A considerable amount of fossil fuels, particularly coal and oil is being consumed as a source of energy for expanding industry and transport sectors. It is apprehended that fossil fuels being non-renewable in nature, are going to be exhausted in the near future.
In view of this, biomass is considered a major alternative clean energy source. As it is a renewable one, efforts are being made in recent decades to utilise the energy obtained from biomass for these two sectors. Since the very beginning, human beings have been using biomass for harnessing energy for cooking food and other domestic purposes. However, the availability of the right type of biomass and its use in industry and transport sectors strongly depend on regional conditions including availability, cost, nature of biomass etc. At present, biomass provides about 8% of the total energy requirement of industries in the world. In some regions of the world like Latin America and Africa, biomass contributes nearly 30% of the energy requirement of industries.
The coke produced from metallurgical coal is predominantly used for iron and steel making but, historically, iron was produced using charcoal exclusively as fuel and reductant. Even now, in countries like Brazil, a significant amount of pig iron is being produced using charcoal. In the transport sector, fossil fuels can also be replaced by biofuels in an efficient manner, hopefully by 2050. The cement, iron and steel sectors in Brazil use biomass for about 34% and 40% respectively of the total fuel consumed.
Some of the applications of bio-energy in the industrial sector are summarised below:
- Liquid biofuels include ethanol produced from the fermentation of sugar and biodiesel through transesterification of vegetable oils. It is reported that 57 kilotonnes (Kt) of production capacity is in operation, and about ten plants each with a capacity of between 50,000 tons and 300,000 tons are coming up very shortly in different parts of the world.
- In some countries, significant quantities of biomass are already being cofired with coal in conventional coal-based power plants. For example, the Amer 9 CHP power plant in the Netherlands, which produces 600MW of electricity and 350 MW equivalent of heat, currently co-fires 35% of biomass mostly in form of wood pellets with 65% coal.
- The two forms of gaseous biofuels, namely biogas produced from anaerobic digestion of organic matters and producer gas or synthetic gas (SYN) from biomass gasification are finding commercial application in recent years. The biogas produced from anaerobic digestion of organic matters after purification (after removal of carbon dioxide) can have a similar composition to natural gas. The biogas after cleaning can be fed directly to the natural gas distribution pipeline or can be used for gas turbine. Biomass gasification, though still in an early commercial stage, offers good prospects for its use for process heat and power generation. Gasifiers produce a synthetic gas (syngas) that can be adjusted for direct use in combined cycle gas turbine plants for power generation, fed into existing distribution networks, or can be used for the production of liquid fuels through the Fischer-Tropsch process. However, most of these are currently in the pilot scale stage.
- Biomass and other organic wastes can be used as fuel in the cement industry. The use of alternative fuels in the cement industry is a long-established practice in many countries. It offers the opportunity to reduce production costs, dispose of organic wastes, and thus reduce carbon dioxide emissions by decreasing the use of fossil fuels. Cement kilns are well-suited for waste combustion because of their high process temperature and the clinker products with limestone feedstock act as gas-cleaning agents. In recent years, used tyres, wood, plastics, chemicals, organic municipal solid wastes and other types of such wastes are being co-combusted in cement kilns in large quantities. Thus, fossil fuels are replaced with alternative biomass fuels that would otherwise have been incinerated or landfilled and thus contributing to lowering the overall carbon dioxide In a survey conducted by the World Business Council on Sustainable Development in 2006, it was reported that 10% was average use of alternative fuels, of which about one third was biomass. European cement manufacturers derived 3% of their energy needs from waste fuels in 1990 and 17% in 2005. Cement producers in some of the European countries like Belgium, France, and Germany have been able to use biomass ranging from 35-80% of the total energy required. The share of alternative fuel use in clinker production in cement kilns in countries like the Netherland, Switzerland, Australia, Germany and Norway are 84%, 49%, 48%, 36% and 28% respectively. It may be mentioned here that, there is a great scope to use urban and industrial organic wastes in cement industries, particularly in developing countries. By the year 2050, it is expected that the developed countries should be able to use 40-60% and developing countries 25-30% alternate fuel in cement industries.
Biomass available in different forms can be utilised to produce electricity, heat and transport fuels. By extensive use of biomass, it is possible to reduce greenhouse gas emissions considerably. By using biomass for producing energy with the best available technology, the carbon dioxide emission can be reduced to 55-98% compared to fossil fuels even when transported over a long distance, but the availability of biomass for meeting the increasing demand for energy and transport fuel is limited. However, large-scale use of biomass may cause deforestation and environmental problems. Reduced bio-diversity is a major risk to our environment having adverse effects on air quality, soil properties and bio-diversity.
However, afforestation of barren land and plantation of fast-growing species should be carried out extensively and in addition to this, there is a great scope for applying better technology for power and heat generation from biomass. The domestic organic wastes and agricultural wastes if collected and utilised properly through incineration or anaerobic digestion can produce substantial amounts of energy and heat.
At present, in Denmark, agricultural residues are collected for producing bioenergy in a big way. In the European Union (EU), considerable efforts are being made to produce heat and power from biomass. It is reported that serious efforts are being made in recent years to produce more bioenergy and heat so that, the amount of bio-energy produced in the EU can be increased to 850 TWh by 2020.
In the present world, most of the energy required in domestic, industrial, transport and similar other sectors are largely derived from fossil fuels releasing millions of tons of greenhouse gases and particulate matter to the environment causing global warming and climate change.
In view of this, efforts should be made in a big way in different countries of the world to produce and utilise increasing quantities of biomass for generating electrical and heat energies so that, the greenhouse gases can be reduced substantially. The electricity and heat energy can be generated through the combustion of biomass or the production of biogas in systems ranging from small-scale domestic stoves to industrial power or heating plants. The biomass including organic wastes can also be utilised more effectively along with coal in thermal power plants. This can be achieved even in the existing coal-fired thermal power plants. This is known as ‘Co-firing’ and it is claimed to be a cost-effective option. In the coming years, serious efforts should also be made to produce fuel from biomass for the transport sector to minimise the use of fossil fuels.
