Strategies For Sustainability

India needs 24x7 availability of power for its economic growth; however, this power cannot be achieved by renewable energy sources alone. Thermal energy cannot be written off till storage becomes cost-effective for Round-the-Clock supply through Renewable Energy. Although generation of thermal energy involves increase of carbon footprints, still there are ways for minimizing that. Optimization is possible and required in all fields of power generation too. Read on…

The government has decided to add 80 GW thermal power capacity by the year 2031-32, as power demand of the country has increased at an unprecedented rate due to rapid growth of the economy. It has been decided not to compromise on availability of power for economic growth. The required power cannot be achieved by renewable energy sources alone, nuclear capacity cannot be added at a rapid pace hence coal-based thermal capacity must be added for meeting our energy needs.

India currently has 27 GW under construction, and further 25 GW was earlier envisaged. But it is decided now that to work on at least 55 GW – 60 GW of thermal capacity. As demand ramps up, this capacity would be added. While the carbon emission from this added capacity may be a cause for concern in terms of increased carbon footprint – the country and generators have opportunities that can pay rich dividends besides reducing the carbon footprint.

The three basic inputs for power are land, water and fuel. We have so far focused on fuel alone in our shift towards RE in the form of solar and wind. If we decide to focus on land and water in partnership with players with demonstrated success, we can have dramatic turn around. We can add waste utilisation to our portfolio to accelerate it. In the long run the cost of natural resources like land and water are bound to go up. The environmental costs are already high, the polluter today must compensate in a big way. Waste disposal similarly is a key issue of consideration not only because of its environmental impact but also because of the economic cost of waste disposal.

The water body underneath the solar modules helps in maintaining their ambient temperature…

Land use optimization

Cost of land is exorbitant in a thickly populated country with increasing awareness of civil rights. The aggregate cost of land includes the cost of land, the valuation of tress or construction on land and the cost of rehabilitation of people affected. It was always a consensus to avoid cultivable, irrigated, fertile land for power plants. A consensus has emerged now to go for high-capacity units (800 MW and above) in brownfield sites avoiding fresh land acquisition. This often involves dismantling of old, inefficient small capacity units and creating space for new high-capacity units.

The sprawling spread out industrial townships are now accommodated in high-rise vertical smart towers. Natural Draft Cooling Towers (NDCT) instead of Induced Draft Cooling Towers (IDCT) are now preferred even at pit head because of the space constraints. Gas Insulated Switch Yard (GIS) as against Air Insulated Switch Yard (AIS) is preferred as it requires less space though a cost must be paid as a tradeoff. Air cooled condenser in place of water-cooled condenser similarly reduces the ground footprint besides reducing water consumption with a small rise in heat rate as a tradeoff. There have been considerable efforts to place the balance of plant facilities to optimize the layout further.

Water use optimization

Water and electricity supply have a historic link. The big names – like Tennessee Valley Authority or Damodar Valley Corporation in India (Water and Electricity Authorities) – are abound, since river valley projects provided water for irrigation as well as electricity. The hydroelectric development in India has been hit by Public perception created against hydro projects, protest against land acquisition for dams, rehabilitation and resettlement issues, lack of fund and technology besides geological surprises. India is endowed with a hydro power potential of around 1,48,700 MW – out of which 51.8 GW has been harnessed till now in form of small and Large Hydro projects.

In order to promote economic growth of the country, faster addition of electricity was required, for which government policy shifted towards addition of thermal projects mainly the Coal Based Power Plants in the country. Coal based plants today constitute around 56% of the total installed capacity whereas it meets 75% of the country’s energy requirement. The linkage between supply of water and electricity has weakened as a result.

However, we must keep in mind that water to our households is delivered after being pumped, in places like Noida for example, water from a distance of 100 Km in Ganga is pumped, mixed with pumped up ground water with high TDS, the households again use a R.O unit to get drinking water and throwback about 65% of the water. In water supply, a considerable amount of electricity is associated – be it in irrigation or in drinking water.

If we build waterbodies and plan lake cities like Udaipur, Bhopal or Hyderabad, we not only bring down the temperature in urban settlement – we reduce electricity consumption substantially because of the reduced HVAC consumption. In peak summer, on a hot day, the coal consumption for electricity was 2.5 MT and on a cloudy day it was 2 MT about 20% lower.

Unlike Hydropower stations that generate electricity by the flow of water through turbines involving minor evaporation loss in dams, thermal power consumes about three litres of water per unit of electricity, a substantial volume, a lot of optimization into the power cycle has been incorporated, condenser material upgraded and the cycle of concentration has been raised to 5 from 3.5 only the water with high TDS is used as blowdown for ash handling.

Water in the constitution of India is a state subject, except for the matters of regulation and development of interstate rivers – which is in the union list, water sharing between nations and among states remain a contentious issue exacerbated by increasing water requirements for industrial use. While welfare strategies prioritise allocation to domestic and agriculture, the link between industry and GDP leading to wellbeing cannot be set aside.  The river catchments and groundwater aquifers are hydrogeological entities having no congruity with the administrative and political boundaries. Hence, it is extremely difficult to contain and manage water resources with the political and administrative limits as the management units. This has made water management and regulation a complex process in the country. This calls for water use optimization in thermal power stations. Before the directive to use treated sewage water, the water for power plants was obtained through irrigation schemes like creation of reservoirs and canal lining that involved massive investment.

Air cooled condensers now at North Karanpura and Patratu Plants of NTPC would reduce water consumption to about 40%, this shall be the future mode of cooling. It would be used in tandem with dry bottom ash system, thus the entire ash handling system would not utilize any water, dry fly ash handling systems are already in place for quite some time.

NTPC declared Commercial Operation of the final part capacity of 20 MW out of 100 MW Ramagundam Floating Solar PV Project at Ramagundam, Telangana with effect from July 01, 2022. The project spreads over 500 acres of its reservoir. With the presence of floating solar panels, the evaporation rate from water bodies is reduced, helping in water conservation. Approximately 32.5 lakh cubic meters per year water evaporation can be avoided. NTPC had declared Commercial operation of 92 MW Floating Solar at Kayamkulam (Kerala) and 25 MW Floating Solar at Simhadri (Andhra Pradesh) earlier. From environment point of view, the other obvious advantage is minimum land requirement mostly for associated evacuation arrangements. The water body underneath the solar modules helps in maintaining their ambient temperature, thereby improving their efficiency and generation.

The blue planet with 70% water has only 4% potable water. A deeper analysis would reveal that the problem of water scarcity is only periodic, it is only about the lean season, managing the water bodies, preventing evaporation loss and harvesting rain water in cascaded storage. Among the various energy storage technologies available, most matured and domestically available technology is the Pumped Storage Hydro Projects (PSPs). Considering the maturity of the technology, life span of the system, cost of the energy over its lifetime, minimum environment impacts in its vicinity, PSP technology is considered to be appropriate for large grid scale application.

Out of 500GW of RE sources as per the INDC, 420GW will be from VRE (Variable Renewable Energy) only comprising of Wind and Solar energy sources – which are intermittent in nature resulting in mismatch of the supply and demand of the VRE generation in the grid rendering surplus power in the grid. The surplus power needs to be either consumed or stored in some form of energy storage system, otherwise VRE generation will have to be curtailed. Curtailment of VRE sources i.e., wind and solar power is already being witnessed in some states in Southern India – where generation from VRE has exceeded 20% of the total energy capacity. The Pumped Storage Hydro Projects are also called Water Battery (PSP) to store the energy in form of potential energy. PSPs primarily use indigenous technologies and domestically manufactured materials. Most of the Electrical and Mechanical parts of PSPs are made in India in comparison to electro chemical and chemical batteries, which are import dependent. PSPs are clean, green, safe, and non-explosive and don’t produce any poisonous/ harmful by-products or pose disposal problems.

Each Pumped Storage Project has two reservoirs. One is the upper reservoir at higher elevation and a lower reservoir at lower elevation at the outlet of the Tail Race Tunnel. Other civil components have almost similar attributes like a normal Hydro Project. Water is pumped from the lower reservoir to the upper reservoir at a higher elevation where it is stored in form of potential energy until needed to be retrieved. The water, when released from the upper reservoir work to rotate a turbine and generates electricity. In case of PSP, the single unit of a machine acts as a pump as well as a turbine but rotates in reversible directions.

Pumped storage Projects may be classified into 3 configurations:

  • On Stream Pumped Storage Schemes where both reservoirs are located on any perennial river/stream.
  • Off Stream Pumped Storage Scheme Open Loop, where one of the reservoirs is located on any perennial river/stream.
  • Off Stream Pumped Storage Scheme Closed Loop, where none of the reservoirs is located on any river/stream.

There is also an uncanny linkage between soil and water. If water is poured on porous soil it not only drains the water it leads to soil erosion and landslide as we often witness in the Himalayan region. Cascaded water bodies connected through elaborate piping network would prevent soil erosion, facilitate energy storage and make more water available for the lean season. Water supply across the country can be taken up with cascaded storage capacity obviating the need for desalination and sewage treatment.

The charcoal treatment of soil at Heartfulness Institute Kanha Shanti Vanam has received national and international acclaim for establishing a rain forest in the arid Ranga Reddy district of Telangana. The charcoal treatment of soil developed by them has been recognised by ICAR and Ministry of Agriculture – and specially mentioned in Jal Charcha – the journal of Ministry of Water Resources Govt. of India, further through tissue culture the climate endangered flora is being revived at this site and other sites in Madhya Pradesh.

Coal based power generation can work closely with organizations like Heartfulness Institute and participate in Carbon offset projects such as afforestation that capture and store carbon dioxide emissions. These actions can create carbon offset credits that can be sold to companies or entities looking to offset their emissions. Besides the Heartfulness Institute has the potential to reduce cost of compensatory afforestation for power producers since land is being made available to them for free by various state governments. They have a model for large scale plantation involving Heartfulness volunteers from across the country.

Waste utilization

Blue Coal or biochar: NTPC Ltd., has successfully implemented a technology to convert Municipal Solid Waste (MSW) into high Gross Calorific Value (GCV) fuel that can be co-fired in conventional boilers at its Dadri Plant in Delhi NCR. In doing so, NTPC has achieved a rare feat of being among the global pioneers to convert waste to energy. The new technology has been installed at NTPC Dadri power plant – where solid waste is being treated to produce coal. Presently, on a daily basis, 20 tonnes of solid waste is converted to produce 10 tonnes of coal pellets. The breakthrough in the technology is expected to address the issue of air pollution, green-house gas emissions, waste management and renewable energy generation in a cost effective and environment friendly way. The heart of the plant is a reactor using unique indigenously developed technology, which can process the carbonaceous component of municipal solid waste into charcoal. The reactor can also be used for ‘torrefaction’ of biomass such as crop straws, tree leafs, forest residue into charcoal. Charcoal will substitute the fossil fuel being used in various applications and will be effective in reducing green-house gas emissions. This step, in future is expected to reduce the menace of MSW and will assure a clean and better environment for all.

Further, in the process of transforming solid waste to power, NTPC is collaborating with municipalities of East Delhi Municipal Corporation along with Kawas, Varanasi, Indore and Mohali. The municipal solid waste will be segregated and processed to utilise combustion fraction for conversion to coal or for power generation, biodegradable fraction for production of methane gas for use as bio CNG, and the recycled residue shall be used for construction purpose after required processing.

NTPC is in the process of purchasing around 20,000 tonnes of agriculture residue per day to make pellets and mix that with natural coal for co-firing. NTPC is presently using 70 to 80 tonnes per day of crop residue-based pellets with coal in its thermal power plant at Dadri in Uttar Pradesh. The project was started in 2017 to reduce air pollution and generate renewable energy by avoiding stubble burning, which was causing huge pollution in Delhi and NCR. The company has envisaged consumption of 1 million tonnes of agro pellets in 2020 for its power plants.

Ash utilization

MOEF & CC is consistent in its denial of land for ash dyke, so 100% Ash needs to be utilized in manufacture of cement, brick or highway building. The demand for ash at pit head stations is low and export potential need to be explored.  Ash can be better traded since construction material is in short supply, we may have to store ash in high-capacity silos and transport ash in vessels. Also, we should explore extraction of minerals from ash like silica, alumina, Iron, Rare-earth and arsenic etc., but we must target the entire value chain. The power saving by avoiding crushing of ore for extraction of mineral is bound to reduce carbon footprint.

Salient elements of the strategy:

  • Partnerships: Collaborate with successful players focusing on land, water, and waste utilization.
  • Diversification: Expand efforts beyond fuel-centric approaches to embrace broader sustainability aspects.
  • Strategic Investment: Allocate resources toward carbon-offset projects like afforestation.
  • Innovation: Explore technological advancements for ash utilization and mineral extraction.
  • Public Relations: Use these initiatives to enhance brand and esteem to attract investor’s attention.

Leveraging these opportunities, generators can not only reduce their carbon footprint – but also generate additional revenue streams and strengthen their positions as leaders in the Indian economy.

Dr. Bibhu Prasad Rath is a highly experienced Additional General Manager with 33 years of experience in the power sector, specializing in Energy, Environment, and Economics, robust foundation in operations, design, procurement, feasibility, policy formulation, investment decisions, and carbon credits. Currently, he is on deputation to Ministry of Power, GOI. He obtained a Ph.D. in Business Administration from Aligarh Muslim University and published numerous papers in various journals and conferences on actionable issues of climate change, sustainability, heartfulness, decision making and leadership.

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