Parametric Sensitivity Study and Optimization of the SDHW and PV Subsystems in an Energy Positive House

International audienceThis study presents a parametric sensitivity analysis of the dynamic simulation of the Solar Domestic Hot Water (SDHW) and Photovoltaic (PV) solar systems in an energy positive house. The optimized parameters concern the solar collectors, the storage tank and the fluid circulator. Significant gains are obtained on most of the parameters which allows for a better solar fraction with the SDHW. The energy need for the DHW auxiliary and pump is divided by three with a load scenario corresponding to a family of four. Moreover, we extended the study to the PV system to provides the best repartition option between thermal and PV panels on the solar roof. This maximizes the opportunity of generating surplus electricity, sold back to the power grid.Nous pre ́sentons une e ́tude de sensibilite ́ parame`trique sur la simulation nume ́rique dynamique des syste`mes d'ECS solaire (CESI) et PV dans une maison a` bilan d'e ́nergie positif. Les parame`tres d'optimisation concernent les capteurs, le ballon de stockage et le circulateur. Graˆce a` cette e ́tude, des gains important sont obtenus pour chacun des parame`tres e ́tudie ́s. Nous re ́duisons d'un facteur trois les besoins e ́nerge ́tiques annuels en appoint et circulation du syste`me initial dans un sce ́nario de charge correspondant a` une famille moyenne de quatre personnes. Nous poursuivons l'e ́tude avec le PV afin de de ́duire la re ́partition optimale de la surface du toit solaire entre les capteurs thermique et PV. Notre re ́sultat permet de produire plus d'e ́lectricite ́ pour la revente au re ́seau

Developing a low cost solar powered water pump for deployment in developing nations for agricultural purposes

Developing a low cost solar powered water pump for deployment in developing nations for agricultural purpose

Optimizing the use of inedible maize in the design of an ethanol production plant in Heilongjiang, China

This paper adapts the ethanol model developed by Aldonza and Blanchard by applying it to maize feedstock in China. Part of the reasoning for this is according to the BP Statistical Review of World Energy 20182, the proven oil reserves in China only accounted for 1.5% of the world reserves in 2017. Meanwhile, Chinese energy demand has soared as a result of rapid economic growth. Dependence on imported oil and serious environmental pollution have forced the government to give priority to energy security issues and actively develop its renewable energy industries. China is a populous country with around 40% of the population living in rural areas. It might be significantly important for the goal of sustainable energy to establish self-sufficient bioethanol manufacturing plants in areas with high agricultural output. This study will predict the potential of an inedible maize-based ethanol plant in a rural area of Heilongjiang Province, China, which can save on transportation costs as well as a benefiting from a large source of raw materials, consisting of degraded stored maize kernels and maize cobs. The estimated operating time is 20 years and the annual throughput of maize is 3650 tons. The prospective ethanol yield is 1800 litres/day with a yield of 0.18 litres per kilogram of maize kernels. Meanwhile, solar energy would be fully utilized to exchange heat with the puree to reach the chemical reaction temperature. The double enzyme process and three consecutive processes of fermentation is used in the ethanol production system. It is concluded that the plant model would recover investment funds in 6 years under government’s tax incentives. The sensitivity analysis for estimated cash flows indicated that the annual yield and retail price of ethanol to be the highest risks of this enterprise

Design of a solar energy centre for providing lighting and income-generating activities for off-grid rural communities in Kenya

One of the biggest challenges in the developing world is the provision of affordable and reliable electricity access to rural and marginalized people where grid extension is prohibitively expensive. Many off-grid schemes to date have focused on household lighting with mixed success. Some of the greatest difficulties have been around affordability and sustainability of the service provided, with systems being abandoned or removed due to broken equipment or inability of the user to continue paying for the service. It has been reported that key to the success of the best programs has been the means to improve the economic prospects of the users. In this paper the design of a solar energy centre for a rural village in Kenya, that enables income-generating activities for the community in addition to basic lighting and mobile phone charging provision, will be reported. We have found that it is possible to use the energy centre model to provide power for activities that could offer a source of income for the community, at an affordable cost with equipment available in Kenya today. It is believed that this will allow the community to develop economically and therefore ensure the sustainability of the off-grid power supply

Developing an open access monitoring device for off grid renewables

Electricity access is a key driver for developing a modern society. The use of locally generated renewable energy can overcome limitations of expensive grid infrastructure. However, there are still barriers to access particularly for the rural poor in the global south. When individuals or communities invest in electricity provision it is important to know how well the system is performing. Commercial monitoring systems have been developed for large scale renewable energy systems. The cost of these can outweigh the cost of a small decentralised renewable energy system. This paper describes the development of a low cost data logger that is going to be used to monitor the system performance of small photovoltaic nano-grids in Kenya and Bangladesh. The device performs within the expected range for the current, voltage, temperature and irradiance sensors. Data from the data logger device is sent via GPRS to a website where it can be accessed as real time graphical displays and data files

Cost benefit analyses for small scale biogas systems development in Ethiopia [Abstract]

In developing countries, anaerobic digestion offers a suitable solution to replace unsustainable utilization of traditional fuels. The full benefits can be gained when the biogas system is fully functional, which requires adequate efforts on the supply and on the demand sides. The National Biogas Programme in Ethiopia aims at developing a “commercially viable, market-oriented biogas sector in the country”. The factors for success and failures are analysed. Costs-benefits analyses are carried out on the supply and demand sides with sensitivity analysis at household level considering two scenario (“potential” and “to date”). The analysis highlights the high potential in economic terms, but the need to address challenges that are specific to the Ethiopian context. The biodigesters are still expensive for the households and not yet fully suited to the energy needs, and the constructors may not get sufficient benefits to remain actively involved in the sector. Biogas development is highly relevant in the Ethiopian context and these challenges are being addressed by the programme, with adequate solutions being put in place, but a pure commercial market model may not easily work at this stage

Maximizing the penetration levels of hybrid renewable energy systems in rural areas with demand side management approaches in achieving SDGs

Access to quality healthcare services is an integral part of sustainable development goals (SDGs) and reliable electricity access is a pre-requisite for improving human lives, enhancing healthcare delivery, education as well as other developmental growth within local communities. However, many rural locations far away from the grid centres have difficulties in accessing electricity, due to distance and cost of extension of grid to such areas, and this has resulted in the inability to provide basic amenities. Rural healthcare centres located in such places are unable to deliver their intended mandate, thus hindering the realization of SDG 3. Therefore, the innovative idea of this study is increasing the penetration of renewable energy technology while minimizing the cost by integrating the users’ perspective with demand side management (DSM) approaches, techno-economic analysis, and environmental impact assessment of hybrid energy system configuration, taking a health institution as the case study. To meet the considered rural healthcare facility’s initial average load demand of 20.58kWh/day, an optimum PV-Gen-battery hybrid system was selected using HOMER with cost of energy (COE) of $0.224/kWh, net present cost (NPC) of$61,917.6 and initial capital cost of $16,046.5. After the DSM measures were applied to reduce the peak and average demand, an optimum hybrid system was obtained, producing a COE of$0.166/kWh, NPC of $18,614.7 and initial capital cost of$10,070.8. The cost saving realized for the considered rural healthcare facility is $0.057/kWh, representing a 25.8% reduction from the current COE and a 70% reduction in Total NPC. On the other hand, the optimal configurations gave around a 75% reduction in CO2 emissions compare to a diesel-alone configuration. The work provides novel insights which may be applicable worldwide. It has the potential to significantly advance the development of high-quality and timely evidence to underpin current and future developments in the rural energy sector and contribute to the implementation of SDG3 and 7

A hybrid biogas system for Kolkata

Municipal solid waste (MSW) is a global problem. Four processes for treatment include landfilling, incineration, recycling and composting the organic fraction. Landfilling can cause the release of the potent greenhouse gas methane into the atmosphere. In many parts of the world, including the European Union, legislation to limit the amount of generated Organic Fraction Municipal Solid Wastes (OFMSW) going to landfill has been introduced. An alternative to landfilling is to anaerobically digest the OFMSW. This paper investigates the concept of a Hybrid Biomass System (HBS) consisting of solar thermal Flat Plat Collector (FPC) providing heat energy to the thermophilic (55oC) anaerobic digestion process, and the potential energy yield of hotel OFMSW in Kolkata. The methodology comprises development and assessment of a theoretical model representing the anaerobic digestion process for optimum biogas yield and TRNSYS simulation of a 5m2 and 10m2 FPC. Theoretical biogas production rates derived are 0.44m3/kgVS or 0.21m3 biogas/guest/day with a C/N ratio of 35:1. 5m2 and 10m2 FPC simulations maintained the thermophilic temperature of 55oC within -1.9 and +2.1. 10m2 FPC provides largest energy contribution at 11% of the annual energy requirement. In is concluded that FPCs can support thermophilic digester heating requirements with heat store or direct integration. In order to meet optimum biogas yield, legislation and policy is required to evolve the current waste management processes with emphasis on infrastructure development and source segregation

An assessment of biogas as a domestic energy source in rural Kenya: Developing a sustainable business model

Energy poverty in the majority of the rural households in Kenya is a threat to economic and social development; hence the availability of an affordable and reliable domestic energy source is important. This study investigated: the potential resources for biogas for cooking, suitable anaerobic digesters that could be deployed in rural households, and also the viability of a small community biogas business model. Conservative estimates of the business model parameters and sensitivity analysis revealed that there was adequate biogas potential in central and western Kenya while water scarcity affected other regions’ opportunities. Cattle manure was the predominant feedstock, although crop waste has possibilities to contribute to biogas production. Economically and technically, the inflatable tubular digester was found to be the most suitable type for biogas production in rural Kenya. Discounted cash flow analysis of the business model proved a profitable business to supply an affordable household energy at 0.55€/Kg of biogas, with projected household savings of 249€ annually. Labor cost was found to have high significance on the feasibility of the business model which was also sensitive to changes in biogas revenues. Kenya’s rural areas have significant biogas potential to reduce energy poverty, generate income and aid social development

Searching for Cooling Signatures in Strong Lensing Galaxy Clusters: Evidence Against Baryons Shaping the Matter Distribution in Cluster Cores

The process by which the mass density profile of certain galaxy clusters becomes centrally concentrated enough to produce high strong lensing (SL) cross-sections is not well understood. It has been suggested that the baryonic condensation of the intra-cluster medium (ICM) due to cooling may drag dark matter to the cores and thus steepen the profile. In this work, we search for evidence of ongoing ICM cooling in the first large, well-defined sample of strong lensing selected galaxy clusters in the range 0.1 < z < 0.6. Based on known correlations between the ICM cooling rate and both optical emission line luminosity and star formation, we measure, for a sample of 89 strong lensing clusters, the fraction of clusters that have [OII]3727 emission in their brightest cluster galaxy (BCG). We find that the fraction of line-emitting BCGs is constant as a function of redshift for z > 0.2 and shows no statistically significant deviation from the total cluster population. Specific star formation rates, as traced by the strength of the 4000 angstrom break, D_4000, are also consistent with the general cluster population. Finally, we use optical imaging of the SL clusters to measure the angular separation, R_arc, between the arc and the center of mass of each lensing cluster in our sample and test for evidence of changing [OII] emission and D_4000 as a function of R_arc, a proxy observable for SL cross-sections. D_4000 is constant with all values of R_arc, and the [OII] emission fractions show no dependence on R_arc for R_arc > 10" and only very marginal evidence of increased weak [OII] emission for systems with R_arc < 10". These results argue against the ability of baryonic cooling associated with cool core activity in the cores of galaxy clusters to strongly modify the underlying dark matter potential, leading to an increase in strong lensing cross-sections.Comment: 9 Pages, 5 Figures, 1 Tabl