Elsevier

Energy Policy

Volume 37, Issue 11, November 2009, Pages 4220-4230
Energy Policy

Future bio-energy potential under various natural constraints

https://doi.org/10.1016/j.enpol.2009.05.029Get rights and content

Abstract

Potentials for bio-energy have been estimated earlier on the basis of estimates of potentially available land, excluding certain types of land use or land cover (land required for food production and forests). In this paper, we explore how such estimates may be influenced by other factors such as land degradation, water scarcity and biodiversity concerns. Our analysis indicates that of the original bio-energy potential estimate of 150, 80 EJ occurs in areas classified as from mild to severe land degradation, water stress, or with high biodiversity value. Yield estimates were also found to have a significant impact on potential estimates. A further 12.5% increase in global yields would lead to an increase in bio-energy potential of about 50%. Changes in bio-energy potential are shown to have a direct impact on bio-energy use in the energy model TIMER, although the relevant factor is the bio-energy potential at different cost levels and not the overall potential.

Introduction

Climate policy, concerns about energy security, and the search for alternative sources of agricultural income have greatly increased interest in bio-energy as an alternative to fossil fuel. Many scenario studies with and without climate policy constraints project substantial increase in bio-energy use, and thus significant transformation of both energy systems and land use (see Fisher et al., 2007; IEA, 2006; van Vuuren et al., 2007). However, the implications of bio-energy is the subject of long-standing and fierce debate (see also (Azar, 2005; Boddiger, 2007; Dornburg et al., 2008; Giampietro et al., 1997; Patil, 2007; Scharlemann and Laurance, 2008; Searchinger et al., 2008; Slesser and Lewis, 1979; Smil, 2003; van Vuuren et al., 2008). The outcomes of this debate may critically influence the rationale for bio-energy and ultimately determine the future use of this energy source. Crucial issues include the greenhouse gas balance of bio-energy and the environmental implications of large-scale bio-energy use (see Section 2).

Several studies have published estimates of potential and actual use of bio-energy under different scenarios (Behringer and Lucht, 2008; Berndes et al., 2003; de Vries et al., 2007; Hoogwijk, 2004; McCarl et al., 2004; Rogner, 2000; Smeets and Faaij, 2004; Smeets et al., 2007). These studies generally take into account factors such as demand for alternative land use and attainable yields in estimating biophysical potential, while the economic potential is determined by production costs and development of international climate policy. However, other factors such as water scarcity and land degradation have been largely overlooked, leading to potential overestimation of both biophysical potential and associated cost. We have re-evaluated our own estimates of bio-energy potentials by using a sensitivity analysis to explore how some uncertainties with respect to bio-energy that could influence its future use. We have taken into account yield estimates and land-use scenarios, land degradation, water scarcity and biodiversity constraints. Firstly, we focused on the potential impact of these factors on the biophysical potential. Secondly, we explored the effect of climate policies on future use of bio-energy, taking into account the uncertainty of the biophysical potential.

Section snippets

Controversies about bio-energy use

Recent political interest in promoting large-scale bio-energy use has fueled the debate on the consequences of this energy source. Key factors in the debate include: (1) the issue of whether bio-energy and, especially, transport fuels make a net positive contribution to greenhouse gas emission reduction or even to energy use; (2) the consequences of large-scale bio-energy production for land use including indirect impacts and thus on food production and biodiversity; (3) the consequences for

Procedure to estimate bio-energy potential

The integrated assessment model IMAGE 2 and the global energy model TIMER have been used to estimate the technical and economic potential of bio-energy. For a brief description of IMAGE and TIMER, see Appendix A. An overview of the methodology used in this study is presented in Fig. 1 and described in detail elsewhere (de Vries et al., 2007; Hoogwijk et al., 2004). First step was to assess, which, areas can be used for bio-energy production based on physical-geographical characteristics and

Impact of different scenarios

Land-use development under the OECD scenario (Fig. 2) shows that the total agriculture area worldwide including extensive grazing is expected to increase significantly, mostly at the expense of forests and grasslands. In our analysis, bio-energy potential was confined to abandoned agriculture and natural grasslands. While the former increases with time, the latter decreases. We assume that most of the first category is available for bio-energy production and only part of the second (see

Conclusion and discussion

There are controversies with respect to future bio-energy use. Obtaining insights into the consequences of large-scale bio-energy is complex because of the large number of factors involved. One method used to assess available bio-energy potential is bottom-up potential estimates. Such studies result in bio-energy estimates of several hundreds EJ per year in the second half of the century, but do not take into account issues such as land degradation and water scarcity. A simple sensitivity

Acknowledgements

The authors acknowledge the support for this work as part of the “Bio-Energy Assessment Project” funded by the Scientific Assessment Programme of the Netherlands Ministry of Housing, Environment and Spatial Planning. They also acknowledge the helpful suggestions provided by other researchers in the same project.

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