Biomass projects in rural areas in the developing world

In much of the developing world, most of the population live in areas where there is little or no access to electricity or modern energy services. There is large potential for creating local biomass projects to provide such services. Figure 11.13 shows a schematic of a modern biogas plant and examples are given of pilot projects,42 all of which could be replicated many times.

Rural power production, India

India, still a predominantly agriculture-based country, produces approximately 400 million tonnes of agro waste every year. A fraction of this is used for cooking purposes and the balance is either burned or left to decompose. India also imports large quantities of fossil-fuel-based furnace oil to supply power and heat to millions of small-to large-scale urban/rural industrial units.

Linus Strategic Energy Solutions, an Indian company, are producing environmentally sustainable briquettes from agro waste suitable for use as a fuel in these industrial units. In addition to the reduction in costly and environmentally damaging fossil fuel use and the cash savings generated by the user, this cycle also has the potential to generate new sources of income for farmers supplying the biomass, new business opportunities for rural entrepreneurs processing and selling the briquettes and additional rural employment in the collection and processing of the agro waste.

Also in India, Decentralised Energy Systems India Private Limited are piloting the first independent power projects of around 100 kW capacity in rural India owned and operated by village community co-operatives. An example is a small co-operative in Baharwari, Bihar State, where a biomass gasification power plant is used as a source of electricity for local enterprises, for instance for pumping water in the dry season. Local income is thereby generated that enables villagers to expand their micro-industries and create more jobs - all of which in turn increases the ability of people to pay for improved energy services. A 'mutuality of interest' is created between biomass fuel suppliers, electricity users and plant operators.

Integrated biogas systems, Yunnan, China

The South-North Institute for Sustainable Development has introduced a novel integrated biogas system in the Baima Snow Mountains Nature Reserve, Yunnan Province. The system links a biogas digester, pigsty, toilet and greenhouse. The biogas generated is used for cooking and replaces the burning of natural firewood, the 'greenhouse' pigsty increases the efficiency of pig-raising, the toilet improves rural environmental hygiene, and vegetables and fruits planted in the greenhouse increase the income of local inhabitants. Manure and other organic waste from the pigsty and toilet are used as the raw material for biogas generation which delivers about 10 kWh per day of useful energy (cf Figure 11.13). The operation of 50 such systems has considerably reduced local firewood consumption.

Biomass power generation and coconut oil pressing, the Philippines

The Community Power Corporation (CPC) has developed a modular biopower unit that can run on waste residue or biomass crops and can enable village-level production of coconut oil. CPC and local partners are using the modular biopower unit fuelled by the waste coconut shells to provide electricity to a low-cost mini-coconut-oil-mill (developed by the Philippines Coconut Authority and the University of Philippines), 16 of which are now operating in various Philippine villages. Furthermore, the biopower unit generates waste heat which is essential for drying the coconuts prior to pressing.

Village electric

Figure 11.13 Schematic of digester for biogas plant for local supply (not to scale). The fuel cell for generating electricity anticipates the availability of more advanced fuel cells. In the meantime the reformer and fuel cell could be replaced by an internal combustion gas engine and a generating set.

Village electric

Cooling coils

Additional industrial heat sinks

Hot water

Figure 11.13 Schematic of digester for biogas plant for local supply (not to scale). The fuel cell for generating electricity anticipates the availability of more advanced fuel cells. In the meantime the reformer and fuel cell could be replaced by an internal combustion gas engine and a generating set.

But what about the greenhouse gas generation from waste incineration? Carbon dioxide is of course produced from it, which contributes to the greenhouse effect (see question 4 Chapter 3). However, the alternative method of disposal is landfill (most of the waste in the UK currently is disposed of by landfill). Decay of the waste over time produces carbon dioxide and methane in roughly equal quantities. Some of the methane can be collected and used as a fuel for power generation. However, only a fraction of it can be captured; the rest leaks away. Because methane is a much more effective greenhouse gas, molecule for molecule, than carbon dioxide, the leaked methane makes a substantial contribution to the greenhouse effect. Detailed calculations show that if all UK domestic waste were incinerated for power generation rather than landfilled, the net saving per year in greenhouse gas emissions would be equivalent to about 10 million tonnes of carbon as carbon dioxide.43 Since this is about 5% of the total UK greenhouse gas emissions, we can infer that power generation from waste could be a significant contribution to the reduction in overall emissions.

Other wastes resulting from human or agricultural activity are wet wastes such as sewage sludge and farm slurries and manures. Bacterial fermentation in the absence of oxygen (anaerobic digestion) of these wastes produces biogas, which is mostly methane and which can be used as a fuel to produce energy (Figure 11.13) There is room for an increasing contribution from these sources. If the potential for power generation from agricultural and industrial waste was taken into account, the savings in emissions arising from domestic waste already mentioned could be approximately doubled.

Turning now to the use of crops as a fuel, the potential is large. Many different crops can be employed as biomass for energy production. However, because of the relatively low efficiency of conversion of solar energy to biomass, the amount of land required for significant energy production by this means is large - and it is important that land is not taken over that is required for food production. An ideal energy crop should have high yields with low inputs. In energy terms, inputs, for instance from fertilisers, crop management or transport, must be no more than a small fraction of energy output. These characteristics tend to rule out annual grasses such as maize but rule in, for instance, short-rotation coppice willow from a list of woody species and Miscanthus ('elephant grass') from a list of perennial grasses (Figure 11.14). Grasses like Miscanthus can also be grown successfully on relatively poor land only marginally useful for agriculture. Because biomass is bulky implying high transport costs, it is best used to provide local energy or additional feed to large power stations.

In the IEA BLUE Map scenario, global biomass use (including biofuels, see below) increases nearly fourfold by 2050 accounting for nearly one-quarter of total world primary energy. It is then by far the most important renewable energy source. About half of this will come from crop and forest residues and other waste, the other half from purpose-grown energy crops. These will require a land area equivalent to about half the land area currently under agriculture in Africa or 10% of the world's total.

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