The main aim of the BieBus project was to contribute to the understanding of the emission of new harmful compounds associated with the combustion of bioethanol via measurements, air dispersion model and integrated analysis. The evaluation of the results and the development of new methodological approaches has provided greater knowledge about the impact of climate change policies and abatement strategies on urban air quality. However, new questions and uncertainties are also raised, and they point out the need for additional research in the field of impact of alternative fuels on urban air quality.
The project has been going from 2011 to 2014, when different activities were implemented.
The work was originally divided in four different work packages dedicated to management and dissemination (WP1), measurements (WP2), modelling activities (WP3) and impact assessment and cost evaluation (WP4). The last year of the project (2014), the work focussed on the modelling activities.
Innovative measurement campaigns were performed in a pilot study in Oslo to contribute to the understanding of the consequences associated with the use of bioethanol-blended fuel (E95) on a series of pollutants.
The highlights from the measurement campaigns are:
Higher ambient levels of harmful compounds (i.e. aldehydes) were measured at locations exposed to bioethanol-fuelled buses (E95) than at locations not exposed
High acetaldehyde and acetic acid values were measured from the exhaust pipe during driving conditions and modelled at close distance to the bioethanol bus
Human exposure to high concentration of acetaldehyde is expected, and it may involve a significantly increased chance in developing cancer. The high concentration of acetic acid will involve odour annoyance and significant material degradation or corrosion
Emission and air dispersion modelling of acetaldehyde associated with bioethanol fuel vehicles were additionally performed.
Two scenarios of bioethanol implementation, both realistic and hypothetical, were considered under winter conditions; 1) realistic baseline scenario, which corresponds to the current situation in Oslo where one bus line is running with bioethanol (E95; 95 % ethanol – 5 % petrol) among petrol and diesel vehicles; and 2) a hypothetical scenario characterized by a full implementation of high-blend bioethanol (i.e. E85) as fuel for transportation. The most relevant results from this activity are:
The results indicate that a full implementation of bioethanol will have certain impact on urban air quality due to direct emissions of acetaldehyde. Acetaldehyde emissions are estimated to increase by 233 % and concentration levels increase up to 650 % with regard to the baseline
In addition, formaldehyde (known carcinogenic compound) levels were modelled in the dispersion plume and at close distance to the bus, resulting in levels above 1 ppm (permissible exposure limit 8-hours) and 0.8 ppm (threshold for cytotoxic damage) at close distance to the bus. This indicates that formaldehyde associated with emissions from bioethanol fuel vehicles may be a concern for human health. An impact pathway approach for estimating an economic value on undesired pollution effects of acetaldehyde associated with the combustion of bioethanol fuelled vehicles was also developed.
The approach rests on results obtained in the measurement campaigns and by the air pollution dispersion model, followed by an impact assessment and economic valuation of the potential negative externalities.
The carcinogenic risk from long-term inhalation exposure to acetaldehyde emissions, leads to a significant cost estimate associated with the combustion of bioethanol in vehicles in Oslo. The total cost per average incidence of oral, nose cavity, and laryngeal cancer is estimated between 9.7 and 11.9 million (2013) NOK (€ 1.3 million - € 1.6 million). Productivity and welfare loss is the dominant cost component, whereas the direct medical cost constitutes only a small part, accounting for less than 7 % of this estimation.
The project assessed the fuelling of public busses by bio-ethanol. This is a base for transport policies on national, regional and local level to support the better kind of propulsion for public transport.