Sustainability assessment of RE technologies at a national scale involves a range of conflicting technological, economic, environmental, and economic indicators. Multicriteria decision-making (MCDM) methods are the best tool that can address these conflicts and choose the most suitable alternative from the pool of many alternatives. In the present study, the indicators such as response to peak demand, social acceptability, environmental risks, and social risks are accessed qualitatively. These qualitative data are generally associated with uncertainties and a fuzzy approach is the best to address these uncertainties. Further, it has been reviewed that sustainability indicators’ values vary widely for each RE technology and there is a great possibility of uncertainties for all input values.
As far as the sustainability assessment of RE technologies in the context of India is considered there are limited studies done [13, 14]. However, neither of these studies have addressed any form of uncertainties associated with input data. Thus, this study aims to address these uncertainties of input data in two ways. Firstly, the RE technologies in the context of India were assessed and ranked using fuzzy-TOPSIS (a technique for order of preference by similarity to ideal solution) to address the uncertainties associated with qualitative data. Secondly, to deal with the uncertainties link with a wide range in input values, the TOPSIS method is run using Monte Carlo simulation (MCS) and probabilistic ranking is obtained. Further, both the fuzzy-TOPSIS and probabilistic ranking are compared with that obtained from the TOPSIS method and the impact of these uncertainties is studied on the overall ranking of RE technologies.
2.2 RE Scenario in India
India is blessed with enormous RE potential. Figure 2.1 shows the electricity generation scenario in India as of 31/01/2021 [6, 15]. RE shares 36.8% of the total installed generation capacity. Coal is vital for India’s electricity security, given that over 53% of electricity generation is coal-based. However, increased dependence on imported fuels exposes the country to higher geopolitical risks and international price volatility [5]. In light of the above concern—along with the initiative to mitigate climate change, which has become a global issue—the various state, nodal and, government agencies in India are promoting the use of RE sources. The most important benefit for RE in India is its untapped potential. As shown in Table 2.1, on average more than 70% of potential is still untapped and the country has a high RE power target of 225 GW renewable capacity by 2022 [16]. The primary RE sources contributing to grid-connect power in India are explained in the next section.
Figure 2.1 Electricity generation scenario in India as on 31/01/2021 [3, 12].
2.2.1 Large Hydropower
Hydropower is an important RE resource in India for electricity generation. The potential of hydropower in India is immense and the country is ranked 6th in the world for hydropower installed capacity [1]. In India, only about 30% of the vast hydropower potential of 150 GW has been tapped so far. Hydropower projects require long planning and land acquisition procedure. In addition to this, due to the resettlement process, lack of transmission infrastructure, inadequate market scope, and long-term financing process, many hydropower projects in India are in a slow pace of development and suffering from schedule overrun. To fast track the hydropower projects, especially the 50 GW hydroelectric initiative, the central electricity authority (CEA), and the Power Ministry are closely monitoring these priority schemes [19].
To promote a large hydropower sector, the government of India has declared large hydropower projects under the renewable category in March 2019, and since then, large hydropower has accounted for the RE target. To assist the power sale from large hydropower projects, the Ministry of Power has issued a memorandum to notify Hydropower Purchase Obligation (HPO) [20]. The HPO covers all the large hydropower projects commissioned after the issue of this memorandum.
2.2.2 Small Hydropower
In India, hydropower projects under 25 MW capacity are classified as small projects. The potential of small hydropower in India is estimated to be 20 GW. Against an installation target of 5 GW by 2022, 4.6 GW has been achieved. Further, 109 projects of a total capacity of 0.54 GW are under various stages of implementation [6]. To set up the small hydropower and speed up its development, both the public and private sector’s participation is encouraged by MNRE, providing them with central financial assistance (CFA). The state government has also been provided with financial support to identify the potential for new sites, and also for renovation and modernization of old small hydropower projects. The states with the maximum hydro potential (i.e., Karnataka and Himachal Pradesh) are now the focal point for small project development.
Table 2.1 Installed capacity and untapped potential of RE against the estimated potential in India as on 31/12/19 [3, 17, 18].
| RE source | Potential (GW) | Installed capacity target by 2022 (GW) | Installed capacity as on 31/01/2021 (GW) | Untapped potential percentage |
| Large hydropower | 150 | 50 | 45.8 | 69.47 |
| Small hydropower | 20 | 5 | 4.8 | 76.00 |
| Solar power | 750 | 100 | 38.8 | 94.83 |
| Onshore wind power | 302.25 | 60 | 38.7 | 87.20 |
| Bioenergy | 25 | 10 | 10.3 | 58.80 |
2.2.3 Onshore Wind Power
The wind power program is growing rapidly in India with significant installation in the last few years with private sector participation and investment. Onshore wind power contributes the maximum after large hydro in the country’s total RE capacity and achieved 4th position at the global level [1]. In India, the wind power potential for generation is estimated to be 302.251 GW at a 100-meter ground level. The states in India with the highest wind power potential and installed capacity are Tamil Nadu, Karnataka, Andhra Pradesh, Maharashtra, Rajasthan, and Gujarat.
The government is providing various financial and fiscal incentives to promote onshore wind projects all over the country, e.g., accelerated depreciation benefit and exemption in concessional custom duty on specific parts of an electric wind generator. In line with these incentives, the government is also providing technical support through the National Institute of Wind Energy (NIWE), Chennai, for identifying new potential sites. To meet the target of 60