One of the biggest, if not the biggest, challenge facing mankind is to supply the world’s growing population with sufficient energy to meet the desired living standards in a sustainable way. Roughly 85% of the global energy supply is currently provided by combustion of fossil fuels, which are finite resources. To be able to maintain current living standards, a more sustainable, economically stable, non-fossil energy supply has to be utilized. There are various sustainable alternatives for fossil fuels. Wind, solar, geothermal, and hydro energy are abundant and we are gaining more and more knowledge about harvesting this energy efficiently. So, problem solved? One could think so. When people consider the transition from a fossil based society to a renewable based one, they often forget (read: neglect) that fossil fuels are not only used to produce gasoline and diesel(i.e., to generate energy). A significant part of petrochemical feedstock naphtha and other oils refined from crude oil is used as feedstock for petrochemical crackers that produce the basic building blocks for precursor chemicals and plastics. Wind, solar, geothermal and hydro power have the ability to provide us with energy in the form of electricity, which can be used to power our houses and cars. But they cannot provide us with the carbon building blocks to make chemical products, such as paints, pharmaceuticals and plastics. This is where biomass comes to play an important role.
Biomass can be converted into so called biobased products. According to the European Commission, biobased products are non-food products derived from biomass such as plants, algae, crops, trees, marine organisms, and biological waste from households, animals and food production. Biobased products vary from high-value added fine chemicals to high volume materials such as bioplastics. Biobased products have the potential to be account for the ‘neglected part‘ of the transition from a fossil based society towards a renewable based one. However, the choice of feedstocks is an important factor in the production process.
In general, there are two types of biomass feedstocks. ‘First generation’ biomass defines the use of the nutritional part of a food crop for biobased production rather than food purposes. Subsequently, ‘second generation’ biomass includes the use of residues of food crops, dedicated energy crops, wood and waste materials. Although ‘second generation’ biomass is more challenging to utilize, increasing pressures from nature on food security, especially in developing countries, make that only ‘second generation’ biomass is a sustainable option. Three factors should be considered while identifying the most suitable feedstock. Firstly, the biochemical composition of the biomass is important, where a high content of sugar is preferred. Secondly, the yield of biomass per hectare is important. Finally, the sustainability of the crop should be considered, taken in consideration land and water use, fertilizer needs, social aspects and greenhouse gas emissions.
A simplification of the production process of biobased building blocks is shown below. Firstly, the sugars from biomass needs to be released prior to fermentation. Then, the fermentation takes place. This defines the microbial conversion of organic material into different substances. After a number of downstream processing steps the platform molecule, or building block, is produced. Finally, some purification and additional modification steps are carried out to obtain the final product.
The processing of biomass does not influence the net CO2 production. This is because biomass converts CO2 into oxygen and organic material during its lifetime, which weighs out to the CO2 production of combustion, contributing to a circular economy. The benefits of biobased production of precursor chemicals and plastics for society would include less pressure on climate change, less dependence on unstable regions, improved recycling of biomass elements, a safer environment and employment options in developing countries. In this way we can achieve a society that is completely sustainable, both in energy generation as in chemical industry aspects.