Aiga Barisa

Waste-to-biomethane Concept Application: A Case Study of Valmiera City in Latvia

Abstract The current needs of sustainable urban development are rising. As the transport sector expands, emissions continue to rise. Due to their negative impact on human health and the environment, air quality requirements are becoming more and more stringent. At the same time, the amount of waste is increasing. Europe Union policies attempt to relieve the pressure that these two stressors place on urban systems as they themselves expand. Today different solutions are available to decrease greenhouse gas emissions, increase air quality and improve waste management systems. Among them, waste-to-biomethane for use in urban systems deserves more attention. The paper focuses on application of the concept of waste-to-biomethane and the case study of Valmiera is evaluated. The results show that the application of the waste-to-biomethane strategy can contribute to a complete substitution of diesel fuel in urban buses and gives savings of around 1,000 tCO2/year. The price of the biomethane was found to be the most sensitive input factor. It is suggested that it should not exceed 0.40 EUR/Nm3 for a fuel conversion project of a fleet of 10 vehicles. Such a price can be ensured, if dry fermentation technology is chosen for biogas production. However, from the sustainability perspective, wet fermentation is more preferable due to the introduction of a source-separated organic waste management system in the region and higher gas yields. Introduction of this alternative requires additional funds which is a question of policy-level decisions.

Modelling transition policy to a sustainable regional transport system: A case study of the Baltic States

Purpose – The purpose of this paper is to address the difficulty of implementing the European Union renewable energy policy in the transport sector. The authors describe a case study illustrating the capacity of the three Baltic States to meet the binding target of 10 per cent renewable energy in the transport sector by 2020. Design/methodology/approach – An excel-based mathematical model is developed and applied to evaluate the effect of a selected set of measures according to the sustainable transportation concept. Findings – The findings demonstrate that the projected renewable energy targets in the transport sector of the Baltic States cannot be achieved without unwavering political commitment towards the promotion of alternative fuel vehicles. Increasing the share of mandatory biofuel blends has a major effect, however, it is not enough to meet the 10 per cent goal. Other measures such as lower transport demand and mode shift are included but do not offer significant benefits under a realistic scenar...

Research of Woody Biomass Drying Process in Pellet Production

Abstract This paper presents results of experimental research on wood chips and sawdust drying in a rotary dryer. Empirical models for the assessment of two dependent parameters of the drying process were created based on the results of experimental data. The mathematical description of the relationship between the independent variable - reduced sawdust moisture content - and dependent variable - specific fuel consumption - is represented by a linear equation.