6 results for Information paper, Energy and Water
Solar pumping can help offset the cost of traditional irrigation fuels. The more often a pump is run, the greater the opportunity for savings from solar. Solar pumps are reliant exclusively on the sun to provide power and therefore operate only during daylight hours unless coupled with battery/storage systems. Solar pumps may be a good option for lower water volume and daytime irrigation systems. As yet, affordable solar technology is unable to supply sufficient power to pump enough water for large-scale flood irrigation.
Provided there is easy access to the electricity network, converting from diesel-driven to electric pumps will improve pumping efficiency and reduce costs. Typical efficiencies for electrical centrifugal pumps range between 70 and 80 per cent, whereas diesel pumps have an efficiency of just 30 to 40 per cent. Other advantages of electric pumps include lower maintenance requirements, less environmental impact and more easily implemented pump controls (such as variable speed drives).
Pump efficiency deteriorates over time, leading to energy wastage. Efficiency losses of between five and 15 per cent can occur after 10 years of operation. When pumps are maintained to restore efficiency close to its original point, significant energy savings can be achieved. Typically, a pump overhaul includes: replacement of wear rings, seals, bearings and if worn, the impeller; cleaning of internals; blast cleaning of externals; and applying new epoxy coating.
Irrigation pumps are typically over-specified at the design stage, resulting in significantly higher power consumption and operating costs. A pump is generally oversized when it is not operated at or within 20 percent of its best efficiency point (BEP), although it is normally considered acceptable if the duty point falls within 50 and 110 percent of the BEP flow rate. By replacing oversized pumps with smaller ones, energy and maintenance savings can be achieved due to lower power consumption requirements and less wear and tear.
The installation of variable speed drives (VSDs) on pumps can be an effective energy-saving measure. Lowering the speed of a motor by just 20 percent can produce an energy saving of up to 50 percent. Variable speed drives can be installed on all pumps, including those associated with HVAC systems. The VSD needs to be connected to a control signal and may also require installation of measurement devices or controllers, which typically are included in costing. The financial viability of installing a VSD depends on the motor application and operating hours. VSDs tend to be most economical when used on large pumps.
Solar hot water works well in buildings that have significant roof area on which to locate solar collectors. A solar hot water system should provide between 40 and 60 percent of your hot water needs. Solar hot water systems come with electric or gas boosters to provide the remainder of your hot water needs. Solar hot water systems use solar collectors – either solar panels or evacuated tubes – which absorb energy from the sun to heat water. The heated water is then stored in an insulated tank until you need it. Typical applications are in dairies, piggeries and worker accommodation.