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Tajikistan's electricity system is in a state of crisis. Approximately 70 percent of the Tajik people suffer from extensive shortages of electricity during the winter. These shortages, estimated at about 2,700 GWh, about a quarter of winter electricity demand, impose economic losses estimated at over United States (US) 200 million dollars per annum or 3 percent of Gross Domestic Product (GDP). The electricity shortages have not been addressed because investments have not been made in new electricity supply capacity and maintenance of existing assets has not improved. The financial incentive for electricity consumers to reduce their consumption is inadequate as electricity prices are among the lowest in the world. Without prompt action to remedy the causes of Tajikistan's electricity crisis and with growing demand, the shortages could increase to about 4,500 GWh by 2016 (over a third of winter electricity demand) or worse. The World Bank undertook this study to assist the Government of Tajikistan (GoT) in finding ways to overcome the current electricity shortages and establish a sound basis for meeting the growing electricity demand in Tajikistan. The study focuses on the investments and policy reforms needed between now and 2020 to strengthen the financial, technical and institutional capacity of the Tajik power sector and prepare the GoT for undertaking a major expansion of power supply capacity. The study excludes large hydropower plants with storage, given their complexity and global experience that such projects are subject to delays. The winter electricity shortages are caused by a combination of low hydropower output during winter when river flows are low and high demand driven by heating needs. The GoT should focus its immediate attention on three ways to eliminate the current winter power shortages: 1) ambitious energy efficiency plans to reduce uneconomic power usage; 2) new dual-fired thermal power supply to complement the existing hydropower supply during winter; and 3) increased energy imports to leverage surplus electricity supply in neighboring countries.

Thermal power generation technologies are widely used for electricity production, for heat provision in district or process heating systems, and for combined heat and power generation. In most cases, thermal technologies are heat driven and electricity is produced as a by‐product, thus resulting in a non‐flexible behaviour of the electricity production. Modern power grids are characterised by an increasing share of renewable leading to a need for enhanced and flexible ways of controlling the power flow. To provide services to the power grid, thermal generating technologies may be used in a more efficient way, coupled to gas and heat storage systems or aggregated in virtual power plants. Several technical factors determine which technologies are suitable for flexibility provision, including power ranges, start up times and ramp rates. In this work, carried out in the frame of the MAGNITUDE H2020 project, the technical characteristics of thermal sector‐coupling technologies were analysed using data from the seven real‐life project's case studies. The technical suitability was determined based on the product requirements in selected European power markets for the provision of identified system services. Expected future developments and trends were highlighted well.

What follows in this chapter relates to any Stirling engine, but the principal value lies in application to the simple hot‐air configuration – for example, to the vertical, coaxial layout. The heat dissipation provision emerges as the thermal bottleneck of the hot air engine. All variants of the Stirling engine exploit forced, convective heat transfer – a physical phenomenon carrying an inevitable penalty – pumping power. Best performance, whether achieved by experiment, through theory, or by both in combination, relies on striking a favourable balance between these two conflicting effects. The value – indeed, the validity – of the method depends essentially on the relevance of steady‐flow heat transfer and flow friction correlations to conditions in the regenerative annulus.

Heating and cooling (H/C) represent the largest share of energy consumption worldwide. Buildings are the main consumers of H/C, while the share of renewable energy for H/C provision still represents a low percentage, 22.0% in 2019. Hybrid photovoltaic-thermal (PV-T) systems are gaining increasing attention both in research and in applications, as they generate both electricity and useful heat simultaneously. The relevance and potential of PV-T collectors and their integration into wider systems are evident, but there is still a lack of review articles that address the potential of these systems in building applications in a comprehensive way. This work aims to review the state-of-the-art of PV-T collectors for building applications, as well as the corresponding PV-T systems for solar combined cooling, heating and power (S-CCHP) provision. The novelties of this work involve the comparison of these systems with conventional solar H/C technologies, the review of the market of H/C technologies, a summary of the challenges for the wider integration of S-CCHP systems and proposal lines of work to improve the cost-competitiveness of these systems. The first section summarises the focus and findings of previous reviews, followed by an overview of the current development status of the main types of PV-T collectors. Then, PV-T-based S-CCHP systems are reviewed, and the potential of PV-T systems’ penetration in the built environment is evaluated and discussed.

The global ocean has warmed substantially over the past century, with far-reaching implications for marine ecosystems1. Concurrent with long-term persistent warming, discrete periods of extreme regional ocean warming (marine heatwaves, MHWs) have increased in frequency2. Here we quantify trends and attributes of MHWs across all ocean basins and examine their biological impacts from species to ecosystems. Multiple regions in the Pacific, Atlantic and Indian Oceans are particularly vulnerable to MHW intensification, due to the co-existence of high levels of biodiversity, a prevalence of species found at their warm range edges or concurrent non-climatic human impacts. The physical attributes of prominent MHWs varied considerably, but all had deleterious impacts across a range of biological processes and taxa, including critical foundation species (corals, seagrasses and kelps). MHWs, which will probably intensify with anthropogenic climate change3, are rapidly emerging as forceful agents of disturbance with the capacity to restructure entire ecosystems and disrupt the provision of ecological goods and services in coming decades.Marine heatwaves are increasing in frequency, but they vary in their manifestation. All events impact ecosystem structure and functioning, with increased risk of negative impacts linked to greater biodiversity, number of species near their thermal limit and additional human impacts.

Because their assets and income represent such a small share of national wealth, the impacts of climate change on poor people, even if dramatic, will be largely invisible in aggregate economic statistics such as the Gross Domestic Product (GDP). Assessing and managing future impacts of climate change on poverty requires different metrics, and specific studies focusing on the vulnerability of poor people. This special issue provides a set of such studies, looking at the exposure and vulnerability of people living in poverty to shocks and stressors that are expected to increase in frequency or intensity due to climate change, such as floods, droughts, heat waves, and impacts on agricultural production and ecosystem services. This introduction summarizes their approach and findings, which support the idea that the link between poverty and climate vulnerability goes both ways: poverty is one major driver of people's vulnerability to climate-related shocks and stressors, and this vulnerability is keeping people in poverty. The paper concludes by identifying priorities for future research.

Although many studies have examined the correlation between temperature and mortality from cardiovascular diseases (CVD), other meteorological factors, such as relative humidity, may modify the relationship. Yet the studies on this aspect are relatively few. We chose a heat index (HI, which is an index that combines air temperature and relative humidity) as an alternative indicator of temperature, and used a distributed lag nonlinear model (DLNM) to analyze the combined effects of temperature and relative humidity on CVD mortality among all of the Beijing residents and subsociodemographic groups by age, sex, and occupation. The heat index can better reflect the human-perceived temperature when relative humidity is combined with air temperature. The results show that females, elderly people, and outdoor workers have higher vulnerability levels in regard to a high heat index. The strongest effect of heat index was found among females, for which the highest mortality risk was about 2.4 (95% CI 1.8–3) times greater than the lowest mortality risk. In addition, we found that there is a significant interaction effect of temperature and relative humidity on CVD mortality. The impact of extreme high temperature may be exacerbated by increases in humidity. Based on these results, we draw the risk level map of CVD death under different temperatures and grades of relative humidity. These findings may aid governments in the development of more accurate heat alerts and the provision of measures to prevent or reduce temperature-related deaths.

Direct numerical simulations (DNS) of subsonic and supersonic impinging jets with Reynolds numbers of 3300 and 8000 are carried out to analyse their statistical properties with respect to heat transfer. The Reynolds number range is at low or moderate values in terms of practical applications, but very high regarding the technical possibilities of DNS. A Reynolds number of 8000 is technically relevant for the cooling of turbine blades. In this case, the flow is dominated by primary and secondary vortex rings. Statistics of turbulent heat fluxes and Reynolds stresses as well as the Nusselt number are provided and brought into accordance with these vortices. Velocity and temperature fluctuations were found to have a positive influence on cooling of the impinging plate. Beside the description of the flow, a second aim of this article is the provision of data for improvement of turbulence models. Modern large eddy simulations are still not able to precisely predict impingement heat transfer (Dairay et al., Intl J. Heat Fluid Flow, vol. 50 (0), 2014, pp. 177–187). Common relations between heat and mass transfer respectively temperature and velocity fields are applied to the impinging jet. These relations include the Reynolds and Chilton Colburn analogy, the Crocco–Busemann relation and the generalised Reynolds analogy (GRA). It was found that the first two deliver useful values if the distance to the jet axis is larger than one diameter, away from the strong pressure gradient around the stagnation point. The GRA, in contrast, precisely predicts the mean temperature field if no axial velocity gradient is present. The estimation of temperature fluctuations according to the GRA fails. As third main topic of this article, the influence of the Mach number on heat transfer and the flow field, is studied. Against the common practise of neglecting compressibility effects in experimental Nusselt correlations, we observed that higher Mach numbers (up to 1.1) have a positive influence on heat transfer in the deflection zone due to higher flow fluctuations.

Although they are primarily installed for specific applications, decentralised energy systems, storage systems, and controllable loads can provide flexibility. However, this varies over time. This study investigates the fundamentals of flexibility provision, including quantification, aggregation, simulation, and impact on energy systems and the power grid. We extended our methods by integrating adjustments to calculate the flexibility potential of heat pumps (HPs) and heat storage (HS) systems, as well as by incorporating variability and uncertainty. The simulations revealed the relevance of energy systems operation to flexibility, e.g., 2 K deviation in HS temperature increased theoretical coverage by 16 percentage points. The results also proved that aggregating multiple systems could obviously enhance their flexibility potential, e.g., six investigated battery storage (BS) systems could have covered up to 20 percentage points more external flexibility requests than any individual unit. The provision of flexibility by decentralised energy systems can lead to energy surpluses or deficits. Such imbalances could have been fully balanced in a system- and grid-oriented manner in 44% of BS simulations and in 32% of HP-HS ones. Overall, the findings highlight the importance of the system- and grid-oriented operation of decentralised energy systems, alongside local optimisation, for a future energy infrastructure.

Developing economies are facing multifaceted problems like dramatic increase in motorized traffic, urban heat island, urban sprawl, and climatic changes. Environmental Performance Index report states that Pakistan is on 169 among 180 countries due to ill-planned development on prime agriculture land, poor air, water quality, and jeopardizing ecosystem of the country. The change of land uses from the natural to the built environment has created problems like loss of vegetation and habitat, enlarged surface flow, and heavy floods. However, this study addresses this core issue by taking responses from the residents of Lahore, Pakistan. Current research focuses on the willingness and perception of residents regarding the adaptation of green roof technology. The resident perceptions are obtained by a structured questionnaire and analyzed by using statistical techniques. The findings of the research highlight that adaptation of green roof is primarily linked with the four factors, i.e., awareness of green roof among all stakeholders, special provision in building regulation concerning green roof, sustainable environmental consciousness, and subsidized cost of green roof materials.