Search

Water is a necessity for the survival of all living beings. Even though 71% of the Earth’s surface is water, there is still an acute shortage of potable water in many countries, as approximately 97.5% of Earth’s water is saltwater in the oceans and only 2.5% is freshwater in groundwater, lakes, and rivers. Thus, access to clean drinking water is a major issue that needs to be tackled immediately and efficiently. Currently, existing technologies for water purification such as multistage flash, multiple effect, vapor compression, reverse osmosis (RO), ion exchange, electrodialysis, and capacitive deionization (CDI) require a lot of energy, leading to environmental pollution caused by the consumption of fossil fuels. It is also found that 70% of water supplied as input to these technologies is wasted, while methods such as RO remove important minerals, and hence, World Health Organization (WHO) standards do not deem this fit. The desalination of saline water using solar stills is an effective solution to overcome these problems. Solar energy is abundant, everlasting, economical and does not cause emission of greenhouse gases. Combining this worldwide availability and inexhaustible nature of solar energy with a desalination process, a water purification system is designed and operated. This paper proposes the design and application of a water purification system which will be beneficial for localities such as residential buildings and bungalows in densely populated cities where the rise in energy consumption has led to an increase in the carbon footprint, reduction in electric power supply, and higher energy costs along with the depletion of fossil fuels and other exhaustible energy sources. This design can be further modified and installed in arid regions and villages where grid electricity is not a feasible option to meet energy demands and water scarcity is prevalent.

Water is eminent for all living beings and is a basic requirement. Even though 71% of the Earth’s surface is water-covered, there is still an acute shortage of drinking water in many countries, as approximately 97.5% of Earth’s water is saltwater in the oceans and only 2.5% is fresh water in groundwater, lakes, and rivers. Thus, access to clean drinking water is a major issue that needs to be tackled immediately and efficiently. The existing water purification technologies like reverse osmosis (RO), electrodialysis, multistage flash, multiple effect, and vapor compression require a lot of energy and fuels, leading to environmental pollution. It is also found that 70% of water supplied as input to these technologies is wasted, while RO also removes important minerals, and World Health Organization (WHO) standards do not deem this fit. The desalination of saline water using solar stills is an effective solution to overcome these problems. Combining the worldwide availability and inexhaustible nature of solar energy, a still that requires only solar energy as the input ensures a sustainable and environmentally friendly method to produce potable water with minimal energy conversions. This paper reviews the performance of a solar still by varying parameters that affect the production of output distillate. The results obtained are studied and presented.

Around 71% of the Earth’s surface is covered in water. However, a severe scarcity of potable water persists in many countries, as only 2.5% of this water is available as freshwater in groundwater, lakes and rivers. Water is salient for the survival of all living beings and hence, providing access to clean drinking water requires the utmost urgency. Currently, existing technologies for water purification such as Multistage Flash (MSF), Multiple Effect, Vapor Compression (VC), Reverse Osmosis (RO), Ion Exchange, Electrodialysis, and Capacitive Deionization (CDI) require a lot of energy, leading to environmental pollution caused by the consumption of fossil fuels. Desalination of saline water using solar stills is an effective solution to overcome these problems. Solar energy is abundant, everlasting, economical and does not cause emission of greenhouse gases. This paper studies the mathematical modelling of a single slope single basin solar still and a still coupled with evacuated tube collectors. The performances of the two designs are compared to analyse their efficiency and the results thus obtained are presented. This design can also be installed in arid regions and villages where water scarcity is prevalent and access to the electricity grid is not feasible to fulfil the energy requirements.

The allocation of decision rights within organizations influences resource allocation, expansion decisions, and ultimately outcomes. Using a newly constructed dataset, I estimate the effects of an earned autonomy program for State Owned Enterprises (SOEs) in India. The program gave managers (the board of directors) of profitable SOEs more autonomy over strategic decisions such as capital expansion and the formation of joint ventures. I find that autonomy allows SOEs to increase their capital stock and form more strategic partnerships which leads to greater sales and profits. I also find that the likelihood that a manager subsequently joins a board of a private firm is greater for managers of those SOEs which were granted autonomy, indicating that career concerns is a consistent explanation for these managerial decisions. Taken together, these results indicate that large gains in SOE performance are possible without privatization (by policies like earned autonomy) and may occur partly through managers' career concerns.

This study predicts the impact of climate change on African agriculture. We use a generalized linear model (GLM) framework to estimate the relationship between the proportion of various Agro-Ecological Zones (AEZs) in a district and climate. Using three climate scenarios, we project how climate change will cause AEZs to shift, causing changes in acreage and net revenue per hectare of cropland. Our results predict that Africa will suffer heavy annual welfare losses by 2070–2100, ranging between US$14 billion and US$70 billion, depending on the climate scenario and cropland measure considered.

Although there is now an extensive literature on the economic impacts of climate change on agriculture, no study has yet addressed the endogeneity of irrigation. This paper examines how climate affects the choice to irrigate and the conditional income earned by each farmer. The paper develops a selection model of irrigation choice and conditional income. Using data from farmers across eleven African countries, the paper demonstrates that the choice of irrigation is sensitive to both temperature and precipitation. Rainfed and irrigated farm income also both respond to climate but have different climate sensitivity. Impact models that fail to account for endogenous irrigation are biased.

African societies exported more slaves in colder years. Lower temperatures reduced mortality and raised agricultural yields, lowering slave supply costs. Our results help explain African participation in the slave trade, which predicts adverse outcomes today. We use an annual panel of African temperatures and port-level slave exports to show that exports declined when local temperatures were warmer than normal. This result is strongest where African ecosystems are least resilient to climate change. Cold weather shocks at the peak of the slave trade predict lower economic activity today. We support our interpretation using the histories of Whydah, Benguela, and Mozambique.\ud \ud