Improving electricity supply security in Ghana—The potential of renewable energy

For decades, Ghana’s economy has been fuelled by abundant inexpensive hydropower. As a developing economy, Ghana’s electricity demand has long been relatively low, though rising in recent times due to increasing economic growth, urbanization and industrial activities. However, the rapid demand growth, as well as periodic hydrological shocks, leaves the country increasingly reliant on expensive oil and gas-based generation power plants, with a resultant drain on the national economy. The main electricity generation company, the Volta River Authority, is not able to generate enough electricity for all the demand sectors. The electricity supply-demand margins - the difference between peak demand and available supply - of the country fall short of the recommended engineering practice and thus presents a high supply security risk. The country has been experiencing an increase in the frequency of power cuts over the last ten years. It is clear that Ghana will have to expand and diversify its generation capacity in order to improve supply security. This paper provides a review of the assessed potential renewable energy resources, their current exploitation status, and their potential contribution to the electricity supply of the country. The paper also presents the barriers to their utilization and the existing policy and regulatory instruments to overcome those barriers, plus the current and expected future impacts of these instruments. The results show that Ghana has several RES, such as wind, solar PV, mini hydro and modern biomass that can be exploited for electricity production. While their exploitation for electricity generation is currently very low, providing just 0.13% of the country’s generation, the review shows a great potential for RES generation to increase substantially over the next decade, looking at the government commitment and legal frameworks that are being put in place

Assessing the Effects of Privatization on State Enterprises in Ghana

This paper examines the effects of privatization on state enterprises in Ghana. Vodafone Ghana and Universal Merchant Bank were selected for this study. Primary data was obtained from 287 respondents through survey questionnaires together with secondary data from the published annual financial reports of the two companies. The results of the study showed that factors such as weak internal controls, bribery and corruption, mismanagement of resources, political interference for self-reasons, and increased debts influence the privatization of state enterprises. The results also showed that non-financial effects of privatization include the improved efficiency in delivering services to consumers. Financially, privatization leads to significant improvement in profits, liquidity, solvency and investments stance of state enterprises. It is recommended that there must be a well-drafted strategic policy to manage the privatization of state enterprises in respective of the government in power. Capacity building through training must be offered to employees of state enterprises to revolutionise the innovative abilities and outputs. Effective internal controls must be institutionalize to bolster the operational efficiency of state enterprises. Keywords: Factors, Financial Ratio, Performance, Privatization, State Enterprise DOI: 10.7176/RJFA/10-8-14 Publication date: April 30th 201

Effects of Ambient Parameters on the Performance of a Direct-Expansion Solar-Assisted Heat Pump with Bare Plate Evaporators for Space Heating

Research on the direct-expansion solar-assisted heat pump (DX-SAHP) system with bare plate evaporators for space heating is meaningful but insufficient. In this paper, experiments on a DX-SAHP system applying bare plate evaporators for space heating are conducted in the enthalpy difference lab with a solar simulator, with the ambient conditions stable. The independent effects of ambient temperature, solar irradiation, and relative humidity on the system performance are investigated. When ambient temperature changes as 5°C, 10°C, and 15°C, COP increases as 2.12, 2.18, and 2.26. When solar irradiance changes as 0 W m−2, 100 W m−2, 200 W m−2, 300 W m−2, and 500 W m−2, COP of the system changes as 2.07, 2.09, 2.14, 2.26, and 2.36. With ambient temperature of 5°C and solar irradiance of 0 W m−2, when relative humidity is 50%, no frost formed. Whereas with relative humidity of 70% and 90%, frost formed but not seriously frosted after 120 min of operating. Frost did not deteriorate but improved the heating performance of the DX-SAHP system. The change of relative humidity from 70% to 90% improves the evaporating heat exchange rate by 35.0% and increases COP by 16.3%, from 1.78 to 2.07

Performance and operational effectiveness of evacuated flat plate solar collectors compared with conventional thermal, PVT and PV panels

The concept of an evacuated flat plate (EFP) collector was proposed over 40 years ago but, despite its professed advantages, very few manufacturers have developed commercial versions. This situation suggests both technical difficulties in manufacturing a competitively-priced sealed for life panel and a lack of awareness of the bene fits of such panels. This paper demonstrates an evacuated flat plate simulation that closely models experimental efficiency measurements. Having established the validity of the model, it compares published data for a commercial EFP collector with predictions for an optimal design to investigate whether any further efficiency improvement might be possible. The optimised design is then evaluated against alternative solar energy devices by modelling a number of possible applications. These comparisons should inform choices about solar options for delivering heat: EFP collectors are well-suited to some of these applications. Evacuated flat plate collectors are a possible alternative to concentrating collectors for Organic Rankine Cycle power generation. The annual output for all the modelled collectors was found to be a quadratic function of delivery temperature: this enabled a novel optimisation of ORC source temperature. Predictions for concentrating and non-concentrating ORC plant are compared with a PV/thermal alternative. The ORC output is significantly less than a PV panel would achieve; applications needing both heat and power are better served by PVT panels. This is an original and novel result

Valorization of biomass for the design of bioactive materials under irradiation

La valorisation des dérivés phénoliques et terpéniques issus de la biomasse s’insère parfaitement dans le défi actuel de nos sociétés qui pousse la chimie traditionnelle à évoluer vers une chimie durable. De par leur nature insaturée, les terpènes se montrent particulièrement intéressants pour synthétiser de nouveaux matériaux par réaction de chimie thiol-ène. Parallèlement, les dérivés phénoliques peuvent être facilement modifiés en synthons insaturés, susceptibles de réagir dans ces mêmes réactions. Ainsi, une large gamme de matériaux à base de linalol et d’eugénol a été élaborée sous irradiation UV. Une approche par photochimie a été privilégiée puisqu’elle s’inscrit parfaitement dans le cadre d’une chimie plus respectueuse de l’environnement. L’effet bénéfique des fonctions oxygénées du linalol et du phénol de l’eugénol sur l’activité antibactérienne a été démontré contre deux souches bactériennes principalement responsables du développement des maladies nosocomiales : S. aureus et E. coli. L’incorporation de nanoparticules de ZnO, de carvacrol ou d’acide tannique lors de la réaction de réticulation permet d’améliorer les propriétés antimicrobiennes de manière significative. L’association avec des polyesters semi-cristallins biosourcés et biodégradables présente une alternative intéressante pour optimiser les performances thermomécaniques des matériaux obtenus.Un deuxième type de matériaux a été synthétisé par photo-réticulation de dérivés phénoliques époxydés comme le résorcinol ou l’eugénol. La polymérisation cationique par ouverture de cycle photoamorcée permet la synthèse de matériaux dont les propriétés mécaniques sont plus élevées que les matériaux obtenus par réaction thiol-ène, et d’autre part de s’affranchir de l’agent réticulant à base de thiol. La synthèse de différents dérivés de l’eugénol mono-époxydés offre l’avantage de pouvoir moduler la composition des matériaux obtenus qui peuvent contenir des fonctions phénol et/ou des insaturations. Les groupements phénols sont indispensables à l’activité antibactérienne et sont à l’origine des propriétés anti-oxydantes. La possibilité d’introduire des insaturations permet une post- fonctionnalisation de la surface des matériaux.Ainsi une large gamme de matériaux réticulés, biosourcés et bioactifs dont les propriétés varient de l’élastomère au thermodurcissable a été synthétisée sous irradiationThe valorization of phenolic and terpene derivatives of biomass is perfectly in line with the current challenge of our societies that drives traditional chemistry to evolve towards a sustainable chemistry. Because of their unsaturated nature, terpenes are particularly interesting for synthesizing new materials by thiol-ene chemistry. At the same time, the phenolic derivatives can easily be modified to unsaturated synthons capable of reacting in these same reactions. Thus, a wide range of materials based on linalool and eugenol has been developed under UV irradiation. An approach by photochemistry has been selected since it fits perfectly within the framework of a chemistry more respectful of the environment. The beneficial effect of the oxygenated functions of linalol and phenolic functions of eugenol on antibacterial activity was demonstrated against two bacterial strains mainly responsible for the development of nosocomial diseases: S. aureus and E. coli. The incorporation of ZnO nanoparticles, carvacrol or tannic acid during the crosslinking reaction makes it possible to improve the antimicrobial properties significantly. The association with semi-crystalline biobased and biodegradable polyesters presents an interesting alternative to optimize the thermomechanical performance of the obtained materials.A second type of materials has been synthesized by photocrosslinking epoxidized phenolic derivatives such as resorcinol or eugenol. The photoinitiated cationic polymerization by opening of the ring enables the synthesis of materials whose mechanical properties are higher than the materials obtained by thiol-ene reaction and on the other hand to get rid of the thiol-based crosslinking agent. The synthesis of various monoepoxidized eugenol derivatives offers the advantage of being able to modulate the composition of the obtained materials which may contain phenol functions and / or unsaturations. The phenol groups are essential to the antibacterial activity and lead to the antioxidant properties. The possibility of introducing unsaturations allows a post-functionalization of the surface of the materials.Thus, a wide range of crosslinked, biosourced and bioactive materials whose properties vary from elastomer to thermosetting have been synthesized under irradiatio

Valorisation de la biomasse pour l'élaboration de matériaux bioactifs sous irradiation

The valorization of phenolic and terpene derivatives of biomass is perfectly in line with the current challenge of our societies that drives traditional chemistry to evolve towards a sustainable chemistry. Because of their unsaturated nature, terpenes are particularly interesting for synthesizing new materials by thiol-ene chemistry. At the same time, the phenolic derivatives can easily be modified to unsaturated synthons capable of reacting in these same reactions. Thus, a wide range of materials based on linalool and eugenol has been developed under UV irradiation. An approach by photochemistry has been selected since it fits perfectly within the framework of a chemistry more respectful of the environment. The beneficial effect of the oxygenated functions of linalol and phenolic functions of eugenol on antibacterial activity was demonstrated against two bacterial strains mainly responsible for the development of nosocomial diseases: S. aureus and E. coli. The incorporation of ZnO nanoparticles, carvacrol or tannic acid during the crosslinking reaction makes it possible to improve the antimicrobial properties significantly. The association with semi-crystalline biobased and biodegradable polyesters presents an interesting alternative to optimize the thermomechanical performance of the obtained materials.A second type of materials has been synthesized by photocrosslinking epoxidized phenolic derivatives such as resorcinol or eugenol. The photoinitiated cationic polymerization by opening of the ring enables the synthesis of materials whose mechanical properties are higher than the materials obtained by thiol-ene reaction and on the other hand to get rid of the thiol-based crosslinking agent. The synthesis of various monoepoxidized eugenol derivatives offers the advantage of being able to modulate the composition of the obtained materials which may contain phenol functions and / or unsaturations. The phenol groups are essential to the antibacterial activity and lead to the antioxidant properties. The possibility of introducing unsaturations allows a post-functionalization of the surface of the materials.Thus, a wide range of crosslinked, biosourced and bioactive materials whose properties vary from elastomer to thermosetting have been synthesized under irradiationLa valorisation des dérivés phénoliques et terpéniques issus de la biomasse s’insère parfaitement dans le défi actuel de nos sociétés qui pousse la chimie traditionnelle à évoluer vers une chimie durable. De par leur nature insaturée, les terpènes se montrent particulièrement intéressants pour synthétiser de nouveaux matériaux par réaction de chimie thiol-ène. Parallèlement, les dérivés phénoliques peuvent être facilement modifiés en synthons insaturés, susceptibles de réagir dans ces mêmes réactions. Ainsi, une large gamme de matériaux à base de linalol et d’eugénol a été élaborée sous irradiation UV. Une approche par photochimie a été privilégiée puisqu’elle s’inscrit parfaitement dans le cadre d’une chimie plus respectueuse de l’environnement. L’effet bénéfique des fonctions oxygénées du linalol et du phénol de l’eugénol sur l’activité antibactérienne a été démontré contre deux souches bactériennes principalement responsables du développement des maladies nosocomiales : S. aureus et E. coli. L’incorporation de nanoparticules de ZnO, de carvacrol ou d’acide tannique lors de la réaction de réticulation permet d’améliorer les propriétés antimicrobiennes de manière significative. L’association avec des polyesters semi-cristallins biosourcés et biodégradables présente une alternative intéressante pour optimiser les performances thermomécaniques des matériaux obtenus.Un deuxième type de matériaux a été synthétisé par photo-réticulation de dérivés phénoliques époxydés comme le résorcinol ou l’eugénol. La polymérisation cationique par ouverture de cycle photoamorcée permet la synthèse de matériaux dont les propriétés mécaniques sont plus élevées que les matériaux obtenus par réaction thiol-ène, et d’autre part de s’affranchir de l’agent réticulant à base de thiol. La synthèse de différents dérivés de l’eugénol mono-époxydés offre l’avantage de pouvoir moduler la composition des matériaux obtenus qui peuvent contenir des fonctions phénol et/ou des insaturations. Les groupements phénols sont indispensables à l’activité antibactérienne et sont à l’origine des propriétés anti-oxydantes. La possibilité d’introduire des insaturations permet une post- fonctionnalisation de la surface des matériaux.Ainsi une large gamme de matériaux réticulés, biosourcés et bioactifs dont les propriétés varient de l’élastomère au thermodurcissable a été synthétisée sous irradiatio

Domestic Septic Tanks for Treating Sewage and Biogas Generation

This study is to design a novel septic tank, named Anaerobic Upflow Domestic Septic Tank (AUDST) to recover biogas as energy and treat domestic sewage. The green technology proposes alternate options to existing Domestic Septic Tanks (DST), encourages anaerobically pre-treatment to reduce bacteria, pollutants, Total Suspended Solids (TSS), Chemical oxygen demand (COD) and Biological oxygen demand (BOD) before the effluent is discharged or is removed by cesspit trucks. Studies have shown that DST in homes partially treat or just store sewage. Again, these DST have to be emptied from time to time because it lack features that will sustain anaerobic activity and usually the sludge is disposed of directly into the sea, water bodies and even into open places such as “Lavender Hills’’ without any treatment or disinfection. These practices cause severe public health and environmental problems. To tackle the challenge at household level, DST are redesigned to treat domestic sewage with less management, low operating cost, low secondary discharge of pollutants. The proposed new design concept is operated through three (3) units: such as desilting, anaerobic digestion and facultative filtration units. The anaerobic digestion stage is made up of baffle and anaerobic filter for accommodating sludge and providing a more intimate contact between anaerobic biomass and sewage which improves treatment performance. The anaerobic unit is fitted with locally woven baskets prefilled with packing materials. The aim is to strengthen the biological treatment process at this stage. The Facultative Filtration unit of the model is also packed with filtering media such as gravels (3-6mm in diameter) that is low in cost, and has a high durability to produce effluent with lower pollutants and suspended solids content to meet Ghana’s Environmental Protection Agency (EPA) standards for the discharge of domestic effluents

A numerical and experimental study of micro-channel heat pipe solar photovoltaics thermal system

A novel micro-channel heat pipe array incorporated with crystalline silicon (c-Si) solar photovoltaic/thermal system (MHP-PV/T) was designed and constructed by the authors. The proposed design configuration combined c-Si solar cells and wide micro-channel heat pipes (MHP) that were filled with prescribed amount of acetone as refrigerant under a vacuum condition in the same insulated frame to simultaneously provide electrical and thermal energy. Heat and mass transfer characteristics of the MHP-PV/T were preliminary investigated using both numerical and experimental methods. The transient behavior and parametric heat transfer limitations of the heat pipe were also examined using MATLAB. A linear relation between the thermal instantaneous efficiency ηth and the reduced temperature parameter (Tout-Tin)GT-1 was established. The maximum instantaneous efficiency was found to be 54.0% with an electrical power output of 70 W. The results indicated that the daily thermal and electrical efficiencies were 50.7% and 7.6%, respectively. The transient behavior of the MHP shows a faster thermal response to heat input within the temperature range of 48.8–49.2 °C and slower response when the thermal diffusivity was reduced to 0.05 cm2/s. The results also reveal good agreements between model simulation and experimental measurement with sufficient confidence

Co-Networks Poly(hydroxyalkanoates)-Terpenes to Enhance Antibacterial Properties

Biocompatible and biodegradable bacterial polyesters, poly(hydroxyalkanoates) (PHAs), were combined with linalool, a well-known monoterpene, extracted from spice plants to design novel antibacterial materials. Their chemical association by a photo-induced thiol-ene reaction provided materials having both high mechanical resistance and flexibility. The influence of the nature of the crosslinking agent and the weight ratio of linalool on the thermo-mechanical performances were carefully evaluated. The elongation at break increases from 7% for the native PHA to 40% for PHA–linalool co-networks using a tetrafunctional cross-linking agent. The materials highlighted tremendous anti-adherence properties against Escherichia coli and Staphylococcus aureus by increasing linalool ratios. A significant decrease in antibacterial adhesion of 63% and 82% was observed for E. coli and S. aureus, respectively

Novel poly(3-hydroxy butyrate) macro RAFT agent. Synthesis and characterization of thermoresponsive block copolymers

WOS: 000532737000001TARAMASCOPUSTARAMAWOSA novel reversible addition fragmentation transfer (RAFT) agent based on the poly-3-hydroxy butyrate (PHB) with threehydroxyl groups (PHB-R2) and thermoresponsive amphiphilic block copolymers derived from N-isopropyl acryl amide(NIPAM) are described. Hydroxylated PHB is obtained by the reaction between PHB and diethanol amine (DEA) to preparehydroxylated PHB (PHB-DEA). It is then reacted with a RAFT agent, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid(DDMAT). Hydroxyl ends of the hydroxylated PHB are capped with carboxylic acid end of the trithiocarbonate. The blockcopolymers obtained by the polymerization of NIPAM initiated by PHB-R2 were characterized by1H NMR and physicochem-ical techniques. PHB content in the obtained block copolymers is varying between 14 and 45 wt%. The thermo-responsive PHB-PNIPAM block copolymers show the lower critical solution temperature (LCST) 28 and 30 °C while LCSTof the pure PNIPAMis 32 °C.Kapadokya Üniversitesi: KuN.2018-BAGP-001 Bulent Ecevit Üniversitesi: BEU-2017-72118496-0