Pump element is overlooked

Mitch Holmes of Grundfos' Water Group argues the environmental impact of the enhanced capital allowance initiative is compromised by a failure to look into hydraulic efficiency

Laser welding on the CR impeller can improve efficiency by up to 4% over spot welding

Laser welding on the CR impeller can improve efficiency by up to 4% over spot welding

Straight blades: loss of eficiency via eddy currents within impeller design
Curved blades: impeller design with minimum efficiency losses
There is still a large amount of confusion over the whole area of enhanced capital allowance (ECA) and the consequences of having just motors, without pumps or pumping systems on the energy technology product list. Although plenty has been written on the subject, very little forms a cohesive picture which can be readily understood.

International rescue
At the Earth Summit in Rio, 1992, in excess of 150 countries agreed to limit man-made emissions of green house gasses (GHG). This decision formed part of the global ambition to stop the atmosphere from overheating. By the 1997 Kyoto Summit, it was agreed that developed countries would aim to reduce GHG emissions by a further 5.2% between 2008-2012. The EU committed itself to an 8% reduction in emissions, with the UK contribution being agreed at 12%.

Following this, a government initiative was introduced to drive down GHG emissions generated from electricity production. The Climate Change Levy (CCL) has been levied on business users to encourage the reduction of energy consumption. The CCL is applied at different rates, depending on the energy content of the different sources. For instance:

  • Liquid petroleum gas (LPG) - 0.07 p/kW/h,
  • gas, coal, lignite and coke - 0.15 p/kW/h,
  • electricity - 0.43 p/kW/h.

Electricity attracts a higher tax rate as a considerable proportion of fossil fuel energy is lost in combustion, transmission and distribution. Petrol, diesel, road fuel gases, mineral oils, waste and other renewable energy sources are not taxable commodities under this scheme.

To encourage companies to switch to more efficient and environmentally friendly options, an incentive was introduced in the 2001 budget. This took the form of a claimable allowance for businesses that invest in energy efficient technologies including boilers, refrigeration, combined heat and power, lighting, pipework insulation, thermal screens and motors and drives.

The ECA helps to lessen the impact of the CCL's affect on fuel bills by allowing companies to set 100% of the cost of approved energy saving equipment against corporation tax in the year of acquisition. Instead of writing down capital equipment over a period of years, the ECA provides a cash-flow advantage which helps to offset the capital investment cost.

How to qualify
The energy technologies list includes both variable speed and fixed speed high efficiency motors with efficiencies typically between 83%-95%. When these motors are fitted onto pumps it is possible to claim the ECA on the percentage of the purchase
price of the motor.

Additionally companies can also claim ECA on costs directly associated with the provision of the product, i.e. transportation, installation, modifications to existing plant and machinery and commissioning. Professional fees also qualify if they are directly attributable to the acquisition and installation. Finally, the allowance can be claimed where costs have been incurred as a result of altering an existing building, incidental to the installation of qualifying plant and machinery.

Defeating the object
With motor efficiency rising as high as 95% there is little scope for improvement in this area, however, considering 20% of the world's electricity bill is spent on powering pumps, it is vital the bigger picture is taken into account. It is possible to claim ECA on a high efficiency motor, irrespective of the efficiency of the pump it is attached to. It is not unusual to have pumps with an efficiency point as low as 40%. Therefore, consider the possible impact on electricity consumption if the same benefits were applied to hydraulic efficiency.

Grundfos has identified a number of ways that hydraulic efficiency could be improved. Enhanced impeller design, for example, can result in a more streamlined flow in the impeller and reduced eddy flow and friction loss. Since such small margins of error are involved, Grundfos has developed highly specialised laser-welding technology, which operates at, so far, incomparable levels of accuracy. With this technology, the impeller design and construction are fine-tuned to the point of theoretical perfection. This alone can contribute to increasing efficiency by up to 4%.

Another method is to minimise internal leakages caused by the pressure differentials within the pump. Tests and calculations have shown that an impeller seal clearance gap of 0.1mm, between the impeller and the chamber in a pump, results in a 5% drop in efficiency. To reduce internal leakage to a minimum, it is now possible to use a floating seal ring between chambers, providing a virtually perfect seal. If a 10% increase in pump efficiency is achieved smaller motors can often be used to power the pump at any given duty point. A smaller motor represents a reduction in both capital investment and running costs.

With these technological advances now available, it is possible to achieve hydraulic efficiencies in excess of 80%. When this factor is combined with the accessibility of high efficiency motors, the result could be a major contributor in reducing GHG emissions and help the UK move towards achieving its environmental goals.

Every year 900,000 multistage pumps are installed around the world, if they were all as efficient as the Grundfos CR range, the electricity saving in the first year would be 1.45tWh. Put into context, this equates to 590,000 tonnes of coal. If this was then used to generate electricity, emissions would be in the region of 1.43M tonnes of carbon.

The way forward
When purchasing white appliances, there are energy rating labels giving an easily identifiable guide to the efficiency of the overall unit. In the case of a washing machine this would include the motor and washing mechanics as one. Could this be the way forward within the pump industry? Perhaps classifying pumps as one complete unit with a combined efficiency, grading and labelling would help to alleviate some of the confusion that currently exists.

Building on this, the combined pump unit should be included on the energy technologies product list, ensuring the pump industries continued contribution to the environment and Kyoto Protocol.

There are many financial, ethical, environmental and practical reasons to look closely at this topic. The environmental abuse of the last century was mainly a result of ignorance. However, the advances being made by manufacturers like Grundfos Pumps will prove valuable when specifiers design products that can make a real difference.


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