Urban Farming - The Future of Agriculture?

Renewable Energy Green Urban Farming in Hong Kong China
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Every person on Earth requires resources to survive. As the population grows, more and more resources will be demanded, the most essential of which are food and water. If supply does not meet demand, we have a situation called food insecurity.

The greatest demand will come from the cities, where by mid-century almost three-quarters of the world’s people will live, and where, according to a CIA report “the number of malnourished people will increase by more than 20 percent and the potential for famine will persist.” The United Nations claims that agricultural production will have to grow by 70% to meet the demand from urban dwellers.

Because of increased competition from increasing numbers, many essential resources are being used up faster than the earth’s natural processes can replace them. By 2025, scarce farmland is expected to impact at least 26 nations. Demand for water already exceeds supply, most of which is used for agriculture. Population pressures have already resulted in unsound farming methods and overuse of land in some places, stripping the soil of its productivity (ability to grow crops). Soil erosion exceeds new soil formation; every year, wind and rain carry away 25 billion metric tons of rich topsoil, leaving behind barren and unproductive land. In addition, the built environments of cities and suburbs are expanding onto land once used to grow food.

Unconventional Solutions

Arable land is being depleted as the need for food is increasing exponentially. What if solutions to this crisis could be found so that the amount of food produced is actually much greater, the amount of water and other resources used is significantly less, and the carbon footprint is negligible compared to current agricultural practices? And what if these solutions take advantage of built environments in the cities themselves, and result in multiple ways of using and occupying a space?

Vertical (Skyscraper) Farming is an ambitious idea attributed to Dickson Despommier, a Columbia University professor. His idea is to build a glass skyscraper made up of many floors of fields and orchards, with a yield that could feed 50,000 people. Inside, the temperature, humidity, airflow, lighting, and nutrients would be controlled to create the optimum conditions for plant growth. A conveyer belt would rotate/move crops on vertically-stacked trays around the windows to try to ensure an even amount of natural light. Unfortunately, plants farthest from the windows would receive less sunlight and grow more slowly. Thus additional light would need to be provided artificially to prevent uneven crop growth, and the energy required for this lighting is expected to significantly increase food production costs.

The Vertically-Integrated Greenhouse should require less artificial lighting because it limits the use of the built environment to where exposure to sunlight is greatest. Plants would rotate on a conveyor system in a narrow space between two layers of glass that have been built around a building’s perimeter. This “double-skin façade” greenhouse can be made part of a new exterior design or a retrofit for existing office buildings. As an added benefit, the greenhouse is expected to reduce the entire building’s energy use up to 30%.

Another vertical approach is to grow crops on top rather than up the sides of a building. A 15,000 square foot commercial rooftop greenhouse in Brooklyn, New York, built by BrightFarms and operated by Gotham Greens, sells 500 pounds of produce every day. The facility relies on automated sensors to activate lights, fans, shade curtains, heat blankets, and irrigation pumps that use captured rainwater. To minimize other costs, i.e. transportation and storage, the greenhouse was intentionally located near the supermarkets and restaurants who will receive the produce the very day it is picked.

Other urban farm ideas minimize the need for artificial lighting by not reaching so high, achieving maximum exposure to the sun’s rays through building design, and using renewable energies. The VertiCrop System, dubbed one of the world’s top inventions by Time magazine, grows lettuce crops for animals at Paignton Zoo in Devon, England. Its single-story greenhouse requires less supplemental energy because plants are surrounded by sunlight from the sides and above. A VertiCrop system with four-meter towers will be built on the roof of a downtown Vancouver, Canada, garage. It is expected to produce 95 tons of produce annually, an output equal to that of 16-acre fields farmed conventionally. The Science Barge, a floating farm prototype in Yonkers, New York, meets its energy needs from sunlight, solar panels, wind turbines, biofuels, and evaporative cooling. It makes use of insects rather than chemical pesticides and gets water by harvesting rainwater and desalinating harbor water.

The Farm of The Future

All of these systems use an existing but less traditional agricultural technology, hydroponics, which does not require arable land. With hydroponics, a plant’s roots are continuously bathed in a solution of water mixed with essential nutrients. Hydroponics is said to produce lusher plants in half the time.

These approaches also emphasize sustainable food production. Crops are grown with minimal use of herbicides, fungicides, and pesticides. Environmental damage and crop loss due to soil erosion and runoff are eliminated. Efficient building design that takes full advantage of natural sunlight and the use of renewable clean energy technologies will reduce dependence on high-cost nonrenewable dirty energy from fossil fuels. Perhaps best of all, hydroponic farming requires only a fraction of the land and water resources consumed by conventional agriculture.

Since hydroponic farms will grow food right where the people live, costs for transportation and spoilage should also be minimized. Reduced resource and operating costs, and greater profits year-round from greater yield should help the greenhouse recoup the initial expense for automated and renewable energy technologies.

The promise of hydroponics and a controlled interior climate is that nearly any kind of crop can be grown anywhere, year-round, shielded from weather and seasonal extremes. Yields are claimed to be 15-20 times greater than conventional farming. These innovative developments bring the farm to the city, where the people live, and if implemented on a large scale, could go a long way toward improving food security in cities.

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