The Importance of Wind Resource Assessment in Plant Factories’ Siting

1. Introduction

Recognizing the challenges that today’s hydroponics industry and tomorrow’s plant factories are and will be dealing with requires some strategic thinking. Hydroponics and greenhouse technologies and intensive crop production systems are well established in the modern world to meet the challenge of feeding 10 billion people before 2050. However, the resource-wasting conditions existing today are not going to last. The systems of the future will be radically different from those used today for this purpose. Various engineering tools, such as wind resource assessment, can prove extremely useful in optimising the energy and food systems of the future. The intensification of agriculture in Europe has sometimes involved economic activities with a major impact on the ecosystem, to the point where environmental stability and geopolitical stability may be at risk. Current systems are not sustainable and in the future, it will be necessary to develop alternative production systems that will be more efficient in terms of water, energy use, and labour. Comparative studies show that 160,000 L of water are needed to produce cotton of USD100 value, compared with 600 L (under optimal conditions) of water to produce at the same value if cotton is hydroponically grown [1].

Therefore, the challenge hydroponic farmers are facing worldwide is to develop water- and energy-efficient systems to provide high-quality, safe products needed while simultaneously protecting the environment. The motto should be that any resource is useful and should not be wasted. To achieve this, the plant factories of the future should:

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Invest in food technology research.

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Develop more efficient production systems with a smaller footprint based on natural resources.

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Align with Renewable Energy Sources.

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Adopt recycling technologies that offset the need for soil, water, and energy for crop production and dramatically reduce the use of natural resources.

A wide range of methods and tools are designed to define sustainable development both individually and collectively.

2. Energy Resources & Challenges for the Future

A key strategy for global sustainability is to reduce the ecological footprint and carbon footprint in large and densely populated cities. Today, more than 50% of the world’s population lives in cities, while by 2030 the percentage will rise to more than 60% and cities in the developing world are expected to absorb up to 90–95% of this growth [2]. Although these cities do not make up more than 3% of the total land area, they demand the largest percentage of energy and materials and produce three-quarters of the total greenhouse gases. In addition to land degradation, agriculture is the largest “consumer” of water in the world; thus, issues of conflict and competition for water resources are intensifying. One of the main concerns for global sustainability is the proper response to climate change through the design of cities with low CO₂ emissions. Practices such as organic farming improve the absorption of carbon from the soil by removing it from the air while reducing water consumption and improving the adaptability of systems, going a step further and introducing negative emissions as one of the weapons to be used by climate scientists in the battle against the climate crisis.

The transition from conventional to indoor and most of the time soilless agriculture came with the transitions from natural light to, e.g., LED lamps, which are now the main source of light for most plant factories [3]. Thus, one of the main obstacles to the mass deployment of hydroponic units is the Capital Expenditure (CAPEX) required from day one. CAPEX is referring to purchasing and installation; however, it is not the primary headache of the plant factories’ owners. Operation Expenditure (OPEX) is the number one challenge. OPEX often includes—like in every other investment in the field—maintenance, service, spare parts, personnel, and other costs; however, in this case, the energy (electricity and heating) required to operate is the number one challenge. In such factories, up to 70–80% of the total cost could be energy-related costs, with lighting to be considered as the main energy consumer [4]. Heating is considered the second, though an equally important, energy-related cost in plant factories. Most plants require a temperature of more than 15–20 degrees, and there are only a few vegetables that thrive below or around 15 degrees Celsius; heating is considered a very important resource, which will secure growth and harvest at optimal conditions.

Several attempts are made to minimise heating losses before selecting the plant factories’ locations, with environmental conditions and specific wind conditions in mind. The overall energy footprint of a plant factory always comes along with the factory siting. In a distributed mass deployment of plant factory scenarios, these are built simply either inside empty apartments or in a container side-to-side structure [5]. As mentioned already above, when introducing plant factories, it is not necessarily meant that factories are widely known. A plant factory could be a hydroponic unit installed in an empty space/apartment not used. There are numerous studies on the concept. In this way, distributed hydroponic vegetables and fruit production in a city could secure food for all in the urban environment, minimising logistics and their cost and CO₂ emissions due to transportation [6]. The method should try to connect heat loss to external conditions and propose—in a populated environment such as in a large village/town—zones in which the investments would lose less heat to the environment compared with other areas where this loss would have been more significant.

3. Purpose of the Future Research

Evidently, a completely new category of studies is needed to deal with the energy behaviour of plant factories and in specific the heat loss under a decentralised concept/design. Small towns should be considered as ideal places for distributed small-scale plant factories. This research will focus on identifying the zones in these small towns where the heat losses can be minimised as a plant factory’s location constraint. In practice, it will be proven that in some of the potential zones for plant factories are better because of fewer losses, while in other zones, these should be avoided because of higher wind and therefore higher heating losses. Optimising the plant factories’ performance across their energy spectrum is essential to making the design sustainable and to ultimately reducing OPEX. This completely new category of studies should be devoted to the detailed wind resource assessment of the area used to identify those zones to try and optimise their operation. Especially in complex terrain, this is more needed [7,8]. Since wind turbines appeared, wind resource analysis has been mostly linked to the performance of wind turbines [9,10]. However, there are many more ways that a wind resource assessment and its findings can be used [11,12]. In this category of studies, a wind resource assessment can reveal where the losses due to the wind chill factor [13] can mean more on the plant factories’ losses and where not.