SMTUC, the public transportation operator in Coimbra, has tested different mixes of biodiesel in four buses under real operating conditions. By doing so, information on energy consumption and atmospheric pollution caused by emissions, as well as percentages of biodiesel tolerated by the conventional engines were collected. Furthermore, a cost-benefit analysis was carried out on the use of biodiesel versus conventional diesel. CIVITAS being a demonstration project, this measure was not be limited to a “laboratory analysis,” moreover a full-scale experimentation on regular public service lines were carried out.
The main objectives of the measure are to:
- Improve air quality;
- Reduce greenhouse gas emission in Coimbra by 2 percent;
- Decrease dependence on fossil fuels;
- Increase use of biodiesel;
- Test the reliability of various biodiesel mixes; and
- Achieve or surpass a level of 20 percent of biodiesel in the fuel mix of SMTUC fleet in the future.
During the first phase of the measure, the test parameters were established. The second phase focused on the training of the personnel that coordinate and carried out the trials, the preparation of the space and the installation of the equipment needed for the tests.
The trial phase itself was divided into three stages, in which the different fuel mixtures were tested. The first test examined a mix of 30%. The level was increased by 10 percent in each stage until a maximum of 50 percent - i.e., 30 percent (B30), 40 percent (B40), and 50 percent (B50) biodiesel mix. Fuel mix tests were conducted every 25 thousand km (roughly five months), which coincided with the scheduled maintenances of the fleet.