How vertical farming can save water and support food security

Water covers 71% of the world’s surface, yet only 3% is suitable for drinking and farming – and water use is growing at more than twice the rate of population increases. If we don't change our habits, global demand for water could increase by 50% by 2030.

Agriculture is both a cause and a casualty of water scarcity. It accounts for an estimated 70% of global water withdrawals, with freshwater resources heavily stressed by irrigation and food production. This also results in soil salinisation, leading to further declines in crop quality. According to the United Nations, China is one of 13 countries contending with serious water scarcity, having 21% of the world’s population, but only 6% of its freshwater. Overall, China’s per capita availability of water is just 25% of the world’s average, and more than 400 Chinese cities are short of water.

Agricultural innovation can help reduce water usage, including remote sensing, artificial intelligence, and machine learning. However, despite the level of innovation taking place today and in the future, there will always be natural variabilities to contend with when it comes to traditional outdoor production methods.

More radical change is needed, such as using controlled environment agriculture (CEA), which in layman’s terms, means growing indoors (without soil) under controlled or semi-controlled conditions, as the name suggests. This sector is primarily made up of glasshouse and vertical farming and is one of the highest growth sectors globally, also creating ties with other important sectors, such as genetics, energy, alternative meat, carbon sequestration, and insect proteins. Natural limitations as to what can be grown in CEA systems will always exist, but even today, when the sector is relatively immature, a sizeable proportion of the average supermarket’s fresh produce aisle is being by produced by local CEA facilities.

Glasshouse farming (and polytunnel growing) is far more prevalent and is already a mature market for many crops, with major operations in most geographies, especially in places like the Netherlands or Southern Spain, where the scale of growing can indeed be seen from space. But greenhouses – whilst benefiting from free energy from sunlight and being able to grow larger, more mature crops – lack in their ability to tailor wavelengths of light to influence crop growth and importantly, must expend a great deal of energy to maintain a climate that is suitable for crops.

Considering most baby leaf crops grow optimally in the low 20Cs, a greater than 50C outdoor environment means a lot of energy must be used to bridge the delta. Even in more temperature climates such as the UK, glasshouses can reach over 50C without adequate control – effectively wiping out plants in the space of a day. In respect of water, glasshouses must also work harder to deal with transpiration – again adding to energy costs.

Vertical farming is like glasshouse growing in some respects but crops grow in stacked layers using artificial lighting to manipulate plant growth, also allowing for 24 hour production, if desired. It is typically far more sophisticated and possesses numerous advantages for crop production, including general metrics, such as fewer food miles, the non-use of chemicals, and encouraging rewilding to a greater degree. Compared to glasshouse growing, it’s an approach that goes further in environmental control, eliminates more variability, and is also beneficial in terms of water conservation.

In advanced vertical farming solutions, water is applied in exact doses meaning wastage is minimised and productivity is boosted – both at a granular and system-wide level. This is achieved through recirculating and treating nutrient-rich water and capturing water that would otherwise be lost through transpiration. Filters, UV treatment, and complex treatment and recirculation systems are tailored to the exact needs of each individual plant – much like a hospital’s treatment regimen would be tailored to a patient and their underlying condition and needs.

Overall, dependent on the crop being grown, vertical farms can use up to 98% less water when compared to traditional agriculture. This is not possible through conventional methods and as stated, even high-tech glasshouses have limitations due to there still being a higher degree of variability in growing conditions due to more exposure to outdoor conditions.

China is also well positioned to be a pivotal leader in this space. As an already global leader in technology manufacturing and research and development, the opportunity for securing water (and food) security in not only China, but also through exports targeting countries with extreme climates for mass infrastructure deployment.

The impact of climate change on water and global crop production are clear to see and well recognised amongst the scientific and academic communities. Water is the lifeblood of not only humanity but to the world that we inhabit and by working together, we may not be able to “turn the ship around” but we can certainly slow it and ensure it doesn’t sink. If we don’t act now, water will certainly be the next crisis – and it’s not too late to change this if we truly put our minds to it.