agriculture in space

Agriculture in Space Expert: Deep Horticultural Expertise is Needed for Vertical Farming to Succeed

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Dr. Gary Stutte is the founder of SyNRGE, a consultancy specializing in Space Agriculture and Controlled Environment Agriculture technology. Stutte, a horticulturalist and university professor, worked at NASA for several years on a program focused on growing crops in space, resulting in some of the first research around vertical farming and LED lighting.

Stutte in the Kennedy Space Center growth chamber holding leafy greens grown in self-contained ‘pillows’ (2011)

Today Stutte is actively engaged in developing ground-based applications for space technology in biosciences, protected agriculture, and commercial horticulture. He has published over 150 scientific articles on the effects of growth conditions on crops grown in closed environments, fruit production, space biology, LED lighting systems, and biological life support systems for missions to the Moon and Mars.

We caught up with Stutte ahead of his speaking slot at YFood’s London Food Tech Week at the end of the month (30 October – 3 November), to find out more about his work and thoughts on the development of the indoor agriculture startup scene globally. (Get 20% off tickets with this code! AGFN20.)

How did you come to start working at NASA on indoor agriculture?

It was a bit of luck that allowed me to transition from teaching horticulture and fruit production at a University to working on closed system crop production for NASA. I had been teaching graduate courses in horticulture when I learned of a new program at NASA, which was starting to look growing plants on long-duration space missions. NASA had started the Breadboard project at Kennedy Space Center in Florida as part of the CELSS (Controlled Ecological Life Support System) program that had the objective of demonstrating the feasibility of using higher plants as a renewable life support system for long duration space missions. When the opportunity presented itself to become involved, it was an opportunity I could not pass up.

The Biomass Production Chamber (BPC) at the Kennedy Space Center was the centerpiece of the Breadboard Project in Florida. The BPC was a large (132 m3) closed chamber had been used as a high-altitude test chamber in the Mercury and Gemini programs. The chamber was fitted with lighting, a nutrient delivery system, and air handling systems and provided 20 meters of growing area on four levels. This was one of the first examples of a vertical farm. Incidentally, this design was driven by the constraints of the volume and diminutions of the chamber, not by a desire to design a vertical farm!

Between 1988 and 1996 the chamber operated on a nearly continuous basis — over 1200 days — without any significant failures, and during that time we grew multiple crops of wheat, soybean, rice, lettuce, potatoes and tomatoes in the chamber. Corn was too high for space!

Many other crops were also tested in controlled environment chambers using hydroponic production systems as potential candidate crops for space. Criteria for selection included a short stature, high productivity, short life cycle, nutritional content:   criteria nearly identical to those required for successful indoor agriculture operations on Earth.

These tests measured all inputs and outputs including transpiration rates, photosynthetic rates, yield, harvest index and nutrient demand. In addition, the production of volatile organic compounds and ethylene were monitored, as well as the dynamics of the microbial communities associated with each crop.

What were some of the main successes of the program?

The CELSS project in general, and the Breadboard project, in particular, were extremely productive, resulting in over 600 publicly available publications on all aspects of engineering, biochemistry, microbiology, and horticulture associated with controlled environment production. Three area’s I think of great importance were demonstrating the feasibility of the continuous production of crops — not just leafy greens, but tubers like potatoes and staple crops like wheat and soy — hydroponically on a continuous basis, generating detailed data on the nutrient, water, and yield potential of those crops, and pushing the limits of their bioproductivity using electric lighting, nutrient management, and CO2 enrichment.

By the end of the program, we had achieved four-to-five times the world record for field yields of wheat, twice the world record field yields for potatoes in two-thirds of the time, and we exceeded predicted yields from hydroponic lettuce production by 20%.

The data developed by that program on productivity, water use, nutrient demand, and oxygen production are still used as baseline design values for long-duration space missions, including the bases on the Moon and Mars.

What were you using technology-wise?

Lighting was provided by 96 400-W high-pressure sodium lamps in the BPC and crops were grown in recirculating nutrient film hydroponics. The nutrient balance and pH of the solution were controlled, and a number of environmental sensors were installed in the chambers. The BPC itself was designed as a closed system, so the water released by the plants through transpiration was condensed, collected and reused. The atmospheric CO2 was controlled during the day, and all systems were continuously monitored and controlled. There was also a very active resource recovery program in which nutrients from the inedible leaves and stems of crops were recovered and then returned to the plants. By careful management of the nutrient solution and water recovery system, we demonstrated the continuous production of potatoes in the closed system for 418 days in a row; that’s over a year.

There seems to be a lot of development in the lighting space. How did your use of lighting evolve during the project?

The testing began with conventional fluorescent, high-pressure sodium, and metal halide lamps. It was recognized early on that these lighting systems were not suitable for space applications. This was primarily a safety consideration: they are hot to the touch, can explode in low pressure, and contain hazardous gases. Plus, they’re made of glass, that if shattered would mean shards of glass floating around in the vehicle. They are also bulky and have a relatively short lifespan meaning we’d need a lot of replacement bulbs which use up limited storage space and crew mission time.

NASA began funding research on LEDs in the late 1980s, which resulted in the first US patents for growing plants under LEDs in 1991. Subsequently, we used LEDs to examine the effects of light quality on the size, form, and shape of plants, as well as the potential to increase the nutritional content of crops. The use of LEDs is revolutionizing indoor agriculture, and much of the critical research enabling this transformation in horticultural lighting can be clearly tracked to NASA-funded research. I was lucky to be able to participate in some of that work at the Kennedy Space Center in Florida.

LEDs are now being used in all the US plant growth chambers currently on the International Space Station, and the use of LEDs to alter optimize spectral quality through a crops life cycle is becoming a reality.

Do you see any big challenges in how some vertical farms are being developed today?

Controlled environment agriculture faces many challenges, but it is increasing quickly in Asia as well as North America and Europe, and it’s starting to expand into Latin America as well. Vertical farms are driven by the demand for a consistent supply of locally grown, high-quality produce that’s free from pesticides and conserves resources. Much of the growth is enabled by the availability of LED lighting, which can be significantly more efficient electrically than traditional lighting systems, and allows the lamps to be placed close to the plants. However, the challenge remains that it is hard to offset the electrical cost of running LEDs; you often need to sell produce at a big premium, and some early pioneers in the industry have learned that lesson painfully. There are now models for particular crops and markets that I certainly think can succeed. Additional challenges include humidity and temperature control in the facility, as well as excluding pests and achieving sustainability. However, these are all surmountable challenges.

Do you see challenges changing depending on location?

Each site will have its own specific set of challenges, particularly regarding the availability and cost of water, power, and labor. I think the challenge of personnel with training in horticulture is under-appreciated. Vertical farming is an information-intensive enterprise and requires an understanding and appreciation of the fact that you’re growing living things. There is a misconception that using technology to collect data and drive the production of plants makes it relatively easy to automate the production cycle. In theory, it does, but in practice, the biological variables make implementation difficult. The challenge is understanding the environment that each plant species will require; each strain or variety of lettuce, basil, or medicinal plant is a little different.

This understanding of living plants will be the knowledge base that will make or break the next generation of vertical farming facilities; how well the founders pay attention to the selection of species and cultivars and to the horticulture required in the production of plants in an indoor factory.

Have you come across many indoor agriculture operations and startups without horticulture expertise?

Some. Most entrepreneurs are visionaries and have an ideal; they have some information on crops they are growing and some sense of how to grow plants in the field. But once a crop is moved into the control environment of indoor agriculture system, the plant responses can vary greatly depending upon spectral quality, atmospheric composition, and nutrient management. Technology enables indoor agriculture to push the limits of productivity; it becomes far more critical to understand the commodity you’re working with.

Do you think you need a better horticulture understanding growing indoors than outdoors?

In many ways, yes. While indoor agriculture gives you control of the environment, there is less room for error in the decisions that are made.

Why are most vertical farms today purely focused on leafy greens?

Most of the vertical farms focus on leafy greens due to economics. Leafy greens generally have a short production cycle (28-35 days), enabling multiple harvests (9-13 per year per meter squared of production area); short stature maximizing the number of levels that can be grown per m2; have relatively modest lighting density demand (15-17 Moles per m2 day), thus minimizing KW energy required per production cycle, and essentially all of the crop is harvested and sold, minimizing harvesting and processing costs.   

It’s hard to do that for wheat; typically the edible grains of wheat makes up less than 20% of a wheat plant. That means you’ve invested all that energy, light and nutrients to grow the inedible roots, leaves, and stems, only to harvest off the seeds that must be processed before they can be sold. In other words, 80% of your investment in the crops not sellable! I anticipate we will start seeing more peppers as shorter season varieties emerge that could be competitive with greenhouse-grown peppers.

I am excited to see that a greater variety of leafy greens, as well as other short cycle vegetables and medically plants produced in indoor farms, are appearing on the market.

We’re not going to feed the world with leafy greens. Are you concerned that there’s not enough research being done on other crops?

I am concerned that there is not enough research being done on other crops. That’s not to say that research is not being done, but it needs to be expanded and conducted in a systematic way to support indoor agriculture. Before I left Kennedy Space Center, our labs had tested over 25 different crops in controlled environments as potential candidate crops for space. It’s imperative to do the research on lighting, nutrient and environmental conditions for new species in vertical farms. While I don’t think that vertical farms will be providing the primary caloric needs for the world, there is certainly potential for it to be a key source of fresh produce that provides critical nutrients and phytochemicals essential to health.

Personally, I’ve yet to see a good business model that would achieve some financial sustainability for a company placing small container type farms in food deserts. That doesn’t mean they don’t exist, but I haven’t seen them. What I can envision is locating a larger scale indoor farm in the economically disadvantaged food desert, in order to stimulate a broader economic impact that could create jobs and generate income for that area. The indoor agriculture model is adaptable to becoming an engine for economic growth and food security in both rural and urban food deserts.

My concern is that many things that indoor agriculture promises are going to be very difficult to deliver, such as the replacement of imported food, fresh food for everybody in large cities, turning food deserts into oases of fresh nutrient vegetables. It is going to be very difficult to do this with the capital and operating costs involved; ultimately you have a perishable product that’s a commodity, and it’s hard to recover the cost of vegetable production unless it is performed at scale.

Cover image: Shane Kimbrough during harvest of Red Romaine Lettuce grown under LED lights on ISS (2016). Image courtesy of NASA

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