Storage Bulletin - July 2011
Getting more from your store
At this time of year, the focus in potato stores should be on preparation for the new season. It's probably already too late to make any major changes - such as an insulation upgrade - if these haven't already been organised but there's no harm in making plans for work to be done in 2012, especially as it is a lot easier to see what needs doing when the store is empty.
But there's still time for some simple tasks to be done, such as fitting electricity meters to individual stores. With the relentless rise in energy costs, can you afford to be running your store if you are completely in the dark when it comes to knowing how much it costs you?
The experts in energy management say that you are virtually guaranteed to save 10% on your bills just by raising your own awareness of energy use. On a store using 35 kWh/tonne/year that's around 35p for every tonne stored, so a £300 meter installation for a 1000 tonne store can pay for itself inside a year.
And why would you not want to know what it's costing you? Potato Council-funded work by Sutton Bridge CSR and Farm Energy has highlighted up to a three fold difference in store running costs across stores supplying the same sector. There are plenty of areas where potential improvements in efficiency can be gained. Here's a few to think about:
Does your store suffer from detached or delaminated insulation? If so, the chances are that water from condensation within the structure has caused it and once water starts to penetrate most forms of insulation, the thermal protection it offers drops off rapidly. A thermal image survey can help to identify any areas of deficiency. See www.potatocouncil.9web.co.uk/energy
Also known as frequency drives or variable speed drives, they work like a dimmer switch on fans or pumps, allowing the speed to be adjusted, depending on the store's needs. For CIPC application in bulk stores, they are now pretty much a 'must have' as there is plenty of research and commercial experience now to show that usage rates can be reduced through their use to circulate the fog during and immediately after application. Take a look at www.potatocouncil.9web.co.uk/cipc for more information.
Inverters can also offer reductions in energy bills as reducing fan speeds to as little as 80% of full speed can provide as much as a 50% energy saving. Recent new store installations have been featuring ever-larger fans (up to 100 cfm/t or 0.05 m3/s/t) fitted into large ducts to provide a major step-up in drying capacity but also the capability to lower airflows using inverters to more traditional levels for the holding period. Talk to your systems supplier if you wish to investigate the options for retro-fitting to your store.
Work is now focusing on quantifying air leakage from stores. There is significant air transfer taking place in most stores even when they are tightly sealed, simply due to factors such as wind pressure and the presence of doors and louvres. Air leakage, in whatever form, results in a change to the controlled condition within the store and this usually then requires use of energy to restore the conditions to those required for optimal storage of the crop. Simple measures such as brush seals around doors and checking louvre seals can help significantly to cut down on air leakage. As a start, try asking a colleague to turn the lights out when you're in the empty store with the doors closed - it can be quite revealing!
Recent surveillance, as part of the PCL project, has been highlighting a wide range of efficiencies within the refrigeration equipment on stores. This is down to a range of factors including the design of the fridge system, the evaporating temperature and the quality of upkeep. A loss of gas from a fridge system can quickly lower its efficiency resulting in extended run times and poor pull-down capability. So it is well worthwhile at this time of year to have refrigeration systems serviced and many store managers will also be asking their fridge engineer for additional support to ensure their business is complying with the F gas regulations (see http://www.fgas.org/).
Sutton Bridge CSR is running a one day beginners' store management course for newcomers to the industry on Thursday 25th August. Contact Kate Balloch on 01406 359418 for more details and a booking form.
Other forthcoming events:
11 August Potatoes in Practice, James Hutton Institute, Dundee
1 September East of England Potato Day, Tuddenham, Suffolk
13 September North of England Potato Day, Colton, York
23/24 November British Potato 2011, Harrogate
Potato Council Storage Advice Line — call free on 0800 02 82 111