Sustainable Energy Consumption

Permanent URI for this collection

https://repository.nrf.go.ke/handle/123456789/13

Browse

Now showing 1 - 8 of 8

Assessment of the implementation of energy conservation opportunities arising from energy audits; A study of four-star and five-star hotels in Nairobi Kenya
(Scientific Research Publishing, 2023-09-26) Ogola, Nicholas; Musau, Peter M.; Wekesa, Cyrus
This study assesses the implementation of energy conservation opportunities in four-star and five-star hotels in Nairobi. The Covid-19 pandemic had a significant impact on the Hospitality Industry. Currently, there is a growing inclination to furnish guests with superior and sustainable services in an energy-efficient and eco-friendly way. Comprehensive research was conducted from energy audits gathered from the establishments and contracted auditing companies, on top of this, hotel staff were given digital questionnaires. To add to the data, the researcher surveyed the hotels with engineering managers. The Energy Audits found that all 10 hotels had adopted Energy Conservation Opportunities (ECOs). After further analysis, the mean adoption rate of Energy Conservation Opportunities (ECOs) during the past three years was 55.83%, which was below the aim of 100%. According to studies, hotel staff manages energy to cut costs. The researcher found that hotels use up a lot of energy. However, they have conservation potential, depending on government policies, costs, ease of implementation, and management commitment to sustainable practices. Essentially, Energy Conservation Opportunities (ECOs) reduce energy expenditures and boost reliable revenues, especially during high energy prices and uncertainty.
Cost benefit analysis of different energy sources used in public secondary schools in Mtito Andei Division, Makueni County
(South Eastern Kenya University, 2020-09-02) Kazungu, Arnold T.
Energy affects all aspects of development: social, economic and environmental,including livelihoods, access to water, agricultural productivity, health, populationlevels and education. Public schools spend a lot of money every year on energy bills.Currently, they are experiencing an exponential increase in student enrolment whichputs more pressure on energy needs. This study focuses on cost benefit analysis ofdifferent energy sources used in public secondary schools in Mtito Andei Division,Makueni County. The specific objectives are to: (1) establish the sources of energyused in public secondary schools, (2) investigate the factors determining the choice ofthe energy source(s), (3) assess environmental and socio-economic impacts of majorenergy sources and (4) conduct cost benefit analysis of major energy sources. Thestudy used Survey Research Design (SRD) and a census survey, with all 30 schools inthe study site studied via questionnaire administration, observation, interview andphotography for data collection. Both descriptive and Benefit Cost Ratio analyticalprocedures were used. The study findings showed that firewood was the most popularcooking energy source with all (100%) schools using it while charcoal came second(23%) followed by LPG gas (10%) and paraffin (7%). Only 3% of the schools usedelectricity for cooking. The over reliance on firewood for cooking is expected to havenegative environmental consequences in the study area. Electricity was the mostpopular source of energy for lighting (60%) followed by solar energy (27%) andparaffin (7%). These are expensive sources of energy. An investigation into forms oflow cost energy technologies as perceived by the respondents revealed energy savingstoves (87%), solar power (27%) and energy saving bulbs (10%). The reasons foradoption of these energy technologies was mainly high cost of other energy sourcesand need to conserve the environment. The challenges associated with the differenttypes of energy identified were; electricity (unreliability), firewood (scarcity),charcoal (scarcity) and solar power (high installation cost). The study found firewoodconsumption was on average 10 tonnes per school per term and that firewood hadbeen used for cooking for more than 13 years on average in all schools in the studyarea. The study found the Benefit cost ratio (BCR) of solar power at 1.19 and BCR offirewood at 0.19. The study concludes that there was over reliance on firewood forcooking and adoption of modern energy technologies like solar power was very lowwith adoption by only 27% of schools. The study recommends: (1) the national andcounty governments to come up with policies such as subsidies, grants and tax reliefthat will make these technologies affordable and accessible to schools for adoption,(2) establishment of school-based woodlots consisting of fast-growing tree varieties toaddress the school wood fuel demands instead of escalating the destruction and loss ofindigenous forest ecosystems in the area, (3) since solar power has a BCR greater than1, the study recommends that schools should consider installing more of solar powerto reduce huge energy bills and to reduce over dependency on firewood.
Energy Characteristics of Five Indigenous Tree Species at Kitulangalo Forest Reserve in Morogoro, Tanzania
(INTERNATIONAL JOURNAL of RENEWABLE ENERGY RESEARCH, 2014-11-29) Warburg, Christopher T; King’ondu, Cecil K
This study presents the investigation of material composition and energy characteristics of B. spiciformis, B. boehmii, C. molle, P. maprouneifolia, and S. birrea indigenous tree species at kitulangalo forest reserve in Tanzania. Energy content of each species mostly depends on its chemical content (C, H and O) and it is reduced by inorganic elements and moisture. Biomass chemical composition was done by proximate and ultimate analyses. Regarding the elemental composition, P. maprouneifolia and C. molle had high energy content of 18.62 and 18.30 MJ/Kg, respectively because of their higher H:C ratio and relatively low O:C ratio. Carbon, oxygen, and hydrogen were found to be highest in P. maprouneifolia with 46.71, 41.96, and 5.7%, respectively. In contrast, P. maprouneifolia had the lowest N:C ratio of 0.014, implying good efficiency for nitrogen use to fix carbon. On the other hand, ash, moisture, and volatiles were highest at 4, 55, and 85% for S. birrea, B. spiciformis, and S. birrea, correspondingly. The ratio of macronutrients to carbon for each species was also calculated. Results show that all species have high demand for nitrogen followed by potassium and calcium, in that order. Finally, heating values have been shown to decrease with increasing moisture content. These experimental results were used for ranking these biomass materials for energy generation. They also furnish vital biomass information for equipments and process designers.
Enhancement of anaerobic digestion by co-digesting food waste and water hyacinth in improving treatment of organic waste and bio-methane recovery
(Elsevier Ltd, 2022-09-01) Oduor, William W.; Wandera, Simon M.; Murunga, Sylvia I.; Raude, James M.
In Kenya, 57% of the municipal solid waste generated is Food waste (FW) which has high organic content. However, the treatment and bioconversion of FW to biogas have always been challenging due to its rapid biodegradation, resulting from rapid hydrolysis and accumulation of volatile fatty acids and lowering pH in the bioreactor. In this study, the anaerobic digestibility of FW as a mono substrate was compared to co-digestion of FW with water hyacinth (WH) for improved biogas production and organic matter removal efficiency in a laboratory batch reactor. Different mix proportions of FW and WH were co-digested under mesophilic conditions (37 °C) at a dilution of 6% (w/v) Total Solids (TS) content. The TS of the substrates (Food waste and Water Hyacinth) were pre-processed to have a concentration of TS at 6% (60 g/L) to operate a wet AD which requires the substrate to be less than 15% TS. The proportions of WH: FW (v/v) were 100:0, 85:15, 70:30, 55:45, 30:70, 15:85, and 0:100. In the batch rectors the anaerobic co-digestion was conducted with Substrate to Inoculum (S/I) ratio of 1:1. FW is generally considered to have high volatile solids which hydrolyze rapidly lowering pH arising from excess production of Hydrogen which in presence of CO2 and acetogenic bacteria leads to more production of acetate, formate and other long chain fatty acids which inhibits methanogenesis as a result of rapid acidification. The rapid acidification of the bioreactors that are used to treat FW results in the inhibition of the methanogenesis process. The co-digestion of the substrates could have improved the process parameters by reducing acidity caused by the high C/N ratio, reducing the inhibitory range, and increasing the buffer capacity which enhanced the bio-methane potential and the microbial activity. The batch experiments were set in triplicate for both cases of FW, WH, mixtures, and Inoculum. The results showed that the average gas yields after 81 days for the various mix proportions were 256.27and 357.69 ml/g-VS for mono-digestion of WH and FW respectively. For the mixtures of WH: FW the average reported biogas production were 305.01, 280.27, 548.91,616.01 and 270.87 ml/g-VS for mixtures of 15:85, 30:70, 55:45,70:30 and 85:15 respectively. The modified Gompertz model showed that the digesters with WH and FW alone had lag times of 2.599 and 1.052 days respectively. The mix substrates of WH: FW 85:15, 70:30, 55:45, 30:70 and 15:85 shown lag times of 2.456, 3.777, 2.574, 1.956 and 1.75 days respectively. A mix (WH: FW) of 70:30 had the highest maximum specific biogas production Rmax and the maximum biogas production potential of 18.19 mlCH4/gVS per day and 607.7mlCH4/gVS respectively. The R2 and RSME values ranged from 0.9867 to 0.9963 and 2.663 to 9.359 respectively in all the digesters. The study shows that the co-digestion of WH and FW in the mix ratio of 70:30 improved the volume of biogas produced and organic matter removal efficiency reached 79%.
Optimization of Binary Mixtures of Biodiesel and Fossil Diesel for Clean Energy Combustion
(Springer Nature, 2019-05-31) Mosonik, Bornes C.; Kibet, Joshua K.; Ngari, Silas M.
There is an urgent interest initiated to develop clean energy resources with the aim of reducing exposure to environmental pollutants and explore model fuels that can hasten the achievement of clean energy combustion. This work investigates various ratios of biodiesel and commercial diesel in order to propose model binary fuels for clean energy combustion. Accordingly, diesel blends of ratios 1:1, 3:2 and 2:3 were each pyrolyzed at a contact time of 5 s in a quartz reactor at 1 atmosphere pressure. A model temperature of 500 °C was explored in these experiments. The charcoal content for pure fossil diesel was compared with the binary diesel residue. Gas-phase molecular components were determined using Gas chromatography (GC) coupled to a mass selective detector (MSD). Elemental composition of thermal char was determined using Smart Elemental Analyzer. Radical intensities for the three types of char (biochar, bio-fossil char, and fossil char) were measured using an X-band electron paramagnetic resonance spectrometer. It was noted that at a ratio of 2:3 (Biodiesel: Fossil diesel), harmful molecular products reduced significantly, 76–99%. Elemental analysis data indicated that the carbon content from commercial diesel was very high (≈ 70.61%) as compared to approximately 53% for biodiesel-fossil diesel mixture in the same ratio 2:3. Interestingly, the free radical content was reduced by nearly 50% in favour of the biodiesel/fossil diesel mixture. These results are encouraging and suggest that a better optimized fuel mixture has been found for better clean energy combustion.
Optimization of the Performance of Hybrid Solar Biomass Dryer for Drying Maize Using ANSYS Workbench
(Journal of Energy Research and Reviews, 2020-02-03) Aukah, Jackis; Muvengei, Mutuku; Ndiritu, Hiram; Onyango, Calvin
In this paper ANSYS workbench was used to optimize the performance of hybrid solar biomass dryer for drying shelled maize in order to find the optimal operating input variables when the air temperature within the drying chamber set within the permissible range at reasonably high flow velocity. Hybrid Solar dryer with biomass as a source of fuel for auxiliary heating during absence or low solar insolation is a feasible option for small scale maize farmers [1]. At times high temperatures are induced in this dryer which may result in grain fissures and breakage during milling, thus reducing the grain quality. Optimization results indicate that in order to keep the air temperature within drying chamber to permissible range [2], the air velocity at collector inlet and biomass heat exchanger outlet should be improved to 3 m/s and 2.8 m/s respectively while the capacity of the biomass heat exchanger should also be enhanced to provide hot air at 85°C. It be concluded from the study that HSBD is suitable for drying maize as well as other agricultural products since continuous interrupted drying can be achieved. The capability of the dryer to maintain uniform temperature and air flow within the drying chamber enable high quality dried products within a short duration.
Quantifying Greenhouse Gas Emissions and Carbon Stocks in Maize-Soybean Cropping Systems in Siaya County, Kenya
(Kenyatta University, 2020-11) Karanja, Anne Njeri
As climate change continues to threaten ecosystems’ functions, agriculture remains one of the major source of greenhouse gas (GHG) emissions that are responsible for global warming. The major GHG in agriculture are; carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). Unfortunately, agriculture is also one of the most affected sectors by climate change. There is therefore need to reduce emissions by adopting agricultural practices with mitigation potential. This is by enhancing soil carbon sequestration to offset emissions, or reducing emissions while safeguarding crop yields. However, little is still known about GHG quantities and intensities that major cropping systems in Kenya emmit. Site specific studies on GHG emissions to establish interventions for mitigation of climate change and enhanced crop production is therefore of essence. The objective of this study was to examine the effect of reduced tillage, crop residue retention and use of controlled release urea (CRU) in maize-soybean cropping systems on GHG emissions, soil N mineralization, organic carbon stocks and yields. Field measurements were carried out in a 13 year old researcher-managed trial in Siaya county, Kenya between March 2016 and January 2017. Four treatment combinations: ZT M-S NU (reduced tilage+maize soybean rotation+normal urea), ZT M-S CRU (reduced tillage+maize soybean rotation+controlled release urea), ZT M/S (reduced tillage+maize soybean intercrop without urea), CT M-S NU (Conventional tillage+maize soybean rotation+normal urea) were tested. The treatments were laid out in a randomized complete block design. DAYCENT model was used to simulate soil carbon, N2O emissions and maize yields. Results showed that daily fluxes of N2O ranged between -0.5-26 g ha-1 d-1 and -2-10 g ha-1 d-1 in the long and short rainy seasons respectively. Cumulatively, N2O emissions were between 0.2 - 0.7 kg ha-1 and 0.2 - 0.4 kg ha-1 in the long and short rainy seasons respectively. In the long rainy season, ZT M-S CRU had significantly higher N2O fluxes than the other treatments (P=0.05). In the short rainy season there were no significant effects of treatment on N2O emissions. In the long rainy season, CO2 daily fluxes were between 9 to 42 kg ha-1 while the cumulative emissions ranged between 2.5 to 2.8 t ha -1. In the short rainy season daily CO2 fluxes ranged between 6 to 30 kg ha-1 while cumulative emissions were 1.8- 2.5 t ha -1. There was no significant effect of treatment on CO2 emissions. Methane emissions were largely negative, and did not differ significantly among treatments. Yield was significantly low for ZT M/S but N2O emission intensities were not significantly different among treatments. DAYCENT simulated soil carbon and maize yield within the same ranges observed by measurement. N2O emissions by DAYCENT were higher during the peak of the seasons, but were comparable with observed measurements later in the seasons. Even though the long rainy season had higher N2O and CO2 emissions, the difference was not significant. These results indicate that emissions in the study area were low.These results further indicate that the current soil management practices in Siaya County influence GHG emissions, and the higher emissions observed with ZT M-S CRU in the long rainy season calls for further investigations of the effect of CRU on N2O emissions. The lower emission intensity shown by ZT M/S despite having lower yield points to the need of evaluating cropping systems for climate change mitigation and adaptation. These results indicated that DAYCENT model can be used to simulate soil carbon and yield but not N2O emissions in the study area.
Synthesis, characterization and spectroscopic properties of Cu2+:ZnO, Ce3+:ZnO, and Cu2+, Ce3+:ZnO
(Springer Nature, 2020-06-22) Mulwa, Winfred Mueni
Pristine ZnO, Cu2+:ZnO, Ce3+:ZnO and Cu2+, Ce3+:ZnO nanopowders with different doping concentrations (0, 0.31, 0.62, 0.93 and 1.24% of dopant) were synthesized by sol–gel technique with low sintering temperature of 600 °C. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), UV–Vis optical absorption and photoluminescence (PL) spectroscopy analysis. XRD patterns revealed that all the compounds are hexagonal wurtzite crystalline structure and that all the dopant atoms substituted Zn atoms in the ZnO lattice and there was no formation of extra Phases. SEM photographs displayed morphology of the prepared nanopowders. The UV–Vis absorption spectrum presented an absorption peak at 355 nm which was ascribed to ZnO nanoparticles. The photoluminescence spectrum displayed emission peaks at 486 nm and 527 nm. The 486 nm peak conformed to bandgap excitonic emission and the 527 nm peak was attributed to the existence of independently ionized oxygen vacancies. Sol–gel technique has capability for application in manufacturing units, because its process is simple and the reagents used are economical. Particle sizes in the range 10–51 nm were realized from the TEM analysis.

Browse

Browsing Sustainable Energy Consumption by Funder "N/A"

Results Per Page

Sort Options