Least-cost targets and avoided fossil fuel capacity in India's pursuit of renewable energy.

India has set aggressive targets to install more than 400 GW of wind and solar electricity generation by 2030, with more than two-thirds of that capacity coming from solar. This paper examines the electricity and carbon mitigation costs to reliably operate India's grid in 2030 for a variety of wind and solar targets (200 GW to 600 GW) and the most promising options for reducing these costs. We find that systems where solar photovoltaic comprises only 25 to 50% of the total renewable target have the lowest carbon mitigation costs in most scenarios. This result invites a reexamination of India's proposed solar-majority targets. We also find that, compared to other regions and contrary to prevailing assumptions, meeting high renewable targets will avoid building very few new fossil fuel (coal and natural gas) power plants because of India's specific weather patterns and need to meet peak electricity demand. However, building 600 GW of renewable capacity, with the majority being wind plants, reduces how often fossil fuel power plants run, and this amount of capacity can hold India's 2030 emissions below 2018 levels for less than the social cost of carbon. With likely wind and solar cost declines and increases in coal energy costs, balanced or wind-majority high renewable energy systems (600 GW or ≈ 45% share by energy) could result in electricity costs similar to a fossil fuel-dominated system. As an alternative strategy for meeting peak electricity demand, battery storage can avert the need for new fossil fuel capacity but is cost effective only at low capital costs (≈ USD 150 per kWh).

The Health and Climate Benefits of Economic Dispatch in China's Power System.

China's power system is highly regulated and uses an "equal-share" dispatch approach. However, market mechanisms are being introduced to reduce generation costs and improve system reliability. Here, we quantify the climate and human health impacts brought about by this transition, modeling China's power system operations under economic dispatch. We find that significant reductions in mortality related to air pollution (11%) and CO2 emissions (3%) from the power sector can be attained by economic dispatch, relative to the equal-share approach, through more efficient coal-powered generation. Additional health and climate benefits can be achieved by incorporating emission externalities in electricity generation costs. However, the benefits of the transition to economic dispatch will be unevenly distributed across China and may lead to increased health damage in some regions. Our results show the potential of dispatch decision-making in electricity generation to mitigate the negative impacts of power plant emissions with existing facilities in China.

Strategic siting and regional grid interconnections key to low-carbon futures in African countries.

Recent forecasts suggest that African countries must triple their current electricity generation by 2030. Our multicriteria assessment of wind and solar potential for large regions of Africa shows how economically competitive and low-environmental-impact renewable resources can significantly contribute to meeting this demand. We created the Multicriteria Analysis for Planning Renewable Energy (MapRE) framework to map and characterize solar and wind energy zones in 21 countries in the Southern African Power Pool (SAPP) and the Eastern Africa Power Pool (EAPP) and find that potential is several times greater than demand in many countries. Significant fractions of demand can be quickly served with "no-regrets" options-or zones that are low-cost, low-environmental impact, and highly accessible. Because no-regrets options are spatially heterogeneous, international interconnections are necessary to help achieve low-carbon development for the region as a whole, and interconnections that support the best renewable options may differ from those planned for hydropower expansion. Additionally, interconnections and selecting wind sites to match demand reduce the need for SAPP-wide conventional generation capacity by 9.5% in a high-wind scenario, resulting in a 6-20% cost savings, depending on the avoided conventional technology. Strategic selection of low-impact and accessible zones is more cost effective with interconnections compared with solutions without interconnections. Overall results are robust to multiple load growth scenarios. Together, results show that multicriteria site selection and deliberate planning of interconnections may significantly increase the economic and environmental competitiveness of renewable alternatives relative to conventional generation.

Avoiding ecosystem and social impacts of hydropower, wind, and solar in Southern Africa's low-carbon electricity system.

The scale at which low-carbon electricity will need to be deployed to meet economic growth, electrification, and climate goals in Africa is unprecedented, yet the potential land use and freshwater impacts from this massive build-out of energy infrastructure is poorly understood. In this study, we characterize low-impact onshore wind, solar photovoltaics, and hydropower potential in Southern Africa and identify the cost-optimal mix of electricity generation technologies under different sets of socio-environmental land use and freshwater constraints and carbon targets. We find substantial wind and solar potential after applying land use protections, but about 40% of planned or proposed hydropower projects face socio-environmental conflicts. Applying land and freshwater protections results in more wind, solar, and battery capacity and less hydropower capacity compared to scenarios without protections. While a carbon target favors hydropower, the amount of cost-competitively selected hydropower is at most 45% of planned or proposed hydropower capacity in any scenario-and is only 25% under socio-environmental protections. Achieving both carbon targets and socio-environmental protections results in system cost increases of 3-6%. In the absence of land and freshwater protections, environmental and social impacts from new hydropower development could be significant.

Global transcontinental power pools for low-carbon electricity.

The transition to low-carbon electricity is crucial for meeting global climate goals. However, given the uneven spatial distribution and temporal variability of renewable resources, balancing the supply and demand of electricity will be challenging when relying on close to 100% shares of renewable energy. Here, we use an electricity planning model with hourly supply-demand projections and high-resolution renewable resource maps, to examine whether transcontinental power pools reliably meet the growing global demand for renewable electricity and reduce the system cost. If all suitable sites for renewable energy are available for development, transcontinental trade in electricity reduces the annual system cost of electricity in 2050 by 5-52% across six transcontinental power pools compared to no electricity trade. Under land constraints, if only the global top 10% of suitable renewable energy sites are available, then without international trade, renewables are unable to meet 12% of global demand in 2050. Introducing transcontinental power pools with the same land constraints, however, enables renewables to meet 100% of future electricity demand, while also reducing costs by up to 23% across power pools. Our results highlight the benefits of expanding regional transmission networks in highly decarbonized but land-constrained future electricity systems.

Toward a low-carbon transition in India.

Electricity sector policies should be designed not only to mitigate carbon emissions but also to reduce inequities.

Lifecycle cost and carbon implications of residential solar-plus-storage in California.

Capacities of residential photovoltaics (PV) and battery storage are rapidly growing, while their lifecycle cost and carbon implications are not well understood. Here, we integrate PV generation and load data for households in California to assess the current and future lifecycle cost and carbon emissions of solar-plus-storage systems. Our results show that installing PV reduces $180-$730 and 110-570 kgCO2 per year per household in 2020. However, compared to solar-only system, adding battery storage increases lifecycle costs by 39%-67%, while impact on emissions is mixed (-20% to 24%) depending on tariff structure and marginal emission factors. In 2040, under current decarbonization and cost trajectories, solar-plus-storage leads to up to 31% higher lifecycle costs and up to 32% higher emissions than solar-only systems. Designing a tariff structure with wider rate spreads aligned with marginal carbon emissions, and reducing the costs and embodied emissions of batteries are crucial for broader adoption of low-carbon residential solar-plus-storage.

Bipolar Hemiarthroplasty of Hip in an Unstable Angina Patient: A Case Report.

INTRODUCTION: Fracture neck of femur is a leading cause of hospital admission in elderly population. Studies have shown up to 25% mortality following hip fracture within 1year of surgery [1]. We report a case of fracture neck of femur in a high-risk patient with end-stage renal disease who was operated with bipolar hemiarthroplasty. We noticed favorable outcome following coronary artery bypass graft (CABG) and orthopedic surgery. CASE REPORT: We report a case of 72-year-old male presenting with the right hip pain for 2 days and inability to bear weight on the right lower limb following history of domestic fall 2 days back. Radiograph of pelvis with both hips anteroposterior view and lateral view of the right hip showed right fracture neck of femur. The patient was scheduled for surgery next day but was deemed unfit on the ground of electrocardiogram reports showing ventricular arrhythmia. Cardiologist opinion was sought and coronary angiography was done. Coronary angiography revealed triple vessel lumen blockade. The patient underwent CABG 2 weeks after admission. We did cement bipolar hemiarthroplasty for the right fracture neck of femur 1 week later. The patient was mobilized on day 2 using walker. Follow-up radiograph showed acceptable prosthesis position. CONCLUSION: Fracture neck of femur with associated cardiac risk and end-stage renal disease require meticulous planning before surgical intervention. Our case highlights the need of stabilizing medical and cardiac parameters before orthopedic intervention. One of the absolute contraindications for surgery in fracture neck of femur is unstable angina. Stabilization of unstable angina is necessary and demands priority over surgery for fracture neck of femur. Although there is time delay due to unstable angina and other medical conditions with fracture neck of femur, there is a need for further evaluation in such patients to get favorable outcome.

Reconstruction of Mirror Foot with Dysplastic Tibia.

INTRODUCTION: The Mirror foot is a rare congenital anomaly associated with duplication of the structures of the foot. Verghese et al have classified these feet into three types. Type three is associated with a Dysplastic tibia of which only 5 have been reported. Surgical management has been reported in only two of these five cases which are in the form of amputation. CASE REPORT: We would like to present the reconstruction of a Mirror foot associated with a dysplastic tibia. Our case which is only the sixth reported case attempts to present a surgical reconstruction to a plantigrade foot. Reconstruction was attempted in this case since the child showed a good quadriceps function at the knee. Reconstruction consisted of excision of the preaxial polydactyly to achieve a more cosmetic appearance to the foot as well as improve the ability to wear foot wear. The dysplastic tibia was osteotomized to correct the varus deformity and achieve a plantigtade foot. This helped the child to ambulate more easily with a shoe raise and a brace to maintain the correction achieved. At a five year follow up the child was walking and running with a shoe raise for a 9 cm limb length discrepancy. There was however recurrence of the deformity due to fibular overgrowth. The child's parents refused further reconstruction and were satisfied with the present function and appearance of the child. CONCLUSION: Reconstruction can therefore be attempted in these limbs associated with good quadriceps function.