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Essay on Energy and Lift Irrigation
Essay Contents:
- Essay on the Introduction to Energy and Lift Irrigation
- Essay on the Solar Energy
- Essay on the Wind Energy
- Essay on Biogas Engines
- Essay on Biomass Gasifiers
- Essay on Hydraulic Rams
- Essay on Water Mills
- Essay on the Conclusion to Energy and Lift Irrigation
1. Essay on the Introduction to Energy and Lift Irrigation:
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India is essentially an agricultural country with 70 per cent of its population living in rural villages and 70 per cent of its gross domestic product emanating from the rural agricultural sector. There are nearly 350,000 villages with a population less than 500. These villages are remotely scattered and widely dispersed from the industrial belt.
Their energy needs are meagre. On the average, these villages need 150 kWh of energy per day for energizing irrigation pumps, for lighting, for cooking, etc. Drip irrigation of corn, wheat, cotton, millets requires about 25 m3 of water per hectare-day whereas food irrigation of rice, sugarcane, etc., would require 50 to 60 m3 of water per hectare-day.
In addition, water requirement for livestock is 40 to 50 liters per head-day. The lifting height of water varies from a few meters to 30m. The equivalent energy requirement would be 135 w per hectare for surface water and 400 w per hectare for ground water.
As the load factor is very low and because these villages are widely dispersed, it is most uneconomical to electrify them. Only 11 per cent of these villages have been electrified so far. It is equally difficult to reach them with fossil fuels.
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Consequently, they have to find an energy source which is locally available. If locally available energy sources could be converted to mechanical energy to drive irrigation pumps, the rural scene in India would change appreciably, and it would help to boost agricultural production which is vitally important in view of growing population.
Out of the total 143 million hectares of land under cultivation in the country, hardly 43 million hectares — a barely 25 per cent of the land under cultivation is irrigated. Out of this irrigated area, 23 million hectares are served by tube- wells, ponds or such similar minor irrigation schemes. There are about 2-3 millions of open wells in our country which are not yet motorized.
The non-conventional and renewable energy sources have assumed considerable importance and urgency after oil crisis.
Various modes of irrigation schemes based on non-conventional energy sources have been discussed in the following paragraphs which are immediately available:
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2. Essay on Solar Energy:
India is bestowed with plentiful of sunshine for 250-300 days per year. In Industrial India, Mumbai south and central India, the annual average daily incidence of solar energy is about 4.5 kWh/m2 with the maximum exceeding even 7.0 kWh/m2. Therefore solar energy offers a viable solution if it can be converted to mechanical energy to drive irrigation pumps.
Requirements of small-scale irrigation and domestic plants are well within the reach of solar energy pumps. A pair of bullocks working continuously can raise one m3 of water per hour from a depth of 30 m. The equivalent of this work can be done by an electric motor pump rated at 0.8 kW for which a solar pump can be designed.
i. Solar Water Pumps:
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Organic vapour Rankine Cycle systems with rotary machines or screw expender or reciprocating engine or spiral expanders can be used to drive water pumps, Sofretes of France have developed simple, rugged, reliable solar water pumps which work on low temperature thermodynamic cycle.
In consists of solar flat plate collectors with methyl chloride as heating fluid, a heat exchanger to transfer heat to working fluid (Butane or Freon), expansion motor working at 150/200 rpm and water pump with hydraulic transmission. A collector area of 60 m2 for example, can lift 10 m2/hr of water over a height of 12 m. A collector surface area of 1500 m3 can be used to lift 150 m3/hr of Water over a height of 40m to irrigate 20 to 30 hectare of land.
The National Physical Laboratory, New Delhi has developed Abhimanyu Solar Pump of 1 kW rating using R114. An area of 10 m2 is used to operate the pump for four hours a day. When not pumping, it can be used to drive a generator or thresher or a lathe. The total cost of the components (condenser, boiler expansion motor, storage tank, collector assembly and pump) is Rs. 12,500 and if we include the development charges, overheads and labour for assembly, the total cost will be of the order of Rs. 37,000.
ii. Solar Photo Voltaic Water Pumping System:
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In a solar photovoltaic water pumping system, the sun light is directly converted into electricity and this energy is used to run an electric motor, pumpset.
The Central Electronics Ltd., Sahibabad (UP) has developed the following system:
The solar array consists of 5 rows of 4 modules each. Each module consists of 36 cells each 76 mm diameter connected in series to generate about 16 peak watts of power at incident radiation of 100 mW/cm2 at 28°C. Four such modules are connected in series and five such series connected module chains are kept in parallel. The complete array is mounted on an angle iron structure which can be oriented to face the sun.
The system can be provided with storage batteries and power conditioning equipment. The total cost of the system including solar photovoltaic array, on off switch, motor pump set, accessories including suction and delivery valves and piping is about Rs. 40,000 which is highly subsidised and installed at a cost of Rs. 5000 only for a small or marginal farmer.
3. Essay on Wind Energy:
The wind is a free, clean, inexhaustible energy source. Until this century, it has served mankind well by sailing ships, driving windmills to grind grains and pump water and even generating small amounts of electricity. The support for wind power is increasing again due to doubtful position of fossil fuels and safety of nuclear power. Following a better understanding of the aerodynamics of rotating aero lifts, there is a revival of interest in harvesting of wind energy.
For a wind speed of 10m/s, the effective power obtained is 0.25kW per m2 of swept area. As wind velocity of 10m/s occurs only for a few hours a year, the mean annual available power is very less. Depending upon local wind conditions, the annual available energy per m2 of swept surface may vary between 100 kWh for calm areas and 500 kWh for very windy areas. At least 25 per cent of our land especially coastal areas are situated in reasonably windy areas. The scope for small water pumping wind mill is quite significant.
The wind energy data for Veraval situated on the windy west coast of India is as follows:
Windmill WP-2 developed at National Aeronautical Laboratory. Bangalore can pump 2.9m3/hr against a head of 10m in wind speed of 3.5m/s. A sail wind developed at the above laboratory uses six triangular canvas sails on a rotor of 7m diameter and pumps 5.4m3/hr against a head of 10m in wind speed of 3.5m/s.
The specification of a propeller type wind mill pump set which has been standardised for installation in India is:
Total cost of machine including transportation and erection is Rs. 11750 and a similar expenditure is to be incurred on well/boring and construction of storage tank. The Government provides a subsidy of Rs. 7500.
The current philosophy is to use the same wind rotor for different wind regimes with modified down-stream components and higher ratings. Given that the power contained in the wind goes as cube of the wind velocity, a two-fold increase in the wind velocity implies an eight fold increase in the power contained.
The windmills installed so far are not only of small sizes (about 5m diameter). But these also require high maintenance support. Research efforts are now needed so as to reduce the maintenance expenditure of windmills to minimum, i.e., to occasional oiling and changing the pump washer. Somewhat larger windmills are required to be developed than presently available. It is also needed to develop cheaper and simpler S-rotors which can cut in at low wind speeds of 1.5 – 2m/s to cover wider areas of regions.
4. Essay on Biogas Engines:
The technology for conversion of animal wastes into biogas via anaerobic digestion is well established, and quite a large number of biogas plants (about one lakhs) are already in operation. Our country has a potential of producing about 22,000 million cubic meters of biogas. The Gobar gas plants are mainly developed by Khadi and Village Industries Commission, New Delhi and in every state; Khadi & Village Industries Boards look after the erection work of the Gobar Gas plants. The Ministry of Agriculture is also helping for the construction of Gobar Gas plants.
In consists of a well-made of bricks putting 2 to 3 steel rods to make it more strong and plastered. The top of the well is covered by 1.6mm thick steel sheet floating dome. The design of the above plant is available from Khadi & village Industries Commission. The size of the plant will depend upon the gas requirement by the engine.
The requirement of Indian farmers for engine varies from 3.7kW to 7.5kW in vertical high speed and vertical slow speed types all over the country. Normally, the engine runs on an average for 5 hours per day. Biogas produced by a digester that is functioning well is approximately 65 per cent CH4 and has a heating value of approximately 21000 kJ/m3.
The biogas engines for pumpsets produced in India are essentially diesel engines where air intake is connected to biogas supply. The diesel is required for starting the engine and about 20 per cent diesel and 80 per cent biogas are mixed automatically to produce power for running the pumpset. The biogas consumption is about 0.46m2/kWh which can be obtained from 13.5kg of cattle dung. i.e., daily produce of one cattle.
The price of a typical 3.7 kW, 1500 rpm biogas engine with centrifugal pump of 100 × 100mm including accessories and trolley is about Rs. 6500. It is subsidised by the Government and can be financed by the State Agro Industries, Land Development Banks and all nationalised banks. The cost of a typical gobar gas plant of 85m3 capacity is about Rs. one lakh.
The human wastes can also be used for production of biogas. Community latrines can be planned in the villages for collection of night soil for feeding to biogas plants. Wastes of 200 persons can be used to produce about 5m3 of gas per day to extract 12 kWh of equivalent energy by running a biogas engine.
5. Essay on Biomass Gasifiers:
The estimated production of agricultural residues in India is 200 million tonnes per year compared to about 130 million tonnes of wood. In equivalent energy content this amount to about 54 million tonnes of coal which is 50 per cent of our annual coal production of 108 million tonnes in the country. Of this total residue, about 40 million tonnes is used in commercial sector; the remaining is burnt in fields, used for fodder roofing material, for composting and other needs. It appears that a substantial amount of residue is available as fuel.
The direct burning of biomass in domestic hearths is grossly inefficient, giving only 8 to 11 per cent useful energy. Biomass residues because of their low bulk density and extensive smoke formation are the most inconvenient and pollutant fuel. It is therefore, desirable to use biomass more efficiently.
Gasifier is essentially a thermochemical reactor in which the biomass undergoes partial oxidation and producer gas is obtained. The agricultural and forest residues can first be derived in solar driers to restrict the moisture content below 15 per cent.
These are pressed in compaction briquetting machines to prepare feed size of 50-75mm for the gasifier. The biomass briquettes are ignited in the gasifier and air flow is controlled to ensure partial combustion. The producer gas is reduced to CO and H2 by carbon present in the burnt lower layers. The main constituents of fuel gas are CO, H2 and CH4.
The gas produced by the gasifier is hot and contains tar, vapours and soot particles. To make it engine worthy, it is cooled to near ambient conditions and cleaned to remove tar and dust by cross-current water scrubbers. Air and clean gas are supplied to the engine in pre-specified proportions. On an average 1 kg of biomass produces 2.5 nm3 of fuel gas and 1kWh of shaft energy to drive the irrigation pump.
The diesel engine utilizes the gas as a supplementary fuel operating on dual-fuel mode. The solar driers, briquetting machines and gasifiers are now made in India. The total cost of a biomass gasifier with gas cooler and scrubber of 15m3/hr capacity, 5kW/1500 rpm diesel engine and 100 × 100 mm centrifugal pump with necessary controls and accessories is about Rs. 37500.
6. Essay on Hydraulic Rams:
The utilization of hydro-energy to operate agricultural and industrial devices is one of the oldest and widespread techniques of human achievements. Hydraulic rams manufactured by John Blake Ltd., UK was installed at Taj Mahal, Agra in 1900 for raising water from the Yamuna at the rate of 2700m3 per day It is still working satisfactorily with very low maintenance cost. Blake Hydrams installed at Risalpur (Pakistan) in 1925 raises 4860 m3 of water per day to a vertical height of 20m and to a horizontal distance of 1600 m. Hydraulic rams are also used in the Alpine areas of the world for the water supply of remote farms for irrigation and drinking water purposes.
Hydraulic ram is a contrivance to raise a part of large amount of water available at some height, to a greater height. This is employed when some natural source of water like a spring or a stream is available at some altitude, e.g., in a hilly region. Work done by a large quantity of water in falling through a small height is used to raise a small part of it to a greater height. Action of water hammer makes it feasible. No external power is therefore, required to work this machine.
Other attractions are negligible amount of maintenance and supervision costs, continuous operation, high efficiency, quite operation and possibility of automatic adjustment of water supply. The lift able volume of water diminishes asymptotically with lifting height. In case of medium lifting heights, the hydraulic ram operates with efficiency absolutely comparable to a piston pump of the same performance.
As the hydraulic ram does not need a driving unit, it is to be considered as ideal for hilly areas, where the supply in fossil energy carries or electricity is problematic. The hydraulic ram operates with water streams of 1 to 40m3/s and fall heads of 1.5 to 30 m and with lifting heights up to 300 m, which means efficiency in the range of about 50 per cent to 2 per cent at the minimum. There is a number of different types which can be distinguished by the operation of the oscillating valves.
Hydraulic ram is a simple and rugged device for operating irrigation schemes and deserves R & D inputs for its performance improvement and adoption to irrigation.
7. Essay on Water Mills:
Poncelet water wheel or a Darrieus Turbine Rotor can be submerged in a river, water stream or canal to tap current energy from water speeds as low as 1m/s. The mechanical energy thus obtained is used for driving irrigation pumps. The blends of water mills can be made from fabricated steel, ferro-cement, glass fibre or timber depending upon the availability of local materials and skills. The power output depends upon the swept area and cube of water velocity. A vertical axis rotor of 3.75m2 swept area runs at 13.5 rpm in 1m/s current velocity.
From this, a belt drives a pulley on an intermediate shaft which rotates at about 110rpm and from this shaft another belt drives a centrifugal pump mounted on the pontoon at approximately 950rpm. A 50 mm floating pipeline is connected to the pump to lift water from the river. In a current speed of 1.18 m/s, it lifts 3.51/s of water against a vertical height of 5 m and horizontal distance of 25 m and can be used to irrigate a one or two hectare riverside horticultural plot.
Although the machine will work at lower speeds, it is unlikely to be economical proposition in a current speed below 1m/s. The energy available in river current increases with cube of water velocity; a two-fold increase in water velocity has an energy flux eight times greater.
8. Essay on Conclusion to Energy and Irrigation:
The bulk of future energy needs of India are not going to be met by fossil fuels and hydroelectric plants alone and have to be met from a variety of sources. Similarly, geographical conditions dictate the exploitation of locally available energy sources for lift irrigation utilising the appropriate intermediate technologies to convert them to mechanical energy for driving irrigation pumps.
Some of the sources and technologies immediately available for this purpose have been discussed. An all-out effort is needed to upgrade the performance of these devices and for adopting them to irrigation schemes. Special attention must be paid to the development and adoption of hydraulic rams and water mills for irrigation schemes which have relatively lacked behind.