Hydro Electric Potential
Indian subcontinent has huge untapped hydro-electric potential. Three major international river systems originating from The Himalayas viz. Ganga, Brahmaputra and Indus, offer India, Pakistan, Bhutan and Nepal huge hydro potential to exploit.
Covering over 1,165,000 km, the Indus River system is one of the largest rivers in the world. Consisting of the main Indus, two western tributaries and five eastern tributaries, this river system is shared between China, India, Pakistan and Afghanistan
The IWT allocated the Indus tributaries between India and Pakistan. India received three tributaries—Ravi, Sutlej and Beas—while Pakistan also received three tributaries—main Indus, Jhelum and Chenab (Indus Waters Treaty, 1960).
The vast volume of water in the Brahmaputra and the natural hydrological gradient allows India, in spite of China’s diversion plans on the Yarlung-Tsangpo, to harness the potential of the river in the lower reaches of Arunachal Pradesh.
Nepal and Bhutan have undeveloped but feasible hydro electric potential and if utilised they could produce more power than they would domestically consume. Bangladesh owing to its flat topography does not have much hydro electric potential.
Figure 1. Snow fed rivers of Indian subcontinent
India is duly concerned about climate change and efforts are on to promote benign sources of energy. Hydro Power is one such source and is to be accorded priority also from the consideration of energy security.
India is endowed with rich hydropower potential; it ranks fifth in the world in terms of usable potential. This is distributed across six major river systems (49 basins), namely, the Indus, Brahmaputra, Ganga, the central Indian river systems, and the east and west flowing river systems of south India. The Indus, Brahmaputra and Ganga together account for nearly 80% of the total potential. In the case of Indus the utilization is, however, governed by the Indus Water Treaty with Pakistan. The economically exploitable potential from these river systems through medium and major schemes has been assessed at 84,044 MW at 60% load factor corresponding to an installed capacity of around 150,000 MW. As mentioned earlier, so far only 32,325 MW has been established. Table 1. shows the status of development of hydropower on a region-wise and basin-wise basis. The assessment of small hydro (up to 25 MW) potential has indicated nearly 10,000 MW distributed over 4,000 sites. It is estimated there is still an unidentified small hydro potential of almost 5,000 MW.
|Basin||Potential (MW) *||Potential Developed (MW) *||Potential under Development (MW) *||Balance Potential (MW) *||Balance Potential (%)|
|Central Indian Rivers||2,740||1,060||1,147||533||19.45|
|West Flowing Rivers||6,149||3,704||41||2,404||39.09|
|East Flowing Rivers||9,532||4,168||144||5,220||54.76|
* MW indicated for a load factor of 60%
Table 1. Break-up (River basin-wise) of Hydro Potential in India
India has an estimated small hydro potential of about 15,000 MW. Out of this total potential of small hydro identified so far, is 10,265 MW through 4278 sites. As on 31.03.2005, 523 small hydro projects (up to 25 MW) with an aggregate capacity of 1705 MW have been installed. Besides these, 205 projects with total capacity of nearly 480 MW are under construction.
The development of pumped storage schemes attracted much attention in recent past because of important role in evening out energy generation from base load thermal stations and in meeting peak load and system contingencies. The reassessment studies of CEA acknowledged the need for identifying PSS sites and identified 56 sites for Pumped Storage Schemes (PSS) with total installation of about 94,000 MW.
It has been recognized that Nepal’s main natural resource is its abundant hydropower potential. The distinct topography of Nepal with its unique high hills and more than 6,000 rivers and innumerable rivulets criss-crossing the country provides many opportunities for both large and small hydro power development. Nepal is estimated to have theoretical hydro potential of 83,000 MW of which 42,000 MW is economically feasible. 11
Environmental problems with the dams (inundation, siltation, negative impacts to river water quality, harm to riparian ecosystems), controversies over India’s position as a price-determining buyer of Nepalese electricity, and the fact that these large projects rely on expensive foreign contracting firms have raised controversies against largescale hydroelectric projects in Nepal. Moreover, when the option for large power plant is considered, the power export agreement has been a major controversial issue with the neighboring power deficient countries like India in order to guarantee the power market.
Bhutan has a power generation capacity of 30,000 MW, out of which only about 1,500 MW has been tapped, while the domestic demand is just about 240 MW. Bhutan is still in a nascent stage of hydro-power development with a low base of only 344.458 MW. The system peak load is about 77 MW and 30% of the population has access to electricity. The hydro-power generation is about 98% and diesel generation is only 2%. The power sector in the country right now is in a dynamic stage of development with corporatization of the Department with effect from 01-07-2002 and load dispatch network and attracting of foreign investment in Hydro-power Sector under active consideration. 12
The rivers with approximate length of 175 km and dropping down from about 7500m to 200m create a natural fall, which is ideal for development of Hydro-power. These rivers provide hydro-power theoretical potential of about 30,000 MW. Against the theoretical potential, techno-economically feasible hydro-power potential for development is about 16,280 MW.
The core of Bhutan’s conservation strategy is a system of national parks and protected areas that form 26 per cent of its land. This pristine impression is partly due to Bhutan’s strong commitment to environmental preservation. Bhutan’s laws reserve 70 per cent of its land for ‘green’ cover, of which 60 per cent should be forests. Bhutan’s development of hydropower plants could also impact the environment.
A very useful measure of environmental costs relative to economic benefits is the ratio of inundated hectares per megawatt (ha/MW) of electricity; it varies by four orders of magnitude for large power projects. The global average for all large hydroelectric dams constructed to date is about 60 ha/MW; it would be environmentally highly desirable for this average to be much reduced in future hydro projects.
Bio-waste to Energy
Biomass has huge potential in an agrarian economy likeIndia. Generation costs for biomass are similar to those of wind. Like small hydropower, biomass remains largely underdeveloped.
Types of Biomass energy
Wood: Wood is the conventional biomass energy used in the home – though it can be used for much larger buildings or even communities. Woody biomass production comprises forestry products, waste wood, cardboard, waste pellets and straw. Used on its own or in conjunction with fossil fuels it is possible for woody biomass fuel to reduce carbon dioxide emisssions, whilst in some instances can also reduce waste treatment costs.
Biogas: Sewage or manure is used to generate biogas. After feeding slurry into a digester, conversion can take from 10days to several weeks.
Landfill gas: Landfill sites produce a 50:50 mix of carbon dioxide and methane as organic materials decompose. Sites which hold less organic material produce less gas.
Fermentation: Bioethanol and Biodiesel are forms of fermented biomass. To produce bioethanol sugars are converted into ethanol. Bioethanol can be mixed with petrol or used directly if an adapted engine is used. The most efficient sources are sugar cane and beet, though potatoes, corn, wheat and barley can also be used. Forestry waste, energy crops and waste paper are all in the research phase to produce bioethanol. Vegetable oils, animal fats or recycled cooking oil can be made into biodiesel. The refining process does have a carbon cost, but typical carbon dioxide emissions are still reduced, as compared to fossil fuels, by 60%.
ForIndia, biomass has always been an important energy source. Although the energy scenario inIndiatoday indicates a growing dependence on the conventional forms of energy, about 32 per cent of the total primary energy use in the country is still derived from biomass and more than 70 per cent of the country’s population depends upon it for its energy needs.Indiaproduces a huge quantity of biomass material in its agricultural, agro-industrial and forestry operations.
Biomass has two unique characteristics. First, biomass plants require large quantities of fuel input for operations (biomass feedstock), which requires a well-developed supply chain. This disadvantage is also strength, because biomass is the only renewable energy technology that can serve as a reliable alternative to diesel. However, the presence of multiple middlemen, difficulties in administering and enforcing agricultural contracts and the development of wastelands have led to underdeveloped fuel supply chains.
Second, the sector suffers from lack of reliable resource assessment. The development of the biomass industry has been limited to only a few parts. Significant potential exists in economically underdeveloped states for developing biomass. Developing biomass in such states is a win-win strategy, as it can both reduce the electricity shortage and provide farmers with reliable additional sources of income.
According to the MNRE,Indiahas nearly 700 million tons a year of biomass agri-residues, of which about a fifth can be used for electricity generation. (The rest goes to alternative usages, including household and small business heating, animal fodder, and packaging.) This biomass could produce about 17GW of power. The MNRE estimates that another 34GW of power could be produced from wood and energy plantations on wasteland. In addition,Indiahas 61GW of additional capacity of bioenergy, which includes agri-residues and biomass, from plantations.
Table 3. Future Potential of Power Generation from Biomass in India for 3 scenarios
According to EAI, the future of biomass industry is just phenomenal with an estimated potential of 34 GW. A more aggressive estimation will result in the biomass potential being close to 75 GW. The major contributors to this massive number (34 GW) are agro residues (54%), followed by a distant second – the livestock wastes (27%) and urban wastes (10%). Realistic projection estimates the market size to be nearly 42 GW by the year 2020.
IEA estimates are very optimistic. Wastelands statistics indicated that about 55.3 million ha, which account for 16.8% of the total geographical area (328.7 million ha) could be categorised as wasteland inIndiain 2003. About 20 million hectares of these wastelands are currently in use for agriculture, but the yields are low. About 34% is land with or without scrub. Another 20% is degraded forest, and 10% is unsuited for cropping (barren rock, snow cover, glaciers etc.). The current assumption is that 20 million ha of the wastelands (36%) are accessible and could yield around 5 tonnes of additional woody biomass per hectare per year if the productivity were restored. With an average lower heating value of 17 MJ per kilogram, this corresponds to 80 Mtoe (100 Mt) of energy, which can be converted in biomass power plants with an efficiency of around 30%. Assuming a load factor of 60%, this biomass can sustain 25 GW biomass power generation capacity. Residual biomass from agriculture and industry is another energy source. Sugar production residues represent the single most important category. With the establishment of new sugar mills and the modernization of existing ones, the technically feasible potential for bagasse cogeneration is estimated to be around 5 GW. Another 39 GW (30% efficiency, 60% load factor) can be obtained from other agricultural and plantation residues, based on a potential for agricultural residues of 145 Mt. The principal total biomass potential inIndiais, therefore, estimated to be around 65 GW to 70 GW.
India and Pakistan, both being among the top 5 producers of sugar cane, have high potential for Bagasse based power generation plants. A ton of sugar cane can produce upto 100 kWh of electricity. Bangladeshbeing a densely populated country has to depend of energy from Urban wastes.
Carbon Capture and Storage
Rapid growth in annual CO2 emissions is likely: in India, the nine planned ultramega power plants alone could add some 257 Mt CO2 to annual emissions. The main potential CO2 storage sites in India are located in the saline aquifers and oil and gas fields around the margins of the peninsula, especially offshore, but also onshore in the states of Gujarat and Rajasthan. There is also thought to be considerable saline aquifer CO2 storage potential in NE India, but this is distant from the main emission sources. CO2 sources in the centre of the peninsula appear to be poorly placed with respect to potential CO2 storage sites. There is estimated to be about 5Gt CO2 storage potential in India’s major coalfields and oil and gas fields. It is important that India’s saline aquifer storage capacity is quantified, as this will determine whether there is significant potential for the application of CCS. Pakistan will have significant CO2 storage potential (c. 1.6 Gt CO2) in its gas fields when they become depleted. It is also thought to have good potential for saline aquifer CO2 storage in the Lower Indus and Potwar Basins and there is a good match between the locations of sources and potential storage sites. Bangladesh’s annual CO2 emissions from large point sources are approximately 17 Mt CO2. It is thought to have significant CO2 storage potential in its gas fields (c. 1.1 Gt CO2) which will become available gradually as the individual fields are depleted. Bangladesh also probably has significant CO2 storage potential in saline aquifers in most of the eastern half of the country, both onshore and offshore.
|Capture Concept||Coal||Natural Gas|
|Post-combustion Capture||Separation of CO2 from boiler flue gas||Separation of CO2 from CCGT flue gas|
|Oxy-combustion Capture||Oxygen-fired boiler, with CO2 recycle loop||(Oxygen-fired CCGT)|
|Pre-combustion Capture||IGCC – gasify coal and shift syngas to H2-fuel||Reformation of natural gas and shift to H2-fuel|
Table 4. CO2 Capture Concepts
There are three leading CO2 Capture concepts as shown on Table 4, each of which could be applied to both coal-fired and gas-fired plant. No capture concept is yet commercially mature. CCS can reduce CO2 emissions from power plants (i.e., 40% of the emissions from the energy sector) by more than 85%, and power plant efficiency by about 8-12 percentage points. Without CCS, overall costs to halve CO2 emissions levels by 2050 increase by 70%. For coal-fired plant expected area for the Capture Plant and auxiliaries is approx 1-2 Ha per 500 MW unit.
Fig. 2 CO2 Capture Technologies – Comparison
Estimates of geological storage potential in India are in the range of 500 to 1000 Gt CO2, including onshore and offshore deep saline formations (300-400 Gt), basalt formation traps (200-400 Gt), unmineable coal seams (5 Gt), and depleted oil and gas reservoirs (5-10 Gt). A recent assessment of coal-mining operations in India gives a theoretical CO2 storage potential in deep coal seams of 345 Mt. However, none of the fields has the ability to store more than 100 Mt. CO2 storage in deep coal seams is still in the demonstration phase.
Analysis of oil and gas fields around Indiashows that relatively few fields have the potential to store the lifetime emissions from even a medium-sized coal-fired power plant. However, recently discovered offshore fields could provide opportunities in the future. The potential for CO2-EOR needs to be further analysed on a basin-by-basin basis. It is not possible to develop a suitable estimate today.
DeccanVolcanicProvince, a basalt rock region in the northwest of India, is one of the largest potential areas for CO2 storage. The total area is 500000 km2 with a total volume of 550000 km3 with up to 20 different flow units. It reaches 2 000 m below ground on the western flank. Storage capacity is around 300 Gt CO2. Thick sedimentary rocks (up to 4000 m) exist below the basalt trap. In order to model the long-term fate of CO2 injection in such mineral systems, geochemical and geo-mechanical modeling of interaction between fluids and rocks is required.
There is considerable potential for CO2 storage in deep saline aquifers, particularly at the coast and on the margins of the Indian peninsula, and inGujarat and Rajasthan. Aquifer storage potential has also been demonstrated aroundAssam, although these reservoirs are 750-1000 km from the nearest large point sources. The Indo-Gangetic area is an important potential storage site. The Ganga Eocene-Miocene Murree-Siwalik formations have good storage potential as deep saline formations, but high salinity and depth preclude economic use. TheGanga area has a basin area of 186 000 km2, with a large thickness of caprock composed of low permeability clay and siltstone. The proximity of sources to the potential storage site makes it a good candidate for a pilot project.
Figure 3 shows the geographical relationship between the major existing and planned sources of CO2. It may be seen that sources in the NW of peninsulaIndia and along the SE coast have good nearby storage potential, whereas those in SE, Central and, in this analysis northernIndia, do not. The good potential in NE India, inAssam and the Assam-Arakan Fold Belt, appears to be stranded relative to most of the major sources. inIndia and areas containing the sedimentary basins considered on the basis of this first-pass assessment to have good, fair and limited storage potential. The basins rated as good are the hydrocarbon-bearing basins, so they also contain all the potential in oil and gas fields.
The calculations in the IEAGHG CO2 sources inventory indicate that each individual UMPP may have annual emissions of between 28 and 29 Mt CO2. If they have a 35 year lifetime they are each likely to emit approximately 1 Gt CO2, and send significantly more CO2 for storage if fitted for CO2 capture. We estimate that the total storage capacity of India’s major coal fields and oil and gas fields is <5 Gt CO2, and none of the fields have the capacity to store the lifetime emissions of a single UMPP. As there is insufficient storage capacity in oil and gas fields and coal fields to make significant inroads into India’s current and future emissions, it is clear that there is a need to quantify the realistic saline aquifer CO2 storage capacity of India’s sedimentary basins. This would require the use of oil and gas exploration data and might best be approached on a basin-by-basin basis, starting with the most strategically placed basins, as it is a time-consuming and resource-intensive process. If the saline aquifers are found wanting, export of CO2 by ship, perhaps to the Middle East, would be the only remaining alternative for CCS inIndia, unless the basalt storage concept can be advanced into a mature technological option.
Fig 3. Geographical relationship between existing and planned CO2 sources and sedimentary basins in India