Continued from Hydroponics & Smarter Agriculture – Part 1

LEDs in Greenhouses

Light is crucial to a plant’s growth. It’s no surprise therefore that huge investments are being directed towards development of lighting solutions that optimise plant growth and crop yields, but also lower energy requirements of greenhouses.

The significance of these ambitions extend well beyond greenhouse efficiency and keeping supermarket fruit & vegetable stands stocked all year round. Rather, they’re contributing solutions to some of the most significant challenges we face in the world today, alongside humankind’s most exciting plans for spaceflight.

Conventional greenhouse lighting systems rely on incandescent lamps, typically high pressure sodium bulbs (HPS). While these have been the standard for decades, they’re far from ideal as a method for supplementing, or replacing sunlight.

The key problem concerns their efficiency as a light source for plant production. While incandescent lamps do produce wavelengths of light that plants need to grow, they also emit ones that plants have no use for — which makes for wasted energy. Additionally, they require relatively high amounts of power — much of which is wasted as thermal energy. Not only can this heat be damaging to plants, but it’s extraction from the greenhouse can require additional energy, infrastructure and maintenance.

These issues translate to a huge financial incentive to improving the efficiency of lighting, as energy can account for some 15-30% of the total costs for a typical greenhouse.

An alternative solution to providing supplemental lighting is found in the form of light-emitting diodes (LEDs) — which have become far cheaper and technologically viable in recent years.

LEDs are superior to incandescent lamps for several reasons: they can deliver light tuned to the specific wavelengths a plant requires; produce very little heat; carry lower maintenance costs; and are far more energy and cost efficient than conventional bulbs. Relative to the running costs of a greenhouse noted earlier, it’s thought that LEDs can achieve energy savings of up to 50%. Though LEDs may carry higher up-front investment, it’s an expense that’s quickly recovered through the energy savings that be achieved.

Optimising Growth

The ability to tune lighting to specific wavelengths opens up a wave of opportunities flush with potential for achieving more productive, sustainable greenhouse practices.

“LEDs can be selected to target the wavelengths used by plants, enabling growers to customize the light produced, to enable maximum plant production and limit wavelengths that do not significantly impact plant growth,”

Deram, Lefsrud &  Valérie (2014), HortScience

Some basic science. We’re all aware that in plants, sunlight provides them with energy. Specifically, however, the process responsible for that — photosynthesis — isn’t dependent on all wavelengths of sunlight. Rather, it’s red and blue wavelengths (of roughly 400 to 700nm)  which are be absorbed by photosynthetic pigments — chlorophyll — of plants to produce chemical energy.

When plants are exposed to lighting that only emits these most essential red and blue wavelengths, they grow faster, and can produce more fruit than compared with HPS lighting (Deram, Lefsrud &  Valérie, 2014, HortScience).

Researchers have also demonstrated how LEDs can be used to enhance development of seedlings, and imbue them with extra strength and other desired characteristics.

All of this to say, as a method to enhance plant growth and increase the rate of greenhouse production, whilst at the same time reducing energy consumption and maximising overall cost-effectiveness of the greenhouse system, artificial lighting featuring LED technology is a proven solution, delivering much improved results over traditional lighting systems.

Of course the story doesn’t end here. The research effort to find the most optimal form of LED lighting is a highly complex landscape, with many avenues of enquiry (see, Massa et al., 2008). That the precise balance of red and blue wavelengths also holds an impact over the growth of plants (a matter investigated in by Deram et al.,), and that different plant species and their varying growth phases also respond in particular ways to varied wavelengths, are all cause for research.

Within that field of research, the optimising of light positioning is also proving a valuable area of investigation. So-called intra-canopy lighting systems are aligned vertically, alongside the plant — as opposed to horizontal overhead lighting — to allow for light to reach plants at all heights and reduce shading. While this isn’t ideal for some plant species, or growth-bed designs, in many instances these arrays have been shown to increase crop biomass per unit energy of lighting.

Even more advanced systems use adaptive technologies which measure light reflectance from leaves, and adjust lights accordingly — ensuring that plants are always subject to optimal lighting conditions throughout their growth and natural movement.

(And in case you’re wondering: no, LED lighting doesn’t reduce the flavour of crops — they’ve done studies)

UV Lights & Plant Growth

More sophisticated use of LEDs can be found in the case of ultra violet (UV) light manipulation. Found at the high end of the spectrum of sunlight, UV is energy intense, and can be damaging to plants just as it is skin (do wear sunscreen). However, there’s a neat trick scientists have found that involves harnessing the reactions of plants to UV light.

A New Zealand-based company called BioLumic, have been experimenting UV light’s influence over crop growth for over a decade. Their goal is to develop UV based technologies which empower producers with precise control over important aspects of their crops.

UV light can lead to a wide range of outcomes in plants…Such outcomes include changes in plant growth, cropping density, taste, colour, shelf-life, and resilience to yield-limiting stresses which are an everyday problem within all crop production industries.

BioLumic

Jason Wargent, Senior lecturer in Horticulture at Massey University and Chief Scientific Officer at BioLumic, explains: “UV in itself is not very useful to plants, but they do have a protective reaction to UV: they produce fewer, thicker leaves, the waxy protective coating on the leaf surface increases, and sun screening compounds are produced in greater quantities. All this means, that done in the right way, UV light can produce a stronger type of plant,”.

BioLumic’s research has resulted in a product called ‘Smart Light Array’ technology, which adjusts quantities of UV light at different wavelengths. Using what they call ‘light recipes’, BioLumic’s technology can accelerate or slow down certain growth characteristics in plants, or enhance or inhibit certain other ones.

The technology has many applications. For instance, UV treatment can induce greater root growth and mass of seedlings; factors which protect plants from so-called ‘transplantation shock’ which occurs when plants are moved between environments.

UV light can also help cultivators produce more homogenous crops; where each fruit or vegetable is grown to a common size and proportion. This is by no means an insignificant aspect of modern agriculture — notably in high income countries, where a massive premium is placed on aesthetics to the extent that a large proportion of food waste results from discarded, but edible, food that doesn’t conform to consumer preferences (see, Food and Agriculture Organization, United Nations).

“…if a certain percentage of their [farmer’s] crop is undersized or under-spec, it’s wasted. If we are able to get homogenous specification across a whole crop then that’s of massive benefit, because it means a much higher proportion of that crop will be picked,” (Warren Bebb, CEO BioLumic).

Specifics aside, BioLumic claim that their UV system can achieve an overall increase in yield of between 17-41%, and over 70% increase in disease and pest resistance (Cleanleap).

BioLumic are still a young company, and mostly occupied with trialling their technology. However, they have commercialised the Smart Light Array: it costs $75,000 and each recipe is licensed at a fee of $45,000 per year. Presently they’re working on scaling up their trials — which were based on seedlings — towards some of the more typical crop varieties.

“We’ve been doing trials with maize and looking at soy, as well, massive crops that are used all through the global food chain. We’re seeing good early stage results there, replicating to a degree the results we are getting with seedlings, including better water-use efficiency, and hardiness. It’s early days, but that’s an application we’re focusing on because it could have huge impact,” (Warren Bebb, CEO BioLumic).

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Of course none of this is to say sunlight is no longer part of the greenhouse solution — in many cases it very much is. Here, lighting is supplemental to sunlight, one used to increase crop production by providing an environment for enriched plant growth, extending growing seasons and shortening times-to-harvest.

However, there are contexts in which sunlight isn’t available. This may be because of circumstance, for instance in space (see Part 3). But complete replacement may also be necessitated by design…

One of the most intriguing developments in modern agriculture is the advent of indoor farming systems in which plants are cultivated under entirely artificial conditions. What’s meant by this is that just as hydroponic greenhouses removed soil from the equation, some systems are doing away with sunlight too.

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For one of the neatest examples of this, we can consider SPREAD: a Japanese company pioneering so-called ‘indoor factory farming’, based off a commitment to establishing sustainable farming solutions. Having established their first factory in 2007, they’ve grown into a fully fledged supplier of fresh lettuce to the Japanese market, delivering produce marketed under the brand ‘Vegetus’ to over 2000 supermarkets.

SPREAD’s first factory — the Kameoka Plant — is in Kyoto. Using technologies developed in-house, Kameoka can output an incredible 21,000 heads of lettuce per day — claimed to be the largest yields of lettuce for a single factory in the world.

What’s remarkable about the factory is the extent to which it incorporates “advanced cultivation management technologies”. The approach involves hydroponic LED growth systems, operating under virtually laboratory levels of cleanliness and precision. Moreover, much of the system’s workings are automated — allowing the facility to be operated by just 50 employees whilst also enhancing control of growth conditions.

SPREAD aren’t standing still though — innovation is at the core of their enterprise, and for that they look toward taking lessons learnt from Kameoka and applying them in something bigger and better. In 2015, they announced plans to establish a new facility — the Vegetable Factory™ — in Kansai Science City using an even more advanced vegetable production system.

The Vegetable Factory will be spread over some 4,800 square meters and intends to improve on its predecessor in virtually every way possible: increased production (up to 30,000 lettuce per day/10 million per year); reduced energy consumption (1.2kW, down from 1.75kW);  improved water efficiency (featuring recycling, filtering and sterilisation systems, and the aim to recycle 98% of the water it uses); and an overall reduction in the cost per head of lettuce.

What’s more — cultivation in the new facility will be run entirely by robots and automated systems. The new plant is anticipated to be completed in summer 2017.

We are seeking agricultural solutions to address food shortages and problems in the global environment, not only for Japan, but for the people of the world.

In the longer term, SPREAD want to see their factories deployed throughout the world as part of a sustainable solution to food insecurity. Of course it’ll take a great deal to make even a dent on a problem of such scale — but from acorns grow oak trees. And besides, SPREAD are far from alone in their application of technological innovation to revolutionise the agricultural landscape.

Interim Conclusion

Taken together, advancements in hydroponics and smart LED systems leave indoor agriculture on track to become remarkably more efficient, cost-effective and sustainable than what we see today. The work is vital: laying sustainable foundations for providing food to a world increasing unable to support growth of crops by conventional means.

We’re a long, long way from the majority of our food being grown in hydroponic greenhouses or factory farms. But the technologies being utilised and developed today are most certainly going to be applied over a much wider scale in the future. In the simplest of terms, because they represent solutions that decouple agriculture from adversely impacting the planet. There are challenges in up-scaling, to be sure. But where there’s necessity — and there surely is — solutions are all but assured.

In considering the future role of these technologies, there are a few other interesting aspects to wonder about. How might these solutions be applied in an increasingly urbanised world? And moreover, how might they be applied on another world altogether?