Topic 2 Energy efficiency principles

Principles of energy efficiency in public transport:

The transport sector consumes 30% of all energy used in the world. The study of different types of alternative fuels for use in public transport systems is essential to increase sustainability, reduce greenhouse gases and optimise fuel efficiency in the different existing vehicles. Currently, governments and public administrations are beginning to introduce alternative fuels capable of producing cleaner and more sustainable energy, such as electric propulsion and other types listed below.

Transport is very important for society and economic development, but it has a negative environmental and social impact due to pollution. Transport provides mobility and facilitates economic growth and trade. Environmental pollution in cities is strongly affected by the fuel type of public transport vehicles. The problem of pollution has existed since the invention of the motor vehicle, gaining in importance with the development of transport and the expansion of the use of motor vehicles and becoming a major concern of organizations concerned with environmental protection.

The sustainability and efficiency energy question in transport is not easy to answer, and thus one cannot state in advance with the most efficient  means of transport in general. The implementation of energy efficiency measures in transport aims to reduce energy consumption, with more environmentally friendly energies, thus reducing CO2 emissions.

2.1 Alternative fuels

Types of alternative fuels: electricity, hydrogen, biofuels, natural gas and liquefied petroleum gas 

An electric vehicle is understood to be one that is totally or partially propelled by an electric motor that uses chemical energy stored in batteries that can be recharged by an external source of electrical energy, and there are hybrid vehicles that combine this energy with others (petrol). One of the problems of this type of alternative fuel in public transport is the excessive refuelling time required, during which the vehicle is inoperative for its function. It has low noise emissions and part of this energy is of renewable origin. The range of autonomy is limited, and is has an high initial investment.

Natural gas is a hydrocarbon containing mainly methane. It is a fossil fuel, but has significant potential for the introduction of renewable sources. They are fuels with low pollutant gas emissions. They stand out for the reduction of noise generated during combustion and for being a more economical fuel, although the initial investment in the acquisition of the vehicle is more expensive. 

used in converted petrol engines or to power a fuel cell that acts as a battery. Is has zero local emissions of pollutants and is potentially renewable. It is an alternative fuel that is little used, because is technology is not commercial and have very hight costs.

are liquid fuels of biological origin, which due to their physical and chemical characteristics are suitable to replace petrol or diesel, either as a whole, in a mixture with the latter or as an additive in a total form, in mixture with the latter or as an additive. These products are obtained mainly from vegetable matter (by fermentation of grains rich in sugars or starch, as cereals and sugar beet). There are currently two main types of biofuels: bioethanol, which replaces petrol, and biodiesel, which can be used instead of diesel. and biodiesel, which can be used instead of diesel. The slow progress of energy crops may hinder the development of biofuels, at a price similar to that of the petrol or diesel they replace.


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Use of alternative fuels in public transport:

Although cleaner vehicles are more expensive to purchase than a conventional petrol or diesel vehicle, more and more administrations are being encouraged to use fuels in captive vehicle fleets (public transport, taxis, car sharing companies, etc.) due to the cost of fuels.

Currently, the average price of compressed natural gas or liquefied petroleum gas vehicles is 15-25% more expensive than a conventional vehicle. There may be further costs related to the infrastructure construction, operation and maintenance of refuelling stations supplying alternative fuels. Maintenance costs for upgraded, state-of-the-art filter-equipped green buses, as well as the conversion of a conventional diesel bus fleet, could lead to increased maintenance and operating costs. Furthermore, it has to be taken into account that staff needs to be trained in the maintenance and repair of new technology vehicles. In general, all new and innovative public policies face significant barriers to adoption and acceptance. All policy makers need to be fully convinced of the positive long-term benefits and the importance of their supporting measures. Cleaner vehicles initiatives should be included in long-term urban transport plans approved by local and regional politicians. It should be borne in mind that the implementation of the measures is a successful strategy to achieve the target set by all EU Member States to reduce the level of greenhouse gas emissions.

2.2 E-Mobility Concept

Electro mobility (eMobility) represents the concept of using electric powertrain technologies, in-vehicle information, and communication technologies and connected infrastructures to enable the electric propulsion of vehicles and fleets.

Market penetration of modern vehicles incorporating eMobility is still in early stages of development, with modern battery electric vehicles barely visible as part of new vehicle registrations. The curve that eMobility follows, as with other technologies, will reflect the policies that governments put in place around eMobility. In the short run, governments may wish to consider targeted interventions that provide access to eMobility. The incorporation of EV (electric vehicles) technologies into public transport fleets could be one way of achieving this. eMobility is not new to public transport. Many cities are already familiar with electrified modes such as metros, trams, and trolleybuses. Cities with an existing trolleybus infrastructure, are finding synergies with integrating battery trolleybuses in their systems.

  • The foremost challenge surrounding electric bus deployment is the need to adapt new vehicles and related charging infrastructure to networks, while maintaining the same level of service.
  • Electric bus deployment and operating requirements often differ heavily across different operational contexts. For example, topography, temperature, right of way, etc. affect performance. Selecting the right technology according to these factors is critical.
  • A key to successful electric bus deployment is finding solutions that can be smoothly integrated into the existing public transport network, without negatively impacting its daily operations. The daily mileage and route characteristics of buses that an operator may target for conversion are key considerations that determine the suitability of eMobility;
  • To date, electric buses are more relevant for urban applications with less application for long inter-city trips. However, advances in battery technology to extend travel range may change this.
  • Existing business such as mobility service providers are finding ways of integrating eMobility in to their business models. At the same time, eMobility is having a disruptive effect on traditional automotive sectors.