Friday, October 22, 2021
This autumn’s energy crises have included rocketing gas prices and a broken cross-channel electricity cable. The inevitably higher electricity prices will be concentrating print factory owners’ minds even if they don’t notice what will be said at COP26. Addressing the global climate crisis is a noble long-term goal, but higher energy bills need paying today.
Initially, you can play musical chairs with energy suppliers if you’re not locked into long-term contracts. To brighten up a boring exercise, ask those that boast they only use renewables if they’ll guarantee their prices won’t go up because of gas cost rises.
It’s also a no-brainer to consider how to optimise and reduce a factory’s energy consumption, with measures that work in the short term, as well as longer range planning for new equipment and new or modified buildings. This is also a major factor in limiting your carbon footprint, which some customers will ask about.
An obvious way to cut energy use immediately is to replace incandescent bulbs, “energy savers” or halogen with LEDs. An LED uses about a 10th of the power of an equivalent-brightness incandescent bulb, 12% of a halogen or about 60% of a CFL ‘energy saver’. LED prices have plummeted in recent years and a range of colour temperatures are offered. It’s so obvious however that a lot of factories will have done it already, often replacing older type bulbs on a rolling basis as they fail
Replacing fluorescent tubes has been slower to take off because they are pretty efficient anyway. Even so each LED array uses about 40% of the energy of an equivalent fluorescent tube, so a 150cm 24W LED is equivalent to a 70W tube. Purpose-built-LED battens however, as swap-out tube replacements tend to be dimmer. Lifetimes are between 30,000 to 70,000 hours depending on who you believe, equivalent to between 15 and 34 years for single-shift, five-day weeks.
Another electricity saving can come from installing room sensors that switch lights on when people enter and off or dim when they leave. This works well for storerooms, restrooms, toilets, corridors and maybe offices, but isn’t practical for production floors.
Retain and recycle heat
All electrical machinery, heat driers and people in a factory give off heat. The age of the building will tend to determine how draft-proof and well insulated it is and thus how much builds up inside, or is lost through single-glazed windows, uninsulated roofs and walls and open loading doors without heat-retaining curtains. Our ever-hotter summers might demand air conditioning.
Factory heat recovery and exchange systems can be installed to recycle excess heat into water tanks and radiators, with prices depending on the size and complexity of the fit. There’s a fairly wide choice of technologies, not just the heat pumps that are somewhat controversially favoured by the government for domestic use.
The Renewable Energy Hub, which has information and links online, reckons that fitting a typical factory heat recovery system would cost from £8,000 to £12,000. According to the Carbon Trust, a heat recovery ventilation system operating at average 70% efficiency will save about 38% of a company’s gas heating bill, with a return on investment over two years.
By 2019 photovoltaic (PV) solar panel arrays generated 2.7% of the world’s electricity, a growth of 24% over a single year. As a global average, utility-scale solar costs dropped by about 14% from 2017-18, according to researcher Lazard, then by a further 7% in 2019-20 according to the International Renewable Energy Agency (Irena).
Print factories are often single-story with large roof areas suited to mounting solar arrays. Whether this can supply all of a factory’s needs depends on the total area installed, but significant contributions are certainly possible even on cloudy days in the UK. Given the rising PV efficiencies promised in future, you need to do your sums before entering into any long-term payment contracts.
Excess power generated at idle times, such as weekends, can be fed into the public grid and sold back to the energy companies. Unfortunately the UK government keeps changing its rules on this. It closed its original ‘feed-in tariff’ scheme (paying 5.38p per kWh) to new entrants in 2019. However, it then introduced the Smart Export Guarantee (SEG). This requires all energy companies with 150,000-plus customers to provide at least one SEG tariff for selling electricity to the grid. Energy companies can set their own rates, however. Today, E.ON Next offers 5.5p per kWh, but Scottish Power only offers 4p.
Another roof-mounted option is solar heaters, a cheap way to heat water. These are little more than boxes of black pipes on your roof plus heat exchanger plumbing to hot water storage tanks. They can even be a DIY job.
Rather than sell your excess self-generated electricity back to the grid, a relatively new concept is to use large lithium batteries to store electricity generated at times of low demand, then release it when the factory needs it. There’s also potential to store grid-supplied electricity at off-peak rates, then release it in peak times.
This not only reduces bills but may partly protect against the grid power cuts that are looming as a future crisis because UK coal and nuclear power stations will shut before there is enough replacement capacity built.
Some batteries can be arranged to form a local grid with other companies (say on the same industrial estate) that could run independently of the national grid.
Tesla offers a factory storage unit called Powerpack, which outputs 130KW per module. You can install as many of these as you want or can afford, and you’ll need an inverter too. Tesla also offers the lower-capacity 13.5KW Powerwall for domestic and SME installations.
Many other companies are now offering battery systems, including LG, Mercedes-Benz Energy, Samsung SDI and Siemens. Prices per kWh are falling all the time.
UV is cool
Across a range of printing processes, the big revolution of the past 10 to 15 years has been the development of cool running, low-power consumption UV-LED lamps that use a fraction of the power of heat driers.
Ultraviolet curing used to be an expensive process with nasty inks and power-hungry high-pressure metal halide lamps that ran very hot, with unhealthy ozone emissions. It was only used for ‘difficult’ materials, usually plastics.
UV-LEDs changed all that and have all but replaced mercury vapour lamps on superwide/grand-format roll and flatbed UV inkjets. They have a knock-on environmental benefit – because they run cool, thinner plastics such as self-adhesive vinyl media can be used without distortion. This costs less and also saves on transport costs, because the rolls weigh less and you can get more on a truck, so fewer journeys. Heat-cured aqueous, solvent or HP Latex inks are still widely used for small to medium-width inkjets, however.
Flexo presses for labels and packaging have used UV-cure for years as alternatives to solvent inks, so are also benefiting from UV-LEDs. The biggest change in the past decade has been in litho presses, where UV used to be a rare speciality process. Nowadays UV-LEDs are not only affordable, but the compact lamp arrays are easy to fit into existing press designs.
Higher ink costs mean that it’s not a complete replacement for conventional heatset litho inks, but prices may come down over time. There are also non-LED UV systems called LE (low-energy) with low-pressure mercury lamps that don’t generate ozone or much heat.
On the other hand, inkjet digital presses, whether web or sheetfed, still mostly use aqueous inks that need heat driers (though note the low consumption of the Kyocera in this month’s Star Product, page 51). UV-LED curing is rare and only offered by the rarely seen Konica Minolta/Komori B2 sheetfed models and the yet-to-be delivered B1 MGI Alphajet. Dry toner presses are quite power hungry.
An ongoing issue is the acceptability and regulation of UV inks in or around food packaging, garments or toys. For general commercial use however, UV is fine as long as safety guidelines are followed.
In 2030 the UK will ban the sale of new diesel, petrol and some (not all) hybrid road cars and vans. Given the recent fuel delivery crisis it may seem like a good idea to go all-electric tomorrow. On the other hand, publicly accessible vehicle charging stations aren’t being installed fast enough for a future where everyone needs them.
Electric vans are suited to shortish runs where they can be recharged at your own factory. A petrol PHEV (plug-in hybrid electric vehicle) still makes the most sense if long-range journeys are needed, as they aren’t dependent on finding a working charging station on the way.
Pure electric running costs are a lot less than petrol, diesel or hybrid (plus there’s less to go wrong, makers claim), but purchase costs are still higher. Also the government will no doubt want to replace lost fuel duty revenues with tax inceases elsewhere.
Don’t forget the humble forklift truck. Battery-electric trucks are at least as powerful as old diesel and propane types, without the fumes and particles that you don’t want in a warehouse. Those with IPX4 waterproofing ratings can also operate outdoors in rainy loading yards.
A thorough examination of affordable ways to minimise power consumption and manage heat can pay off in both the short and long term. You can cut your running costs, minimise carbon footprint, impress your clients and ease your environmental conscience. It’s called ‘enlightened self-interest’.