According to the U.S. Department of Agriculture, more than 2.3 million Americans live in food deserts - urban areas that do not have convenient access to fresh produce. In many of these areas, individuals have easier access to fast food and junk food than to healthy choices. Urban agriculture, urban farming and urban gardening initiatives - cultivating, processing, and distributing fresh food in the community, for the community - are one way to increase healthy living, combat obesity, and promote sustainable urban development, one garden at a time. Let’s take a look at three inspiring and innovative solutions from around the world for growing food in urban environments - underground, on rooftops and in the sky. You can also get more innovative solutions for urban gardens by searching “green” on CADdetails.com.

Growing Underground, London, England

The world’s first underground urban farm opened for business last June in London, England making use of old World War II air raid shelters underneath the city to host an eco-friendly, sustainable farming business. The ambitious subterranean farm is the brainchild of entrepreneurs Richard Ballard and Steven Dring, in partnership with Michelin-starred chef, Michel Roux Jr.

Growing Underground uses hydroponics and LED lighting to produce a wide range of vegetables and herbs including celery, rocket lettuce, parsley, radish, and mustard leaf. A pesticide-free farming process - the results of 18 months of research and preparation - has been designed to produce crops with the least amount of energy expenditure possible.

The operators claim the hydroponics and looped irrigation system they use requires 70 percent less water than open-field farming and can produce crops all year round, but perhaps Growing Underground’s greatest asset when it comes to low-impact farming will be its location.

Buried underneath urban London, the project’s backers claim they’ll be able to deliver produce “from farm to fork in under four hours”, and all without the usual environmental impact of truck-based food transportation across England’s motorways. The farm will first supply local restaurants through market distribution, but will later sell directly to the public.

The farm makes use of WWII-era bomb shelters located 12 stories underground that were originally designed to provide shelter for 8,000 Londoners during air raids. The depth of the facility provides the insulation necessary to help grow crops 52 weeks of the year, with the temperature constant at 16 degrees Celsius (60.8 °F).

Not only is this an excellent example of how to breathe new life into an empty, pre-existing space, but it also provides a glimpse of how farming is moving into the 21st Century, thanks to pioneering high-tech agriculture ideas.

Gotham Greens, Chicago, Illinois

Brooklyn-based urban farming company Gotham Greens opened the world's largest rooftop farm in Chicago in fall 2015.

Located in the historic Pullman area on Chicago's South Side, the farm is the company's fourth greenhouse facility, and the first outside of New York. The 75,000-square-foot farm is located on top of a Method manufacturing facility, and is powered completely by renewable energy. The farm employs more than 50 people and will produce nearly 10 million heads of local, premium-quality, pesticide-free, leafy greens and herbs.

Gotham Greens produce will be available in select markets around the Chicago area, including Whole Foods Market, Peapod, Treasure Island, Sunset Foods, Plum Market, Target and others. The company has also partnered with local institutions such as the Greater Chicago Food Depository, Greater Roseland West Pullman Food Network, Pilot Light, Chicago Botanical Garden's Windy City Harvest and more.

Thanks to sophisticated computer control systems that continually adjust the greenhouse environment to ensure optimal growing conditions all year round, the farm is able to produce despite even the coldest of temperatures. For Chicagoans, this means premium-quality, hyper-local produce that often hits store shelves and restaurant plates the very same day it's harvested, 365 days a year.

There are numerous benefits to growing food this way in addition to year-round production. According to the company, their proprietary growing methods produce up to 30 times more crop per acre than field production. This means the two-acre facility can produce yields equivalent to more than 50 acres of conventional field production.

And because Gotham Greens recycles all of its irrigation water, the company says it uses 10 times less water than conventional agriculture, while also eliminating all agricultural runoff—one of the leading causes of global water pollution. Additionally, by growing and selling their food in Chicago, they drastically reduce the food waste and environmental footprint inherent in long-distance food transport.

Finally, the unique partnership between Gotham Greens and Method Products, leaders in their respective industries — urban farming and eco-friendly cleaning products — is a groundbreaking vision for the 21st century manufacturing facility. Method’s factory, designed by William McDonough + Partners, is the world's first LEED-Platinum certified manufacturing plant in its industry. Gotham Greens flagship facility in Brooklyn, built in 2010, was the first commercial scale rooftop greenhouse in the U.S. The company now has four operational greenhouse facilities, totaling 170,000 square feet, making them the largest and most commercially successful urban agriculture company in the world.

Sky Greens, Singapore

With an area of 710 square km and a population of 5 million, the wealthy island city of Singapore is one of the most densely populated cities in the world. With most parts of the island’s land utilized for urban development, the remaining 250 acres of farmland is hardly sufficient to feed the growing population. As a consequence, more than 93 percent of Singapore’s food consumption is met by imports from over 30 countries, including neighbors Malaysia, Thailand and the Philippines, as well as more distant trading partners like Australia, New Zealand, Israel and Chile. This dependency on the external world makes the country highly vulnerable to turbulence in food supply and prices.

The solution to the problem came in the form of a public-private partnership and the launch of what has been hailed as the “world’s first low-carbon, water-driven, rotating, vertical farm” for growing tropical vegetables in an urban environment. The result of a collaborative agreement between the Agri-Food and Veterinary Authority of Singapore (AVA) and a local firm, Sky Greens, this venture aims to popularize urban farming techniques that are also environmentally friendly. With 74 buildings towering 45 stories or more, it is not surprising that Singapore would be at the outset of high-tech vertical farming.

Designed by engineer and entrepreneur Jack Ng, Sky Farms consists of a series of aluminum towers — some of them up to nine meters (30 feet) high — each containing 38 tiers equipped with troughs for the vegetables. In keeping with Sky Greens’ focus on environmental sustainability, the water used to power the rotating towers is recycled within the system and eventually used to water the vegetables. Each tower consumes only 60 watts of power daily — about the same amount as a single light bulb.

The multi-layered vegetable tower rotates very slowly, taking some eight hours to complete a full circle. As the plant travels to the top it absorbs ample sunlight and when it comes back down it is watered from a tray that is fed by the hydraulic system that drives the rotation of the tower. This closed cycle system is easy to maintain and doesn’t release any exhaust.

Sky Greens recently took home the INDEX: Award 2015 in the "work" category. The prize, one of the most prestigious in the design world, recognizes innovations that help improve the world. The Sky Urban Vertical Farming System was given the award for representing "the next generation of sustainable urban agriculture" and for proving that "vertical farming can compete with, and produce better results than traditional farming.”

Times are changing. Today, around 15 percent of the world's food is grown in urban areas. According to the U.N. Food and Agriculture Organization (FAO), urban farms already supply food to about 700 million residents of cities, representing about a quarter of the world’s urban population. Urban agriculture is about more than just addressing the trendy ‘locavore’ movement, or beautifying the built environment. It’s about re-connecting with our food supply, educating our youth and nourishing our souls.