| 1. |
- Azimoh, Chukwuma Leonard, et al.
(författare)
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An assessment of unforeseen losses resulting from inappropriate use of solar home systems in South Africa
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 136, s. 336-346
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Tidskriftsartikel (refereegranskat)abstract
- One of the challenges to the sustainability of the Solar Home System (SHS) electrification program in South Africa is equipment theft. In response to this, communities susceptible to solar panel theft resort to mounting their panels flat on the ground so they can be looked after during the day and taken indoors at night for safe keeping. Other households use their security lights to illuminate their environment and provide security for pole and roof mounted solar panels at night. These actions have consequential effects on the performance of the SHS. Several studies have detected resentment from households regarding the low power quality from these systems. Most scientific contributions on the issue of low power from SHS have focused on the challenges based on the technical designs of the systems. The power losses due to the usage pattern of the system has not received much attention. This study therefore reports on the technical losses as a result of the deviation from the designed and installed specification of the system by the users in order to protect their systems. It also investigates the linkage between the technical and economic losses which affects the sustainability of SHS program. A case study was performed in Thlatlaganya village within Limpopo province in South Africa. Technical analysis using PVSYST solar software revealed that the energy output and performance of the battery is compromised as a result of these practices. Economic analysis indicates that the battery life and the economics of owning and operating SHS are affected negatively. The study recommends solutions to mitigate these losses, and proposes a cost effective way of optimizing the operation of SHS using a Bench-Rack system for mounting solar panels.
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| 2. |
- Azimoh, Chukwuma Leonard, et al.
(författare)
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Electricity for development: : Mini-grid solution for rural electrificationin South Africa
- 2016
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; :110, s. 268-277
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Tidskriftsartikel (refereegranskat)abstract
- The objective of most rural electrification programs in the developing world is to bring about socioeconomicdevelopment to households. Governments have put in place a number of measures to achievethis goal. Previous studies on rural electrification programs in developing countries show that solar homesystems and mini-grid systems are the dominant technologies. Assessments of a pilot hybrid mini-gridproject at Lucingweni village have concluded that mini-grid projects are not feasible due to high electricityproduction costs. As a result efforts toward rural electrification have been focused on the solar homesystem. Nevertheless, previous studies of the South African solar home system program have shown thatthe development objectives of the program are yet to be met more than a decade after commissioning.Therefore, this study investigates the viability of a hybrid mini-grid as a solution for rural developmentin South Africa. Investigations were based on Lucingweni and Thlatlaganya, two rural Villages where themini-grid and solar home system have been introduced. The mini-grid systems were designed taking intoconsideration available natural resources and existing load profiles. The results show that a village of 300households needs about 2.4 kW h/household/day of electricity to initiate and sustain income generatingactivities and that the solar home system is not capable of supporting this level of demand. We also showthat in locations with hydro resources, a hybrid mini-grid system has the most potential for meeting theenergy needs of the households in a cost effective manner. The assessment shows that with adequateplanning and optimization of available resources, the cost of electricity production can be reduced.
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| 3. |
- Azimoh, Chukwuma Leonard, et al.
(författare)
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Illuminated but not electrified : An assessment of the impact of Solar Home System on rural households in South Africa
- 2015
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 155, s. 354-364
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Tidskriftsartikel (refereegranskat)abstract
- The introduction of the off-grid electrification program in South Africa using the Solar Home System (SHS) was a central component of the government policy aimed at bringing development to un-electrified households. An assessment of the performance of SHS in many countries provided little evidence to support the development impact of the system. The general perception is that the SHS program is wasting government funds and has no hope of achieving the set objectives. Previous scientific reports have concluded that SHS is the most viable technology for bringing about socio-economic development to rural households. Most of these conclusions have been based on one sided arguments and largely on anecdotal evidence. This study provides a pluralistic view of the subject from the perspective of the energy service companies (ESCOs) and the households using the equipment. The development impact of SHS is subjected to scientific analysis by investigating the economic and social dimensions of the program. Additionally, the sustainability of the South African SHS program is assessed by investigating the challenges facing the ESCOs and the households. The study reveals that illumination provided by SHS electricity has profound impact on the livelihoods of rural households. Due to the limited capacity of SHS for productive and thermal use, there are limited direct economic benefits to the households. The associated economic impact is peripheral to the secondary usage of SHS electricity. SHS has improved the productivity of small scale business owners who utilize the light from SHS to do business at night. Irregularities in payment of subsidy funds and energy bills, high operation cost, non-optimal use of SHS, grid encroachment, and lack of customer satisfaction contribute to make the business unsustainable for the ESCOs.
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| 4. |
- Azimoh, C. L., et al.
(författare)
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Replicability and scalability of mini-grid solution to rural electrification programs in sub-Saharan Africa
- 2017
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Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481. ; 106, s. 222-231
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Tidskriftsartikel (refereegranskat)abstract
- The assessment of off-grid electrification programs in developing countries largely based on mini-grid and solar home system (SHS) has shown that they are faced with low development imparts and sustainability challenges, which has resulted in failure of many projects. This study provides solutions on how to surmount these challenges, leaning on the experience of a hybrid solar-diesel mini-grid at Tsumkwe village in Namibia. It provides analyses of a case study based on empirical evidence from field studies, interviews of representatives of households, public institutions and energy providers. In addition, it investigates the technical challenges and economic impacts of the electrification program. HOMER™ and MATLAB™ models were used in the analysis and investigations. The findings show that despite the challenges, the system has been sustained because it keyed into an existing structure with growth potentials. The progressive tariff system adopted by the government helped to cushion costs and allow low income households in the energy matrix. Adoption of strict maintenance measures, and implementation of energy efficiency measures prior to the commissioning of the program, resulted in the reduction of costs. The success elements identified in this study could be extrapolated in other sub-Saharan African countries if the challenges are properly addressed.
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| 5. |
- Azimoh, Chukwuma Leonard, et al.
(författare)
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The burden of shading and location on the sustainability of South African solar home system program
- 2015
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 75, s. 308-313
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Tidskriftsartikel (refereegranskat)abstract
- Most contributions on the issues of sustainability of rural electrification projects have focused on the technology and business models used to drive the projects. The issues of user education and environmental impact on the technology have received little attention, despite the fact that these challenges affect lives of projects after commissioning. The usage pattern of solar home systems (SHS) by most users that placed their solar panels close to obstructing objects, results in shading of the panels, and geographic location of households in the concession areas of the South African SHS program affects the performances of the system. The non-optimal use of SHS is mainly due to lack of user education. Therefore this paper reports on the impact of geographic location and shading of panels on the economics and technical performance of SHS. The study was done by investigating the performance of 75 WP solar panels operated at two sites in South Africa (Upington in Northern Cape Province and Thlatlaganya in Limpopo Province), the performance of an optimized shaded SHS and a non-shaded one was also investigated. The results show that both geographic location and shading compromise the performance of the systems, the energy output of a solar panel located at Upington is increased by 19% and the state of charge of the battery (SOC) increased by 6%, compared to the panel situated at Thlatlaganya village. Also the life span of the battery is increased by about one year. The SOC of the partially shaded SHS is reduced by 22% and loss of power to the load increased by 20%. The geographical location of the SHS concession areas in South Africa and lack of adherence to the manufacturer's installation specification affects the economics of SHS and the energy output vis-a-vis the sustainability of the program due to reduction in life cycle of the batteries.
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| 6. |
- Borgegard, Tomas, et al.
(författare)
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Alzheimers Disease: Presenilin 2-Sparing gamma-Secretase Inhibition Is a Tolerable A beta Peptide-Lowering Strategy
- 2012
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Ingår i: Journal of Neuroscience. - : Society for Neuroscience. - 0270-6474 .- 1529-2401. ; 32:48, s. 17297-17305
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Tidskriftsartikel (refereegranskat)abstract
- gamma-Secretase inhibition represents a major therapeutic strategy for lowering amyloid beta (A beta) peptide production in Alzheimers disease (AD). Progress toward clinical use of gamma-secretase inhibitors has, however, been hampered due to mechanism-based adverse events, primarily related to impairment of Notch signaling. The gamma-secretase inhibitor MRK-560 represents an exception as it is largely tolerable in vivo despite displaying only a small selectivity between A beta production and Notch signaling in vitro. In exploring the molecular basis for the observed tolerability, we show that MRK-560 displays a strong preference for the presenilin 1(PS1) over PS2 subclass of gamma-secretases and is tolerable in wild-type mice but causes dose-dependent Notch-related side effect in PS2-deficient mice at drug exposure levels resulting in a substantial decrease in brain A beta levels. This demonstrates that PS2 plays an important role in mediating essential Notch signaling in several peripheral organs during pharmacological inhibition of PS1 and provide preclinical in vivo proof of concept for PS2-sparing inhibition as a novel, tolerable and efficacious gamma-secretase targeting strategy for AD.
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| 7. |
- Borgegård, Tomas, et al.
(författare)
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Alzheimer's Disease : Presenilin 2-Sparing γ-Secretase Inhibition Is a Tolerable Aβ Peptide-Lowering Strategy
- 2012
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Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 32:48, s. 17297-17305
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Tidskriftsartikel (refereegranskat)abstract
- γ-Secretase inhibition represents a major therapeutic strategy for lowering amyloid β (Aβ) peptide production in Alzheimer's disease (AD). Progress toward clinical use of γ-secretase inhibitors has, however, been hampered due to mechanism-based adverse events, primarily related to impairment of Notch signaling. The γ-secretase inhibitor MRK-560 represents an exception as it is largely tolerable in vivo despite displaying only a small selectivity between Aβ production and Notch signaling in vitro. In exploring the molecular basis for the observed tolerability, we show that MRK-560 displays a strong preference for the presenilin 1 (PS1) over PS2 subclass of γ-secretases and is tolerable in wild-type mice but causes dose-dependent Notch-related side effect in PS2-deficient mice at drug exposure levels resulting in a substantial decrease in brain Aβ levels. This demonstrates that PS2 plays an important role in mediating essential Notch signaling in several peripheral organs during pharmacological inhibition of PS1 and provide preclinical in vivo proof of concept for PS2-sparing inhibition as a novel, tolerable and efficacious γ-secretase targeting strategy for AD.
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| 8. |
- Campana, Pietro Elia, et al.
(författare)
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An open-source optimization tool for solar home systems : A case study in Namibia
- 2016
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 130:15, s. 106-118
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Tidskriftsartikel (refereegranskat)abstract
- Solar home systems (SHSs) represent a viable technical solution for providing electricity to households and improving standard of living conditions in areas not reached by the national grid or local grids. For this reason, several rural electrification programmes in developing countries, including Namibia, have been relying on SHSs to electrify rural off-grid communities. However, the limited technical know-how of service providers, often resulting in over- or under-sized SHSs, is an issue that has to be solved to avoid dissatisfaction of SHSs’ users. The solution presented here is to develop an open-source software that service providers can use to optimally design SHSs components based on the specific electricity requirements of the end-user. The aim of this study is to develop and validate an optimization model written in MS Excel-VBA which calculates the optimal SHSs components capacities guaranteeing the minimum costs and the maximum system reliability. The results obtained with the developed tool showed good agreement with a commercial software and a computational code used in research activities. When applying the developed optimization tool to existing systems, the results identified that several components were incorrectly sized. The tool has thus the potentials of improving future SHSs installations, contributing to increasing satisfaction of end-users.
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| 9. |
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| 10. |
- Hakalehto, E., et al.
(författare)
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Some remarks on processing of slaughterhouse wastes from ecological chicken abattoir and farm
- 2016
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Ingår i: Microbiological Industrial Hygiene. - : Nova Science Publishers, Inc.. - 9781634852937 - 9781634852685 ; , s. 271-293
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In the meat industries, it is always of high importance to follow up the zoonotic and other hazardous micro-organisms, and to prevent their risky distribution, emission and dissemination. Besides proper hygiene control, as well as organized exploitation of the side streams and slaughterhouse wastes helps in the hygienization of the biomasses, processes, and the entire industry. During this experimentation it turned out that it was possible to produce gases and chemical goods, not only from the carboxylates, but also from the more tedious protein and lipid containing wastes. Moreover, these promising results were obtained from a substrate mix with manure and wood chips. These results implied to the high versatility and flexibility of the bioprocess during Pilot A tests within the European Union Baltic Sea region project ABOWE. In Sweden these tests were carried out using the combined wastes from the ecological chicken farm and abattoir as the raw materials. This is a report of the practical set up during intensive experimentation conducted jointly by the Swedish and Finnish personnel. The report of the runs in Sweden is presented also in the public report of the European Union funded project (www.abowe.eu).
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