How to Use Heat Energy Radiating from the Earth’s Core To Produce Food


In some developing economies, as much as half of all food produced is lost post-harvest – that’s due in part to a lack of affordable energy for food processing, according to “Uses of Geothermal Energy in Food and Agriculture”.

This makes the use of heat energy for drying foods, pasteurizing milk and sterilizing produce especially interesting for developing countries, where increased food processing can give a boost to food security.

Food drying can prolong the shelf life of nutritious foods like fish and vegetables and make them available year-round, including in times of drought.

Geothermal energy is also a prime source for heating greenhouses, soils, and water for fish farming, the report says.

Developing countries that have much to gain from harnessing heat energy for agriculture include those in the so-called Ring of Fire along the Pacific Plate, such as Mexico, Indonesia, the Philippines and various countries along the Pacific Coast of South America.

So do Ethiopia and Kenya in Africa’s Rift Valley, and transitioning economies in Eastern Europe, including Romania and Macedonia.

The case for geothermal

“It’s an energy source that’s renewable, clean and low-cost once you’ve made the initial investment to harness it,” says Carlos da Silva, Senior Agribusiness Economist in FAO’s Rural Infrastructure and Agro-Industries Division.

“By using a clean energy source, you’re not only addressing cost but also the environmental impacts of food production and processing,” according to da Silva.

Agriculture both consumes energy and emits greenhouse gases that contribute to global warming.

Research suggests that using geothermal heating for greenhouses decreases fungus infections and cuts fuel costs by up to 80 percent, providing significant savings to operating budgets.

And while oil and gas can be costly and scarcely available in parts of the world, the estimated 42 million megawatts (MW) of power that radiates from the earth’s 5000-degrees-celsius core won’t run out for billions of years.

“Geothermal energy for agriculture can be done even at small-scales and can significantly contribute to income generation, providing employment and improving food and nutrition security in developing countries,” adds Divine Njie, AGS Deputy Director and co-editor of the report.

From electricity to agriculture

Worldwide, 38 countries currently use geothermal energy for direct application in agricultural production and some 24 countries harness it to generate electricity, with Iceland, Costa Rica, El Salvador, Kenya, New Zealand and the Philippines deriving more than 10 percent of their electricity needs from natural heat sources.

Of the 23 developing countries that are using geothermal, the majority currently apply it to space heating and recreational purposes like bathing only, leaving its significant potential for agricultural uses untapped.

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Woman workers cultivating cucumbers in a greenhouse heated by hot spring water in China. | FAO

Still, successful geothermal agricultural projects are underway in just under half of those countries, including in aquaculture, farming and processing.

Success stories

A government-funded project in Algeria is supporting the building of fish farms that utilize hot water from drill holes to heat Tilapia ponds. The three farms built so far produce an average 1700 tonnes of Tilapia per year.

Iceland – which derives most of its heating and electricity from geothermal power — has been a leader in the use of geothermal power for agriculture since the 1920s.

In addition to greenhouse heating, some 20 companies across Iceland dry between 2000 and 4000 tonnes of fish each year, while an emerging industry for geothermal pet food drying is currently producing 500 tonnes of animal feed annually.


Start-up costs remain the main barrier to developing countries’ exploring geothermal energy uses on a larger scale, making it all the more necessary for governments to take a leading role in attracting investment and creating policy environments that support the sector, according to FAO.

“You can invest in ground proofs and not find any economically viable heat sources,” says da Silva, adding that even in successful cases, selling energy at a low cost can be a challenge when having to recover start-up costs.

Nevertheless, various projects outlined in the FAO report show that these obstacles are not insurmountable and investments worth exploring in the larger effort of making agriculture more sustainable. Indeed, “the FAO report also shows that there are direct-use opportunities which do not require high-cost exploration and exploitation,” says Njie.

An example of geothermal energy use: Drying chilies and garlic in Thailand

Chillies and garlic are highly popular in Thailand, where people eat them both fresh and dried. In one project there, waste heat from a geothermal power plant is being used to dry these important food products in compartments that can hold 450 kg of chilies or 220 kg of garlic at a time.

The required air temperatures are 70 °C for chillies and 50 °C for garlic. The total energy consumed is just 13.3 megajoules per kilogram of water evaporated for chillies, and 1.5 mj/kg of water for garlic. This type of dryer has relatively low running costs and can be used in any weather conditions. (*Source: FAO).

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