By Olivia Strigari
The fridge is a common sight in our kitchens, a staple appliance whether we live in a scorching hot region or freezing cold climate. But with the traditional system of chilling comes a high cost to the environment – chances are your fridge eats electricity like it's a free buffet. Luckily progress is being made internationally in developing ways to keep our food cold without overheating the planet. It seems some are digging deep into their heritage to find the solution of the future, while others look to high-tech inventions, such as solar energy, magnetic cold and even heat conversion.

Going underground In colder climes, before the arrival of the fridge, the ground itself was used to store food. Canadian Houzzer Cancork Floor Inc. recalls: "In Northern Canada, people built permafrost storage rooms. These were dug into the tundra below the snow line, and some of these freezers were the size of a small house. Sadly, many homes have lost them because of climate change. The permafrost level is sinking deeper, making it harder to store meat during the summer." But even though global warming is a major concern, people are rediscovering underground food storage, and new solutions are emerging.

A moveable feast in the Netherlands

Anybody who wants to dig an underground food storage facility in the Netherlands faces challenges. Construction permits are needed and, in this low-lying country, they have to deal with possible floods and underground water that's usually around 3 meters deep. But Floris Schoonderbeek, art director and designer for his own company, Weltevree, didn't let this stop him. He invented the Groundfridge, a specific root cellar, which resolves all these problems.

Five years ago, Schoonderbeek noticed householders and chefs alike were changing their way of life, mostly by growing their own fruit and vegetables. He realized many would benefit from a specific storage room to stock the produce. In collaboration with different partners, including Wageningen University, the Groundfridge was born. Waterproof thanks to its polyester membrane, and easy to carry and move to wherever it has to be installed, this organically shaped cellar doesn't need any building permissions, just thorough knowledge about the ground where it's to be installed.

Totally off-line, it enables the same amount of food storage as 20 traditional fridges, and maintains a temperature of between 7°C and 12°C all year round. Schoonderbeek set up two models: one has a solar-panel door, which produces a small amount of electricity to offset summer temperatures and cool down the Groundfridge. Another one is linked to the natural supply of underground water (which always stays at 10°C) to constantly cool the goods without a temperature gap. It's a good example of a product that combines the tradition of old root cellars and the modernity of a designed one.

A whole house built around the food storage in Sweden

When building engineers and husband-and-wife team Linda Hurtigh and Daniele Balzanetti decided to build their own house in Östersund, northern Sweden, they set out to create the perfect home for themselves and their two daughters, Anna-Linnea and Fiamma. They wanted to make it a passive house with extra attention spent on the growing and storing of food.

"We bring back a lot of food from Daniele's native Italy," says Linda, "plus we have a 49-square-metre greenhouse being constructed and a garden. So we need plenty of storage for long periods of time."

The underground food storage space was planned from the start and included on the architectural drawing board. The house is semi-subterranean, with the kitchen on the lower level, so the food storage is accessed through a door straight from the kitchen. "The only fridge we have is a very small one in the kitchen itself, under the counter top, where we store milk and cheese," says Linda.

There are two spaces in the food store: an anteroom that keeps a temperature of about 12ºC, and an inner room at a colder 8-10ºC. "We placed our freezer in the anteroom. Because it's in such a cold environment, it doesn't have to work quite so hard to keep things cold, and so uses less energy," says Linda. "According to the manufacturer, it should consume an annual 211kWh, but we have measured it, and it only uses about 150kWh per year! And that is taking into consideration the fact that we use it every day, so open and close it a lot, which increases energy use."

In the slightly warmer room, the family keep wine, oil and dry goods. The inner room "is perfect for storing onions, potatoes, prosciutto and the preserves and jams we make during the autumn harvest season," says Linda. More is to come when the new greenhouse is finished and put into use in 2016.

"The shock freezer avoids the loss of crispiness in food because it's able to maintain the structure during the freezing process."

Inventions to try in the kitchen

If you have no earth to dig into, or are not planning a new-build property, appliances that use innovative techniques are worth looking at. A distant relative of the fridge and freezer, the shock freezer (or blast chiller) uses a much wider range of temperatures with superb precision. Massimo Caudullo, the managing director of Italian company Coldline, explains what a shock freezer is for. "It's not a fridge. This specific appliance deep-freezes cooked food or chills fresh food in an amazingly fast way. While a traditional one takes up to 12 hours to freeze food, a shock freezer works much faster, taking less than half an hour! "Because the air inside the appliance can go down to -40°C, it cools to -18°C so quickly. It also chills fresh foods at 4°C in a few minutes. The deep-frozen food can then be stored in a normal freezer, but it gains 70% of additional shelf life, maintaining a high quality."

The shock freezer also helps to prove bread dough, make homemade yogurts, chill wine bottles quickly… Anything that needs to go up or down in temperature. To meet such a challenge, the appliance uses R290 gas, a refrigerant-grade propane that has a low environmental impact. It's non-toxic with zero ODP (Ozone Depletion Potential) and a very low Global Warming Potential (GWP) of 3.8 – a normal fridge usually has around a 10 GWP.

The technology has been used by pros, such as restaurants and hotels, for years, but is now available for home use. "It radically changes the food experience," says Robert Eckstein, a senior consultant for PCV Group in The Netherlands, dedicated to new product development. "The shock freezer avoids the loss of crispiness in food because it's able to maintain the structure during the freezing process." Increasingly desired by customers for its higher sensorial food experience and better food safety, the shock freezer has just been made for domestic use. The challenge was mainly to deal with the size and to fit it in a normal kitchen, like a microwave.

Same old fridge, but in new cool ways

The chill in our fridges is normally generated by a compression system, using a refrigerant that changes from a liquid to a gas state. It absorbs the food's heat and cools down the temperature of the airtight appliance. But now new alternatives are breaking through, with encouraging European technologies keeping our fridges frosty while being kind to the environment.

FrigoMobile, a kind of trolley with a cold unit, a solar light and a solar mobile charger exists. It's perfect for cold-drink sellers, isolated houses and those with nomadic lifestyles.

Solar cold

A dream for anyone wanting to live green, the solar fridge is now a reality. Made in France with European components, the fridges and freezers made by the Freecold company work with solar energy. Lionel Bataille, innovation and prospective manager, explains: "Thanks to a photovoltaic panel, this appliance uses solar energy to directly supply the compressor without a battery or voltage regulator. As soon as the sun appears, even if it's for a few minutes, the system produces cold, giving it complete independence for three days. It also has a strengthened thermic insulation to answer to A++ energy class." (The EU energy efficiency rating for domestic appliances starts at A+++ for the least energy consumed, and G for the most). A domestic version is still under development, but the FrigoMobile, a kind of trolley with a cold unit, a solar light and a solar mobile charger exists. It's perfect for cold-drink sellers, isolated houses and those with nomadic lifestyles.

Magnetic cold

This technology stems from the magnetocaloric effect discovered in 1881 by German physicist Emil Warburg. Magnetic cold works in a magnetic field under control, using cycles of magnetisation and demagnetisation done by specific alloys. To make it simple, these alloys are repeatedly submitted to the magnets' action: they get warm and then cool down. The heat is cleared by ventilation. The cold generated (around 0°C) then circulates in the fridge.

Cooltech Applications, a French company based in Alsace, has been developing this technology since 2003, and has won prizes for its sustainable innovations. Vincent Delecourt, commercial and marketing manager, illustrates its benefits: "Magnetic cold is totally green, without gas, and is a credible alternative to refrigerants used today that contribute to global warming. Also magnetic cold is much less energy-consuming. It could reduce a fridge's electric consumption by half." In 2016, a first test phase will be done on the professional market. It should be ready for domestic use in 2020, since technical limits and size have to be adjusted for home use.

Create cold using heat

Thinking that electricity is a sparse energy we have to save for appliances that really need it, young French company Coldinnov asked the question: to make cold, why don't we collect waste heat made by, for example, car mufflers or industry kilns? From this basic premise, Coldinnov is developing a new process to create cold using waste heat without electricity or compression.

So how does it work? In a specific reactor, gaseous ammonia is absorbed by a mix of expanded graphite and salts producing heat. This reaction is used to relax ammonia into an evaporator and to produce cold. This thermo-chemical process is totally reversible and reproducible. The contribution of heat collected on mufflers will invert the reaction: ammonia condense and a new cycle can start again. The development of home appliances is ongoing, but after its industrial launch, especially for refrigerated trucks, this technology may appear in our kitchens faster than we think!

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