Assessment of environmental and economic performance of Waste-to-Energy facilities in Thai cities

Highlights

• WtE systems evaluated in Thai cities do not show very impressive results unlike the cases in developed countries.

• Selected WtE projects shows GHG mitigation and fossil resource savings potentials as compared to BAU practice.

• Financial returns from these projects are very low due to low efficiency of energy recovery and high logistics costs.

• Efficiencies of WtE plants in cities can be enhanced significantly by adopting improved designs and management practices.

• Learning through these imperfect cases would give strong inspirations to the cities to avoid similar faults.

Abstract

Waste-to-Energy (WtE) technologies seem to be an option to tackle the growing waste management problems in developing Asia. This paper presents a quantitative assessment of the environmental and economic attributes of two major WtE technologies: landfill gas to energy (LFG-to-energy) and incineration in Thai cities. Net greenhouse gas (GHG) emissions, net fossil resource consumption and net life-cycle cost (LCC) were used as the basic indicators for measuring performance of these two technologies from a life cycle perspective. The assessment found that at the current efficiency level, both the LFG-to-energy project and the incineration facility contribute to GHG mitigation and fossil resource savings as compared to the Business as Usual (BAU) practice. However, the financial returns from these operations are very low and insufficient to compensate the costs. The paper argues that substantial improvements of WtE plants can be made by adopting proper management practices, enhancing the efficiencies of energy production. Such upgrading would further reduce GHG emissions, increase fossil resource savings and strengthen the financial performance to the benefit of local governments. The authors recognize the potential of incorporating other treatment options along with WtE technologies, for moving towards more sustainable waste management approaches like integrated waste management systems.

Introduction

Rapidly growing populations have accelerated the generation rate of Municipal Solid Waste (MSW) in cities, causing this issue to become more and more crucial both for the daily management and long term sustainability of cities. The urbanisation of the world's population is set to continue: by 2025 the world's population is projected to be about 8 billion, of which nearly 5 billion will live in urban areas. By 2015, there will be 33 mega-cities in the world, and 27 of them will be located in the developing world especially in South-East-Asia [1], [2]. At present, MSW generation in Asia surpasses 1 million tonnes/day, and it is estimated that in 2025, this figure will increase to 1.8 million tonnes/day [3].

Most of the cities in developing Asia are practicing open dumping and partly controlled landfilling without gas recovery. These simple disposal methods have well-documented adverse impacts on climate change, human health and the environment and there is general agreement that improvements are needed [4], [5]. In addition, space for landfill construction is limited in and around cities. Waste therefore often has to be transported long distances out of the urban area which requires additional resources and increases operation costs [6].

Climate change is a global issue of increasing importance and urgency, thus leading cities in developing Asia need to plan climate-abating waste management plans [7]. Energy recovery from waste could be an option for greenhouse gas (GHG) mitigation as this energy would meet some of the increasing energy demands in cities while minimising long-distance waste hauling that consumes a great deal of energy. Therefore, it would appear that developing cities in Asia are strong candidates for refining renewable energy from waste streams as this would contribute to gradually replacing traditional petroleum refineries [8]. There is a fast-growing trend in Asia to move towards properly designed and managed sanitary landfills with gas recovery systems since such projects both provide an opportunity to generate renewable energy and opportunities to receive financial support through carbon financing [9]. In addition, some developing Asian cities are interested in waste incineration, which reduces waste mass by 75% and volume by up to 90%, as a solution to the acute lack of landfill sites. The prospects of improving sanitary conditions combined with the expected financial benefits from energy recovery add further to this interest [10], [11]. Incineration would directly eliminate methane emissions from anaerobic degradation of waste at landfill sites and could also displace some fossil fuel-based electricity generation. Due to all these reasons, there is growing interest in the application of these technologies as a near-term solution to the growing waste management challenges in developing Asia.

In general, the application of WtE technologies which are well-designed to suit the local situation would contribute to GHG mitigation, energy recovery and reducing health risks. Efficiency of energy recovery would strongly effect the significance of achieving the environmental and economic co-benefits [12]. However, inefficiencies are a common obstacle in most of the cases of failure in developing Asia [9], [13]. For instance, there is a high possibility of failure if these technologies are implemented in developing countries without proper adaptation to local conditions since these are designed mostly for the situation in developed countries. Further, these technologies are relatively expensive treatment options in waste management due to high capital investment and high operating and maintenance costs. Therefore, the design phase of any kind of WtE project is very important for careful selection and adaptation of technologies which best suit the local conditions. This study assessed the environmental and economic performance (GHG emissions, fossil energy consumption/savings and financial returns to local entities) of two WtE technologies based on data from currently operating facilities in Thailand. Further, possible improvements have been suggested for enhancing the efficiency of WtE technologies for improving environmental and economic benefits. The research findings would be beneficial to all levels of stakeholders in waste management for understanding the common issues of WtE technologies in developing Asia and also for identifying opportunities for strengthening the financial returns and environmental benefits. It should be noted that the toxicological effects of pollutants emitted from incineration has been the subject of much debate in many countries. Therefore, such toxicological effects and the potential for implementing efficient pollution control devices should be a topic for future studies.