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).

India emitted 3.2 billion metric tons of CO₂e in 2016, or 6% of annual global greenhouse gas emissions, placing it third only to China and the United States (1). One-third of these emissions were from coal-based electricity. At the same time, both per capita emissions and energy use remain well below global averages, suggesting a massive potential for growth of electricity generation and emissions (1). India’s primary energy demand is expected to double by 2040 compared to 2017 (2). Whether this energy comes from fossil or low-carbon sources will significantly affect the ability to limit average global temperature rise to below 2 °C.India is already pursuing significant technology-specific renewable energy targets—100 GW of solar and 60 GW of wind by 2022—and, in its Nationally Determined Contributions (NDC), committed to a 40% target for installed generation capacity from nonfossil fuel sources by 2030 (3). In 2019, in part to fulfill its NDC commitment, the Indian government proposed to install 440 GW of renewable energy capacity by 2030, with 300 GW of solar and 140 GW of wind capacity (4). Although costs of solar photovoltaic (PV) and wind technologies have declined significantly in recent years (5–7), the low cost of coal and integration costs associated with variable renewable energy (VRE) technologies like wind and solar may hinder India’s cost-effective transition to a decarbonized electricity system. This paper seeks to answer a number of questions that arise in the Indian context. What targets for wind and solar capacity have the lowest associated integration costs? Will these targets significantly offset the need to build fossil fuel generation capacity? What additional measures can we take to mitigate VRE integration costs?Merely comparing the levelized costs of VRE with the costs of conventional generation ignores additional cost drivers, which depend on the timing of VRE production and other conditions in the power system (8, 9). Quantifying these drivers requires models that choose lowest-cost generation capacity portfolios and simulate optimal system operation with detailed spatiotemporal data. Several prior studies address these system-level integration costs in a capacity expansion planning framework (10–16), often making decisions based on a limited sample of representative hours. Other studies explicitly estimate the relationship between long-run economic value (including integration costs) of VRE penetration levels (17, 18) but do not include VRE investment costs in their analysis. Few prior studies explore the impacts of high VRE penetration on India’s electricity system, and those that do either use the capacity expansion framework and do not evaluate the economic value of multiple VRE targets (4, 19, 20) or do not optimize capacity build around proposed VRE targets (21).Here we address this gap by estimating how different VRE targets affect the cost to reliably operate the Indian electricity system. To do so, we work with three interrelated models. First, using a spatially explicit model for VRE site selection, we identify the lowest levelized cost wind and solar sites to meet different VRE capacity targets, and study how the resource quality—and corresponding levelized cost—of selected sites changes with increasing VRE targets.Second, using a capacity investment model that accounts for VRE production patterns and optimal dispatch of hydropower and battery storage, we determine the capacity requirements and investment costs for coal, combined cycle gas turbines (CCGT), and combustion turbine (CT) peaker plants. Due to uncertainties in their future deployment (22), and because their current targets are relatively low (4), we did not consider new nuclear or hydro capacity in the main scenarios but include those in the sensitivity scenarios presented in SI Appendix, section 2. Third, we use a unit commitment and economic dispatch model to simulate hourly operation of the electricity system and estimate annual system operational costs. This model captures important technical constraints, including minimum operating levels, daily unit commitment for coal and natural gas plants, and energy limits on hydropower and battery storage. Rather than cooptimize VRE capacity, we compute the system-level economic value of a range of VRE targets by comparing the sum of the avoided new conventional capacity and energy generation costs to a no-VRE scenario. The net cost for a scenario is then the difference between the levelized cost of the VRE and the system-level economic value. Materials and Methods provides more detail on this process.Our results show that, despite greater levelized cost reduction forecasts for solar PV compared to wind technologies, VRE targets with greater amounts of wind have the lowest projected net carbon mitigation costs. This finding is robust to a range of scenarios, including low-cost solar and storage, and lower minimum generation levels for coal generators.We find that, although VRE production displaces energy production from conventional generators, it does very little to defer the need for capacity from those generators due to low correlation between VRE production and peak demand. Our findings suggest that VRE in India avoids far less conventional capacity than VRE in other regions in the world. These capacity requirements are slightly mitigated if India’s demand patterns evolve to more closely resemble demand in its major cities. Overall, we conclude that the importance of choosing the right VRE mix is significant when measured in terms of carbon mitigation costs: Whereas most solar-majority scenarios we examined lead to costs greater than or equal to estimates of the social cost of carbon (SCC), wind-majority mixes all cost far less than the SCC.     

Iodinated curcumin bearing dermal cream augmented drug delivery,antimicrobial and antioxidant activities

Objectives: Curcumin (Cur) exhibits weak microbicidal activity owing to high lipophilicity and low cell permeability. Therefore, in the present investigation, Cur was iodinated using elemental iodine (I₂) to synthesise Cur–I₂ powder that was later formulated as Cur–I₂ dermal cream and characterised in vitro for antimicrobial and antioxidant activities.

Methods and results: Electrophilic addition of I₂ saturated the olefinic bonds of Cur, as confirmed by UV/visible spectroscopy, FT-IR, ¹H NMR and DSC techniques. In addition, in vitro skin permeation and retention analysis indicated that Cur–I₂ cream followed the first order and Higuchi model for drug release through the rat skin. The minimum inhibitory concentration (MIC) of Cur–I₂ powder was measured to be 60 and 90?µg/ml significantly (p?Staphylococcus aureus and Escherichia coli, respectively. Moreover, Cur–I₂ also exhibited strong antioxidant potential.

Conclusions: Cur–I₂ cream warrants further in vivo study to scale up the technology for clinical translation.     

Potential neuroprotective role of astroglial exosomes against smoking-induced oxidative stress and HIV-1 replication in the central nervous system

Introduction: HIV-1-infected smokers are at risk of oxidative damage to neuronal cells in the central nervous system by both HIV-1 and cigarette smoke. Since neurons have a weak antioxidant defense system, they mostly depend on glial cells, particularly astrocytes, for protection against oxidative damage and neurotoxicity. Astrocytes augment the neuronal antioxidant system by supplying cysteine-containing products for glutathione synthesis, antioxidant enzymes such as SOD and catalase, glucose for antioxidant regeneration via the pentose-phosphate pathway, and by recycling of ascorbic acid.

Areas covered: The transport of antioxidants and energy substrates from astrocytes to neurons could possibly occur via extracellular nanovesicles called exosomes. This review highlights the neuroprotective potential of exosomes derived from astrocytes against smoking-induced oxidative stress, HIV-1 replication, and subsequent neurotoxicity observed in HIV-1-positive smokers.

Expert opinion: During stress conditions, the antioxidants released from astrocytes either via extracellular fluid or exosomes to neurons may not be sufficient to provide neuroprotection. Therefore, we put forward a novel strategy to combat oxidative stress in the central nervous system, using synthetically developed exosomes loaded with antioxidants such as glutathione and the anti-aging protein Klotho.     

Comparative Evaluation of Local Anaesthesia with Adrenaline and Without Adrenaline on Blood Glucose Concentration in Patients Undergoing Tooth Extractions

Background  

Lignocaine hydrochloride is the most widely used and easily available local anaesthetic agent. Adrenaline is frequently combined with lignocaine to enhance the duration of anaesthesia, decrease toxicity, to achieve vasoconstriction and to provide a bloodless field.     

Solitary sacral osteochondroma without neurological symptoms: a case report and review of the literature

Purpose

To report a case of solitary sacral osteochondroma without neurological symptoms and describe the en bloc excision of the tumour, as well as review the literature on osteochondroma involving the sacrum.

Methods

Summary of the background data: although osteochondromas are among the most common benign tumours of the bone, they uncommonly involve the spine. Its occurence in the sacrum is rare, accounting for only 0.5 % of the osteochondromas involving spine. All previous cases of sacral osteochondroma have reported neurological symptoms on presentation.

Case report

A 21-year-old male presented with a palpable, painless mass in the left side of the sacral region of 1 year duration, without neurological symptoms. Radiological studies showed a well-circumscribed lesion with bony osteoid within arising from the sacrum at S3–S4 level left to midline, with features suggestive of osteochondroma. The tumour was excised en bloc through posterior approach. A literature review of sacral osteochondroma was conducted using MEDLINE search of English Literature and bibliographies.

Results

Histopathological studies showed the lesion to consist mature bone trabeculae with active enchondral ossification with cap of normal hyaline cartilage. Literature review yielded only 8 cases of sacral osteochondroma reported earlier.

Conclusion

This is the 9th case of solitary osteochondroma of the sacrum to be reported, the first to be reported without any neurological symptoms, and third case reported for which en bloc excision was performed.

     

Finger pulp reconstruction with thenar flap: Aesthetic and functional outcome

Purpose: Fingertip injuries are common in industrial production activities as well as in domestic work. Loss of pulp hampers daily life activities. Functional and aesthetic aspects are important in fingertip reconstruction. The bone is usually exposed along with soft tissue loss. Therefore to reconstruct the pulp flap with adequate bulk is required. Methods: We reported a case series of 12 patients with the injury over the volar aspect of distal phalanx of the index or middle finger. In all cases, laterally based thenar flap was chosen. The flap donor site was closed primarily in most of cases, while 4 patients required skin graft. The flap was detached between 2-3 weeks. Functional assessment was done using static and dynamic 2-point discrimination and range of motion at each joint. The aesthetic outcome was assessed through questionnaire. The results were analyzed using the unpaired t-test (SPSS version 21). Results: Partial necrosis occurred in 2 cases while rest of flaps survived successfully. Static 2-point discrimination ranged from 6e10 mm, mean 8.6 mm; and dynamic 2-point discrimination ranged from 8-10 mm, mean 8.9 mm. The mean satisfaction score was (4.0 ± 0.55). Conclusion: Thenar flap is a good choice for reconstruction of the finger pulp as it provides the bulk with good functional and aesthetic outcome.     

Multiple Myeloma—Effect of Induction Therapy on Transplant Outcomes

BackgroundPatients with multiple myeloma (MM) aged ≤ 65 to 70 years, with a good Eastern Cooperative Oncology Group performance status and no major comorbid conditions, are considered potential candidates for autologous stem cell transplant (ASCT) and will be treated with novel agent-based induction therapy for 4 to 6 cycles before ASCT.Patients and MethodsWe analyzed the data from 326 patients with MM who had received novel agent-based induction before ASCT at our center to evaluate the effect of induction therapy on ASCT response, stem cell mobilization, engraftment characteristics, and survival. The median age was 52 years (range, 29-72 years), 216 patients were men (66.3%), 32.7% had stage III using the Revised Multiple Myeloma International Staging System, and 15.8% had high-risk cytogenetics. Of the 326 patients, 75 (23.0%) had undergone ASCT in second remission after salvage therapy for relapse. Also, 194 patients (59.5%) had received doublet induction therapy and 132 (40.5%) had received triplet induction therapy.ResultsTriplet-based induction therapy was superior to doublet-based therapy for response (95.4% vs. 84.02%; P < .003), stem cell mobilization (CD34⁺ ≥ 2 × 10⁶/kg; 88.6% vs. 76.8%; P < .005), and lower 100-day transplant-related mortality (P < .001). The ≥100 day post-ASCT overall response (97.4% vs. 91.7%; P = .124) and complete response (72.5% vs. 68.0%; P = .38) rates were similar. At a median follow-up of 62.5 months, the overall survival (97.5 months vs. 100.0 months; P = .606) and progression-free survival (54.5 months vs. 57 months; P = .515) were similar between the triplet and doublet induction groups.ConclusionAn initial response (chemosensitivity) to induction therapy will prepare patients better for subsequent consolidation therapy and ASCT, leading to favorable outcomes.