuels were the main driver of motor vehicles, enabling people to travel vast expanses and to connect the world in a global transport system. Large reserves of this natural resources and a relatively low price for decades were the reason for the mass production of motor vehicles powered by fossil fuels. The growing energy crisis and the negative impact of motor vehicles on the environment have led to the need for new energy sources. Some of the most important alternative fuels of today are:

• Ethanol
• Bioethanol
• Biodiesel
• Natural gas
• Electricity, hydrogen and solar energy

In addition to the undoubted positive effect on the reduction of environmental pollution, new energy sources for motor vehicles have a major impact on reducing energy dependence of countries on non-renewable energy sources, the development of local economies and sustainable technologies.

Ethanol

Ethanol or ethyl-alcohol is an organic compound obtained by fermentation of sugar. Ethanol used as fuel is most commonly produced from grain, corn, barley or wheat. It can be mixed with gasoline to increase octane and reduce emissions of harmful gases. Ethanol mixed with gasoline as a motor fuel is used in Brazil since 1970. Besides cities in Brazil, some of the cities in their public transport buses are powered with ethanol as Stockholm, San Paulo, Nanyang and Madrid. The most important positive characteristics of ethanol are low emissions and reproducibility of the origin of this fuel, while the negative attributes are reflected in higher fuel consumption and engine modifications.

Bioethanol

Similar to ethanol, methanol is obtained by processing agricultural and forest waste, or by other methods (oxidation of methane from natural gas, etc.). Bioethanol is well known to the automotive industry since the 60's of the last century, from when it has been used in race cars. In order to methanol could be used in combination with gasoline, it is necessary to make engine corrections, that is one of the main obstacles when it comes to wider use - is mostly used in China and in the US, while in Europe bioethanol is application to a limited extent (Sweden is the largest producer of the fuel).

Biodiesel

Biodiesel can be obtained by processing crude petroleum, but also from natural oils (algae, animal fats, sunflower, rapeseed, soybean, etc.), which classifies it into category of "clean fuel". Biodiesel is significant because it is biodegradable, burning releases considerably less carbon-monoxide and nitrogen-oxide compared to standard fossil fuels. Also, biodiesel has a higher cetane number than diesel fuel and it does not contain sulfur. The biggest flaw of biodiesel is, when used in diesel engines (with a share of 5% biodiesel in diesel), because of its physical and chemical properties, shortens engine life. Biodiesel is widely used in Brazil, the US, while in Europe the benefits of a smaller scale.

Natural gas

Natural gas contains methane with a share of 80-90% (dry natural gas). Apart from methane, natural gas contains ethane, propane and butane and certain amounts (wet natural gas). It originated from the sludge microorganisms exposed to low pressures and effect of the bacteria in the absence of oxygen. Is widely used as fuel in industry and households, in the chemical industry, and lately in road transport, as well as a propellant. In the transport occurs in two physical states, which are: compressed natural gas (CNG) and liquefied petroleum gas (LPG).

For use in motor vehicles, compressed natural gas is compressed to a pressure up to 300 bars and more. It is quite widespread as motor fuel because with minor modifications can be used by gasoline engines. Reduced emissions and low price are the main advantages of this alternative fuel.

Liquefied petroleum gas is obtained by converting the gas mixture of propane and butane from natural gas in a liquid state. It's colorless, highly flammable and explosive. It is stored in liquid form, and during use exceeds to the gaseous state. It's interesting that the composition of liquefied petroleum gas variable depending on the season. Each country prescribes the composition of the mixture, depending on the season. Advantages of liquefied petroleum gas as fuel in the automotive industry are: small amount of carbon dioxide, nitrogen oxides, sulfur dioxide and particulate emissions during combustion. Liquefied petroleum gas is widely used in the world. In Europe Vienna is the leader in the use of this fuel in public transport passengers - almost all buses are using LPG. Apart from this case, there are numerous examples of the use of LPG in the United States (almost 20 million vehicles are using this fuel), in Japan and other countries (Italy, the Netherlands, etc.). The biggest disadvantage of of this fuel is its low calorific value, which causes high fuel consumptionleading to the need for more storage tanks that must be installed on motor vehicles.

Electricity, hydrogen and solar energy

The concept of the use of electricity to run motor vehicles has long been known, so until recently, due to the low autonomy of the batteries that drive cars, electric motors were present only in the prototype vehicle. Electric vehicles are triggered in several ways: by using the battery, a fuel cell stack, and in the last time energy of the sun.

Vehicles on battery provide energy from lithium-ion batteries that can be recharged from the mains, supplying it with electricity through special or standard connectors. Vehicle on fuel cell stack, receive electricity from the electrochemical processes in fuel cells (compressed chemical reaction of hydrogen and oxygen, with the end goal of the steam). The third most common way of getting electricity to run the motor vehicle is the energy of the sun, which is collected by the solar panels, which convert solar energy directly into electricity using photovoltaic solar cells.

Given that engine operation to the electric drive is not based on the internal combustion of fossil fuels, these vehicles are, from the standpoint of greenhouse gas emissions "the cleanest". In a broader sense, it can't be said that electricity is 100% clean because they sources of energy are often thermal and nuclear power plants that, each in their own way, greatly endanger the environment. Also, the negative impacts on the environment are reflected to the technologies and the exploitation and production of lithium batteries and the problems of environmental pollution in the event of disposing of used batteries (good news is that these batteries can be recycled).

Electric vehicles are increasingly used in the world, a few examples are the cities of Amsterdam, Reykjavik (fuel cell vehicles), Vienna, Adelaide (solar Tindo bus), Gumi, Pohang and Seoul (South Korea), Tokyo, Beijing, Shanghai, Shenzhen and others.