All tea plants in India rely on the national grid for their electrical needs and diesel for their thermal energy and transportation, which are encountering high costs, high emissions, and issues of accessibility. In this paper, hybrid renewable systems based on both standalone and grid-connected technologies have been modeled using HOMER Pro software for supplying power to a tea manufacturing plant in a typical rural area in India, namely, Gudalur village (Nilgiris), geographically located at 11°30.2′N and 76°29.5′E, which is presently run by the state grid to meet their energy requirements. The different configurations comprised of Solar PV, biomass, hydro, electrolyzer, boiler, thermal load controller to utilize excess electricity, and waste heat recovery options, and lead-acid batteries were designed to meet 650 kWh/day of electricity for processing units, 101 kWh/day of electricity for general applications, 4,450 kWh/day of thermal energy, and 86.35 kg/day of hydrogen energy. To determine the most feasible system design among various scenarios, several criteria such as NPC, COE, LCOH, and CO2 emission of the system have been investigated. In the case of off-grid hybrid systems, results show the highest NPC of $7.01 M with an LCOE of $1.06/kWh is obtained for the diesel generator/boiler/reformer/TLC system. It is reduced to $1.75 M with an LCOE of −$.420/kWh for the PV/biomass-CHP/hydro/TLC scenario. In a grid-connected system, the maximum NPC of $6.20 M with an LCOE of $0.835/kWh is obtained for a diesel generator/boiler system, and it is reduced to −$10.5 M with an LCOE of −$.240/kWh for the PV/biomass-CHP/hydro/TLC scenario. Additionally, in the off-grid systems, the PV/biomass-CHP/hydro/TLC system has LCOH of $4.27/kg, which is economical with the highest renewable fraction of 93%. The PV/biomass-CHP/hydro/TLC hybrid system has the lowest LCOH of −$64.5/kg with a maximum renewable fraction of 96% in on-grid systems. The findings show that recovering excess electricity and waste heat would increase renewable fraction, decrease the energy cost and emissions from the system, and emphasize the importance of TLC and CHP in HRES. According to the simulation results, the grid-connected system is more cost-effective than a stand-alone system due to the revenue obtained from selling renewable power to the grid.

https://www.frontiersin.org/articles/10.3389/fenrg.2022.806870/pdf

An Examination of the Techno-Economic Viability of Hybrid Grid-Integrated and Stand-Alone Generation Systems for an Indian Tea Plant

In this work, sugarcane vinasse combined with organic waste (food and wasted tea) was demonstrated to be an excellent source of biomethane synthesis from carbon-rich biowaste. The discarded tea trash might be successfully used to generate bioenergy. The uncertainties and costs associated with experimental testing were recommended to be decreased by the effective use of contemporary machine learning methods such as Gaussian process regression. The training hyperparameters are crucial in the construction of a robust ML-based model. To make the process autoregressive, the training hyperparameters were fine-tuned by employing the Bayesian approach. The value of R2 was found to be greater during the model test phase by 0.72%, assisting in the avoidance of model overtraining. The mean squared error was 36.243 during the model training phase and 21.145 during the model testing phase. The mean absolute percentage error was found to be under 0.1%, which decreased to 0.085% throughout the model’s testing phase. The research demonstrated that a combination of wasted tea trash, sugarcane vinasse and food waste may be a viable source for biomethane generation. The contemporary methodology of the Bayesian approach for hyperparameters tuning for Gaussian process regression is an efficient method of model prediction despite the low correlation across data columns. It is possible to enhance the sustainability paradigm in the direction of energy security via the efficient usage of food and agroforestry waste.

/pdf/biomethane-production-from-the-mixture-of-sugarcane-vinasse-1lo68cg2.pdf

Biomethane Production from the Mixture of Sugarcane Vinasse, Solid Waste and Spent Tea Waste: A Bayesian Approach for Hyperparameter Optimization for Gaussian Process Regression

The tea industry in Kenya is among the main consumers of firewood for its intensive thermal energy demand. Along with the growing concerns about firewood depletion, tea factories have begun transitioning to alternative fuels to power their boilers. Briquettes made of biomass residues are among the promising solutions; however, they are not yet widely adopted. This study was conducted to identify the factors that motivate the tea factories to use biomass briquettes instead of firewood and the factors hindering such substitution. The substitution potential was assessed, and the drivers and barriers of the substitution were examined using a combination of SWOT (strengths, weaknesses, opportunities, and threats) analysis and a PESTEL (political, economic, social, technological, environmental, and legal) framework. The findings suggest that even though using biomass briquettes is technically possible, it is not economically favorable for tea factories. The SWOT/PESTEL analysis identified 27 factors influencing the substitution. Among the key drivers are the depleting supply of firewood, the availability of biomass residues, and the external support from development organizations to improve the technical capacity in both tea and briquette industries. The study revealed the barriers to substitution include the cost competitiveness, insufficient supply, and varying quality of briquettes, as well as the lack of awareness and knowledge of briquettes.

/pdf/drivers-and-barriers-to-substituting-firewood-with-biomass-1abxx2lu.pdf

Drivers and Barriers to Substituting Firewood with Biomass Briquettes in the Kenyan Tea Industry

A Review of Drying Technology in Tea Sector of Industrial, Non-Conventional and Renewable Energy based Drying Systems

The use of dual metal hydride system for thermal energy storage consists of high and low-temperature metal hydrides. In this study, a 3D cylindrical Magnesium Nickel hydride bed is analyzed for thermal energy discharge. The energy discharge from metal hydride bed initially at temperature of 400 K, a heat transfer fluid at 500 K temperature is supplied to extract the heat generated due to exothermic chemical reaction. In this article, variation of the number of heat transfer fluid tubes and effect of variation of aspect ratio (ratio of diameter to height) on energy desorption and heat transfer from metal hydride bed is performed. The optimal number of heat transfer fluid tubes is determined for various aspect ratios. The temperature variation of the metal hydride bed with an increase in the number of heat transfer fluid tubes is analyzed. The study of aspect ratio variation on energy desorption and heat transfer characteristics is analyzed for three aspect ratios 0.5, 1, and 2. The variation of thermal energy desorbed, net heat transfer and temperature variation of metal hydride bed are analyzed. The adequate number of heat transfer fluid tubes for AR 0.5, 1, and 2 is identified as 32, 48, and 72, respectively. The cumulative heat released from MH bed with AR 0.5, 1, and 2 is 350.94 kJ, 330.56 kJ, and 310.42 kJ, respectively. The study will be useful in designing the optimized metal hydride bed reactor for thermal energy storage applications.

https://dergipark.org.tr/en/download/article-file/1824939

Numerical investigation of energy desorption from magnesium nickel hydride based thermal energy storage system

In tea production, India ranks second largest in the world, after China. Indian tea industry is one of the largest in the world and with over 13,000 gardens and produces 1350 million kg of tea leaves. Tea production and processing require electrical and thermal energy in various processes such as irrigation, withering, rolling, fermentation, drying, sorting/grading, and packaging. To produce one kg of tea requires thermal and electrical energy in the range of 4.45–6.84 kWh and 0.4–0.7 kWh respectively. In tea gardens, diesel generators are commonly used for irrigational needs in off-grid areas. In tea industry, fossil fuels such as coal, low sulphur diesel are mostly used to encounter the thermal energy needs and these energy sources heavily pollute the environment. This is a serious cause of concern for all including national and international agencies. These conventional fuels may be replaced by suitable renewable energy resources to meet the energy demand of tea plantations and industries. The identification of suitable renewable energy technologies to satisfy the energy requirement of both tea plantation and industry for north-eastern states and the southern part of India are reviewed extensively and the technological barriers are delineated.

/pdf/feasibility-assessment-of-renewable-energy-resources-for-tea-bvfpxevgbp.pdf

Naveen Krishnan

Papers

Feasibility assessment of renewable energy resources for tea plantation and industry in India - A review