*7.2.1. Anaerobic digestion*

Anaerobic digestion is process of converting of organic material directly into a gas teemed biogas. Biogas is a mixture of methane (CH4) and carbon dioxide (CO2) with other small quantities of gases such as hydrogen suphide (H2S) [23]. Anaerobic digestion is a proven technology and is widely used for treating high moisture content organic waste [19]. Biogas a product from anaerobic digestion can be used directly in gas turbine to generate electrici‐ ty, and can be upgraded to higher quality i.e. natural gas quality by removing carbon diox‐ ide (CO2).

**ACTION**

**Table 10.** Ranking of bio chemical conversion Technology:

ever, the pyrolysis process is inefficient.

**Input material** Energy crops, bio waste,

**Post treatment** Particulates and tars

**Table 11.** Summary of conversion technologies

**Direct Environmental**

**Indirect environmental**

**Impact**

**Impact**

removal

Sulphide, NOX

Forest, forest product

Carbon dioxide, hydrogen

Energy requirement of downstream processes

**Product** Syngas Pyrolysis Heat **By product** Char Gases and char Ash

tion fuel.

and 12.

Conversion level ++ ++ Simplicity +++ - Plant cost +++ - Applicability +++ - Conversion time + ++

**PROCESS**

Biomass Conversion to Energy in Tanzania: A Critique

http://dx.doi.org/10.5772/ 52956

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**Anaerobic digestion Fermentation**

Direct combustion is an ancient technology for heat production purposes. It is a common technology in the country. Pyrolysis is a technology that can be used in large-scale for com‐ mercial purposes. The product from pyrolysis i.e. pyrolysis oil, is demanding to upgrade to transport fuel. The pyrolysis oil can be used for combined heat and power generation; how‐

Fermentation process is a commercial technology but competes with food production. The produced ethanol can be used for heat and power generation and preferably as transporta‐

Sensitization on the use of these conversion technologies in the country is required. At the same time training institution should be involved in more research and development aim‐ ing at improving the technologies. With this approach, it is clear that the potential of bio‐

Thermo-chemical and bio-chemical biomass technologies can be summarized in Tables 11

**Applications** Synthetic fuel production Fuel for engine Heat production, electricity

**CONVERSION TECHNOLOGY Gasification Pyrolysis Direct combustion**

Oxygen removal Name

Biomass, wood waste

generation.

practices

Fly and bottom ash, particulates

Land use impacts of unsustainable forestry

Energy Crops, mill wood waste, Urban organic waste

Carbon dioxide, Carbon monoxide, Methane

Energy requirement of downstream processes

mass available in the country could contribute to energy mix of the country.

By- product of anaerobic digestion are settled fibre, which can be used as soil conditioning and liquid fertilizer, which can be used in the farms directly without additional treatment [24-25].
