The type of fuel and its quality are two important components of costs and emissions to the environment of public transport, making it necessary to examine the use of cheaper and environmentally friendlier alternative fuels. Natural gas is one of them and is rapidly entering the public transportation in the world due to its low cost, abundance as it is much friendlier to the environment than petroleum.

   The amount of public transport buses operating on natural gas continues to grow in the world, not only with new buses but also buses converted from the existing fleet to a Dual Fuel type ('Bi-Fuel'). In other words, these vehicles can be used alternatively compressed natural gas (CNG) or diesel. This modification is simple and requires the installation of a conversion kit. Only in the city of Santa Cruz, Bolivia, "is scheduled to convert to natural gas for vehicles at least 7.000 buses that run on diesel." Natural gas tanks are filled in a manner quite similar to a tank of diesel or gasoline, including the filling time.

   According to the Green Car Journal, "the buses are a high-profile example of how natural gas can be successfully applied to buses of all types -urban public transport, school buses and special buses. One reason is the reduction in fuel costs compared to petrol and diesel.

   However, the benefits of clean air are also very important. The use of natural gas is often chosen as the most efficient and affordable for cities and fleets of buses to meet environmental mandates. Because the buses are often fed with fuel in a central location, infrastructure needs are not a big problem."

   The growing use of natural gas for school buses must be "primarily to clean emissions with no particulate matter from diesel, which are harmful to children. Studies have shown that natural gas buses emit 90% fewer particles compared with new diesel engines."

   Not only the costs and emissions to the environment of natural gas are much lower, but also natural gas buses require less maintenance on the engine because the combustion process is cleaner. Are achieved longer periods between oil changes and less wear on the motors, so that the lower maintenance costs means an additional saving.

   Several cities are already beginning to use also hybrid buses with natural gas and batteries, instead of diesel and batteries, which further enhances the status of costs and emissions to the environment.

   If natural gas was used in Costa Rica, reductions in costs and emissions to the environment would benefit the users of public transport, bus companies and society in general.

By Roberto Dobles, Former Minister of Environment, Energy and Telecommunications of Costa Rica.

Periódico La República

May 28, 2012