Aeroponics

Growing Vertical

Thomas W. Gurley

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000061345
• Edition: 1
• Topic: Sciences biologiques
• Subtopic: Science générale

Aeroponics: Growing Vertical covers aspects of the emerging technology, aeroponics, which is a sister to hydroponics, involving state-of-the-art controlled environment agriculture. The book begins with an introduction of aeroponics followed by a summary of peer-reviewed technical literature conducted over 50 years involving various aspects of aeroponics. It covers the science and all the patent literature since 2001 to give the reader a comprehensive view of the innovations related to aeroponics.

This book is a useful reference for people interested in learning about how aeroponics works. This book is for novices as well as scientists interested in research activities conducted in countries around the world as well as work in using aeroponics in outer space. Designed for the user interested in research conducted in the past, this a helpful resource for those in the next generation of profitable agricultural endeavors.

Features:

· Comprehensive resource presenting key aspects of aeroponics

· Focus on areas of aeroponics including its history, science, innovations, business, and practice

· Provides a complete overview of the intellectual property associated with aeroponics

· Presents a broad overview of research using aeroponic systems across the globe

· Features information on key start-up businesses and activities that drive this technology

Thomas Gurley earned a BA in chemistry from Houghton College and a PhD in analytical chemistry from Case Western Reserve University and has 40 years industrial chemistry experience with companies including Goodyear, Abbott Labs, and his consulting company, Manning Wood LLC. He holds two Fulbright scholarships to Ukraine and Uganda. He is currently R&D Director for Aero Development Corporation, a manufacturer of aeroponic commercial growing systems. He conducts research in aeroponics as an adjunct professor at Charleston Southern University in South Carolina.

1 Introduction

Agriculture … is our wisest pursuit, because it will in the end contribute most to real wealth, good morals, and happiness.

Thomas Jefferson

Aeroponics is a new emerging growing technology that is best defined as a soil-less method for growing plants in which their roots are suspended in air. Nutrients are provided to the roots either by misting a nutrient solution or by trickle down gravity flow of the nutrient solution. Hydroponics is a much more familiar technology to the public because it has been in practice for almost 100 years. Hydroponics is similar to aeroponics except that the roots of the plants are submerged in water, also called water cultures. The roots of these plants absorb nutrients from the nutrient solution that the roots are in constant contact with. These technologies will be further discussed in more detail in Chapter 3 of this book. There are many similarities between the development of aeroponics and the development of hydroponic systems. For example, the nutrient solutions, pH, electrical conductivity, and other parameters are very similar for these two sister technologies. There is also some overlap with what is called controlled-environment agriculture (CEA). Aeroponics and hydroponics are both considered to be CEA technologies because they are normally practiced in a controlled environment, such as a greenhouse, a warehouse, or a shipping container, where many of the environmental variables are controlled. This would include temperature, light intensity, photoperiod, nutrient concentration, humidity, carbon dioxide levels, etc. There can also be overlap with soil-based growing (geoponics) that is conducted in a greenhouse or warehouse.

Why is aeroponics important? It is important mainly because the future production of good, pure, and safe food is uncertain. In an article in Newsweek, the question was asked, how are we going to feed humankind in the future if we keep farming like we’ve been for the past century (Newsweek, 2015)? The current population on the earth is about 7 billion humans and by 2050 that number is projected to be nearly 10 billion. The problem is that most of the land we can use for food production is already being cultivated; which means that we are going to have to make some large-scale changes to how we farm.

Professor Despommier

Professor Dickson Despommier (Columbia University) tells the story of a Florida farmer who had a 30-acre strawberry farm that was destroyed in 1992 by Hurricane Andrew. The farmer obtained the insurance money to rebuild his farm, but instead of replanting strawberries, he used the money to build a greenhouse: “He did this because he thought if he built the greenhouse strong enough it might survive the next hurricane, and he was right,” says Despommier. His hydroponic greenhouse was so efficient that 1 acre of indoor space could grow more strawberries than the farmer had previously been able to produce on 30 outdoor acres—30-fold increase. This left the farmer with 29 acres of unused land (Newsweek, 2015).

In his book Vertical Farms (2011), Despommier describes a vision for urban agriculture in what is being described now as CEA. He contrasts yesterday’s agriculture with today’s, and projects the future of agriculture evolving into vertical farms. He describes the advantages and all the benefits of this innovative idea. He proposes that the need for food will be where the people are in the cities so the food should be grown close to where they are. The economic benefit is obvious, that is, the reduction in shipping costs for food being shipped thousands of miles from farm to table. He summarizes the following four key themes that would be necessary to implement vertical farming:

1. capture sunlight and disperse it evenly among the crops;
2. capture passive energy for supplying a reliable source of electricity;
3. employ good barrier design for plant protection;
4. maximize the amount of space devoted to growing crops.

He shows several pictures of futuristic multistory buildings with crops growing on every floor. He concludes his book with a chapter titled “Food Fast-Forward” in which he concludes that disruptive technology is simple. It disrupts the present and jump-starts the future. The vertical farm has the potential to do that by advancing agriculture to a place in history it has never before occupied, which is one of true sustainability. His recommendation is a revamping of the United States Department of Agriculture (USDA) to help facilitate this transformation (Despommier, 2011).

Despommier in his TEDx Middleburg talk in 2013 listed ten benefits of vertical urban farming (Despommier, 2013):

1. no agricultural runoff;
2. year-round crop production;
3. no crop loss due to severe weather;
4. uses 70% less water, no agrochemicals, no fossil fuels;
5. allows for the restoration of the ecosystem;
6. remediates gray water;
7. creates jobs in the city;
8. supplies fresh produce to city dwellers;
9. uses abandoned city properties;
10. can grow biofuels and drugs.

He cites examples of vertical farms already in place around the world.

Examples are:

• Rural Development Agency Suwon, Korea
• Nuvege Kyoto, Japan
• SkyGreen, Singapore
• TerraSphere Vancouver, Canada
• Plantagon Linkosing, Sweden
• The Plant Chicago, USA
• Vertical Harvest, Jackson Hole, USA

Other TED Talks

Christine Zimmermann-Loessl, the head of the Association of Vertical Farming in Munich, Germany, gave a TED talk in Liege in 2015 entitled, “Taking food production to new heights.”

She presented the “real” reasons for the benefits of vertical farming. She gave the main three reasons—fresh, safe food; less use of natural resources; and less traveled food miles and spoilage. She emphasized the need for increased food production based on the projected population growth from 7 to 10 billion people in the next 30 years. She presented the picture of vertical farming or CEA as a utopia for growing produce. Her presentation included the ideal conditions for optimum growth—temperature, light, water, nutrients, specific light spectrum, light duration, and protection from severe weather conditions. The benefits were presented as two to three times the growth rate, reduction in land use by 10-fold, and produce that is rich in vitamins, minerals, and antioxidants as well as tastes good. This she stated was one of the pillars of the future of agriculture (Zimmermann-Loessl, 2015).

According to a TED talk in Tanzania in 2017, Sara Menker indicated that by 2050, there will be a need for a 70% increase in worldwide food production. Can we feed the population using our current methods (Menker, 2017)? According to an article in the Atlantic magazine the world is divided into two groups—the wizards and the prophets. The wizards believe that we can technically innovate and solve this challenge. The prophets believe that we need to conserve, reduce, and adjust to this new reality or we won’t survive (Mann, 2018). Achieving this goal will most likely take several technical solutions to address this issue. These include traditional farming methods and many new technologies.

New Technology

Companies like Aqua Design are capturing the CEA idea for the urban dweller. Toni Beck, their chief marketing officer says, “For many people who live in urban areas, like New York, it’s rare that you have a backyard or even enough indoor space to grow your own healthy veggies so we designed EcoQube Sprout for the urban dweller who wants fresh greens but just doesn’t have enough space or time. We believe that the future of food production is through the use of aquaponics, hydroponics, and aeroponics. With these technologies we can grow food 30%–50% faster while using 90% less water,” said Beck. “We can grow more efficiently using less space and less water, allowing us to produce more food. It was really important for us to design the Sprout for everyone, of all ages, to grow their own fresh food easily indoors” (Mashable.com, 2018).

The Tabernas desert, in southern Spain, is the driest place in Europe. But in the 1960s the land began to blossom, and today the arid desert is where more than half of Europe’s fresh vegetables and fruits are grown (Tremlett, 2005). The credit goes to greenhouses. The first few were built there in 1963, courtesy of a land distribution project spearheaded by Spain’s Instituto Nacional de Colonización. Fruits and vegetables from those greenhouses, where the environment could be controlled and beautiful produce could be grown, consistently soon outsold comparable crops grown elsewhere in open fields. Money was reinvested, greenhouses were expanded—with inexpensive plastic sheeting replacing glass as the material of choice for the majority of the controlled environments—and today greenhouses cover 50,000 acres in the Tabernas desert, adding $1.5 billion annually to the economy of Spain.

That’s because from an environmental and land-use perspective, controlled-environment farming is a great idea. Fruits and vegetables grown indoors tend to have far greater yields per area than comparable produce grown outside. Put a roof and walls around produce, and thus, most problems caused by weeds, pests, and inclement weather vanish. Add technology like hydroponics—growing plants so the roots sit in a customized nutrient slurry instead of in plain old dirt—to the equation, and yields increase even more. Better yet, build a hydroponic rig that is modular, rotates, and stacks—which means you can have several “stories” of produce growing atop the same ground (assuming the stacks all get sufficient light).

In 2011, a calamity in Japan made it necessary to rethink agricultural production strategies. The tidal wave that caused the Fukushima disaster wiped out most of the farmland near Sendai, a coastal area in the northern half of Honshu, the largest island of Japan. The Japanese government decided to jump-start a vertical farm building boom, there in an effort to replace the lost land. Four years later, Japan boasts hundreds of vertical farms, greenhouses stacked high into multistory skyscrapers, where plants rotate daily to catch sunlight. Instead of transporting dirt into the buildings, the plants grow with roots exposed, soaking in nutrients from enriched water or mist.

The number of Japanese plant factories (PFs) producing more than 10,000 heads of lettuce daily is estimated to be around ten. Japan’s PFs are expanding to meet the increasing demand for safe, pesticide-free, and locally grown food. Japan has more PFs than any other country. The largest number of PFs are located in Okinawa Prefecture near Taiwan. The rapid commercialization and financial subsidization by the Japanese government of PFs, which began in 2010, are helping to drive interest in their development (Kuack, 2017).

Another reason for the increase in PFs in Japan is that the country has been importing a large amount of fresh, sliced salad vegetables from China. The Japanese are concerned about the amount of pesticides being used for Chinese vegetable production and looking for alternative sources of fresh vegetables and herbs.

In 2014, there were about 170 PFs in Japan. Of these, 70 are producing more than 1,000 lettuce heads (50–100 g per head) or other leafy greens daily. The average floor area of a PF with 10–15 tiers for producing 10,000 lettuce heads daily is 1,500 square meters. The main components of a PF are:

1. a thermally well-insulated and airtight warehouse-like structure with no windows;
2. tiers/shelves with a light source and culture beds;
3. a carbon dioxide supply unit;
4. 4. nutrient supply units;
5. air conditioners;
6. an environment control unit;
7. other equipment includes nutrient solution sterilization units, air circulation units, and seeders.

Aeroponics, a companion technology to hydroponics, has taken off in Japan and is helping high-tech greenhouses produce remarkable yields quickly: unlike hydroponic systems, where plants dip their roots in nutrient slurry, aeroponic systems spray the plants’ deliberately exposed roots with a nutrient-laden mist. “The root systems grow much longer because they have t...