Vertical farming: How sustainable is it really?

Vertical farming uses considerably less land, water and soil than open field agriculture. These three key resources are likely to grow in importance over the next few decades. (More on that later…)

Cutting food miles

At present, the UK imports a whopping 45% of our food. Not exactly sustainable, even before you factor in Brexit. The rest of our food is mainly produced in rural areas such as Devon, and often transported to several different destinations before it finally reaches a dinner table. According to Defra, transporting food produces 19 million tonnes of CO2 annually. To put that in context, that’s the same amount that’s produced by 5.5 million cars. And that’s just for the UK.

At the moment, vertical farms often supply local shops. On average, there are just 43 food miles between a vertical farm and the consumer. The average for open field farms? 2,000 food miles.

Vertical farms don’t need diesel-guzzling tractors. And by reducing the number of workers needed, they reduce transport emissions even further.

Cutting pesticides

Vertical farms are controlled, indoor environments. Slugs, snails and other pests cannot reach the crops. Neither can weed seeds or roots. Therefore, there’s no need for pesticides or insecticides. In other words, vertical farm crops are (usually) organic.

Energy efficiency

Critics of vertical farms often point to energy use. Indoor farms rely on artificial light and heat to grow crops, rather than the sun. HPS (High Pressure Sodium) lamps have been the main source of heat and light for glasshouses over the last 15 years. However, many farmers are now moving to LED grow lighting, and vertical farmers tend to use these from day one.

LED grow lighting

HPS lamps typically consume anywhere between 400W and 1,000W. LED grow lights bring this down to 150–500W, a 50% saving.

When determining how efficient an LED bulb is, we need to look at how many Micromoles the LED diode can produce per Joule of energy. This varies greatly between bulbs, typically from 1.4–3.1umol/j. So clearly there’s a considerable difference in how ‘green’ one bulb is compared to another.

At Light Science Technologies, we focus on LEDs that offer 2.6–3.3umol/j. While higher grade LEDs do come with a slightly higher price tag, they can reduce energy consumption (and therefore operational costs) considerably.

There are other actions a vertical farm can take to reduce energy consumption, which we’ll discuss in more detail later on.

Future-proofing

‘Sustainability’ is often used as just another word for ‘green’. But of course, the dictionary definition of sustainability is ‘the quality of being able to continue over a period of time’. So when it comes to vertical farms, we need to consider the long-term viability of them, not just their short-term impact. And to do that, we need to look at where the world is heading.

An increasing population

We probably don’t need to tell you that the global population is growing exponentially. In fact, it’s tripled in just 100 years.

That said, fertility rates are actually reducing in developing countries. In the UK, our current total fertility rate (TFR) is 1.65 children per woman. If there was no immigration and life expectancy remained stable, the UK population would gradually start to reduce, as our TFR is below ‘replacement’ level.

However, in other countries the TFR is far above replacement level. And life expectancy is increasing, so people are living for longer. The current global population is somewhere around 7.7 billion. It’s expected to reach 9.77 billion by 2050 before peaking at around 11 billion by 2100.

Climate change is expected to drive mass migration, as regions become unstable and water scarcity becomes more common.

Diminishing available land

Around a third of arable land has been lost over the last 45 years. And as the population grows, more may be lost to houses, schools and leisure facilities. Meat tends to require greater areas of land, both for grazing and for growing animal feed. But even if the entire population goes vegan (which is unlikely), it’s going to be extremely difficult (if not impossible) to allocate enough extra land to feed more than 3 billion more people.

The problem is likely to be further complicated by climate change. Flooding is expected to increase, both in terms of severity and frequency. Areas currently used for housing or agriculture may become unusable, particularly in coastal regions.

Agriculture is currently one of the biggest contributors to rainforest loss. Huge areas are being carved out of rainforests to grow palm oil and other crops. Not only is this exacerbating climate change, it’s also affecting biodiversity and threatening many species with extinction.

Vertical farms need far less land than open field farms. According to one estimate, a 30-story building covering just five acres could potentially produce the same amount as a typical farm covering 2,400 acres.

Water scarcity

While flooding is expected to get worse, so too is water scarcity. Vertical farming uses up to 95% less water than open field agriculture. In an open field environment, one lettuce may need up to 250 litres of water to take it from seed to plate. In a glasshouse, that drops to 20 litres. In a vertical farm, that plummets to just one litre thanks to water recycling and intelligent sensors.

While farmers in the UK can mainly rely on rainwater at present, that may well change as we start to see longer dry periods.

Soil depletion

It’s not just landmass that’s the issue, soil quality is also crucial. According to the Environment Agency, in England and Wales:

arable soils have already lost around 40 to 60% of their organic carbon due to intensive farming
almost 4 million hectares of soil are at risk of compaction
over 2 million hectares are at risk of erosion
soil degradation could cost us in the region of £1.2 billion every year

The situation doesn’t look much brighter in other countries. And that’s before you consider the growing pressure of feeding an increasing population.

Vertical farming requires little or no soil.

The move to urban living

As the population increases, more people will end up living in urban areas. The UN has projected that 68% of the population will live in urban areas by 2050. As already detailed, the emissions related to food transport are considerable. How much better then, to have more food produced in the areas where it will actually be eaten?

Making vertical farms more sustainable

It’s clear that traditional open field farming will not be able to feed the growing population on its own. As time goes by, we are likely to become increasingly reliant on vertical farming. And we may well see the types of crops that are grown in a vertical farm increase.

As with many new innovations, vertical farms should become even more efficient as the years go by. In the meantime, there are things farmers can do to reduce waste and emissions.

Reducing electrical waste

At LST, our lighting systems are bespoke and designed to last. Around 80% of each system is reusable (compared to around 0% of our competitors’ systems). Not only does this save on electrical waste, it also saves our customers a considerable amount of money.

Bringing energy consumption down

As discussed, the majority of a farm’s energy requirement is down to providing plants with light and, in some cases, heat. Farms can reduce their carbon footprint by using renewable energy, whether purchased from the grid or generated onsite.

Energy efficiency is perhaps even more important, however. Thankfully, LEDs are becoming ever more efficient.

Farmers will want to purchase the most energy efficient lights they can afford in order to save both emissions and operational costs. The problem that many vertical farmers face is that they’re stuck with the LEDs they buy for several years, as the bulbs are integrated in the lighting system. LEDs can only be changed if the whole system is replaced.

No farmer would want to change the LEDs every year. It wouldn’t be financially viable. However, there will come a time when the difference between their current LEDs and the market leader is considerable enough to warrant an upgrade. And with LST, this just means changing the LEDs, not the whole rig, which is significantly cheaper. In fact, for every luminaire life cycle, an LST client could save up to 25% on CapEx costs.

This allows farmers to take advantage of technological advancements in order to bring emissions (and costs) down even further.

At LST, we’re also unusual in that we’re not tied to a particular manufacturer. So we can source the best lights for your particular operation.

Optimising the farm

Thanks to our laboratories, vertical farmers are now able to create the perfect growth recipe for each individual crop. LST lights can also be provided with built in sensors and data transfer nodes. These communicate with remote bots in order to give farmers real-time data. This information can then be used to tweak conditions as needed, ensuring that a plant gets what it needs, but only what it needs.

As well as enabling a farm to reduce water, nutrients and energy, optimising conditions can also increase yield. In short, our products help you to grow more with less.

Is vertical farming financially sustainable?

We’ve focused on environmental sustainability in this article, but a key concern for many farmers is whether vertical farming is cost effective. There is no getting away from the fact that CapEx is high for vertical farms, and OpEx can also be of concern to startups. A typical vertical farm can take seven years to recoup its initial investment.

However, both CapEx and OpEx are expected to reduce as vertical farming becomes more common and technology advances. There are also several actions a vertical farmer can take to considerably reduce their expenses right now.

If you’re considering launching a vertical farm, or want to make your current farm cheaper to run and more sustainable, we’d be happy to talk through your options. Call us on 01332 41060