Constraints Resulting from the Linkage of Resources

A central focus of this book has been to explain how most, if not all, of the options for meeting future demand turn out to have consequences for resources other than that which is targeted. These resource "linkages" can severely constrain potential solutions. Because all major resource categories are challenged in this way, a quantitative understanding of the linkages is very important for exploring pathways toward sustainable development. At present, this is a strikingly underdeveloped research activity, although a realization that the availability of a specific resource may be constrained by a supporting resource is beginning to appear in the literature (e.g., Stokes and Horvath 2006; Feltrin and Freundlich 2008; Field et al. 2007; Sovacool and Sovacool 2009).

A first group of examples of linkage constraints is related to the ongoing urbanization of populations. It is expected that the share of people living in cities will increase. From a sustainability point of view, this is not at all a bad thing: concentrating people means that services can be provided much more efficiently. However, the population density in urban areas implies that there will be an increased need for infrastructure, such as industrialized water supplies and wastewater treatment facilities, because water availability as well as quality are major issues in urban areas. Typically, water infrastructure has a high energy demand, however, and the required infrastructure has significant material requirements. Emission reduction technologies attached to waste and water treatment plants, power plants, and other such large-scale facilities are necessary in urban areas to prevent further environmental deterioration. If implemented on a large scale, the quantity of materials involved is large. The use of emission reduction technologies, such as CCS, may reduce CO2 emissions, but it also reduces energy efficiency considerably.

A second cluster concerns the rising demand for virtually all resources, linked to an increased difficulty in accessing resources. Declining ore grades, as mentioned above, have substantial energy and water implications. Biomass supply for a growing population (food and energy' may lead to increased pressure on land as well as on water resources; agriculture already accounts for 70% of the world's total water use. To offset a declining supply and meet future demand, energy-intensive efforts (e.g., purification of polluted resources or desalinization of seawater' may be needed to ensure the water supply.

A third set of issues relates to the envisaged energy transition: the viability and upscaling of alternative energy pathways. To supply the world with a significant share of bioenergy, for example, biomass production will have to rise by an order of magnitude. A shift to bio-based energy, therefore, has dramatic implications for land and water use, and is likely to encounter constraints quite quickly. A shift to solar energy appears to be a more sustainable solution. However, present photovoltaic technologies utilize several metals whose long-term supplies are uncertain. A large-scale transition to solar energy technology may therefore be negatively impacted by constraint in rare metal resources.

A fourth category of linkages concerns the possible impairment of resource supply due to environmental degradation that results from the use of (other' resources. A continued use of fossil energy sources, for example, may harm the potential for biomass production via climate change, especially via changes in precipitation patterns. Water quality degradation may increase as a result of the agrochemicals needed to secure the (increased' supply of biomass. Similarly, the increased need for mining can have consequences for water depletion and water quality degradation, especially when mines are located in water-poor regions.

Once we appreciate that linkages among resources can impose constraints to sustainability, the next issue is to ask to what degree the linkages have been explored, qualitatively and quantitatively. Any such assessment will inevitably be incomplete, but here we examine those addressed in this book, by which we infer that the authors have identitied most or all of the extant studies.

Table 25.1 lists the linkages discussed in this book, where we adopt the relationships between resources and functionality as originally proposed by Baccini and Brunner (1991). The degree to which those linkages relate to the conceptualization proposed in Chapter 1 is illustrated in Figure 25.1 in three different groupings. Figure 25.1a shows the linkages that have been quantified:

1. The energy necessary to extract and process metal ore. The relationship that was used applies to Australian mines; this appears to be the only such data publicly available.

2. The water necessary to extract and process metal ore. Again, the relationship that was used applies to Australian mines; this appears to be the only such data publicly available.

Table 25.1 Identified linkages among resources.

Function

Resource

Supporting resource

Source (this volume)

Nourishment

Water (drinking)

Energy

Lindner et al., De

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