Conclusions

Jo Dewulf and Herman Van Langenhove

19.3 Introduction

Although the word did not exist as such, renewables have been the main sources for energy and material supply in societies for many centuries, and this roughly until 1850. With the start of the era of power machines based on coal and other fossil fuels (first coal, later oil), the predominance of renewables decreased. The explosive growth of mainly the organic chemical industry after World War II, driven by the production of fossil fuel-based polymers, further reduced the role of renewables. However, in the last decades of the twentieth century, some drawbacks of the fossil resource-based society became obvious. Although non-renewables undoubtedly have contributed tremendously to the welfare, it became obvious that gaseous, liquid and solid emissions into the environment had detrimental effects (Chapter 1). Environmental concerns expressed by pressure groups and supported by the public forced the authorities to undertake environmental regulations on emissions. This resulted mainly in the 1980s and 1990s in environmental technology (mainly end-of-pipe approach), enabling gas, liquid and solid waste treatment. At the end of the twentieth century, the sustainability issue became widespread in the society. It became accepted wisdom that technology not only should perform well in terms of preventing emissions, but also that it had to be rethought in a broader perspective. Based on the concept of sustainability, it is clear that, with a growing world population, an increasing standard of living and with long-term detrimental effects caused by fossil resources, particularly global warming, renewable resources are ready to make a comeback after 150 years. According to scenarios developed by academics and industry, the share of renewables of about 50% is expected in 2050.

Chapter 2 demonstrated that renewables indeed have the potential to play a significant role as resources for energy and materials. In our free market economy, the condition sine qua non for the introduction of more renewable resource-based technology will be cost effectiveness. The growing industrialization of especially Asian countries is raising the demand for energy and materials, whereas it is expected that fossil resources will not be able to cope fully with this growing demand. This situation may lead to an acceleration in research and development of renewables-based technology.

Attention is drawn to the fact that ‘renewables’ as such is a quite vague term, covering biomass, wind, solar and hydropower. Basically, the engine of renewable resource production is the sun, inducing biochemical processes (biomass growth) and physical processes in the atmosphere resulting in wind and precipitation. Both biochemical and physical processes lead to a large diversity of ‘renewables’. Chapter 2 illustrates that this wide range of resources can be used both for energy and material purposes. It is shown that the renewable resources can be divided into two main groups. First, there are the pure energy resources delivering predominantly electricity: solar radiation, wind and hydro­power. Second, there is biomass, which can be a resource for both energy and materials. Biomass is a much more complex renewable resource, with traditional applications of food and materials such as wood and cotton. However, in the past decade, two major new applications of biomass have been developed. First, new materials have been developed from biomass. A typical example is biodegradable polymers such as corn-based polylactic acid plastics. Through fermentation of corn, followed by polymerization, renewables – based plastics are manufactured and commercialized by NatureWorks LLC (formerly Cargill Inc.). Finally, regulations on solid waste disposal and growing energy prices have given an incentive to valorize the energy content of biomass material in solid waste streams.

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