Assume a conservative estimate of 30 MW/sq km for solar PV and 5 MW/sq km for wind, with 5% of the area directly impacted.
By Shoibal Chakravarty & E Somanathan
The Indian Government’s ambitious programme for renewables expansion aims to increase capacity in solar PV to 100 GW and that in wind to 75 GW by 2022. Substantial progress has been made in this direction, and infrastructure for 33.7 GW of solar PV and 37.5 GW of wind energy generation has been installed as of December 2019. Most of this renewable capacity is in the states of the western and southern regional grids, and the state of Rajasthan.
Large-scale renewable power requires a lot of land, though researchers from the Indian Institute of Science have argued that its life cycle impact on land is comparable to that of coal. In a recent article titled “Renewable Energy and Land Use in India: A Vision to Facilitate Sustainable Development”, The Nature Conservancy (TNC) and the Centre for Science Technology and Policy (CSTEP) have claimed that the 2022 target would require a land footprint between 55,000 to 125,000 sq km, roughly the area of Himachal Pradesh or Chhattisgarh.
This is a huge overestimate of the actual land that will be permanently disturbed, as will be seen below. Unplanned and ill-thought-out expansion of solar and wind, especially in ecologically-sensitive semi-arid regions and grasslands is indeed a great concern. On the other hand, it is very important that land requirement estimates be nuanced and as accurate as possible, and clearly communicated to avoid bad policy decisions.
Some studies on the land requirement of utility-scale solar PV, based on planned or in-operation projects, show a range of 31-83 MW/sq km, with an average of 50 MW/sq km. TNC and CSTEP assume a significantly lower value of 25 MW/sq km. The land requirement of wind farms requires a more nuanced discussion. Most studies take a value of of 5-9 MW/sq km as the land requirement for wind farms in India. The direct physical footprint of wind is much lower at about 3% of the area of the wind farm. The rest of the land of the wind farm is available for farming or pasture. Here, TNC and CSTEP use a figure of 2MW/sq km, a drastic overestimate of the land use impact of wind farms. Significantly, the study uses a high land use impact, and fails to consider that most of the area of a wind farm is available for other productive use.
Assume a conservative estimate of 30 MW/sq km for solar PV and 5 MW/sq km for wind, with 5% of the area directly impacted. The area required for the 2022 renewables goal is about 3,400 sq km for solar PV, and 15,000 sq km for wind farms, with approximately 450 sq km directly impacted by infrastructure for wind turbines. In other words, instead of 55,000 to 125,000 sq km, less than 4,000 sq km will be permanently impacted. Quite likely, the land required would be less than half of our estimate given that much of the solar PV will be installed on rooftops, and assuming 50 MW/sq km for utility scale PV.
The direct impact of wind farms on land is actually lower than that of solar PV. While the temporary impact during installation might be larger, the long-term physical footprint of wind farms is lower as about 97% of the land is available for other use. The footprint of wind turbines continues to fall with the recent advances in technology such as the increase in size of the individual turbine. Leasing of land for wind could provide a stream of income while retaining most of the land for its original use. Offshore wind, yet to be deployed in India, would eliminate this remaining land footprint as well. Utility scale solar PV currently inhibits any other use of the same land, but this can change in the future. Agrivoltaics, or raised solar PV plants that allow agriculture in their partial shade can solve this problem, while also providing better productivity and water savings, especially for horticulture. There is a significant potential of solar PV installations on building rooftops.
Even if all of India’s electricity generation of 1,561 Terawatt hours in 2018-19 came from solar PV, the total area required would be about 20,000 sq km. The International Energy Agency, in its 2018 World Energy Outlook considered an electric scenario with significantly higher electrification of the Indian economy. In this scenario, about 6,000 Terawatt hours of generation is projected, which would require about 80,000 sq km, if entirely provided by solar PV. As wind turbines need less area, these estimates provide an upper bound for the total area required for powering India using renewables only. Note that the urban area of India is about 220,000 sq km, and a large fraction of this could be used for solar PV.
Renewables are already cheaper than electricity from coal, so economics is not a barrier to the expansion of renewables. Land availability is not a limiting factor as we emphasise here. A lot of renewables can be absorbed in the grid if the right regulatory support is provided for grid balancing, and electricity system flexibility. The real challenge is that the coal generation sector is under financial stress, and is likely to suffer further with the expansion of renewables. Quite a few of the poorest regions of the country depend on economy of coal and coal powered electricity. A policy package that aids these regions is essential for this transition to occur smoothly. Attempting to delay the inevitable transition would only lead to an even greater financial crisis in the future. It is never wise to throw good money after bad.
Chakravarty is with Ashoka Trust for Research in Ecology and Environment & Somanathan is with Indian Statistical Institute, Delhi (Views are personal)