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Vertical farming has longstanding roots. Right now it’s capturing renewed attention from the agriculture industry and investors. Fundamentally, vertical farming is still limited by its economics. Essentially, it’s still too expensive and can’t compete with traditional agriculture. What will it take to bring vertical farming to the industrial scale where it can make a true impact? This blog will discuss the biggest technical hurdles facing large scale implementation of vertical farming and consider some ways we might approach solving these problems.

A short introduction from the beginning . . .

When our ancestors became tired of hunting and gathering they had to find something else for survival. Learning from nature, utilising their necessity fuelled ingenuity, they invented farming.

Over the millennia, our ancestors improved farming by discovering new products and developing new techniques. Ancient cultures developed ways to control their environments to improve the reliability and yield of their farms, including irrigation, terraced farming, and fertilizer.

Humanity could be in for a rough road . . .

Today we are using almost all available arable land on the earth, using pesticides and fertilizers in many ways that are not sustainable and are harmful to the environment. And although agricultural technology is advancing, our population is predicted to continue growing at an alarming rate that will challenge our ability to feed everyone. According to the UN by 2050 world population will reach up to 10 billion. The arable land we have is facing erosion, salinization, rising sea levels, drought, and desertification. Population growth and increasing strain on our arable land forces us to convert more land into farms.

World Map of Cropland and Pastureland. Source: Our world in data

Thoughts about the future . . .

From precision agriculture to advances in biotechnology, there will be room for plenty of innovation in agriculture. A valuable part of the solution may lie with vertical farming.

Vertical farming is actually a rather old idea. Indigenous peoples used vertically layered growing techniques like the rice terraces of East Asia. The term vertical farming was coined by American geologist Gilbert Ellis Bailey in 1915. In 1999, Dickson Despommier, a professor at New York's Columbia University, popularized the modern idea of vertical farming, building upon the idea together with his students.

What exactly is vertical farming?

Vertical farming isn’t just growing plants along vertical trellises, as I initially thought. It’s the practice of growing food in a modular system that can be arranged vertically to produce much more food per acre than traditional farms. Vertical farms are a type of controlled environment agriculture (CEA) that usually has closed atmospheric systems with artificial lighting systems and hydroponic or aeroponic nutrient delivery.

Going from farming in fields to farming in huge buildings might seems like a big jump and could be considered unrealistic by some. Oren Harari once said, “the electric light did not come from the continuous improvement of candles,” and, although all technological development stands on the shoulders of that which came before it, it is important to remember that combining technological innovation can lead to truly transformational changes. And vertical farming technology is not so farfetched as it may first seem. In fact, there are numerous vertical farms operating today!

Vertical farming has some very interesting benefits, including:

  • Extremely land efficient (can produce orders of magnitude more food per acre than traditional farms)
  • Extremely water efficient (can produce crops for 5% of traditional water consumption)
  • High quality food (conditions can be optimized to produce very healthy, good tasting food)
  • Capable of multiple harvests per year (since it’s always growing season inside)
  • Climate agnostic (able to grow food in any climate from tundra to desert – even outer space)
  • Reliable (resistant to drought, climate problems)
  • More nutrient rich food (food loses nutrient value during transportation)
  • Less risk associated with food (less risk of contamination from pathogens such as E. coli and no need to use pesticides, herbicides, fungicides)
  • Environmentally friendly (see points above)
  • More amenable to automation (CEA makes the robotics challenges much easier to solve)

What’s the catch?

If vertical farming is so great, why isn’t there one on every corner? Of course, there are some challenges to overcome before vertical farming can reach its full potential. Some of the limitations of vertical farming are:

  • High costs

    • Electricity for artificial illumination
    • Environment control of large volumes to maintain the optimal temperature, humidity, and CO2 levels for growing
    • Labour costs, rent, and capital equipment depreciation
  • Urban real estate is more profitably used in other ways (opportunity cost is high)
  • Certain plants are not as well suited for vertical farming as others
  • Existing agricultural system is extremely large and well established, enabling vast economies of scale and with many people vested in keeping the current agriculture model. (This will not be covered in depth here, but the authors believe that vertical farming and traditional agriculture will actually benefit from each other rather than facing each other adversarially).

Technological development in horticulture has already pushed the concept of vertical farms from fantasy to reality through the use of solutions like hydroponics, aeroponics, and artificial illumination. Companies are popping up all over with world (e.g. AeroFarms, Spread, Plenty, Green Sense Farms) setting up vertical farming plants and producing a limited variety of products. In the big cities some groups are providing fresh products for gourmet restaurants. Some dairy farms are vertical farming in transport containers to grown barley.

Windows of opportunity

Despite the advances that have been made in controlled environment agriculture, it isn’t quite ready for prime time and many opportunities for innovation remain. In CEA, artificial illumination eats the lion’s share of the energy and is currently the biggest technical road block vertical farming faces.

Data is taken from: Vertical Farm 2.0 Report

Today many different types of light sources are being used to mimic the sun to get plants to perform photosynthesis: incandescence, halogen, compact fluorescent lights (CFL), metal halide, high pressure sodium (HPS), and LEDs.

Various lighting technology efficiency improvements; Source: Osram

As we can see from the chart above comparing the most efficient light source, LEDs aren’t quite able to produce the same lumen per watt as some other sources. But the trajectories are what is interesting to notice. By all indicators, LEDs have an extremely bright future. Today the most efficient LEDs produce 200 lumens/watt, literally off the chart shown above!

Even though lumens per watt is an interesting way to compare light sources, it doesn’t tell the whole story. Plants are able to use certain wavelengths of light better than others (and different wavelengths produce different characteristics at different points in the plant’s life, but more on that later).

The absorption spectrum of photosynthesis, source: Fluence

The most important wavelengths are known as photosynthetically active radiation (PAR) and the measure of how many photons are produced in the PAR spectrum is called the photosynthetic photon flux density (PPFD). Light in the PAR spectrum produces less heat relative to others and ensures that every dollar spent on electricity is used as efficiently by the plants as possible and not just wasted light that will drive up the HVAC costs.

As mentioned above, to further complicate the process, plants use different regions of the spectrum during different phases of growth (and this varies from plant to plant). For example, for lettuce growth, blue light helps increase plant mass at the beginning. And during the blooming and stem developing phase red light is more effective. Also, green light may be more necessary for certain plants with carotenoid cells that require deep photon penetration.

Plant growth absorption spectrum mimicking light sources; Source: Research Gate

OLEDs (organic light emitting diodes) are a relatively new technology whose development is mostly being driven by the electronics industry, especially display technology (e.g. smart phone screens and TVs). People are beginning to look into using OLEDs as grow lights and in vertical farming. Some of the potential advantages of OLEDs are:

  • Much simpler structure than LEDs and can be ink-jet printed, which could reduce the manufacturing cost.
  • OLEDs can even be manufactured or printed on flexible substrates, which might possibly be shaped to optimize growing conditions for plants.
  • OLEDs are translucent, and if made on a transparent substrate for film, means natural sunlight can supplement the artificial illumination, further reducing the energy requirements.
  • Like other LEDs, OLEDs emission spectrum can be tuned and optimized for photosynthesis.
  • OLEDs produce much less heat than LEDs.

OLED vs LED ; Source: Alkilu

Plant growth absorption spectrum mimicking light sources; Source: Research Gate

The structure of OLEDs could be altered to be suitable for photosynthesis, while cost and power demand drop.

Efficiency of Printed OLED lighting is expected to rapidly increase in the future. Source: Semi Org

The second largest energy consumption culprit in a vertical is the environmental conditioning. This area is ripe for new concepts, which could turn the disadvantages of certain climates into advantages. For example, very cold nights of deserts could be used to cool a thermal reservoir, which could be used for reducing the energy usage for cooling during the hot day.

Since vertical farming is a type controlled environment agriculture operation, we have the chance to control all of the environmental parameters that a plant experiences during its growth cycle. With care process monitoring by a network of sensors (e.g. photo sensors, temperature sensors, pH sensors, and humidity sensors) it will be possible to optimize the growing parameters like light intensity, light spectrum, light exposure period, nutrition type and intervals, temperature, humidity, and CO2 level. It may even be able to control these parameters in real time on an individual plant-by-plant basis to truly optimize the growing potential of a vertical farm. Of course, this would be a very complex problem that would require very sophisticated algorithms. It is a problem that’s very well suited to AI (artificial intelligence) and ML (machine learning).

Another benefit of CEA is that different VFs in different global locations could be learning from each other’s experiences and sharing data about how best to optimize the systems for maximum efficiency. It may be possible for one vertical farm to pioneer the recipe which can then be shared or replicated as much as wanted. A collaborative algorithm like this would create the opportunity for robots and automation to relieve humans of the drudgery of repetitive work.

Adapting AI and Automation; Source: Techno Farm

One of the criticisms of vertical farming is that using electricity to illuminate the plants rather than using the sun’s light will lead to greatly increased CO2 emissions because the electricity may be generated from environmentally harmful sources like coal. We too share this concern, and it is legitimate. However, increasing adoption of renewable energy across the world and improvement of renewable energy technology is helping to drive us toward a sustainable energy infrastructure.

Here at Cambridge Consultants we can help companies develop the technology to let vertical farming live up to its true potential

Vertical farming has the potential to help solve many of the problems faced by traditional agriculture.

We have deep technological capabilities in fields like AI, bioengineering, optics, automation and robotics, control, and software to solve difficult technical challenges and make exciting technologies like vertical farming commercially viable. We provide our clients with strategic and technical leadership for complex, ambitious, and multidisciplinary projects like those facing vertical farming as it seeks industrial scale viability.

The people of Babylon saw and acted on an innovative farming strategy long ago. Perhaps we should follow that example.

 

By Mehmet Kaya and Ben Lawson

Author
Mehmet Kaya
Principal Mechanical Engineer

Based in our Boston office, Mehmet has a strong interest in developing products for industrial automation, electro-mechanical systems and R&D design projects, from concept creation to building prototypes and testing. His previous career includes working for major industrial companies as a product development engineer.