Food production from biomass

Similarly to oil-based refineries, where many energy and chemical products are produced from crude oil, biorefineries will produce many different industrial products from biomass. These will include low-value, high-volume products, such as transportation fuels (e.g. biodiesel, bioethanol), commodity chemicals, as well as materials, and high-value, low-volume products or speciality chemicals, such as cosmetics or nutraceuticals. Energy is the driver for developments in this area, but as biorefineries become more and more sophisticated with time, other products will be developed. In some types of biorefinery, food and feed production may well also be incorporated. 

In recent years, though, the situation somehow reversed, and the exploitation of biological resources for products (including energy products) from biomass has become a concern, and it is even actively opposed by some sectors of civil society (environmental nongovernmental organisations mainly). In fact, the use of land to produce biomass is perceived as a competitive use of land for the production of food. 

The aim is to produce biomass or a mass of cells such as microbes, yeast and fungi. The commercial production of biomass has been seen in the production of baker s yeast, which is used in the baking industry. Production of single cell protein (SCP) is used as biomass enriched in protein.6 An algae called Spirulina has been used for animal food in some countries. SCP is used as a food source from renewable sources such as whey, cellulose, starch, molasses and a wide range of plant waste. 

A large increase in biomass energy production has the potential to cause serious environmental problems. Land use issues and concerns about pollution are major concerns. Areas with fragile ecosystems and rare species would need to be preserved. Agricultural lands would also compete with food production. The loss of soil fertility from overuse is a concern. Biomass production would need to be varied and sustainable while preserving local ecosystems. 

Both in the USA and the EU, the introduction of renewable fuels standards is likely to increase considerably the consumption of bioethanol. Lignocelluloses from agricultural and forest industry residues and/or the carbohydrate fraction of municipal solid waste (MSW) will be the future source of biomass, but starch-rich sources such as corn grain (the major raw material for ethanol in USA) and sugar cane (in Brazil) are currently used. Although land devoted to fuel could reduce land available for food production, this is at present not a serious problem, but could become progressively more important with increasing use of bioethanol. For this reason, it is important to utilize other crops that could be cultivated in unused land (an important social factor to preserve rural populations) and, especially, start to use cellulose-based feedstocks and waste materials as raw material. 

In the continuous system, as shown in Figure 30.4C, by constantly removing contents from the fermentor, the process is now open with respect to all components. Typically, the addition of feed and the removal of broth are equal, resulting in a constant volume. Under these conditions, a steady state is achieved wherein all parameters become constant. Such a system is widely used for physiological studies. However, industrial uses are typically limited to the production of biomass (single cell protein) for food or feed, and waste treatment plants. 

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