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In the 80's, due to the oil crisis, natural gas (NG) began to be regarded as a fuel with great potential for replacing diesel in heavy duty vehicles. At that time, Petrobras, together with other companies, developed conversion kit technology for heavy duty diesel engines to run burning simultaneously diesel and NG, known as diesel gas. For several reasons, the trials were interrupted. In the late 90's and beginning of the 2000's, factors such as NG availability, expansion of NG distribution network; increase of NG converted light duty vehicle fleet, government interest in increasing NG's energy matrix share, all together made a scenario which stimulated new developments in diesel gas technology. The scenario changed in the last couple of years, with Brazilian NG demand reaching its offering, mainly due to thermoelectricity generation guarantee of supply. This makes the diesel gas technology more attractable than the NG dedicated technologies.

Uncertainty in measurements is a complex issue to obtain accurate results in vehicle fuel consumption tests. Petrobras Research Center carried out a study to calculate the final uncertainty of measurement during a vehicle fuel economy test following a feasible method that can be used in many laboratories. This study was based on the ISO-GUM (Guide to the expression of uncertainty in measurement) and on the Brazilian legislations ABNT NBR-6601 (pollutant emission) [1] and NBR-7024 (fuel economy tests) [2].

In the last years, world's general concern about climate changes and their effects on human life has strongly increased. Some countries, such as European Union members and the USA, are improving their legislations in order to limit vehicular CO2 emissions. To comply with these limits, new vehicle and fuel technologies are being developed in many places. Thus, the main goal of this paper is to present a comprehensive overview of some of these technologies for light-duty vehicles based on international published references and some experiences of Petrobras Research Center (CENPES). Also, this work addresses to some regulatory initiatives, such as new CO2 emission legislations and fuel economy labeling programs.

Due to worldwide concern regarding greenhouse gases emission, mainly CO₂, automakers are developing new technologies to reduce vehicles' fuel consumption. One of the most promising technologies, growing fast in USA, Japan and Europe is the Hybrid Electric Vehicles (HEVs). In the Brazilian Market, HEVs availability is still absent, which causes uncertainties about possible impacts caused by the introduction of this new vehicle technology in the big cities. However, as requirements of non-pollutant technologies arise, HEVs are expected to be available in Brazilian Market in the next years. Within this scenario, in 2002, aiming to evaluate the adequacy of Brazilian Gasolines blended with up to 25% v/v of Ethanol in HEV technology, Petrobras Research and Development Center (CENPES) purchased from USA a 2002 Toyota Prius and a 2002 Honda Insight. Since then, both HEVs are being tested at CENPES's Vehicle Test Laboratory (LEV).

In 2005, it was published a paper in Brazil reporting significant values of aldehydes emissions for some old Brazilian diesel SUVs (Sport Utility Vehicles). In 2008, PETROBRAS (Brazilian Oil Company) together with LACTEC (Institute of Technology for Development) decided to study methods for measuring aldehydes from diesel vehicles, including SUVs and heavy-duty engines. In 2008, National Environmental Council (CONAMA) published legislation 408/08, establishing that IBAMA (Brazilian National Environmental Institute) must provide a procedure for aldehyde measurement at the end of December 2010 and that engine manufacturers must report typical aldehyde emission values of diesel vehicles before the end of December 2012. A technical group was created in 2009 by the Brazilian Automotive Engineering Association (AEA) to discuss and elaborate a new method for aldehyde measurement in diesel vehicles and heavy-duty engines. The new procedure must be published before the end of 2010.

The automobile industry has developed and marketed hybrid electric vehicles (HEV) internationally for over 10 years. The presence of batteries in these vehicles poses difficulties for their approval in laboratory trials. The difference between the initial and final battery state of charge changes the energy balance measured in the tests, affecting the emissions and fuel economy levels. Two proposals have emerged to address this problem. One is described in ISO 23274, which consists in determining and applying a correction factor to the emissions and fuel economy results. This factor is based on the difference between the initial and final battery state of charge after the test. The other is described by SAE J1711 which consists in conditioning the battery, in order to equal the state of charge level at the end and start of the test, avoiding the factor recalculation.

Natural gas (NG) produced in the Urucu area (Amazon Forest) has low methane and high nitrogen and therefore does not meet current NG specifications for vehicular use, as established by standard number 104 of ANP (National Petroleum Agency). This paper reports the steps for these NG conversion kit adjustments and also the results and comparisons of vehicle performance, emissions and fuel economy tests on a chassis dynamometer. The vehicles were tested with different fuels like regular NG, Amazon Forest NG, gasoline and ethanol. The results were presented to ANP that authorized in the beginning of 2005 the experimental use of the Urucu natural gas for 30 months. Also reported on this paper is an overview of the Brazilian NG fleet, present and future emission legislation, fuel specification, new trends on NGV (Natural Gas Vehicle) market and conversion kit technologies. Updated information is included regarding the experimental project of Urucu natural gas that is running on Manaus city.

Due to the worldwide trends to develop new automotive technologies for vehicle emissions and fuel consumption reduction, and because PETROBRAS (Brazilian Oil Company) decided to act as an energy company, CENPES (PETROBRAS Research Centre) imported two hybrid electric vehicles (HEV) to study this technology. The main objective was to verify if Brazilian gasoline (which is blended with 25% ethanol) was adequate to use with hybrid electric vehicles. Preliminary emissions tests with both vehicles, following the FTP-75 cycle, indicated a significant variation in the results, motivating further research to study the problem. It was verified that one of the main causes for this poor repeatability was the battery charge level of the hybrid system at the beginning of the emission tests. Based on this conclusion, CENPES studied ways to develop procedures that could guarantee the same initial conditions for the battery in emissions tests and also how battery charging system works.

Natural gas (NG) produced in the north of Brazil (Amazon Forest) has low methane and high nitrogen and therefore does not meet current NG specifications for vehicular use, as established by ANP (National Petroleum Agency). This paper reports the steps for NG conversion kit adjustments and also the results and comparisons of vehicle performance, emissions and fuel economy tests on a chassis dynamometer. The vehicles were tested with different fuels like regular NG, Amazon Forest NG, gasoline and ethanol. Also reported on this paper is an overview of the Brazilian NG fleet, present and future emission legislation, fuel specification, new trends on NGV (Natural Gas Vehicle) market and conversion kit technologies.

The worldwide concerns and some countries stricter legislations regarding the CO2 emission of light duty vehicles are motivating new technologies adoption, such as hybrids and electric battery vehicles, and discussions about what fuel economy data comparison between different countries. International discussions were done about the need to reevaluate the existing standardized driving cycles due to large emission and fuel economy differences when compared to the real road values, leading to the creation of a new cycle called WLTC (Worldwide Harmonized Light Duty Vehicle Test Cycle). Light duty vehicle fuel economy tests are usually performed on a chassis dynamometer using standard driving cycles under controlled laboratory conditions. Each country regulation defines the standard cycles used for the fuel economy tests.

Hydrogen is considered one of the cleanest solutions for sustainable mobility. This paper presents an overview of some of these applications, such as internal combustion engines, fuel cell application and also blends of hydrogen and natural gas. This paper addresses questions regarding hydrogen properties such as net heating value, flame speed, power density, range of flammability and ignition energy. Also, the paper will draw a comparison between H2 and fossil and biofuels, such as ethanol. Questions regarding storage conditions, emissions levels, Internal Combustion Engine (ICE) air/fuel ratio among others are expected to be covered as well.