Food Trend Concepts E-Book

Patrick Siegfried

• Herausgeber: BoD - Books on Demand
• Kategorie: Fachliteratur
• Sprache: Englisch
• Veröffentlichungsjahr: 2024

Seitenzahl: 344

Beschreibung

This book deals with current food trends. These case studies were compiled and presented by Master's students at Trier University of Applied Sciences in the Department of Food Technology.

Leseprobe

This book deals with current food trends.

These case studies were compiled and presented by Master's students at Trier University of Applied Sciences in the Department of Food Technology.

Table of Contents

1. Vertical farming: A comparative analysis with conventional agriculture and an assessment of its potential for urban areas in the future

Baureis, Moritz

2. Social responsibility and sustainability in the food industry: A comprehensive analysis if Koawach’s practices

Baureis, Moritz

3. Pulque: Market Analysis of a Traditional Mexican Beverage and its Commercialization Prospects in Germany

Bottler, Chiara

4. The Impact of Local Production on Marketing Strategies - Let’zkola

Döner, Melis E.

5. Optimizing Production Planning, Logistics, and Quality Control in the Fresh Produce Industry: A Case Study of Grosbusch

Döner, Melis E.

6. Analysis of the rise of Japanese Whisky into a global powerhouse

Kemme, Moritz

7. Potential for exotic fruits on the German market, an analysis of peach palm fruit

Mounier, Louise

8. Sustainability Marketing - Strategies and Challenges in the Introduction of Seaweedbased Packaging in the Food Industry

Schmitz, Katja

9. Postharvest Coatings: Extending Shelf Life of Produce and Their Implications on Logistics and Sustainability

Schmitz, Katja

1

Vertical farming: A comparative analysis with conventional agriculture and an assessment of its potential for urban areas in the future

Baureis, Moritz

Abstract

In a world where the population is constantly expanding and food security concerns are on the rise, the use of alternative methods of food production, such as vertical farming, is becoming increasingly important.

This article looks at conventional agriculture and compares it with vertical farming. After a closer look at the system, the opportunities and risks are explained and recommendations for action are given.

Looking at the approach, it's been found that vertical farming is clearly superior to conventional farming in terms of water use efficiency, land use efficiency as well as yield, but the biggest challenge is the immense energy requirement, as the plants in closed systems are artificially lit using LEDs.

It should be noted that there are geographical differences depending on the prevailing stage of development. By looking at both systems, the potential of vertical farming to ensure food security in urban areas is considered. This article is useful for research institutes, horticultural companies, farmers, policy makers. It is also useful for anyone wishing to broaden their awareness of the origins and impacts of food production and who is interested in new technologies.

Keywords: agriculture, food security, vertical farming

1.3 Introduction

In recent decades, the world has experienced unprecedented population growth and rapid urbanization. The State of Food Security and Nutrition in the World 2022 says, that the world is regressing in its goal to end hunger, food insecurity and malnutrition in every form by 2030. In 2021, between 720 and 828 million people faced hunger, an increase of more than 100 million from 2020 (FAO, IFAD, UNICEF, WFP, & WHO, 2022). With the United Nations predicting a population of 9.7 billion by 2050, food security can no longer be put off to the future. (United Nations, 2019).

Agriculture represents humanity's most important provider of food. In addition to feeding the world, conventional horizontal farming has several negative environmental impacts.

As a result of globalization in recent decades, the production of goods has shifted from the place of consumption to places where production costs are low due to low labour costs. On the one hand, this leads to cheap goods, but on the other, it leads to logistical challenges and lower quality products.

A study by Barbosa et al. shows that food has to travel an average of 2,000 to 3,500 km from processing facilities to market shelves, with an average transport time of 4-6 days. The distance a product travels to the point of sale is also known as food miles. This complex logistics not only contributes to climate change, but also leads to drastic nutritional losses. Produce loses 30% of its nutritional value every three days after harvesting and root removal. (Barbosa et al., 2015).

Sustainability and regionalism reached a new level of importance among the population due to extreme situations such as the Covid-19 pandemic. Food shortages, especially in highly urbanized areas, highlighted the dependence of cities on conventional agriculture (Yuan et al., 2022). The trend: "Support your local dealer" is continuing: a consumer survey in Germany in 2021 shows that 76% of the people questioned pay attention to whether the products they buy come from the region when they buy food. The top four reasons given by respondents for wanting local produce were supporting the local (agricultural) economy and shorter transport distances, freshness and sustainability (Bundesverband, 2022).

Regional food can make an important contribution to climate change mitigation due to short transport distances and seasonality. Urban farming is a form of agriculture that can make an effective contribution to improving food security in highly urbanized areas because, as the name suggests, this form of agriculture can be applied in urban areas.

According to (Smit et al., 1996), who defined urban agriculture for the United Nations Development Programme, it is: “an industry that produces, process and markets food and fuel, largely in response to the daily demand of consumers within a town, city or metropolis, on land and water dispersed throughout the urban and peri-urban area, applying intensive production methods, using and reusing natural resources and urban wastes, to yield a diversity of crops and livestock.”

Social community gardens, raised beds, indoor farming and vertical farming are just some of the ways that urban farming can be implemented. One of the key characteristics of urban agriculture is whether it is a commercial or private enterprise. The concept is not new and there are many examples throughout human history, like the Hanging Gardens of Babylon, which have been the first form of vertical farming (Al-Kodmany, 2018) or the self-sufficiency of people in cities during World War 2.

1.4 Problem and goal

Natural resources are finite, which is why the current approach – to expand agricultural land by destroying ecosystems in order to meet growing demand – would lead to ecological collapse if there is no rethinking. Forests account for most carbon removal by terrestrial ecosystems, removing 29 % of annual CO2 emissions (Friedlingstein et al., 2019). The attempt to successively replace ecosystems such as rainforests with farmland can only fail when facing population growth in the future, as agricultural land has to be used for energy production, urbanization or infrastructure growth (Lotze-Campen et al., 2008). In view of these facts, and the fact that 10 % of the world's agricultural land is lost for every degree of temperature increase (Despommier, 2010), it is clear that an expansion of conventional agriculture would, in turn, increase climate change and has reached its limits.

Agriculture and urban infrastructure must be compatible, and we must provide solutions to ensure a secure food supply for humanity, given the forecasts by the United Nations showing 80% of the world's inhabitants expected to live in urban areas in 2050 (United Nations, 2019).

Vertical farming as part of urban farming could be a part an important part of this solution. Because they are not dependent on the weather, vertical indoor farms achieve up to 100 times more annual output per unit area than traditional agriculture. Not only the productivity of this model, but also the growth without pesticides or herbicides as well as the possibility of harvesting 365 days a year, regardless of weather conditions or seasons, is a major advantage over traditional farming (Avgoustaki & Xydis, 2020).

Figure 1:Forecasted market size of alternative food production methods worldwide in 2030 (Statista, 2022)

Furthermore, the following statistics shows that vertical farming is expected to take the largest share of the alternative food market in the year 2030, along with plant-based meat. However, it should also be noted that vertical farming can also produce the raw materials for plant-based meat.

With growing awareness of vertical farming and the need for change in agricultural practices, this article examines the possibilities of vertical farming in feeding the world in the future.

2.1 Structure and methodology

The following chapters outline the current situation of human food security. This is done by first describing conventional agriculture, its consequences for humans and the environment, and a possible approach to a more sustainable form of conventional agriculture. Vertical farming is then examined in more detail, explaining aspects such as how the system works and the technological background. This will be followed by a presentation of the system's implementation in practice.

In order to compare the two systems in terms of agricultural KPI’s, the two methods are compared for the production of lettuce.

The opportunities and challenges of this innovative form of farming are then discussed. After an analysis of the current market situation and a consideration of European best practice, recommendations for the industry are given and possible visions for the future are presented. This is followed by a conclusion and summary.

1.5 Conventional agriculture

Conventional agriculture is the generally accepted and widely used form of agriculture and therefore represents the "norm" of agriculture. The aim of conventional farming is to produce as much food as possible for as low a price as possible - farming has to be profitable.

Conventional farming practices vary from country to country. However, in order to achieve the highest possible yields, conventional agriculture has some common features. These include the use of technological innovations, the cultivation of the largest possible areas and often the cultivation of monocultures. Cultivation usually requires large amounts of capital and fields are treated with large amounts of synthetic fertilizers, pesticides and herbicides.

In Germany, more than 90 % of farms are managed conventionally. The more land is cultivated, the more profitable a farm is. What is grown, and under what conditions, is of secondary importance. Farms are expanding and specializing in a small number of agricultural products. Fertilizers come from industry, seeds from seed companies, animal products from factory farming.

The number of traditional farms that manage their fields according to a crop rotation system, keep less livestock or use their own seed has fallen sharply. In Germany, the number of farms has fallen from over two million to less than 300,000 in the last 40 years. Specialization has had a weakening effect on rural areas: there are fewer jobs on the countryside, as many work steps are outsourced (Hagenau, 2022).

According to the Federal Environment Agency, around 60 % of Germany's agricultural land is used to grow feed for animal feeding. 16 % of the land is used to grow energy crops, such as maize for biogas plants or rapeseed for biofuels. This means that only 23 % of Germany's agricultural land is used for food production (Stoll, 2022). One of the most significant human influences on the environment is the expansion of agriculture and food production. Due to the variety of farming methods, the overall negative effects of agriculture and food production on the environment differ considerably. Regulations vary from country to country and, as technology advances, different practices are used in different parts of the world, with different environmental consequences.

The challenges of conventional agriculture in terms of its impact on the environment and the approach of a more sustainable form of agriculture are presented below. Finally, an assessment of conventional agriculture in terms of food safety is made at the end of this chapter.

3.1 Environmental impacts of conventional agriculture

Agriculture takes place in and with nature and lives from it. Natural conditions play a crucial role in determining the potential for agricultural activity in a region.

This paper discusses only the general and most important impacts of agriculture on the environment; no geographical classification is made. It is clear that impacts vary according to local regulations, customary practices and technological standards.

The following is an overview of the various impacts of conventional agriculture on the environment. For illustration purposes, a graphic was used, which is described in more detail below.

Figure 2:Environmental impacts of food and agriculture (Ritchie et al., 2022)

One of the world's most pressing challenges, man-made emissions of carbon dioxide and other greenhouse gases are a main contributor to the global climate change. More than a quarter of global greenhouse gas emissions are caused by agricultural practices used to produce food. The main drivers are methane from livestock and nitrous oxide, which is 300 times more damaging to the climate than CO2. Nitrous oxide is mainly released during the application of nitrogenous mineral fertilizers.

Agriculture is one of the most important land uses. Half of the world's livable land is currently cultivated by agriculture. Large-scale land use has a significant impact on the Earth's environment, degrading wilderness and affecting biodiversity. Agriculture accounts for the largest direct cause of deforestation, according to the United Nations Framework Convention on Climate Change. Deforestation is the extensive cutting down of the Earth's forests, which frequently occurs worldwide and leads to various forms of soil degradation. Deforestation leads to the loss of habitat for millions of plant and animal species. Of the 28,000 species on the IUCN Red List of Threatened Species, 24,000 are threatened by agriculture.

As trees absorb CO2 and act as carbon sinks, deforestation is also a contributing factor to climate change. Cutting down trees also releases CO2 into the atmosphere, leaving decreasing numbers of trees to absorb the growing amount of carbon dioxide in the atmosphere. (Ritchie et al., 2022).

Global water consumption increased about six times between 1930 and 2000 (Bundeszentrale für politische Bildung, 2017). Conventional agriculture accounts for 70% of the world's fresh water. In addition, agriculture is responsible for 78 % of global marine and freshwater eutrophication. Eutrophication is the accumulation of nutrients, particularly nitrate and phosphorus, in a lake or slow-moving body of water. This leads to a change in oxygen levels in the affected body of water, depriving many living organisms of the basis of their life. This is caused by over-fertilization in agriculture. Furthermore, the pesticides and herbicides used have a direct impact on the animals that live in this ecosystem. For example, the herbicide atrazine, which is used to control weeds, affects the hormonal balance of a wide range of animals. This leads to reproductive problems in mammals, amphibians and fish (Awuchi et al., 2020).

The graph also shows that 94 % of the biomass of non-human mammals is domesticated. This means that there are 15 times more livestock than wild mammals. For the world's bird population, the ratio of poultry to wild birds is 3:1.

The graph serves as a rough guide to the global impact of agriculture on the environment. As described above, the impact and strength of this varies from country to country, depending on the technologies and practices used.

3.2 Approach: agroecological agriculture

Agroecological farming (organic, ecological farming) is a sustainable and environmentally friendly form of agriculture based on working in harmony with nature.

Ecological farms aim to achieve as closed a nutrient cycle as possible. Soil fertility is maintained and animals are kept in a speciesappropriate manner. Biodiversity is promoted by the absence of synthetic chemical pesticides and low levels of fertilizer.

Organically bound nitrogen is mostly applied in the form of manure or manure compost, green manure through nitrogen fixing plants (legumes). Soil fertility is maintained through strong humus management. Compared to conventional farming, agroecological farming pollutes groundwater and surface water less with nutrients such as nitrates. Organic farming preserves and conserves natural resources and has many positive effects on the environment: Organic farming methods are best adapted to climate change and reduce climate emissions, protect the soil and promote humus formation and soil life. Natural soil fertility is increased. Organic farming produces food and promotes environmental and landscape protection (Stoll, 2022). The concept of sustainability has often been lost in the process of industrialization.

In 2021, the proportion of organically farmed land in Germany reached 9.7 % of the total agricultural area (Wilke, 2022). For a more sustainable future, Germany plans to expand agroecological farming to 30 % by 2030 (Bundesministerium für Ernährung und Landwirtschaft, 2023).

3.3 State of safety

Food safety is a collective term covering many aspects of food handling, preparation and storage to minimize illness and injury. This includes chemical, microphysical and microbiological aspects of food safety. Chemical aspects include the control of allergens, as these can be extremely risky for highly sensitive people. In addition, the chemical properties include the levels of minerals and vitamins, which have more of an impact on the overall quality of the food than on the safety of the food.

The absence of microphysical particles such as glass, metal or plastic is essential to prevent injury. Microbiological contamination by pathogenic bacteria, viruses or other microorganisms can result in food spoilage and also harm to consumers through the production of toxins.

Food can be contaminated at any point in the production or logistics process, and to counter this risk there are concepts such as HACCP to reduce the risks to food safety. Various limits have been introduced because some contaminants are unavoidable (Hanning et al., 2012).

The most common form of contamination is microbiological. A WHO report from 2019 shows that every year, 600 million people become sick and 420,000 people lose their lives due to the consumption of contaminated food (Ärzte Zeitung, 2019). Again, it is important to note that regional guidelines and standards have a significant impact on the number of outbreaks that occur in each country.

Because conventional agriculture is exposed to all kinds of environmental conditions, the effects can be very diverse. Pesticides are used to protect crops, and while there are limits to their use, they vary greatly from place to place. The effects of pesticides on humans range from acute to chronic skin diseases, poisoning, cancer and genetic damage. Every year, 385 million people suffer from pesticide poisoning. Most pesticides are used in Asia, Africa and South America, but we continue to receive reports of product recalls due to exceeding limits (Heinrich Böll Stiftung, 2022).

As our practices change in different areas, new factors that can affect food safety may emerge at any time. For example, a new issue has emerged in recent years: Microplastics. Researchers have already detected them in food products such as drinking water, beer, honey and sea salt (Smith et al., 2018). People can be harmed by the ingestion of microplastics through both physical and chemical pathways. Preliminary studies show that there may be increased inflammatory responses, disruption of the gut microbiome and transfer of adsorbed chemical contaminants. However, to understand the impact of microplastic toxicity on humans and the environment, further studies are needed. (Wright & Kelly, 2017).

Since conventional agriculture is mostly carried out in places where the food is not needed, and therefore travels an average of several thousand kilometers, the occurrence of secondary contamination during storage and transport is very likely. It is estimated that around 30 % of food is lost in this way (Despommier, 2009)

It can be seen that many factors influence the food safety of food from conventional agriculture. Due to the open system of conventional agriculture, many factors need to be considered and controlled. It has been shown that the occurrence of food-borne diseases is not an isolated case and must be taken seriously. Solutions are needed for a healthy and sustainable food supply.

4. Vertical farming

Depending on stakeholder interests, there are different definitions of vertical farming. (Sharathkumar et al., 2020) provide a commonly used definition for commercial vertical farming:

“A multilayer indoor plant production system in which all growth factors, such as light, temperature, humidity, CO2 concentration, water, and nutrients, are precisely controlled to produce high quantities of high-quality fresh produce year-round, completely independent of solar light and other outdoor conditions.”

The fact that the system is completely under control suggests that this is a very recent innovation. But the first approach to vertical farming was depicted in the Belgian comic strip Spike and Suzy in 1945.

This comic already showed the artificial irrigation, lighting and cultivation of two vertical layers on top of each other. The first idea for an efficient growing system, hydroponics, was developed by the Austrian Ruthner in the 1960s, but the concept lost interest due to high maintenance and energy costs (Kleszcz et al., 2020). Ruthner's idea was taken up and renewed in the early 2000s by Dickson Despommier. He recognised its potential and proposed using it as a way to increase food security for growing urban populations (Despommier, 2010). A little earlier, a group of scientists in Japan were developing a multilayered, closed, artificially-lit plant production system, the first modern vertical farm was invented (Kozai et al., 2006).

Figure 3: Part of the comic Spike and Suzy dealing with an early concept of a vertical farming. Published from 19.12.1945-13.05.1946 in De Nieuwe Standaard (Van Gerrewey et al., 2021)

Due to the fact that vertical farms do not require a large horizontal area, vertical farms can be incorporated into urban areas. By growing under controlled conditions, the food can be grown free of pesticides and herbicides, maximizing the nutritional value. Vertical farming is using advanced technology such as hydroponics, aeroponics and aquaponics to create ideal growing conditions for plants. These techniques allow plants to be grown in nutrient-rich water solutions, aerosols that nourish the roots, or a combination of plant and fish farming in a symbiotic ecosystem. By precisely targeting factors such as light, temperature, humidity and nutrient levels, vertical farming maximizes plant growth and minimizes resource waste (Yuan et al., 2022).

There are two reasons for the growing interest and expansion of the vertical farming industry in recent years. First, consumer interest in sustainably grown, fresh, healthy and locally produced food has increased. And second, the development of affordable and effective LED technologies (Van Gerrewey et al., 2021).

The following chapters deal with the technology on which the system is based and the most common types of growing systems.

It also discusses the different ways in which vertical farming is implemented in commercial practice. Vertical farming is then assessed from a food safety perspective. The direct comparison of conventional and vertical farming allows an analysis of both methods with regard to the cultivation of lettuce. Finally, the main opportunities and challenges of vertical farming are discussed.

4.1 Operation mode and factors of growth

For commercial purposes, vertical farming requires a great amount of technology, as it is a multi-tiered plant production system in which all essential growth factors are precisely controlled.

In most cases, vertical farms are divided into different units, each with its own purpose, to ensure the best conditions for the plants at each stage of their development. The whole process usually consists of three stages. After seeding, the seeds are grown in germination chambers with high humidity to encourage germination. In the second stage, the plants are moved to the propagation room to provide optimum conditions for the young plants. In the final stage, the plants are integrated into the main growth system and provided with the necessary growth parameters until harvest (Avgoustaki & Xydis, 2020).

In order to explain the basic components of a vertical farm, the structure is outlined in the following.

A vertical farm usually has insulated, airtight walls. Plants are planted in trays and stacked vertically in several layers up to the ceiling. Humidity, temperature and CO2 levels are controlled in the closed system to maintain optimal conditions. Artificial light, mostly LED, is used to illuminate the plants. The plants are supplied with nutrients and water through a growth system, a hydroponic system is shown in the illustration. The different growth systems are discussed in more detail in the following chapter. The whole system is constantly monitored by sensors and advances in technology allow automatic adjustment and control of growth factors.

Figure 4:Illustration of a vertical farm (Sharathkumar et al., 2020)

The following describes how the growth factors for plant growth in vertical farming are being implemented on a commercial scale.

Artificial lightning

Plant development is heavily influenced by lighting, and plants can show differences in morphology, bloom and production of biomass according to the lighting solution chosen.

It is a form of electromagnetic energy. It includes both visible and invisible wavelengths. Sunlight provides plants with the entire wavelength spectrum and is a free-energy source. 97% of the light from the sun is in the 280-2800nm wavelength range. Studies in recent years have shown that the wavelengths of greatest importance for photosynthesis, plant morphology and blooming are those in the visible (400-700 nm) and infrared (700-800 nm) spectrums (Lin et al., 2013). Plant yield is directly related to light intensity as it increases soluble sugars in plants and leads to some dry matter (Larsen et al., 2020). It has been shown that, depending on the plant species, a 1 % increase in light intensity results in a 0.25-1.5 % increase in yield (Marcelis et al., 2006). Optimum ranges vary by plant, but this research advance allows lighting to be matched to the plant's optimum growing conditions. Light is the most important plant growth parameter in regard to quality, quantity, direction and duration (Paradiso & Proietti, 2021).

Since the beginning of commercial vertical farming, a number of lighting types have been tested and studied. Technological advances have made LED’s the preferred light source over alternatives such as fluorescent, incandescent, high-pressure sodium and high-intensity discharge (HID) lamps. Arguments in favor of the use of LED’s are their robustness, their durability, the constant power generated immediately after the power is switched on and the fact that their photometric output is controllable (Avgoustaki & Xydis, 2020).

Thanks to LED lighting and advances in technology and research, it is possible to provide the ideal growing conditions for each plant.

Irrigation and nutrients

Irrigation and the supply of essential nutrients to the plants is provided by the growing system. The use of chemicals such as pesticides, herbicides and fertilizers are completely eliminated as the plants receive all the nutrients, they need through the growth system. Nutrient levels are constantly monitored and adjusted to the optimum conditions of each plant through the recirculating systems. The closed system allows the water collected by the heat pumps to be returned to the water cycle, which results in a high-water use efficiency. The most common growth systems and how they work are presented in the next chapter.

Temperature and humidity control

The temperature as well as the humidity are adjusted to the optimal conditions at the respective plant stage.

The biggest influence on the ambient temperature is the operation of the LED’s. Various techniques are implemented to keep the temperature constant at the desired level. A major influence on the temperature has the structure of the farm. Thermally insulated walls are essential to be able to produce cut off from the outside conditions. For a long time, heaters and air conditioners were used to control the temperature, and fans were used to circulate the air. In the last few years, more and more focus has been placed on heat pumps, as they can provide both heating and cooling. Furthermore, in combination with cooling panels, these can provide optimal humidity in the farm. The transpiration of the plants ensures that absorbed water evaporates and is released into the environment. In nature, this water would return to the earth in the form of rain a few days later (Bundesministerium für Bildung und Forschung, n.a.). The heat pumps can condense this water from the environment, collect it and thus optimally regulate the humidity.

CO2 control

Plants grow in a closed system in which, unlike in nature, there is no CO2. Therefore, CO2 has to be supplied externally and at the right dose. A CO2 content of 1000 ppm during the photoperiod (lights on) of the plants results in a maximum photosynthesis rate (Avgoustaki & Xydis, 2020).

The overview of the main growth factors shows that vertical farming requires not only a high level of technology, but also specific plant knowledge in order to implement the concept successfully. Optimal growth conditions in terms of essential growth factors vary from plant to plant and must be considered on an individual basis. In addition to the main growth factors, it is also important to monitor factors such as the conductivity and pH of the nutrient solution or the speed of the airflow in the room.

4.2 Growing system

With the aim of contributing to sustainable food production, researchers have developed several growing systems. The growing system is responsible for irrigating the plants and adjusting nutrient solution parameters such as the right amount nutrients, pH and conductivity. It provides optimal levels of the key growth nutrients nitrogen, phosphorus and potassium, as well as trace elements such as sulfur, magnesium and calcium.

In a controlled, closed-loop system, growing systems are designed to use much less water and produce higher yields. In recent years, hydroponics, aquaponics and aeroponics have become widely used (Kalantari et al., 2018). The following is a more detailed description of these growing systems.

4.2.1 Hydroponics

Hydroponics is defined by the Encyclopedia Brittanica as follows: "The cultivation of plants in nutrient-enriched water, with or without mechanical support from an inert medium such as sand, gravel, or perlite" (Encyclopedia Britannica , 2023).

The plants are therefore grown without soil using a mineral nutrient solution. The choice of substrate is a crucial aspect of hydroponic cultivation. Organic substrates with low bulk density and high-water holding capacity, such as peat moss and coconut fibers, are commonly used as primary substrate components (> 40% of substrate volume). Absorbents such as perlites, clays, sands and composts, which improve drainage and cation exchange capacity and boost oxygen and nutrient uptake, are often used as secondary components (< 40% of substrate volume).

Urban hydroponic systems vary in construction and applicability to specific plants and growing conditions. Nutrient film technology (NFT), deep water culture (DWC), aggregate culture and aeroponics are the most popular systems.

In NFT, plants are cultivated in angled trays where a fine layer of nutrient solution runs over the roots, applied either permanently or intermittently. In DWC, roots of plants are continuously immersed into a nutrient medium. In aggregate culture, plants are grown in sacked substrates (e.g., rockwool or coconut fibers) or in pots, using nutrient solution applied by drip injectors.

For short-cycle, non-fruit crops such as leafy vegetables or herbs, NFT and DWC systems are used. Long-cycle fruit plants, such as tomatoes, cucumbers and strawberries, are grown in aggregate cultures (Gomez et al., 2019).

Figure 5:Illustration of nutrient film technology (NFT) in practice (Bowery, 2023)

The nutrient reservoir in which excess nutrient solution is stored is a common feature of the various methods. In addition, they all have some mechanism for delivering the nutrient solution to the medium tray. This can be done by an electric water pump mechanism or passively by using water wicks.

4.2.2 Aeroponics

Compared to traditional hydroponics, aeroponics is a technological leap forward.

The key difference is that the first uses water as a grow medium, while the second uses none at all. Aeroponics works by misting or using nutrient solutions rather than water, so there is no need for pots or trays to hold water.

The planters are stacked so that the plants are suspended in the air at the top and bottom, so that the plant head can grow upwards while the roots can grow downwards without hindrance. Closed system means nutrient mix is entirely recycled, resulting in extensive water savings (Yuan et al., 2022).

4.2.3 Aquaponics

Aquaponics is a biological system combining recirculating aquaculture fish farming with hydroponic production of plants. This is achieved by the use of nutrient-rich waste from the fish tanks to fertilize the hydroponic beds. It creates a symbiotic relationship between plants and fish. As the system has integrated fish farming in a recirculating system alongside plant growing, there are more opportunities to commercialize (König et al., 2016). The following is an illustration of how the system works.

Figure 6: Illustration of the Aquaponic system (Francoillustration, 2021)

In essence, an aquaponics system is made up of three main components. The fish farm, the filtration system and a hydroponic growth system.

The fish farm can consist of a varying number of tanks, depending on the size of the system, in which the fish are raised and fed. The system works as follows: The addition of fish feed to the fish tank is the only regular external supply parameter of the closed loop system. The water contaminated with the fish excrements is fed into the hydroponic growth system through two filters. The sediment tank is used to separate coarse solids. In addition, the ammonia contained in the excreta is converted into nitrite by ammonia-oxidizing bacteria. The second filter contains a medium with a high surface area per volume, in which nitrite oxidizing bacteria ensure that the nitrite is converted into nitrate. At the same time, the solids remaining in the water are broken down into various other micro- and macronutrients through mineralization by heterotrophic bacteria. The nutritious water is then transferred to the hydroponic growth system. Here the nutrients are utilized by the plants. The plants absorb the various nutrients and the water purified by the plants is returned to the fish tank to be recycled for use by the fish (Engineers Without Borders Karlsruhe Institute of Technology e.V., 2020).

In this way, the aquaponic system mimics a natural ecosystem, eliminating the need to add fertilizer and other nutrient solutions. This results in enormous water savings and both ecosystems benefit from each other's closed loop. Different growth systems are appropriate depending on the design of the farm and the objectives being pursued. The most common is the hydroponic growth system, as it is much easier to regulate in terms of structure and control than the aeroponic or aquaponic growth systems.

4.3 Realization

In general, the commercial approach distinguishes between two main forms of vertical farming. The PFAL (plant factory with artificial lighting) approach involves warehouse-like structures with artificial lighting. These often have thermal insulation and even control of all environmental factors. The approach where all environmental factors are controlled is called Controlled Environment Agriculture. Here, as described in the previous chapter, all growth factors involved get automatically monitored and adjusted (Gomez et al., 2019). Below is the commercial scale of such a farm, the German start-up Hydrofarms, which uses hydroponics to produce lettuce and herbs all year round in Cologne.

Figure 7: Vertical farming in Cologne, Germany (Lessmann, 2023)

The optimal growing conditions result in high production efficiency, plant quality and year-round food production. In the commercial sector, there are different approaches to realizing a vertical farm, which will be examined below. Depending on the investment budget, the control and adjustment of growth parameters can be done manually or remotely via a smartphone. Here, the Internet of Things and AI technology make it possible to create a system that independently regulates and adjusts all possible growth parameters without external input (RBTX, n.A).

In addition, it is possible to fully automate a vertical farm through the use of robotics. A start-up from Constance offers an interesting approach here. The intelligent harvesting robot developed by the startup has a 360° camera that can scan the fruit and determine the degree of ripeness and harvest class. The fruit can then be harvested, sorted and packaged.

Figure 8:Intelligent harvesting roboter from Organifarms (Klotz, 2022)

There are several approaches to automation of a vertical farm. Robots can be used for pollination, plant care or to monitor the growth process (Klotz, 2022).

There are also different approaches to the implementation of vertical farms. The most common approach is the large crop production hall approach. Here, as many plants as possible are grown on a large scale in a central location to ensure economic viability. In the same breath, the largest vertical farm in the world must be mentioned - Bustanica in Dubai. The farm is designed to produce one million kg of leafy vegetables per year, or 3000 kg of food per day, using the latest technology (Herzog, 2023).

Another approach comes from the German start-up company Infarm. They have managed to reduce the size of the vertical production unit. This allows plants to be produced directly at the point of sale, for example in supermarkets or at the point of consumption, like in restaurants. In this way, food miles can be reduced to zero (Grasel & Grasel, 2020).

Figure 9:Plant production at the point of sale with a production unit from infarm (Schirmroszik & Schütze, 2023)

The French company Agricool has succeeded in placing vertical farms in mobile shipping containers. This approach makes it possible to mobilize vertical farms with Controlled Environment Agriculture technology to produce fresh strawberries, herbs or leafy vegetables in different locations (Stimmler, 2015).

Figure 10:Concept of Container farms by Agricool (Stimmler, 2015)

Other commercial approaches include growing food in abandoned subway tunnels or using greenhouses. Aquaponic systems are also coming to the fore, as they can be used to sell fish as well as plants.

In addition to the physical implementation, there are different approaches to how the plants are arranged in the farms. There are other approaches to increasing production efficiency besides the traditional system of growing plants in trays next to each other. An advanced approach is the rotating garden, where plants rotate around a light source.

Figure 11:Modell of a rotating garden (Rotary Garden, n. a.)

Due to the company, which developed this approach, the key to this system is geotropism. This is the response of plant organs to change their position in relation to the gravity vector. This greatly accelerates plant growth (Rotary Garden, n.a.).

An alternative to the conventional approach is aeroponic tower farms. Here, the towers are designed at different heights according to demand, allowing high production efficiency as with the conventional approach (Tower Farms, n.a.).

Figure 12:Illustration of a tower farm (Tower Farms, n.a.)

The realization chapter shows that there are different approaches to how vertical farming can be applied on a commercial scale. Companies from different countries are pursuing different approaches to the concept of vertical farming. As technology and science progress, the range of methods will become more diverse in the future.

4.4 State of food safety

Indoor vertical farms' growing rooms are hermetically sealed and located in strictly monitored spaces to ensure the maximum level of food safety, especially during the cultivation period.

The closed nature of the system and the absence of various chemicals means that the plants do not need to be washed before consumption and are free from microbiological or chemical contamination. Growing without soil also means that the plants are free of dirt. Urban production results in better freshness and nutritional value.

But being totally isolated, the system is also susceptible to contamination. Contamination can come from staff, and technical failures can create perfect conditions for bacteria to grow. In addition, contamination can occur during processing, packaging and transport (Avgoustaki & Xydis, 2020).

4.5 Comparison resources efficiency for growing lettuce

The per capita consumption of vegetables in Germany in 2020/2021 was 109 kg. On average, each German eats 5.7 kg of lettuce per year. In 2020/2021, Germany was able to grow 67 % of its iceberg lettuce and 47 % of its other lettuce varieties. The rest was imported mostly from Spain and Italy ( Bundesinformationszentrum Landwirtschaft, 2022).

In the following, the resource efficiency of lettuce is presented for both, conventional farming and indoor vertical farming, in order to better classify both methods in terms of agricultural KPI’s according to the current state of technology. This comparison was made by (Avgoustaki & Xydis, 2020) and highlights the differences between the KPI’s for the different production forms. This comparison is for illustrative purposes only; the KPI’s for conventional agriculture may vary from country to country, depending on the techniques used and the climatic conditions.

The agricultural key performance indicators for growing lettuce show the opportunities and challenges for vertical farming. The production process shows a significantly better water use efficiency for vertical farming. Conventional agriculture requires 250 liters of water per kg of lettuce per year, whereas the vertical farming approach requires only 1 liter. Due to the open system, irrigation in conventional agriculture is done by irrigation and rain, whereas vertical farming uses efficient closed-loop systems, which are responsible for this highwater use efficiency. Other advantages of vertical farming over conventional farming can be seen in yield. With optimal growing conditions and 365 days of cultivation in the closed system of vertical farming, up to 30 times more can be harvested per m2 per year. This results in a land use efficiency of 0.3 m2 for 1 kg of lettuce per day, compared to 93 m2 for 1 kg of lettuce per day in conventional farming. Pesticide-free growing in urban areas results in fresher produce that has to travel significantly less distance to the point of consumption. The sticking point for vertical farming is energy consumption. Vertical farms require 250 kWh of electricity per kg lettuce per year, compared to 0.3 kWh for conventional farming.

Table 1: Comparison of agricultural KPI’s for the production of lettuce in conventional agriculture and vertical farming

Resource efficiency

Conventional

Vertical farming

Water use efficiency

250L/kg lettuce/year

1L/kg lettuce/year

Water use

Irrigation and rainfall

Usually, hydroponics or aeroponics

Energy use

0,3 kWh/kg/year

250 kWh/kg/year

CO

2

emissions

540kg/tons of lettuce

158kg/ton of lettuce

Light source

Solar radiation

Artificial light (10-24 h/day)

Pest control use

EPA-approved pesticides, herbicides and fungicides as also traditional methods as plowing, weeding and mulching

Indoor cultivation Sterilize environment

Yield

3,9 kg/m

2

/year

80-120 kg/m

2

/year

Land use

275 days/year

365 days/year

Land use efficiency

93 m

2

for 1 kg lettuce/day

0,3 m

2

for 1kg lettuce/day

Harvests per year

2

8-12 year

Food miles

3200

43 km

In conclusion, the KPI’s for conventional agriculture can be significantly worse in underdeveloped countries. Overall, the significantly higher yield and better water use efficiency of vertical farming compared to conventional farming is outstanding.

4.6 Opportunities