PROF. KITHINJI JACOB PETER

Abstract

Rising demand for energy is one of the major challenges facing the world today and charcoal is a principal fuel in Kenya. Faced with energy poverty many poor households turn to briquette making. This study assessed the additional cooking fuel obtained from recycling charcoal dust into charcoal briquettes. It applied Life Cycle Assessment (LCA) to assess the global warming potential (GWP) from use of charcoal and production of briquettes from charcoal dust and cooking a traditional meal for a standard household of five people. Native vegetation of Acacia drepanolobium and a low efficiency kiln were considered the common practice, while an Acacia mearnsii plantation and a high efficiency kiln was used as an alternative scenario. Charcoal and kerosene were considered as reference fuels. Recovering charcoal dust for charcoal briquettes supplied an additional 16% cooking fuel. Wood carbonization and cooking caused the highest GWP, so there is a need for technologies to improve the efficiency at these two stages of charcoal briquettes and charcoal supply chain. Supplying energy and cooking a traditional meal in a combined system using charcoal and recovering charcoal dust for charcoal briquettes and charcoal alone accounted for 5.3–4.12 and 6.4–4.94 kg CO2 eq. per meal, respectively, assuming trees were not replanted. These amounts declined three times when the carbon dioxide from the carbonization and cooking stages was assumed to be taken up by growing biomass. This requires replanting of trees cut down for charcoal if the neutral impact of biomass energy on GWP is to be maintained.

Description
Charcoal is the principal cooking fuel in Kenya which provides energy to 82% of urban and 34% of rural households. Poor households are opting to use unhealthy sources of fuel such as tyres, old shoes and plastics especially those in urban and peri-urban areas while many families are shifting from traditional meals that require long cooking times and are compromising dietary diversity and nutrition as a result. Faced with poverty and unemployment, communities are turning to fuel briquette which is made by compressing biomass material into a solid unit. Fuel briquette production methods in Nairobi and surroundings and their implications on the quality of the product were studied through focus group discussions with eight groups and one private company. The fuel briquette producing community SHG‘s in Nairobi comprised all those identified and located using an existing database on self-help groups involved in waste management in Nairobi. One group SHG that produced sawdust fuel briquettes was identified in Naro Moro through PactKe an NGO working on Natural Resource Management in Laikipia county. Implications of fuel briquettes on the community livelihoods were also investigated. Theresults obtained were applied in designing experiments to assess different fuel briquettes producing techniques using, (i) different binders namely soil, paper, cowdung and gum Arabica, (ii) pressing machines, (iii) charcoal dust from Acacia mearnsii, Eucalyptus spp and Acacia xanthophloea,(iv) sawdust from Grevillia robusta, Pinus patulaandCupressus lusitanica and (v) carbonized sawdust from the three tree species above in (iv).combustion …

Description
There are practically no low cost, environmentally friendly options in practice whether incineration, autoclaving, chemical treatment or microwaving (World Health Organisation in Health-care waste management training at national level, [2006] for treatment of health-care waste. In Kenya, incineration is the most popular treatment option for hazardous health-care waste from health-care facilities. It is the choice practiced at both Kenyatta National Hospital, Nairobi and Moi Teaching and Referral Hospital, Eldoret. A study was done on the possible public health risks posed by incineration of the segregated hazardous health-care waste in one of the incinerators in each of the two hospitals. Gaseous emissions were sampled and analyzed for specific gases the equipment was designed and the incinerators Combustion efficiency (CE) established. Combustion temperatures were also recorded. A flue gas analyzer …

Coal gasification tars were extracted with supercritical carbon dioxide at different temperatures and pressures, and the properties of the extraction residues (pitches) were determined by elemental analysis, size-exclusion chromatography and simulated distillation. Extract fractions were analysed by supercritical fluid chromatography. The pitches generally had softening points near the temperature of extraction. Raising the extraction temperature at constant pressure reduces the solvent density, and hence reduces the solubility of tar constituents. Extraction is optimized by extracting at low flow rates, initially at low temperature (high density) to remove low molecular mass compounds, and then increasing the temperature to ensure good contact with molten pitch and increasing the pressure to increase the density. Contact with powdered pitch is preferable. In agreement with calculated solubilities, polycyclic aromatic hydrocarbons, especially naphthalene, fluorene and phenanthrene, are the principal constituents of the extracts. More polar compounds remain in the pitch.