A review of multi-criteria decision-making methods for bioenergy systems

Abstract

Bioenergy schemes are multi-faceted and complex by nature, with many available raw material supplies and technical options and a diverse set of stakeholders holding a raft of conflicting opinions. To develop and operate a successful scheme there are many requirements that should be considered and satisfied. This paper provides a review of those academic works attempting to deal with problems arising within the bioenergy sector using multi-criteria decision-making (MCDM) methods. These methods are particularly suitable to bioenergy given its multi-faceted nature but could be equally relevant to other energy conversion technologies. Related articles appearing in the international journals from 2000 to 2010 are gathered and analysed so that the following two questions can be answered. (i) Which methods are the most popular? (ii) Which problems attract the most attention? The review finds that optimisation methods are most popular with methods choosing between few alternatives being used in 44% of reviewed papers and methods choosing between many alternatives being used in 28%. The most popular application area was to technology selection with 27% of reviewed papers followed by policy decisions with 18%.

Introduction

Bioenergy remains a fringe technology when compared with fossil fuel sources for many developed countries. However this situation could change rapidly with the continuation of attractive financial subsidies combined with market forces moving the interest of power suppliers and transport fuel producers towards the bioenergy resource. It is well recognised that the large scale expansion of biomass use for energy (heat, transport or power) can result in negative impacts upon the environment, society and the economy. The misuse of this resource creates many short and long-term problems which could outweigh the climate change benefits available from using these conversion technologies. Proper and sustainable management of bioenergy systems is therefore required.

The problems around managing, designing and implementing a bioenergy scheme are complex and multi-faceted. There are many stakeholders for each project and many requirements that must be satisfied for the successful long-term operation of a project. This multi-stakeholder, multi-requirement nature of problems regarding bioenergy [1] lends itself well to the application of multi-criteria methods. The intention of this paper is to systematically classify the existing literature using multi-criteria methods to address challenges in the bioenergy industry. To do so this review will address the following two questions: (i) Which methods are the most popular? (ii) Which problems attract the most attention? The answers to these questions will give an indication of current trends in research and the best direction for future research in order to further address the known barriers to bioenergy implementation. The bioenergy resource and related conversion technologies represent a major opportunity for the sustainable production of energy and is a route to meeting national carbon reduction targets. As governments continue to aim towards such targets decision making for bioenergy is likely to be a growing area of concern for governments, developers and utilities as well as the general public in the coming decades.

Given the expected rise in the importance and rate of decisions being made in the bioenergy sector and the complexity of the systems being designed there is a clear application for decision making methods to be applied. Decision support systems (DSS) cover a wide and heterogeneous range of tools used for assisting decision makers. According to Alter (1980 p.71) [2] referenced by Power (2002, p.9) [3] a DSS can “take on many different forms and can be used in many different ways”. The purpose of a decision support system is not to replace the decision maker but rather aid the decision making process by presenting complex and interlinked data in a way which allows the impacts of different choices to be more clearly understood. Decision support systems and multi-criteria decision making methods have been used to great effect in other energy industries to assist in decision making. The wind industry for instance has benefited greatly from the development of DSS software packages [4], [5] which cut down on development time and create a platform for understanding between different interested parties. Energy models in general are reviewed by [2] whilst Zhou et al. [3] observe a growing proportional application of MCDM methods to the topics of electricity and renewable energy between 1975 and 2004.

Bioenergy project developers must interact with a wide reaching and complex system to bring a project to a stage where it is ready to construct. Decisions must be made regarding which technology should be used, which fuel sources should be contracted, how materials should be stored and transported, the capacity of the scheme and how the finances of the project are best managed and the choices made can impact on future decisions. For some of these decisions support systems already exist from other disciplines such as project finance or logistics. However other decisions are unique to the bioenergy industry. Many of the papers reviewed here offer some method which could be used to support the design of projects or decisions within the planning phase of bioenergy schemes, even if they are not explicitly described as DSS.

Previous reviews exist on decision making in renewable energy and biomass. Notably Baños et al. [6] presented a review of optimisation methods that have been applied to sustainable energy. This review differs from that of Baños et al. [6] as it focuses on multi-criteria methods only and also on those applications regarding biomass and bioenergy. Wang et al. [7] presented a review paper of multi-criteria methods for renewable energy although in this case the review aimed to collect the different criteria which have been used by different authors, similarly to Baños et al. [6] the scope of the review is not focused on a particular technology. Iakovou et al. [8] presented a review in the related area of energy from waste biomass which aimed to identify which barriers are being faced by that industry. This paper is different as the reviewed studies here cover a different scope and are focused on the methods to solve problems rather than the barriers being faced by industry.

This paper is organised as follows. Section 2 presents the procedure used to search for and identify the papers for review. Section 3 describes how the papers have been categorised and sections 1 Introduction, 2 Research methodology, 3 Classification of papers give more detail on the reviewed articles. Section 4 discusses which methods have been used to address each problem and Section 5 shows which problems attract the most attention. Section 6 describes other observations made on the reviewed literature including year of publication and national contexts studied. Section 7 gives recommendations for future research direction. Finally Section 8 gives a conclusion to the paper.