| dc.description.abstract | Renewable energy-based power has gained significant global momentum—to minimize fossil-fuel use, combat climate change, and ensure energy security. While renewable energy (RE) is fast-growing, stand-alone single resource-based power plants (the most widespread RE plants) face challenges to generate stable power because of resource intermittency. Consequently, grid operators find it challenging to plan power supply relying on RE plants. Employing electrical storage, thermal energy storage, and hybridization in stand-alone plants could provide some solutions. However, electrical and thermal storage have limitations at megawatt scales, primarily in cost-effectiveness, greater installed capacities than nameplate ratings, and land requirements. This study identified that the hybridization of various renewable energy sources is a promising way to address intermittency challenges.
The study involved techno-economic modeling and analysis of various RE systems along with hybridization. The plant capacities of the individual-resource and hybrid systems were chosen for the Indian context. Five hybrid configurations have been proposed while modeling and analyzing these hybrid-RE configurations. The resources and technologies considered for the hybrid system were solar energy (concentrated solar power and photovoltaic), biomass (combustion and gasification), and on-shore wind (horizontal-axis wind turbine). The specific details of the hybrid scenarios studied for the Indian context are provided below.
1. Synergetic-based hybrid option for grid-connected power: Concentrated Solar Power (CSP) and Biomass Combustion
2. Cost-effective hybrid option for grid-connected power: Photovoltaics (PV) and Biomass Combustion
3. Distributed hybrid option for off-grid power: Photovoltaics (PV) and Biomass Gasifier connected to a gas-engine
4. Multi-RE hybrid effective land-use option for grid-connected power: CSP, Biomass Combustion, and Horizontal Axis Wind Turbines
5. Hybrid opportunity to improve wind farms energy production: Horizontal Axis Wind Turbines and Biomass Combustion
The study's techno-economic aspects provide insights on detailed modeling methods, the level of challenges on the single-resource-based RE plants, and improvement potential through hybrid plants. The results in all of these hybrid scenarios have been analyzed for the following:
1. Requirements of solar field area and biomass fuel requirements for a given plant capacity
2. Reduction possibilities of solar field area and biomass with an increase of plant capacities
3. Energy share from each source in the total energy mix, the extent of grid-friendly energy supply through hybrid systems
4. Plant load factors for various modes of plant operation (solar/wind-alone, hybrid with day-time, and hybrid with the day-night operation) and plant capacities
5. Levelized cost of electricity
The suitable large hybrid capacities, for the Indian context, to generate firm power with biomass integrated solar plants are up to 20 MW. At higher capacities (up to 100 MW), the multi-renewable hybrid system (solar-biomass-wind) is a desirable option with increased solar and wind plant capacities.
The results indicate that the stand-alone solar plants intermittently produce energy for about 2,700 hours of sufficient sunshine hours of 3,700 in a year. In the case of wind-alone plants, they produce intermittent energy for ~85% (7,500 hours) of the time in a year. Upon hybridization with the biomass system, it fulfills the required nameplate capacity in intermittent solar/wind periods by its flexible operation of a boiler with a ramp rate of 3%.
Small-capacity solar-biomass hybrid plants (1 MW) require larger solar fields of 10,000 m2 and biomass of 3,300 tonnes per annum (day-only operation). Large-capacity plants show effectiveness in terms of these requirements. Solar-field area and biomass requirements for a 20 MW plant are 5,000 m2 and 1,600 tonnes per MW, respectively.
The plant load factors (PLF) of solar-biomass hybrid plants from day-time operation results in 45–48% (against the single-resource plants with PLF of less than <18%) and day-night operation offers around 80%. Solar-biomass-wind hybrid systems offer similar PLFs when the plant capacities of CSP and biomass are equal (20 MW). At larger capacities (50 MW and 100 MW), the PLF are observed to be 40–50% with near firm power (better compared to highly intermittent power and lesser PLF of single resource solar/wind plants).
From an economics perspective, the large scale solar-biomass hybrid plants result in an LCOE of ~ INR 5.0/ kWh. Small-capacity plants at distributed levels offer an LCOE of INR 6–9/ kWh. The wind integrated solar-biomass hybrid plants generate electricity at INR 3.4–4.6/ kWh. | en_US |
