Proceedings Biodigester Workshop March  2002

http://www.mekarn.org/procbiod/huong.htm

Utilization of biogas technology for generating electricity
 and storing oranges

Ho Thi Lan Huong

Biogas Department
Institute of Energy, Hanoi, Vietnam 

Abstract

Biogas technology has been introduced and developed in Vietnam since the 60's. All main types of simple biogas plant and their utilization have been tested and developed. There now are more than 25 thousand family-size biogas digesters of 1 to 50m³ in rural areas of the whole country. Biogas produced from these plants is used for cooking, lighting, generating electricity, storing fruit and other purposes. Anaerobic digesters for treating industrial waste water and night soil have been tested in pilot scale. 

The institutions engaged to the program were: Institute of Energy, Technology University of Hanoi, Technology University of Ho Chi Minh City, Technology University of Da nang, Can Tho University, provincial departments of Science, Technology and Environment, among which the Institute of Energy has been the leading institution. 

This article describes two ways of utilisation of biogas such as generating electricity and storing orange.

Key words: Biogas, electricity, storage, oranges
 

Introduction

·        Biogas Energy Department.

·        Wind and Solar Energy Department.

·        Rural Energy Planning and Fuel Department.

·        Hydro-Power Department.

 

Research activities of Energy Institute in the field of Biogas Technology

·        Design, construction, fabrication and test experiment of biogas plants and  appliances

·        Implement development projects in the whole country.

·        Provide technical services for users.

·        Provide training services for technicians and masons and transfer technology to other organizations.

·        Prepare technical manuals, papers, television programs.

 

The main results of the development activities are as follows:

Number of plants installed in localities:

·        Floating-gasholder made of steel sheet:              97

·        Floating-gasholder made of ferro-cement:          50

·        Fixed-dome built of brick:                                 186

Number of video tapes: 5, of which 4 video films have been diffused on Vietnam Television.

Number of manuals: 4, of which one has been published by Scientific and Technological Publication House.

In collaboration with "Institut de I'Energie des pays ayant en commun I'usage du francais (IEPF)" on preparation of the manual "La filiÌre biogaz dans les pays en developpement".

Number of training courses: 7

Implementation of 3 projects supported by OXFAM, UNICEF and ACCT (Agence de cooperation culturelle et technique).

Design, construction, and test experiments of biogas plants

To evolve low-cost designs suitable for Vietnam, two main types of digester have been popularized all over the country.

Floating gasholder plant (Figure 1).

This type of plant was mainly developed before 1984 with digester volume of 1 to 50 m³. Disadvantages are the cost of the plant needs to be brought down further, especially by replacing the steel gasholder.

Fixed - dome plant (Figure 2)

Since 1984 IE has concentrated on the design and development of a fixed dome digester with the spherical shaped wall built of brick. The first digester of this type was installed in 1987. More than 200 plants with the digester volume from 1 to 15 m³ have been constructed since 1988. This type was evaluated in 1990 and has replaced the floating gasholder one for popular extension. A computer program was compiled for calculating volumes, dimensions and drawing. The spherical structure is now applied for design of floating gasholder plants.

Figure 1:  Spherical shaped floating gasholder plant

  

Figure 2:  Spherical shaped fixed - dome plant

 

Application of biogas

Besides researching biogas for cooking and lighting, we are also interested in researching biogas as a clean fuel for other aspects. For example, biogas can be used for electricity generating, tea processing, fruit storing and hatching chickens. But some are still in process of trial, demonstration or further development. In this paper we only discuss two applications of biogas to generate electricity and for the storing of oranges.

Biogas in electricity generating

To use biogas as a fuel for the international combustion engine, the engine must be refitted. We have chosen to modify the smallest capacity of 4-stroke petrol engine popular in the Vietnamese market named Shriram Honda EM650. It is simple to refit the petrol engine: add a biogas-air mixer to the original carburettor, and then biogas can be used to replace petrol to power the engine. 

The experience shows that to generate electricity with biogas produces good economical results as 1m³ of biogas can replace 0.85 litres of petrol. A generator of 450 VA requires 3 m³ of biogas for 5 hours each evening. The biogas plant must have a minimum digester volume of 10 m³ (30 pigs with weight of about 50 kg/head or 15 cattle). The electricity power is sufficient for 3 electric bulbs of 100W (or 7 fluorescent lights of 40W) and 2 electric appliances like television or radio sets of  75W.

Biogas in orange storing

Conclusion

The experience gained from the multi-use and social response to biogas technology reveals it to be appropriate for wide scale application in rural areas in Vietnam. Biogas plants set up in villages can utilize animal dung, human excreta and farm wastes, thus enhancing village sanitation. They produce not only a good quality fuel but also an excellent organic fertilizer and soil conditioner, and in addition they destroy pathogens and parasites. The technology has inherent advantages like simplicity, low cost, and capacity to produce a good quality fuel without any deterioration in fertilizing properties of the natural resources used as feedstock. 

In addition, in urban areas, anaerobic technology can be also applied to treat industrial wastes and waste waters. It not only saves energy but also produces more energy during wastewater and solid waste treatment processes. The tropical climate is a very suitable condition for anaerobic fermentation. Consequently, this technology should be disseminated for meeting the demand of solving pollution problem in the industrial zones. Therefore we recommend that the government must provide a political framework in favor of promotion of biogas technology such as:

·        Integration of biogas programs at all levels of policies and planning processes.

·        Local, regional and national budgets have to provide allocations mainly for promotion, training, building and improvement of necessary infrastructure, R&D and implementation programs.

·        Initially, adequate incentives and regulatory measures in tax-structures and other laws must be provided to bring biogas programs to equal terms with competing technology systems. This will also encourage NGO¢s and private entrepreneurs.

 

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