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The smart grid is a product of the advances in computer and communication technology and power electronics that creates a more resilient, reliable and one that supports a two-way flow of electricity and information. The smart grid enables more uptake of the variable renewables like wind, solar and variable loads like the plug-in cars and improves the efficiency of power systems and facilitate several products and services supported by the grid like automatic healing and re-routing of power in case of a fault and demand side management. The deployment and use of smart grids will enhance the realization of shared goals of grid stakeholders, promote energy security, enable economic growth, and help in the mitigation of climate change.

The Levelized Costs of Energy/Electricity (LCOE) is widely used to compare different power generation technologies by considering the various fixed and variable costs as a single cost metric. The levelized cost of electricity (LCOE) measures the average net present cost of generating electric power over the power plants entire life. As a metric, the levelized cost of energy does not capture all costs that affect the cost of electricity like the system costs. For accuracy of cost analysis, the LCOE is modified to account for other costs e.g., system levelized cost which considers externalities. The value-adjusted levelized cost of electricity (VALCOE) is a metric developed by the International Energy Agency (IEA) that captures the cost and value to the electricity system since the same amount of power may be less or more valuable during peak demand. The levelized cost of storage (LCOS) is another metric applied in comparing alternative energy storage systems for specific energy scenarios i.e. long-term, short-term, and medium-term storage. Another related metric is the Levelized avoided cost of energy (LACE) which n captures information about how the grid operates without the new power plant or storage facility entering service making it more complex than LCOE or LCOS, but more insightful. The value-adjusted levelized cost of electricity (VALCOE) captures both cost and value to the electricity system. Another metric, the Levelized Full System Costs of Electricity (LFSCOE), metric is used to analyze the costs incurred to supply the entire energy market with one power source plus storage presented as one value just like the levelized cost of energy (LCOE). Therefore, the levelized cost of energy (LCOE) metric is universally accepted as a tool for preliminary cost evaluations of generation technologies, but for accurate and reliable assessment, various modifications of the levelized cost of energy/electricity must be applied.

Diesel power plants use diesel engines as prime movers powered mainly by heavy fuel oil or industrial diesel oil and with potential for conversion to gas engines or dual fuel engines. The global concerns over prices of diesel and heavy fuel oil and energy related greenhouse gas emissions have created demand for natural gas as an alternative fuel for power generation by diesel power stations. This study involved a performance analysis of an operating diesel power plant and its potential conversion to dual fuel engine power plant. Dual fuel engines have reduced fuel costs and greenhouse gas emissions since natural gas is the cleanest fossil fuel. For a conventional diesel engine to run on diesel, the fuel injection system is modified to handle gas and a mixture of gas and diesel. Other modifications are the introduction of an electronic control unit, reduction in air fuel ratio, installation of a fuel mixer, and reduction of compression ratio. The conversion requires provision for natural gas storage facilities and supply system which were introduced in the proposed design modification. The study showed that dual fuel engine power plants have better performance indicators like lower specific fuel consumption, higher indicated and brake thermal efficiency, cheaper power produced, less emissions per unit power and thus reduced environmental impact. Conversion to dual fuel engines will reduce the cost of electricity generation, reduce emissions particularly Sulphur dioxide while accommodating fuel flexibility like use of biofuel to substitute diesel.

Biogas is a renewable energy resource that can play a leading role in the sustainable energy transition through green electricity generation. Biogas can be converted to electricity and renewable fuels through different technologies and prime movers. Prime movers that can be used for biogas power generation include gas and steam turbines, diesel engines, Otto cycle engines, Stirling engines as well as direct conversion in fuel cells. Since biogas has high octane rating, it can be used directly or with minimal modifications in spark ignition or petrol engines, but needs several modifications for use in dedicated diesel biogas engines or dual fuel engines and bi engines. The dual fuel mode which uses biomethane or biogas and diesel requires little or no engine modifications unlike the conversion to a dedicated gas engine. The performance of biogas prime movers is greatly enhanced if enriched biogas or biomethane is used in place of raw biogas. Other than use in various engines, biogas can be cleaned and used in fuel cells and manufacture of renewable hydrogen. As renewable natural gas, biogas in the form of biomethane can be injected to the natural gas grids for domestic and industrial application as natural gas substitute in applications which include power generation.

The Sugar industry faces several sustainability challenges due to dumping of excess global production which cause stiff competition for high cost sugar producers like Kenya. Through diversification into cogeneration and ethanol production, sugar companies in high cost producing countries can remain competitive and survive in the market. In this study, the technical and economic feasibility of ethanol production is done for the case of Nzoia Sugar Company in Kenya whose milling capacity is 3000 tons of cane per day (TCD). Molasses is taken through a series of stages starting with pretreatment, followed by fermentation and distillation to produce ethanol. The ethanol formed is then transferred to the distillation columns for fractionation to remove water and hence have ethanol rich product. Through further distillation and molecular sieve dehydration the purity and quality of the final ethanol product is enhanced. The main equipment for the process includes the fermenter, boilers, condensers, and distillation columns, design to suit the product characteristics and design capacity of the plant. The analysis showed that ethanol production by a 3000 TCD sugar factory is a profitable venture. The study showed that investment is both technically and economically feasible and will improve the financial performance and sustainability of the sugar factory in a competitive market environment. Therefore, diversification into ethanol production is an important strategy in sustaining the sugar industry in a competitive global market.

Kenyan sugar factories are facing challenges in the market from low cost sugar producers as a result of high cost of production. As a result, a number of factories have closed down while operating factories are struggling with cash flow problems. Diversification into both ethanol and export cogeneration is a promising solution to the challenges. In this study, the feasibility of export electricity generation for a Nzoia sugar factory in Western Kenya is undertaken. The 3000 tons of cane per day crushing capacity (TCD) factory has effective generation capacity of 2.8 MW for own internal consumption against installed capacity of 7 MW. The study showed that the factory can develop a continuous power plant of 15 megawatts (MW) but modernization of the factory is necessary to reduce steam consumption mainly by replacing steam turbine drives with electric drives, increase generation efficiency by use of a condensing extraction turbine. The three boilers which are over 30 years old should be replaced with more efficient modern boilers of steam pressure between 45–60 bars. A well negotiated power purchase agreement that captures the challenges facing the factory should then be signed with a utility company to avoid the challenges in implementation due to external factors.

Waste heat recovery systems convert the thermal energy in waste fluid streams into useful work. Diesel engine cogeneration systems are waste recovery systems using technologies and devices with main elements being the diesel engine prime movers, the electric generator, Rankine cycle steam turbine, exhaust heat recovery boiler super heaters, and control and instrumentation devices. Diesel engines exhaust significant recoverable heat energy that can be converted to extra electricity using a Rankine cycle plant. In this study, the cogeneration potential of an operating diesel engine power plant was established. The cogeneration potential of a 119.7 MW operating power plant in Kenya is established. The study showed that subject to limits imposed by presence of sulphur in fuel and hence existence of sulphur dioxide in the exhaust, each engine of capacity 17.1 MWe has recoverable thermal energy of about 1.33 MWth while the whole plant with seven engines is about 9.3 MWth for the 7 engines at plant optimum loading conditions which can generate 8.5 MWe extra electricity under optimum conditions. The study recommends the development of up to 9 MWe Rankine cycle steam turbine-based cogeneration power plant. Diesel power plant cogeneration is a technically and economically viable strategy to increase the generation efficiency of diesel power plants and reduce the pollution intensity and financial performance of the diesel power plant leading to reduction in cost of power and higher return on investment for investors.

PurposeTo investigate the trends, prevalence and distribution of ocular trauma in a Zimbabwean Tertiary Teaching Hospital (Parirenyatwa).MethodA hospital-based retrospective cross-sectional study was conducted at the Parirenyatwa Group of Hospitals, Sekuru Kaguvi Eye Department in Harare, Zimbabwe, to review medical records of patients with ocular trauma visiting for treatment at the outpatient department between January 2017 and December 2021. Information on patients' demographics, presenting visual acuity, type of ocular trauma, and the number of eyes affected were collected and analysed using descriptive and inferential statistics.ResultsA total of 863 patients (1007 eyes) were identified to have experienced ocular trauma of one kind or another, with the youth (18-35 years) reporting with most cases (331, 38.4%). About 71.2% of patients were classified as having open-globe injuries and of that number, 90% were caused by blunt trauma, while the rest were caused by penetrating, intraocular, and perforating injuries. Patients with open-globe injuries were about 10 times more likely to develop blindness than those with closed-globe injuries after adjusting for age and gender, and this was statistically significant (ARR = 9.65, 95% CI: 5.53-16.84, p < 0.001). The prevalence of distance vision impairment due to ocular trauma was 60.1% (95% CI: 56.8%-63.4%), with majority resulting in blindness (22.0%, 95% CI: 19.4%-24.9%).ConclusionThere is a high prevalence of open-globe injuries in Zimbabwe with blunt trauma being the most significant cause. This suggests the need to promote and intensify public eye health awareness and sensitisation on safety strategies for the prevention of ocular trauma throughout the country.

Plastics are cheap, lightweight, and durable and can be easily molded into many different products, shapes, and sizes, hence their wide applications globally, leading to increased production and use. Plastic consumption and production have been growing since its first production in the 1950s. About 4% of global oil and gas production is being used as feedstock for plastics, and 3–4% is used to provide energy for their manufacture. Plastics have a wide range of applications because they are versatile and relatively cheap. This study presents an in-depth analysis of plastic solid waste (PSW). Plastic wastes can be technically used for oil production because the calorific value of the plastics is quite comparable to that of oil, making this option an attractive alternative. Oil can be produced from plastic wastes via thermal degradation and catalytic degradation, while gasification can be used to produce syngas. Plastic pyrolysis can be used to address the twin problem of plastic waste disposal and depletion of fossil fuel reserves. The demand for plastics has continued to rise since their first production in the 1950s due to their multipurpose, lightness, inexpensiveness, and durable nature. There are four main avenues available for plastic solid waste treatment, namely, reextrusion as a primary treatment, mechanical treatment as secondary measures, chemical treatment as a tertiary measure, and energy recovery as a quaternary measure. The pyrolysis oil has properties that are close to clean fuel and is, therefore, a substitute to fresh fossil fuel for power generation, transport, and other applications. The study showed that plastic wastes pyrolysis offers an alternative avenue for plastic waste disposal and an alternative source of fossil fuel to reduce the total demand of virgin oil. Through plastic pyrolysis, plastic wastes are thermally converted to fuel by degrading long-chain polymers into small complex molecules in the absence of oxygen, making it a technically and economically feasible process for waste plastic recycling. The process is advantageous because presorting is not required, and the plastic waste can be directly fed without pretreatment prior to the process. Products of plastic pyrolysis are pyrolysis oil, a hydrocarbon-rich gas, with a heating value of 25–45 MJ/kg, which makes it ideal for process energy recovery. Hence, the pyrolysis gas can be fed back to the process to extract the energy for the process-heating purpose, which substantially reduces the reliance on external heating sources.

Sugar industries have huge potential to contribute to the sustainable energy transition through electricity generation and production of biofuels. Sugar-producing countries generate huge volumes of sugarcane bagasse as a byproduct of sugarcane production. In this study, the performance of an operating traditional sugar factory is analyzed for electricity generation and export potential. The study presents characteristics and energy potential of modern and traditional sugar factories. The challenges facing a traditional sugar mill are inefficient boilers, less efficient and back pressure steam turbines, and wasteful and inefficient use of steam turbine drives as prime movers instead of modern electric drives for the mills and cane knives. Others are the use of inefficient and energy intensive cane mill rollers instead of the diffusers which have low energy requirements. It was demonstrated that the cogeneration potential of sugar factory is quite significant but currently underutilized. Sugar factories can make significant contribution towards mitigation of greenhouse gas emission mitigation through supply of green electricity to the public grid. The study showed that the factory uses very old and inefficient boilers aged over 39 years which contributes to poor performance and low electricity generation capacity. Modernization is required to increase the generation and electricity export capacity through investment in new and modern high-pressure boilers, replacement of inefficient back pressure boilers (BPSB) with more efficient condensing extraction turbines (CEST), and reduction of factory steam consumption by electrification of mills and cane knife turbine drives among other measures. This study showed that the 3,000 TCD factory can invest in a 15 MW power plant based on current average factory performance indicators and more if the throughput and overall performance is close to design parameters.

Abstract The long gestation period, high upfront costs and the risks in the development of central geothermal power plants are the main reasons for the slow rate of geothermal electricity growth and its contribution to the global electricity mix. The overall objective of this study was to make a comparison between central geothermal power plants and wellhead power plants in the delivery of geothermal electricity projects. The study showed that wellhead power plants are generally less efficient compared to central power plants because of higher specific steam consumption, but are financially attractive because of the quicker return on investment, early electricity generation and the lower financial risks. The study showed that permanent wellhead power plants are a better option for geothermal wells with too low or too high steam pressure compared to others in the steam field. Temporary use of wellhead power plants as opposed to their permanent use is preferred when only limited time is available between the commissioning of a wellhead plant and the commissioning of a central power plant in the same steam field. Technical, operational and environmental challenges, including higher specific steam consumption and lower efficiency than central power plants as well as absence of geothermal fluid reinjection system make wellhead plants less economical and less sustainable in resource use. It can thus be concluded that wellhead power plants can reduce the long wait to generate geothermal electricity and make an early return on investment for investors. Both central and wellhead power plants have relatively higher capacity factor than many other power plants and so can be used to supply base load electricity for the grid or off-grid power supply. This study is a review of the central and wellhead power plants and additionally provides policy guidelines in the execution of geothermal electricity projects either as central or wellhead power plants for grid electricity generation.

The greatest sustainability challenge facing humanity today is the greenhouse gas emissions and the global climate change with fossil fuels led by coal, natural gas and oil contributing 61.3% of global electricity generation in the year 2020. The cumulative effect of the Stockholm, Rio, and Johannesburg conferences identified sustainable energy development (SED) as a very important factor in the sustainable global development. This study reviews energy transition strategies and proposes a roadmap for sustainable energy transition for sustainable electricity generation and supply in line with commitments of the Paris Agreement aimed at reducing greenhouse gas emissions and limiting the rise in global average temperature to 1.5°C above the preindustrial level. The sustainable transition strategies typically consist of three major technological changes namely, energy savings on the demand side, generation efficiency at production level and fossil fuel substitution by various renewable energy sources and low carbon nuclear. For the transition remain technically and economically feasible and beneficial, policy initiatives are necessary to steer the global electricity transition towards a sustainable energy and electricity system. Large-scale renewable energy adoption should include measures to improve efficiency of existing nonrenewable sources which still have an important cost reduction and stabilization role. A resilient grid with advanced energy storage for storage and absorption of variable renewables should also be part of the transition strategies. From this study, it was noted that whereas sustainable development has social, economic, and environmental pillars, energy sustainability is best analysed by five-dimensional approach consisting of environmental, economic, social, technical, and institutional/political sustainability to determine resource sustainability. The energy transition requires new technology for maximum use of the abundant but intermittent renewable sources a sustainable mix with limited nonrenewable sources optimized to minimize cost and environmental impact but maintained quality, stability, and flexibility of an electricity supply system. Technologies needed for the transition are those that use conventional mitigation, negative emissions technologies which capture and sequester carbon emissions and finally technologies which alter the global atmospheric radiative energy budget to stabilize and reduce global average temperature. A sustainable electricity system needs facilitating technology, policy, strategies and infrastructure like smart grids, and models with an appropriate mix of both renewable and low carbon energy sources.

Geothermal energy has a significant role to play in the global transition to renewable and low-carbon energy systems because of its ability to supply steady and flexible electricity particularly for baseload demand because of its cost competitiveness compared to fossil fuel energy options. However, geothermal faces a challenge of long project development times with conventional power plant taking an average of 5–10 years and with high risks associated with drilling of unproductive wells which discourage private investment and quick deployment. Although geothermal energy has a huge potential for power generation, it currently contributes less than 1% of global electricity generation capacity. The generation capacity grew from 8.7 GWe in 2005 to 15.61 GWe at the end of the year 2020, representing average annual growth of 4.01%. The overall objective of this study was to determine the potential, features and application of wellhead power plants in electricity generation both to complement and substitute central powerplants. It was established that wellhead power plants can be used on temporary basis during the project development or permanently as grid connected or off grid generation facilities. With current technology, wellhead generators of up to 15 MW capacity can be installed on well pads of production wells for temporary or permanent electricity supply. Wellhead generators can facilitate optimum resource utilization especially for wells with unique conditions like too high or too low pressure and temperature compared to others in the same steam. They are generally inferior to central power plants due to lack of economies of scale hence higher unit cost of power. Successful adoption of wellhead powerplants for faster electrifications calls for state support and incentives in terms of subsidies, development of electricity gid, attractive feed in tariffs and tax incentives without which they won't compete favorably against the conventional central powerplants. Generally, wellhead powerplants can make geothermal electricity projects more feasible with reduced barriers in investment and early electricity and revenue generation for investors. However, investment on temporary basis makes reasonable economic sense if the time between drilling the first productive well and completion of a central plant is more than one year. Incentives like high feed in tariffs and tax incentives may be necessary to make them competitive against the superior conventional powerplants.

Biogas is competitive, viable, and generally a sustainable energy resource due to abundant supply of cheap feedstocks and availability of a wide range of biogas applications in heating, power generation, fuel, and raw materials for further processing and production of sustainable chemicals including hydrogen, and carbon dioxide and biofuels. The capacity of biogas based power has been growing rapidly for the past decade with global biogas based electricity generation capacity increasing from 65 GW in 2010 to 120 GW in 2019 representing a 90% growth. This study presents the pathways for use of biogas in the energy transition by application in power generation and production of fuels. Diesel engines, petrol or gasoline engines, turbines, microturbines, and Stirling engines offer feasible options for biogas to electricity production as prme movers. Biogas fuel can be used in both spark ignition (petrol) and compression ignition engines (diesel) with varying degrees of modifications on conventional internal combustion engines. In internal combustion engines, the dual-fuel mode can be used with little or no modification compared to full engine conversion to gas engines which may require major modifications. Biogas can also be used in fuel cells for direct conversion to electricity and raw material for hydrogen and transport fuel production which is a significant pathway to sustainable energy development. Enriched biogas or biomethane can be containerized or injected to gas supply mains for use as renewable natural gas. Biogas can be used directly for cooking and lighting as well as for power generation and for production of Fischer-Tropsch (FT) fuels. Upgraded biogas/biomethane which can also be used to process methanol fuel. Compressed biogas (CBG) and liquid biogas (LBG) can be reversibly made from biomethane for various direct and indirect applications as fuels for transport and power generation. Biogas can be used in processes like combined heat and power generation from biogas (CHP), trigeneration, and compression to Bio-CNG and bio-LPG for cleaned biogas/biomethane. Fuels are manufactured from biogas by cleaning, and purification before reforming to syngas, and partial oxidation to produce methanol which can be used to make gasoline. Syngas is used in production of alcohols, jet fuels, diesel, and gasoline through the Fischer-Tropsch process.

Nanostructured lipid carriers (NLC) are capable of encapsulating hydrophilic and lipophilic drugs. The present study developed an NLC containing epidermal growth factor (EGF) and curcumin (EGF–Cur-NLC). EGF–Cur-NLC was prepared by a modified water-in-oil-in-water (w/o/w) double-emulsion method. The EGF–Cur-NLC particles showed an average diameter of 331.8 nm and a high encapsulation efficiency (81.1% and 99.4% for EGF and curcumin, respectively). In vitro cell studies were performed using two cell types, NIH 3T3 fibroblasts and HaCaT keratinocytes. The results showed no loss of bioactivity of EGF in the NLC formulation. In addition, EGF–Cur-NLC improved in vitro cell migration, which mimics the wound healing process. Finally, EGF–Cur-NLC was evaluated in a chronic wound model in diabetic rats. We found that EGF–Cur-NLC accelerated wound closure and increased the activity of antioxidant enzymes. Overall, these results reveal the potential of the NLC formulation containing EGF and curcumin to promote healing of chronic wounds.

We introduce a 10-fs hyperspectral source architecture for facilitating nonlinear spectroscopy with multi-color sequences of arbitrarily shaped 10-fs UV/Vis, near-IR, and mid-IR pulses. Design principles and initial experimental results are provided.