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The chances of a global hydrogen economy becoming a reality have increased significantly since the COVID pandemic and the war in Ukraine, and for net zero carbon emissions. However, intercontinental hydrogen transport is still a major issue. This study suggests transporting hydrogen as a gas at atmospheric pressure in balloons using the natural flow of wind to carry the balloon to its destination. We investigate the average wind speeds, atmospheric pressure, and temperature at different altitudes for this purpose. The ideal altitudes to transport hydrogen with balloons are 10 km or lower, and hydrogen pressures in the balloon vary from 0.25 to 1 bar. Transporting hydrogen from North America to Europe at a maximum 4 km altitude would take around 4.8 days on average. Hydrogen balloon transportation cost is estimated at 0.08 USD/kg of hydrogen, which is around 12 times smaller than the cost of transporting liquified hydrogen from the USA to Europe. Due to its reduced energy consumption and capital cost, in some locations, hydrogen balloon transportation might be a viable option for shipping hydrogen compared to liquefied hydrogen and other transport technologies. [Display omitted] • A new approach to transporting hydrogen with balloons. • Possible paths for hydrogen balloon transportation. • Estimation of the optimum altitude to transport hydrogen in balloons. • The global potential for hydrogen balloon transportation is accessed. [ABSTRACT FROM AUTHOR]

The most challenging aspect of developing a green hydrogen economy is long-distance oceanic transportation. Hydrogen liquefaction is a transportation alternative. However, the cost and energy consumption for liquefaction is currently prohibitively high, creating a major barrier to hydrogen supply chains. This paper proposes using solid nitrogen or oxygen as a medium for recycling cold energy across the hydrogen liquefaction supply chain. When a liquid hydrogen (LH2) carrier reaches its destination, the regasification process of the hydrogen produces solid nitrogen or oxygen. The solid nitrogen or oxygen is then transported in the LH2 carrier back to the hydrogen liquefaction facility and used to reduce the energy consumption cooling gaseous hydrogen. As a result, the energy required to liquefy hydrogen can be reduced by 25.4% using N 2 and 27.3% using O 2. Solid air hydrogen liquefaction (SAHL) can be the missing link for implementing a global hydrogen economy. • The energy required to liquefy hydrogen reduces by 25.4% with N 2 and 27.3% with O 2. • Solid O 2 is a better hydrogen liquefaction energy carrier than solid N 2. • Solid N 2 is selected as the energy carrier due to the risk explosion using O 2. • The solid N 2 occupies 44.5% of the liquid H 2 tank volume. [ABSTRACT FROM AUTHOR]

Abstract In tropical climates, the energy consumed by ventilation and air conditioning can exceed 50% of the total consumption of a building. Demand for cooling is rising steadily, driven mainly by growing incomes in developing economies, and is expected to also increase with climate change. Tropical, coastal areas with narrow continental shelves are good sites for the implementation of Seawater Air Conditioning (SWAC), a renewable and low CO 2 emission cooling process. This paper presents the existing SWAC projects around the world and gives details on the technology. Data on ocean temperature profiles, ocean bathymetry and world surface temperature are processed with the intent of estimating the world potential of SWAC. The results present the required distance from coast to reach seawater with a temperature of 5 °C or less. This is combined with the potential demand for air conditioning, taking into account surface air temperature and a set SWAC design for cooling from 30 to 20 °C. The pipeline length, seawater depth and capacity factor are then used to estimate the costs of SWAC projects around the world. It is concluded that the locations with the highest potential for SWAC are intertropical islands and some continental locations. Highlights • This renewable source is ideal for tropical coastal areas with narrow continental shelves. • The energy in a m3/s of SWAC can be equivalent to 49 ha of solar PV or 42 MW of wind turbines. • A novel SWAC potential model is developed to identify the most promising sites worldwide. • Capacity factor, pipeline length, depth extraction and cost estimates are presented in detail. • The cheapest SWAC project costs $0.0185/KWh t and is located in Nauru, Pacific Ocean. [ABSTRACT FROM AUTHOR]

Renewable sources of energy are providing an increasing share of the electricity generation mix, but their intermittency drives a need for energy storage. At the same time, water resources are increasingly scarce due to changes in demand, such as from population growth, supply side pressures such as climate change and governance challenges relating to poor management. Large storage reservoirs are used for water management and for energy storage. However, some existing and proposed hydropower reservoirs require vast areas of land and have considerable social and environmental impacts. Growing concerns on water and energy storage from a water-energy-land nexus approach motivated this study. Our objective is to compare how energy and water storage services, such as hydropower generation, electricity grid and water management, are provided with Seasonal Pumped-Storage (SPS) and Conventional Reservoir Dams (CRD) plants. Our case study region is Brazil, a country with extensive hydropower capacity and development plans, for which we compare the cost, land requirement and social impacts between CRD and potential SPS plants. Whilst seasonal pumped-storage have higher capital costs than conventional reservoir dams, given the much lower land requirements and evaporative losses, they are a valuable water and energy storage alternative especially in locations with plain topography and high evaporation. Results show that if Sobradinho CRD was built today it would result in a $USD 1.46 billion loss, on the other hand, Muquém SPS plant would result in a $USD 0.67b revenue. [ABSTRACT FROM AUTHOR]

From the end of 2013 to the end of 2015, Brazil faced serious challenges to supply its demand for electricity due to a prolonged drought in the Southeast and Northeast regions with the consequent loss of hydroelectric generation. This paper presents an historical analysis of major world energy crises from 1988 to 2015 and in Brazil from 1924 to 2015. Analysing the natural river flow of key Brazilian dams from 1931 until 2017, this paper suggests that hydropower generation in Brazil has a 10–15 years cyclical pattern of hydropower generation. The periods of drought in this cyclical pattern usually coincides with energy crises due to the reduction in hydropower generation. It was found that the drought in 2015 had an impact of 110 TWh in hydropower generation, from which 25 TWh are due to head loss and 70 TWh are from lack of stored hydropower in July of 2014. In addition, 48 TWh were not generated due to delays in the construction of new power plants. Other causes of the Brazilian energy crisis of 2015 are presented and the overall electricity generation impact of these causes are compared. In addition, this paper presents the impacts on the energy, water and food supply sectors in Brazil, and the strategies employed to reduce the impact of the crises. With the intention of preventing future energy crises, the paper then shows the potential alternatives to improve electricity supply security in Brazil, particularly in terms of diversifying and widening the share of renewable sources and increasing the energy storage potential of the country. [ABSTRACT FROM AUTHOR]

There is an enormous untapped potential for hydropower generation in rivers with large head and high flow variation, currently not feasible for conventional hydropower dams. Conventional dams make use of the potential energy, but waste kinetic energy from spillage during periods of high flows. This article studies the possibility of harnessing energy from potential and kinetic energy from hydropower dams with large head and flow variation, analyses its potential, and shows possible technologies. Focus is given to a Moveable Hydro-Electric Power Plant (HEPP) system in which the turbine module can be adjusted according to the flow and water level in the river. During floods the exceeding flows can pass above and below the Moveable HEPP results in a sub-pressure environment after the turbine module, thereby reducing the dam’s downstream head, increasing the pressure difference between the turbine inlet and outlet and the flow through the turbine, which increases the electricity generation of the dam. Dams with head increaser arrangement have been implemented in several dams in the 1930–1950s and now are regaining attention in Middle Europe. The main intention for its implementation is harnessing hydropower generation at run-of-river plants, with low-head, with a 20%–30% cost reduction, lower flooded area at the dam site, the resulting evaporation and the impact on the aquatic fauna. A case study was performed with the proposal of the Aripuanã Moveable HEPP in the Madeira River with a 26 ms height dam and a generation capacity of 1400 MW. The increase in generation with the head increaser effect is as high as 21%. The estimated potential for this technology in the Amazon region is 20 GW. Other potential locations are discussed in the article. Dams with head increaser effect have been successfully implemented and have the potential to become a major alternative for base load renewable energy in the future. [ABSTRACT FROM AUTHOR]

In order to maintain greater control over the country's water resources and reduce the vulnerability of the Brazilian electricity sector, this paper presents a review of the Seasonal-Pumped-Storage (SPS) potential in Brazil, its benefits and the different ways in which SPS can be integrated with hydroelectric dams in cascade downstream. In addition to increasing the Brazilian energy storage potential, SPS has the potential to: regulate river flows allowing the control of hydropower generation; reduce the spillage and increase power generation in the hydroelectric dams in cascade; turn the construction of new dams more viable where there is no suitable geology for the construction of conventional storage reservoirs; control floods when the geology does not permit the construction of storage reservoirs; decrease the evaporation of accumulation reservoirs; store the electricity generated from intermittent renewable sources; store energy for peak generation; reduce transmission bottlenecks; decrease the cost of electricity transmission from hydroelectric plants in the Amazon; decentralize the energy storage capacity in Brazil to increase energy security and to reduce the risk of electricity rationing. [ABSTRACT FROM AUTHOR]

The world is undergoing a rapid energy transformation dominated by growing capacities of renewable energy sources, such as wind and solar power. The intrinsic variable nature of such renewable energy sources calls for affordable energy storage solutions. This paper proposes using lifts and empty apartments in tall buildings to store energy. Lift Energy Storage Technology (LEST) is a gravitational-based storage solution. Energy is stored by lifting wet sand containers or other high-density materials, transported remotely in and out of the lift with autonomous trailer devices. The system requires empty spaces on the top and bottom of the building. An existing lift can be used to transport the containers from the lower apartments to the upper apartments to store energy and from the upper apartments to the lower apartments to generate electricity. The installed storage capacity cost is estimated at 21 to 128 USD/kWh, depending on the height of the building. LEST is particularly interesting for providing decentralized ancillary and energy storage services with daily to weekly energy storage cycles. The global potential for the technology is focused on large cities with high-rise buildings and is estimated to be around 30 to 300 GWh. • A new gravitational energy storage solution based on the operation of lifts in high-rise buildings. • LEST is a decentralized solution for energy storage with daily to weekly cycles. • The installed capacity energy storage cost of LEST is 21–128 USD/kWh. • LEST is particularly interesting for providing decentralized ancillary services. • The world potential for LEST is estimated to be 30 to 300 GWh. [ABSTRACT FROM AUTHOR]

The world switching to more sustainable energy sources to curb CO 2 emissions and haul climate change. One sector expected to see rapid growth in energy consumption is the cooling sector due to population growth and climate change. A sustainable solution for cooling needs in coastal areas that are not often addressed is seawater air-conditioning, which pumps cold water from the deep sea to the shore and uses it for cooling. The main challenge for this technology is to distribute the cooling service. This paper proposes using pressurized ammonia to distribute the cooling services provided by SWAC plants. Results show that ammonia district cooling allows SWAC to significantly increase its load demand and lower cooling costs. Ammonia district cooling could be the missing piece for implementing seawater air-conditioning due to its potential to increase the cooling load of district cooling systems. • Ammonia district cooling, the missing link for district cooling solutions. • A 17 m3/s seawater flow can provide 1 GWt of cooling load. • Ammonia, a better alternative for thermal energy transport than steam. [ABSTRACT FROM AUTHOR]

Due to the lack of energy storage in the new hydropower plants in the Amazon region, Brazil will require thermoelectric power plants to generate electricity during the dry period (May–October). Biomass based electricity generation, especially eucalyptus trees, can be used to replace the expensive liquefied natural gas infrastructure required to generate electricity during the dry seasons and emergency generation during dry years in Brazil. This article presents a new electricity generation scheme called “Energy Crop Storage”. In this scheme, biomass is grown and stored in eucalyptus plantations in order to match the supply of energy to its demand. For example, during wet years in Brazil, when biomass plants operate at 50% capacity, the eucalyptus trees are allowed to continue growing. During dry years, the biomass stored is used more intensively as biomass generation raises to 90% of its capacity. It was concluded that natural gas is a high risk investment in Brazil because, if there are several consecutive wet years, the expensive infrastructure dedicated to natural gas based electricity generation will remain on standby. Biomass plantations, on the other hand, are a more reliable investment as the biomass is stored when the biomass demand is lower. [ABSTRACT FROM AUTHOR]

The world is undergoing a substantial energy transition with an increasing share of intermittent sources of energy on the grid, which is increasing the challenges to operate the power grid reliably. An option that has been receiving much focus after the COVID pandemic is the development of a hydrogen economy. Challenges for a hydrogen economy are the high investment costs involved in compression, storage, and long-distance transportation. This paper analyses an innovative proposal for the creation of hydrogen ocean links. It intends to fill existing gaps in the creation of a hydrogen economy with the increase in flexibility and viability for hydrogen production, consumption, compression, storage, and transportation. The main concept behind the proposals presented in this paper consists of using the fact that the pressure in the deep sea is very high, which allows a thin and cheap HDPE tank to store and transport large amounts of pressurized hydrogen in the deep sea. This is performed by replacing seawater with pressurized hydrogen and maintaining the pressure in the pipes similar to the outside pressure. Hydrogen Deep Ocean Link has the potential of increasing the interconnectivity of different regional energy grids into a global sustainable interconnected energy system. • A novel strategy to create a global sustainable interconnected energy system. • The role of offshore wind power in the creation of the ocean link is shown. • Multi-purpose ocean electric transmission connection is introduced. • Reversible electrolysis ship for flexible production of green hydrogen or electricity. • World potential for deep ocean compressed hydrogen transportation is illustrated. [ABSTRACT FROM AUTHOR]

The world is undergoing a transition to a more sustainable energy sector dominated by renewable energy sources. This paper proposes an innovative solution that consists of catching water from streams at high altitudes to fill storage containers and transport them down a mountain, converting the potential energy of water into electricity with the regenerative braking systems of electric trucks and storing it in the truck's battery. The energy stored in the electric truck can be sold to the grid or used by the truck to transport other goods. Results show that the levelized cost of the electricity truck hydropower is 30–100 USD/MWh, which is cheap when compared with conventional hydropower 50–200 USD/MWh. The electricity generation world potential for the technology is estimated to be 1.2 PWh per year, which is equivalent to around 4% of the global energy consumption in 2019. Apart from being a low cost and impact electricity generation technology, electric truck hydropower can operate in combination with solar and wind resources and provide energy storage services to the grid. • Innovative hydropower generation alternative. • Levelized cost of the electricity truck hydropower is 30–100 USD/MWh. • The electricity generation world potential for the technology is estimated to be 1.2 PWh per year. • Asia and South America have the highest potential for ETH. [ABSTRACT FROM AUTHOR]

Before the COVID pandemic, oil and gas companies invested only a small fraction of their capital on sustainable energy technologies. With the substantial improvement in the performance of batteries and their rapid cost reduction, the oil and gas industry could potentially lose a large share of their market in the transport sector. A similar shift in energy sources is happening with the surge in renewable energy sources to supply electricity, heating and cooling. In an ever more sustainable future, the need for an oil and gas industry could reduce significantly. This paper reviews the possible paths that an oil and gas company could follow to become a sustainable development corporation and continue to be relevant in the future. This paper aims to describe alternative sustainable pathways such as the extraction of natural hydrogen, a hydrogen economy, offshore wind power, deep sea mining, biorefineries, seawater air-conditioning, geothermal and geoengineering. This paper also proposes the use of electrolysis ships for the flexible production of green hydrogen and showed that its investment cost can be three times smaller than in fixed electrolysis plants. The oil and gas industry has substantial intellectual, financial capital and geopolitical influence that would not be lost during a shift to a more sustainable world. Indeed, these assets should be used to facilitate the transition to a more sustainable future. • Hydrogen is a good alternative for sustainable development in O&G companies. • Natural hydrogen is a good alternative to the upstream O&G companies. • Benefits of electrolysis ships to produce green hydrogen. • Case study to produce green hydrogen in Brazil. [ABSTRACT FROM AUTHOR]

The new frontier for hydropower electricity generation in Brazil, the Amazon region, cannot be used for energy storage as the construction of storage reservoirs would have deep environmental and social impacts, thus run-of-the-river dams have been built instead. If Brazil still wants to generate 80% of its electricity from hydropower, there is the need to increase the country's energy storage capacity so that the excess generation coming from the dams in the Amazon region during the wet period can be used during the dry period. This article presents four ways to increase the storage capacity of a watershed. The most innovative alternative involves a large-scale pumped-storage site combined with a series of hydropower dams in cascade, which could store energy by pumping water to a new reservoir during the wet period and generate energy by releasing the stored water during the dry period. Even though pumped storage schemes have an average efficiency of around 75%, it has been calculated that the combination of a pumped storage site and a series of hydroelectric dams in cascade can increase the overall storage efficiency up to 90% and double the storage capacity of a watershed. This scheme was called EPS (Enhanced-Pumped-Storage). [ABSTRACT FROM AUTHOR]

This paper presents the first systematic study on power control strategies for Modular-Gravity Energy Storage (M-GES), a novel, high-performance, large-scale energy storage technology with significant research and application potential. Addressing the current research gap in M-GES power control technology, we propose two corresponding compensation modes and several power control strategies for Hybrid M-GES and M-GES. The effectiveness of these strategies is validated through simulations on the MATLAB/Simulink platform, including tests using sinusoidal power and feasibility verification based on a natural California load curve. Additionally, we analyze the normal and abnormal operating conditions of M-GES. In conclusion, the characteristics of the proposed control strategies are summarized, providing a guideline for further research. [Display omitted] • Modular-gravity energy storage (M-GES) power control system studied. • Two compensation modes and four control strategies are systematically studied and validated. • The center switching method with hysteresis control (CSM-H) excels in continuous compensation mode. • The center switching method with hysteresis control and dead zone (CSM-HD) excels in overlap compensation mode. • Based on the power control system proposed in this paper, the M-GES plant performs highly in natural power systems. [ABSTRACT FROM AUTHOR]

• Swimming pool as a seasonal, cooling, thermal energy storage solution. • Case study in Phoenix, Arizona, USA. • The pool is used for heating in the winter and cooling in the summer. • An average pool stores 3500 kWh of cooling energy at 0oC. • Cooling energy storage cost of 0.078 US$ kWhe−1. The rise in distributed renewable energy generation creates a growing need to find viable solutions for energy storage to match energy demand and supply at any time. This paper evaluates the possibility of using swimming pools as a long-term cooling energy storage solution, i.e., Swimming Pool Thermal Energy Storage (SPTES). This technology allows a small building to store solar energy for cooling purposes in a yearly cycle, by filling the pool with ice slurry in winter and using that ice to cool the house in the summertime. Additionally, the pool can be used as a heat sink for a heat pump to heat the house during the winter. Results show that the energy storage cost of 0.078 US$ kWhe−1 is substantially smaller when compared with batteries (125 US$ kWhe−1). This makes SPTES a good alternative to support the development of 100% renewable energy systems in locations where the climate has a highly seasonal variation in temperature and the cooling demand is high in summer. [ABSTRACT FROM AUTHOR]

The energy sector is undergoing substantial transition with the integration of variable renewable energy sources, such as wind and solar energy. These sources come with hourly, daily, seasonal and yearly variations; raising the need for short and long-term energy storage technologies to guarantee the smooth and secure supply of electricity. This paper critically reviews the existing types of pumped-hydro storage plants, highlighting the advantages and disadvantages of each configuration. We propose some innovative arrangements for pumped-hydro storage, which increases the possibility to find suitable locations for building large-scale reservoirs for long-term energy and water storage. Some of the proposed arrangements are compared in a case study for the upper Zambezi water basin, which has considerable water storage limitations due to its flat topography and arid climate. Results demonstrate that the proposed combined short and long-term cycles pumped-storage arrangement could be a viable solution for energy storage and reduce the cost for water storage to near zero. • Review of existing pumped-storage types. • Pumped-hydro storage an effective alternative for water, energy and land nexus issues. • Proposed arrangement for combining short- and long-term energy and water needs. • Proposed arrangement for combining hydropower and pumped-hydro storage. • Comparison of proposed pumped-hydro storage projects in the Zambesi river basin. [ABSTRACT FROM AUTHOR]

The world is undergoing an energy transition with the inclusion of intermittent sources of energy in the grid. These variable renewable energy sources require energy storage solutions to be integrated smoothly over different time steps. In the near future, batteries can provide short-term storage solutions and pumped-hydro storage can provide long-term energy storage with large generation capacities. However, none of these technologies can provide long-term energy storage in grids with small demand. This paper proposes a new storage concept called Mountain Gravity Energy Storage (MGES) that could fill this gap in storage services. MGES systems move sand or gravel from a lower storage site to an upper elevation. The higher the height difference the greater the amount of stored energy in a given installed capacity, as this technology is constrained to the topography of the location. MGES cost varies from 50 to 100 $/MWh of stored energy and 1–2 M$/MW of installed capacity. MGES could be a feasible option for micro-grids, for example, small islands and isolated areas, and power systems where electricity costs are high, demand for energy storage is smaller than 20 MW with monthly or seasonal storage requirements. • A new energy storage solution based on mountain gravity is found particularly for grids smaller than 20 MW. • MGES is a solution for seasonal storage where there is no water for pumped-storage solutions. • We show the world potential for MGES using a GIS based tool. • The new storage solution can fill the gap in terms of size and duration of existing storage options. [ABSTRACT FROM AUTHOR]

The global concern to reduce greenhouse gas emissions and increase the use of renewable sources has led Brazil to stand out as a promising nation in this context, with a large portion of its energy capacity coming from renewable sources. However, renewable sources have the disadvantage of intermittency and seasonality, which has prompted the search for solutions to these challenges. This study assesses the feasibility of integrating hydro and solar power with a Hydrogen-based Electrical Energy Storage System (H 2 EESS) at the Serra da Mesa hydroelectric Brazilian power plant. Hydrogen would be produced through water electrolysis, taking advantage of the available excess renewable energy, and subsequently converted back into electricity through fuel cells. The integration of hydro and solar power with H 2 EESS resulted in an increase of 11.10 % in the energy produced compared to conventional hydroelectric generation, with 36.06 % of this increase coming from H 2 EESS. Additionally, there was a 9.71 % increase in the utilization of substation capacity. These results highlight the feasibility and benefits of integrating hydro and solar power with H 2 EESS. This approach allows for maximizing renewable energy generation, reducing greenhouse gas emissions, and better utilizing available resources without the need for significant infrastructure investments. • Feasibility of integrating hydro and solar power with a hydrogen-based electrical energy storage system. • Case Study with real data from Serra da Mesa hydroelectric brazilian power plant. • The integration of hydro and solar power with Hydrogen resulted in an increase of 11.10 % in the energy produced compared to conventional hydroelectric generation. • There was a 9.71 % increase in the utilization of substation capacity. [ABSTRACT FROM AUTHOR]

The global transition to renewable energy is driven by the fight against climate change. Wind power plays a crucial role in reducing dependence on fossil fuels and greenhouse gas emissions. Therefore, addressing uncertainties in wind speed variations requires innovative solutions. This study proposes a Bayesian-based approach using a Dynamic Factor Model to generate synthetic monthly average wind speed series. The Dynamic Factor Model framework captures temporal and spatial correlations, improving wind resource representation in operational planning models. The model's autoregressive configuration with common factors, prior distributions, and Bayesian inference techniques enhances predictive capabilities. Validation exercises confirm the model's reliability, accurately capturing seasonal oscillations and spatial correlations across eight wind farms. The study highlights the usefulness of the Dynamic Factor Model in evaluating wind projects and optimizing energy generation strategies, effectively mitigating wind uncertainty, and facilitating renewable energy integration in Brazil's power mix. [ABSTRACT FROM AUTHOR]

Modular Gravity Energy Storage (M-GES) systems are emerging as a pivotal solution for large-scale renewable energy storage, essential for advancing green energy initiatives. This study introduces innovative capacity configuration strategies for M-GES plants, namely Equal Capacity Configuration (EC) and Double-Rate Capacity Configuration (DR), tailored to optimize energy storage efficiency and stability. Through comprehensive MATLAB/Simulink simulations, we demonstrate each configuration's distinct power characteristics and operational advantages. Our findings reveal that while the EC configuration offers enhanced power accuracy and stability, it requires a larger number of units. In contrast, the DR configuration, characterized by fewer but larger units, shows a trade-off with reduced power stability. This paper contributes significantly to the field by presenting a first-of-its-kind comparative analysis of these configurations, offering insights into their practical applications and scalability. The proposed strategies and findings lay a foundation for future research and development in gravity energy storage systems, marking a step forward in pursuing sustainable and reliable energy solutions. [Display omitted] • Two typical unit capacity configuration strategies for M-GES power plants are proposed. • The unit scheduling method of the M-GES power plant is proposed. • The coordination control method is provided for each proposed configuration strategy. • Equal capacity configuration has better power accuracy but requires more units. • Double rate configuration needs fewer but larger units and less power stability. [ABSTRACT FROM AUTHOR]

Implementing Circular Economy (CE) strategies has recently become one of the essential strategies for sustainable development and corporate social responsibility. However, despite the promising role and potential benefits of the CE for companies and society, there has still been insufficient analysis examining the challenges for circular transition faced by micro, small, and medium-sized enterprises (MSMEs) and the role that standards, such as British Standard (BS) 8001:2017, play during the transition process from linear to circular economy practices. Given this context and to further increase our understanding of the factors preventing the transition from linear to CE, this study aims to assess the CE implementation in MSMEs in developing economies in light of BS 8001:2017 through a survey with Brazilian MSMEs. The primary findings emphasize that CE practices from the Administration dimension occupied top positions in the ranking of implementation, along with one practice from the Innovation dimension. However, the results show that several practices associated with Transparency and Product Optimization in the value chain held the last level of evidence of implementation. Findings suggest that assessing MSMEs through BS 8001:2017 is beneficial for aiding them in analysing and reconsidering their practices related to the conventional linear business models of take-use-dispose. Collectively, the findings improve our understanding of the level of adoption of CE components implementation, the most and the least adopted practices during the CE transition. The study also provides implications for policy, theory, and practical applications in cases where there is an interest in assessing the maturity of CE implementation within MSMEs in developing economies. [ABSTRACT FROM AUTHOR]

Tesla turbines can be employed as small-scale turbines to recover waste energy in several industrial applications. However, there is no consensus on the turbine efficiency as experimental studies show significantly lower values than those obtained by analytical and CFD approaches. The present work addresses that question by performing a systematic literature review (SLR) on Tesla turbines, comparing the efficiency values reported by experimental and simulation works. To validate the SLR findings an experimental small-scale air driven Tesla turbine was built. The Design of Experiments (DoE) methodology was applied to understand the effects of selected independent variables on the turbine output power and mechanical efficiency. Inlet air pressure, temperature, and rotational speed were chosen as controllable factors of a Central Composite Design applied to the prototype of < 1 kW output power. The results indicate a 5% efficiency increase when inlet pressure increases 1 bar, on average. In the SLR, the average efficiency of 40%–60% was reported by simulation works, while experimental articles reported maximum efficiencies of 20%, on average. The experimental turbine analyzed in this paper presented a maximum efficiency of 14.2% ± 0.4% at 3 barg and 4,000 rpm, agreeing with other experimental studies. • Literature review shows a lack of consensus regarding the TT maximum efficiency. • The designed TT is limited to efficiencies below 20%. • From SLR, higher experimental efficiencies are found for output power ≤1 kW and forward into sub-Watt scale. • Is still to be proven that TT performance can be competitive concerning other turbine technologies. [ABSTRACT FROM AUTHOR]

Complex engineering systems, such as power plants, deliver their best performance when operating along a designed range of some priority parameters. However, plant field operation may deviate from design conditions, and new references must be identified. Actions towards high-quality operation can be supported by fine modeling, which helps building decision support tools. The present work proposes a standardization strategy for the operation of an actual coal-fired power plant based on a Design of Experiment approach, partially tested onsite and finally accomplished with surrogate models built upon a 2 year long database. Artificial Neural Networks (ANNs) and Mass and Energy balances (M&Es) are used to represent the plant's steam generator and its mills subset, which is the core of an operational guide to increase system efficiency under actual operation. Primary and secondary air flows, pulverized coal outlet temperature, speed of the dynamic classifier, primary air flow, excess O 2 , primary and secondary air pressures are the seven controllable factors selected as the most relevant ones among an extensive set of parameters, able to perform effective maneuvers. The application of the operational guide indicates combinations of ranges of the seven controllable parameters that allow for achieving steam generator efficiency within the 84.0% to 88.92% range. The proposed methodology aims as well to improve safe and stable conditions to a system that undergoes operation different than the one prescribed by the original design. The study case results show an opportunity to raise efficiency by up to 2.28% during operation, which represents a reduction in coal consumption by 3.1 t/h and above 6% on CO 2 emissions. • Real plant data, operational information and real experiments on site from the PECEM power plant. • System performance process standardization employing decision support tools. • A high-quality operation by the fine modeling of plants systems. • Surrogate models applied on coal-fired power plants literature reviewed. • Logbook to perform a Design of Experiments approach in a power plant in operation. [ABSTRACT FROM AUTHOR]