A SUSTAINABLE IMPLEMENTATION OF RURAL ELECTRIFICATION BY GENERATING ELECTRICITY

FROM BIOGAS

Nelson Mukwaya

David Wakyiku

Mid-Term Project Presentations – Electrical Engineering, 13th February 2008

Problem: Uganda’s current consumption of energy is unsustainable

Goal: To establish the most appropriate system for sustainable generation of electricity from biogas for rural electrification.

The options being considered are:• Biogas as an alternative fuel for diesel/Petrol generators through design

modification.

• Steam turbine- generator systems with biogas used for water heating.

The project weighs these options against sustainability issues which are:

Project Executive Summary

• Technical • Environment

• Economic • Climate

• Grasping the Current Situation

• Understanding the Problem in Greater Depth

• Presenting the Solution (your project)

Agenda

• Five million tones of oil equivalent used per annum.

– 16% of this energy consumption is electrical.

– The rest is mainly wood fuel and charcoal which over 95% of all households use for cooking.

Uganda’s Current Energy Consumption is Unsustainable.

1Van Nicholas Wamaniala, Develop Management of Hydropower in Uganda.

SUPPLY SIDE

• Hydro electricity accounts for 95% of Uganda’s electricity generation.

• Other sources include Diesel generators, Thermal generators (3approx. 100MW), Solar power, Biomass (e.g Kakira – 7MW).

• Biogas electrification is yet to be exploited!!

• Liberalisation of the energy sector accommodates suppliers to the grid.

Electrical Energy Situation in Uganda

3CFL Program Baseline Report, 2007

DEMAND SIDE

• The current demand measures up to about 4340MW which is far greater than the supply.

• The drive for rural electrification among others has increased the demand for electricity now estimated to increase by about 4-5MW per month.

Electrical Energy Situation In Uganda

4CFL Program Baseline Report, 2007

• Approximately 2% of rural households are electrified.• The current sources of electricity are solar, hydro, car batteries, diesel

and petrol generators.• Rural electrification and increased access to electricity are development

goals for the government.• The Rural Electrification Agency’s medium –term objective is to add

100,000 new customers within the period 2006-2008.• Increasing overall generation capacity to service rural electrification

demand is central to the success of the entire Rural Electrification Strategy.

• Biogas electrification is an option yet to be exploited!

Electrical Energy Situation In Rural Uganda

Source: REA 3-Year Business Plan 2005/06-2014/12

Sustainable systems for small scale(household) and large scale (community)are being investigated basing on the sustainability criteria.

Sustainability is being quantified by modelling the criteria. The criteria are being systematically weighted w.r.t their impact on sustainability. A weighted index computed will be the pointer to the system sustainability and will be the basis upon which the more appropriate option will be determined.

A sustainability model is thus being developed and will be used to determine the most appropriate biogas-to-electricity system for both small scale and large scale rural electrification.

What is the project about?

PROPOSED PROJECT WORKFLOW

Technical model

Economical model

Environmental model

Establish sustainability model

Check the impact of a changing climate on sustainability

Perform Detailed Implementation Design using an option that is sustainable and less impacted by a changing climate

Collect data on design option

Reflects the technical sustainability of a particular biogas electrification option. A sustainable system should be efficient, reliable, with long maintenance period. The factors being considered reflect this. They include:

•Energy Conversion Efficiency.

•Maintenance schedule.

•Reliability.

The above factors can easily be quantified, their sum reflecting the impact of the technical model on the sustainability model.

Technical Model

The model aims to capture the economic aspects of setting up the project. It reflects the financial ability of the targeted market.

Factors being considered include the following:

•Project set-up cost per kW capacity.

•Operations and Maintenance (O&M)costs.

•Power Purchasing Power (PPP).

The sum of these factors will be taken as the contribution of the economic model in the sustainability model.

Economic Model

Carbondioxide is emitted from the combustion process involved (burning of the methane). However, since carbondioxide is more environmentally friendly than methane (less damaging to the ozone layer), biogas combustion to generate electricity plays a role in environmental conservation.

A model is being developed that will evaluate the index of direct Carbondioxide emission – Carbondioxide equivalent of would be emitted methane .

Environmental Model

The model aims to consider project sustainability for a period of 50 to 100 years. Climate effects become influential in determining sustainability for such periods.

Climate modeling is being done for temperature and rainfall since temperature and presence of water are essential for biogas production. There is a particular range of temperatures for which anaerobic thermophilic bacteria operate optimally.

Quantiles of Probability Density Function for climate change have been obtained for the East African region. The variables dealt with include change in temperature, precipitation and percentage change in precipitation for low emission, medium emission and high emission scenarios.

Climate Model

• Lack of precedence in Uganda. Absence of manufacturing workmanship may lead to construction defects which is a very serious limitation for system performance.

• Startup capital is large for a rural community or household. Government subsidies are needed.

• The set up of the entire system including the animal farm requires a large area as compared to alternative energy sources of equal capacities.

Project Weaknesses

• Increased power production in an environmentally friendly way, promoting sustainable economic growth as well as better living conditions.

• Increased employment opportunities to mainly the young population which will reduce the tendency for rural to urban migration.

• The digestion process is effective in killing dangerous organisms providing a public health benefit beyond that of any other treatment in managing the rural health environment.

Project Strengths

Thank You