Volume 14 [2012]

The introduction to the European Market of biodiesel blends along with the minimization of the
sulphur content in automotive diesel has rejuvenated the research interest on the microbial stability
of diesel fuel. Several microorganisms are able to metabolize hydrocarbons contained in
conventional fuels and particularly in diesel and jet stocks. With the advent of FAME (Fatty Acid
Methyl Esters) as a diesel fuel substitute there has been an increase in the number of samples
suspect of microbial contamination with confirmative results. The aim of this study was to investigate
the microbiological stability of FAME/diesel blends and consequently the impact of microbial
proliferation on their quality. A commercially available FAME was blended with Ultra-Low Sulphur
(ULSD) and Low Sulphur (LSD) conventional automotive diesel fuels in mixing ratios of 5, 10 and 20
% v/v. The resulting blends were contaminated with bottom-water of known viable microbial colonies
and were stored for a period of 16 weeks. During storage the microbiological growth was evaluated
by employing both semi-quantitative and quantitative methodologies. At the same time the
devolution of certain quality parameters, namely oxidation stability and acid number, which could be
influenced by microbial growth was examined. The overall results reveal the need to establish a
scheduled inspection plan adapted to the diesel fuel supply chain infrastructure aiming to control and
remedy efficiently the microbiological growth issues.
KEYWORDS:

In order to assess the influence of reducing the speed limit from 50 km h-1 to 30 km h-1 in one-lane
streets in local residential areas in large cities, real traffic tests for pollutant emissions and fuel
consumption have been carried out in Madrid city centre. Emission concentration and car activity
were simultaneously measured by a Portable Emissions Measurement System. Real life tests
carried out at different times and on different days were performed with a turbo-diesel engine light
vehicle equipped with an oxidizer catalyst and using different driving styles with a previously trained
driver.
The results show that by reducing the speed limit from 50 km h-1 to 30 km h-1, using a normal driving
style, the time taken for a given trip does not increase, but fuel consumption and NOx, CO and PM
emissions are clearly reduced. Therefore, the main conclusion of this work is that reducing the
speed limit in some narrow streets in residential and commercial areas or in a city not only increases
pedestrian safety, but also contributes to reducing the environmental impact of motor vehicles and
reducing fuel consumption. In addition, there is also a reduction in the greenhouse gas emissions
resulting from the combustion of the fuel.

The transport sector in Greece has the largest share in the final energy consumption and the
resulting emissions are one of the main sources of atmospheric pollution. This situation is worse in
the region of Attica, where nearly half of the country’s private cars circulate in an area equal to 3 %
of the total country area; the region’s climatic and geomorphological characteristics further aggravate
the environmental problem.
This paper examines energy saving and environmental impacts reduction from the penetration of
eco-friendly technology passenger cars in this region. Three vehicle technologies are considered: (i)
conventional hybrid electric vehicles, (ii) battery electric vehicles and (iii) fuel cell electric vehicles.
The influence of the driving cycle is examined through the comparison of two different cycles, the
New European Driving Cycle (a regulatory driving cycle) and the Athens Driving Cycle, based on
actual driving data.
Two alternative scenarios are formulated. The first involves the substitution of all the passenger cars
that were registered during the last year (2010) with hybrid and battery electric vehicles that already
exist in the Greek market. The second scenario examines the penetration of fuel cell electric
vehicles. Both scenarios are evaluated on the basis of their expected energy savings and
greenhouse gas emissions reduction. A 7.5 % to 9 % reduction of the CO2 emissions is expected,
for the Athens Driving Cycle, if these measures are applied in a five year period.

Municipal Solid Waste (MSW) management is the field of science which explores and evolves
strategies minimizing the final amount of wastes delivered to landfills and reducing the corresponding
pollution related to all stages of treatment and collection. In the best practices of MSW the inherent
energy of wastes is being recovered. In this study, the most appropriate energy recovery methods
utilizing MSW for Greece (i.e. Sorting plant at landfill site with biogas recovery and RDF production,
Incineration of MSW with small pre-treatment and Controlled landfill site with biogas recovery) are
investigated based on the composition of wastes, the compatibility of the methods with the EU
legislation, their technical availability, energy recovery capacity and contribution to the national
energy balance, as well as economic issues, the maturity of the technologies involved and the land
occupation requirements. A detailed multi-criteria analysis is applied considering the expected MSW
production of Greece until 2020 along with different scenarios of waste utilization. Based on the
results obtained, as well as on the elaboration of a sensitivity analysis, the “Controlled landfill”
method is designated as the most prevalent energy recovery method for Greece, although under
specific prioritization of the main parameters involved, the “Incineration” may be equally appropriate
as well.