*7.2.2. Fermentation*

Fermentation process converts biomass into ethanol by the metabolism of microorganisms [26, 20]. The fermentation process is normally anaerobic, but also aerobic process can be fea‐ sible. The process consists of two notable steps. First, biomass starch, the sugars are ferment‐ ed to ethanol using yeast.

The solid residues from fermentation, which still consists of amount of biomass, can then be used for direct combustion or gasification. Typically sugarcane and sugar beet (in Europe) are can theoretically fermented [27].

The final fermentation product allows easier handling and storage when compared to gases produced from anaerobic digestion. However, the intensive feedstock pre-treatment, the necessary temperatures and diluted intermediate product obtained, the fermentation proc‐ ess is complex than anaerobic digestion.

Despite the advantages of storage and transportation, fermentation process is less suitable for micro-scale energy production than gas production technologies. Besides, a major envi‐ ronmental impact of fermentation is the waste water of fermentation process. Treating the waste water can be very energy intensive. The high contents of Nitrate and phosphates in the waste water might influence the development of certain species such as algae.

### *Ranking of bio-chemical conversion technology*

Table 10 summarizes the findings of performance of bio-chemical conversion technology and ranking the applicability. The assessments vary from very poor (-), good (+) and very good (+++).

From the above ranking, it is evident that anaerobic diction is more promising as a biomass conversion technology in the country, especially due to its simplicity.

Gasification and anaerobic digestion are promising conversion technologies in the country. Anaerobic digestion is an excellent technology to produce biogas from wastes in a very small scale i.e. at house hold level. The produced gas (biogas) can be utilized as cooking gas, transportation fuel, and for electricity generation. Gasification is a more demanding technol‐ ogy in small- scale projects with special feed stock requirements.


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

*7.2.1. Anaerobic digestion*

262 New Developments in Renewable Energy

ide (CO2).

good (+++).

*7.2.2. Fermentation*

ed to ethanol using yeast.

are can theoretically fermented [27].

ess is complex than anaerobic digestion.

*Ranking of bio-chemical conversion technology*

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‐

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].

Fermentation process converts biomass into ethanol by the metabolism of microorganisms [26, 20]. The fermentation process is normally anaerobic, but also aerobic process can be fea‐ sible. The process consists of two notable steps. First, biomass starch, the sugars are ferment‐

The solid residues from fermentation, which still consists of amount of biomass, can then be used for direct combustion or gasification. Typically sugarcane and sugar beet (in Europe)

The final fermentation product allows easier handling and storage when compared to gases produced from anaerobic digestion. However, the intensive feedstock pre-treatment, the necessary temperatures and diluted intermediate product obtained, the fermentation proc‐

Despite the advantages of storage and transportation, fermentation process is less suitable for micro-scale energy production than gas production technologies. Besides, a major envi‐ ronmental impact of fermentation is the waste water of fermentation process. Treating the waste water can be very energy intensive. The high contents of Nitrate and phosphates in

Table 10 summarizes the findings of performance of bio-chemical conversion technology and ranking the applicability. The assessments vary from very poor (-), good (+) and very

From the above ranking, it is evident that anaerobic diction is more promising as a biomass

Gasification and anaerobic digestion are promising conversion technologies in the country. Anaerobic digestion is an excellent technology to produce biogas from wastes in a very small scale i.e. at house hold level. The produced gas (biogas) can be utilized as cooking gas, transportation fuel, and for electricity generation. Gasification is a more demanding technol‐

the waste water might influence the development of certain species such as algae.

conversion technology in the country, especially due to its simplicity.

ogy in small- scale projects with special feed stock requirements.

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‐ ever, the pyrolysis process is inefficient.

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‐ tion fuel.

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

Thermo-chemical and bio-chemical biomass technologies can be summarized in Tables 11 and 12.


**Table 11.** Summary of conversion technologies


Within the biological conversion technologies, the development of power generation from biogas is at advanced stage. Currently there are more than 6,000 biogas plants in operation. More plants are expected to be in operation in the future. However, awareness on use of bio‐ gas in particular to areas with large forks of livestock is still low. This is a challenge to the

Biomass Conversion to Energy in Tanzania: A Critique

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

265

There is an increasing interest in gasification technologies for power generation, but a com‐ mercial implementation has not yet been received since there are still draw backs such as

Co-generation technology is the only technology at advanced stage of implementation in the country; in particular to sugar processing plants. Electricity generated from these plants is used by the same plants and the excess is supplied to the nation grid. It is anticipated that with "Kilimo Kwanza"[28] initiatives are in the pipe line, production of sugar is expected to increase in the near future; hence more electricity is expected to be generated and supplied

Modern energy generation from biomass resources has a great potential in saving for rural energy needs with sustainable benefits. The existing biomass conversion technology such as co-generation, biogas and recently improved thermo-chemical, could be effectively utilized

These technologies should be used in the right way to utilize the available biomass energy potential. The power generation from biomass would make the rural areas productivity. The use of local resources would also enhance the employment opportunities and income gener‐ ation in the rural areas. The available biomass potential in the country should be used to

Biomass is one of the renewable energy sources that can make a significant c contribution to the developing world's future energy supply. Tanzania has a large potential for biomass production. The forms in which biomass can be used for energy are diverse, Optimal resour‐ ces, technologies and entire systems will be shaped by local conditions, both physical and

Though I have mentioned it numerous times, it bears repeating that the majority of people in the country will continue using biomass as their primary energy source well into the next century. A critical issue for policy-makers concerned with public health, local environmen‐ tal degradation, and global environmental change is that biomass-based energy truly can be modernized, and that such a transformation can yield multiple socioeconomic and environ‐ mental benefits. Conversion of biomass to energy carriers like electricity and transportation fuels will give biomass a commercial value, and potentially provide income for local rural economies. It will also reduce national dependence on imported fuels, and reduce the envi‐ ronmental and public health impacts of fossil fuel combustion. To make progress, biomass

system reliability, high operation and maintenance cost, which has to be solved first.

developers of biogas plants.

in the process of energy conversion from biomass.

take the nation towards a clear and secure energy source.

into the grid.

**9. Conclusion**

socio-economic in nature.

**Table 12.** Summary of conversion Technologies
