Hydroponic farming and other vertical farming technologies are viewed by some as the solution to solving the world’s food security issues, and preventing potential food shortages caused by an overpopulated planet. But is indoor farming really as environmental friendly as thought? Is a question recently raised by Washington Post food columnist Tamar Haspel.

The advantages of vertical farming is it makes the most out of land coverage, where stacked plants 10 or 100 high can raise the yield of crops, which immediately boosts one acre of agricultural produce yield to the equivalent of 10 or 100 acres. Moreover, the plants will grow faster under artificial light because the plants are no longer limited by periods of sunset. The yield rate per square feet for lettuce is greatly increased.

Indoor farming also reduces waste of fertilizers and water because the plants are only fed the amount of fertilizers they need through water (hydroponic) or misted onto dry roots (aeroponic). This also reduces potential water pollution, where runoffs from agricultural fertilizers might trigger algae blooms in rivers, lakes and estuaries.

The new farming technique can cut water consumption by 95%.

Due to the controlled climate, no pests or diseases are harbored by the soil, and it requires fewer farm pesticides. So organisms including farm workers, honeybees, and other plants and animals are exposed to less toxic substances.

Current studies have also found little difference in the lettuces nutrition levels grown naturally under the sun, and by artificial light.

However, there are a couple of disadvantages including the higher cost, and a the large carbon footprint indoor farming might generate.

Traditional farming techniques make the most of sunlight, but indoor lighting relies heavily on artificial lighting, which can consume a lot of electricity.

Artificial light used to replace sunlight can be energy-intensive business. According to Louis Albright, director of Cornell University’s Controlled Environment Agriculture findings, for every kilogram of indoor lettuce it emits about four kilograms worth of carbon dioxide.

This does not include energy required fro humidity control, ventilation, heating and cooling that is required to form the comprehensive indoor farming system.

According to the article, indoor lettuce production might have a carbon footprint 7 to 20 times greater than outdoor lettuce production.

Even more efficient lighting presents significant limitations to improvements. A spokesman for Philips Lighting estimates LED lights will become 10% more efficient. Albright estimates 50% or more is achievable, but currently only 50% of electricity is efficiently converted into light in LED bulbs.

The article goes on to suggest pumping carbon dioxide into the air might make lighting more efficient, since plants photosynthesize carbon dioxide if there’s more of it in the atmosphere, and plants can grow just as well with the same amount of light.

However, even with these methods in place it will total to only 40% efficiency improvement in the short term, which is not enough to make indoor farms climate-competitive.

The article concludes for indoor farming the source of the energy and electricity determines the total carbon footprint.