Minimising laundry’s carbon footprint – how much further can we go?

Over the past several years, LCN has issued advice on nearly every area of energy consumption in laundering and identified a host of areas where, with simple management actions, it has been possible to make significant reductions in energy usage and reduce appreciably the laundry sector’s carbon footprint. Large laundries serving the UK hospitality sector have led the way, and the UK Textile Services Association has reported many have achieved improvement of 25% since 2008. The market leaders have substantially exceeded this (both for hospitality and healthcare), so the laggards still have a way to go. This month we review each of the areas where good management can make a real difference and point the way even further ahead. There is yet more to be gained for most sites, with some ‘low hanging fruit’ still available to many!

Textile purchase

Success in textile rental depends to a large extent on skilful purchase of hotel and restaurant linen stocks and the success of 70:30 cotton-rich has been instrumental in reducing washing and drying energy, whilst maintaining quality. The ability to reduce moisture retention because of the polyester content has led to higher ironer speeds and ever-increasing productivity. Even though this has had its own problems (because there are limitations on ironer bed temperatures with polyester) the net effect has been significantly reduced drying energy achieved at greater productivity.

Cotton rich can look and feel as good as 100% cotton, provided good quality fibres are used, spun to give the correct texture and handle. Advanced detergent systems have enabled superb whiteness retention and excellent stain removal (despite the oleophilic tendency of the polyester fibres to cling onto oily, fatty staining and soiling). This has been obtained by shrewd use of non-ionic surfactants and other emulsifiers to break the bond between the fatty staining and the yams. The product has become firmly established in the European textile rental sector and those who are benefiting would probably be most reluctant to go back to 100% cotton.

However, there is one more step to be taken by some. Wash cost is directly proportional to textile weight and although items made from cotton rich are generally no heavier than those made from 100% cotton, the cotton rich fabric is susceptible to thermal softening and distortion if ironed with too high a bed temperature. This can lead to permanent stretching in the machine direction (usually the width direction of a sheet) and ‘necking-in’ in the length of each sheet. The resulting distortion gives the appearance that every sheet has shrunk progressively in the length, although it is usually found that the total area of the sheet is unchanged. It is the shape which has changed; cotton rich fabric is not prone to excessive shrinkage. One ‘solution’ to this is to make every sheet 15 – 20% overlength in the first place, but this is the wrong solution, because it increases wash energy and drying energy by 15 – 20% and reduces washhouse productivity by 15 – 20%! The right answer is to adjust ironer bed temperatures to prevent the distortion and then maximise ironer productivity by following the advice given later in this article.

Electricity, the primary fuel of the future

Those planning the long-term future of their laundering business probably recognise the shorter life now envisaged for fossil fuels as the main way of generating heat energy for washing and drying. France probably leads Europe with its heavy strategic investment in nuclear power generation to offset its lack of domestic oil and natural gas. Other countries could follow this lead, or there could be development of liquid hydrogen as a fuel, which can be made from solar powered electrolysis of aqueous solutions. Looking further ahead, many researchers are still working on nuclear fusion, which in theory could liberate large amounts of energy with none of the disadvantages of nuclear fission (on which the present generation of nuclear power plants worldwide are based). 

This all means that the laundry industry in the short and medium term must look to low temperature washing as the permanent route to cleaning textiles, tiles, with processes which operate at 30-toe leading the way. Dryers may, in future, need to operate with electric heating elements, which will demand more efficient designs than the present ones (which give not much over 5o% in terms of thermal efficiency). It will also demand much more careful operation on the part of the launderer. The following paragraphs are written with these potential developments in mind. The recommendations can start to be implemented immediately, with benefits which are equally immediate, but the results will be even more beneficial long-term. They will also address the pressing problems of climate change head on and perhaps represent the response of the textile care sector.

Fate of the central boiler

There is a fast-approaching horizon for fossil fuel powered central boiler houses in laundries. In a recent issue of LCN, we predicted the demise of the central boiler-house and nothing has changed to vary this prediction. It has become more urgent to dispense with this, because the considerable capital and running costs that it represents must be reduced now for financial survival in the post Covid world.

Low temperature washing

All leading suppliers of laundry chemicals now offer low temperature processes which are designed to work as well as the high temperature ones which they replace. They use chemical combinations to pull the staining and soiling off the textiles, rather than relying on heat to swell the cotton fibres and yarns (which was formerly used to aid the release of contamination). Not surprisingly, the new chemistry may cost more than before, but the best low temperature processes not only give effective stain and soil removal they also achieve disinfection. The ability to deal with most pathogens (including Covid 19) would bring a welcome step improvement in the wash quality, not just in care homes and hotels, but also on cruise liners, military bases and the like.

Membrane pressing

Disciplined management control of the membrane press on every tunnel washer line is the key to minimising the enormous cost of drying energy in tumble drying and ironing. It is also the key to maximising productivity in drying and ironing. It is still up to fifteen times more expensive to remove moisture in the tumble dryer than it is to squeeze it out in the membrane press (or in the final spin in a washer extractor), despite the reduction in gas and oil prices during the Covid 19 pandemic. Even the greater thermal efficiency of the laundry ironer still makes it up to five times more expensive.

A properly tuned membrane press should give at least 30 seconds at full pressure, in order to deliver the correct moisture retention in the washed and rinsed textiles. This increases to 60 seconds for older presses which deliver less than 28 bar. This is so important that press manufacturers fit a clearly visible pressure gauge on a new press, the purpose of which is to enable the washhouse supervisor to check the time at pressure on a regular basis. This vital management step is fundamental to control of costs and productivity in tumble drying and ironing, but it is surprising how often it is neglected, even in the most shrewdly managed laundries.

Tumble drying and conditioning Policies

There are three keys to minimising energy costs in tumble drying:

a. If conditioning of sheets, pillowcases and table is reduced to the minimum necessary to open out the textiles, so that they are ready to be fed into the ironer, then the bulk of the drying is transferred from the dryer (thermal efficiency 35 55%) to the ironer (thermal efficiency So 95%). The benefits are immediate and substantial, but they do require the ironer to be properly maintained and tuned. Doing this also frees up vital tumbler minutes, enabling useful increases in towel drying capacity.

b. Setting the tumble drying time to deliver towels with just 2 3% moisture retention is exceptionally difficult, because optimum times vary with the initial moisture level and with the ambient temperature and humidity. Fitting automatic cycle terminators overcomes this problem and enables minimisation of drying energy and drying times, freeing up still more tumbler minutes.

c. Getting load weights spot on by use of weigh scales and by allowing for the moisture content in used towels completes the list of essential management actions for minimisation of drying costs.

Ironer tuning and high productivity Operation

Moving more of the drying from the tumble dryers to the ironers may require the ironers to be tuned. This means:

a. Setting the roll diameters to exactly match that of each of the curved beds the next time the rolls are re-clad, in order to maximise roll to bed contact.

b. Checking the vacuum across each roll (it should lie in the range 6o go Pascal) and rectifying any shortcoming.

c. Checking the ironer bed temperatures and rectifying any cold spots.

d. Adjusting the roll to roll stretch in line with the manufacturer's recommendations (or achieving about 5omm stretch in 10 turns of the roll in the absence of these).

A well trained laundry engineer will prove their worth in tackling the above list on a regular basis and lay the foundations for a really productive ironer section that mates up with the improvements achieved in tumble drying.

Day to day management of each ironer then calls for disciplined operation to maximise the bed coverage, which is sadly neglected in many plants (often in the mistaken belief that ironer performance is governed by linear speed, rather than usage of the full heating area available). Feeding edge to edge and operating with every lane requires some careful planning, but the best ironer supervisors achieve this and reap the rewards.

Conclusion

Achieving the improvements described in this month’s Material Solutions should not require any capital investment (apart from the cycle terminators for the dryers) and there is sufficient saving available to make a real difference to costs and productivity in the present lean times. Good luck!