While most experts predict wind and solar will dominate the renewable energy mix in the decades to come, there’s another abundant energy source with massive potential: the earth itself.
Geothermal energy is heat derived from the sub-surface of the earth and can be used for heating, cooling and electricity generation. Like wind and solar, it’s considered an abundant resource — lasting some 17 billion years in the case of a global conversion to geothermal energy — but it has the added benefit of being free of the uncertainty of weather conditions.
So why isn’t the whole planet powered by the heat beneath our feet?
Geothermal energy is theoretically accessible from anywhere, but requires producers to drill at much deeper depths than what is standard today. This drives up costs and also poses technical challenges, which explains why geothermal has remained a niche energy source that only accounts for less than 1% of the world’s energy supply since it was first tapped into over a century ago.
But the calculus is shifting, as new drilling technologies developed in recent years have brought geothermal back into the public consciousness, with investment increasing and new research projects underway. Here’s an overview of the benefits, challenges and innovations moving the sector right now:
GEOTHERMAL ENERGY BENEFITS
- Global access. The center of the earth is the same temperature as the surface of the sun (6,000 C), but our ability to harness the heat isn’t dependent on weather conditions. Unlike many other renewable energy sources, geothermal is accessible from anywhere on the planet.
- Small land impact. Geothermal power plants tend to be compact, occupying eight times less land per GWh than coal and solar, and three times less than wind farms.
- Low or Zero CO2. While the technology used to turn the resource into electricity varies, the most modern “closed-loop systems” (gases removed from the well are injected back into the ground) emit no greenhouse gases at all. If accounting for emissions released during plant material fabrication and construction, CO2 emissions from geothermal plants are still four times less than solar PV and up to 20 times less than natural gas-fired power generators.
GEOTHERMAL ENERGY CHALLENGES
- Geographical limitations. Geothermal heat is usually exploited by pumping up hot water from 1.5 to 3 kilometers underground. But regions rich in shallow hot springs and other natural hot water reservoirs — like those that exist in Iceland and California — are few and far apart. In order to access heat from anywhere on the planet, geothermal companies that typically drill to a maximum depth of 5 kilometers would have to go three times deeper which poses technical issues and drives up costs.
- Logistics. Geothermal power plants must be built near the reservoirs since long-distance transportation would cool the steam and hot water.
- Up-front costs. geothermal systems remain expensive to develop, with estimates typically hovering around €2,000 per installed kilowatt for larger facilities — or roughly double that of wind farms. For geothermal, the exploration and drilling of new reservoirs typically accounts for half of total costs. However, geothermal systems can be more cost competitive in the long run due to lower system maintenance.
- Earthquakes. Many of the places suited for geothermal energy extraction are also located in areas that are very tectonically active, which means there is a risk of earthquakes or volcanic activity.
INNOVATIVE SOLUTIONS, NEW PROJECTS
- Oil &Gas to the rescue .
As geothermal is gaining a following, oil and gas companies see an opportunity to apply their exploration and drilling expertise in a renewable sector. Chevron and BP recently announced they will invest $40 million in Eavor Technologies, a Canadian geothermal company — marking the first time in recent history that the oil industry has made a big investment in geothermal. With geothermal startups multiplying around the world, oil and gas majors can fill the triple function of transferring valuable skills, buying up promising companies while developing new drilling technologies that can reach much deeper into the earth.
- Self-powered system.
Eavor Technologies has pioneered an unpowered looping fluid design that doesn’t require hot-water reservoirs to produce electricity. Instead, water is pumped through a closed-loop network of pipes 3 to 4 kilometers below the surface where it’s heated, creating an underground radiator. The hot liquid is then converted into electricity or transferred to a district heat grid. Similar technologies typically lose between 50-80% percent of the yield due to the power needed for pumping, while Eavor’s closed-loop system self-perpetuates once it's running.
- Horizontal drilling.
A Dutch-led consortium of European partners have developed a drilling technology that could enhance geothermal energy production at lower costs. Based on oil and gas-drilling techniques, the technology allows for horizontal drilling from a main well which increases production at much lower cost. It also increases the chance of finding good reservoir formations.
- Domestic heating
U.S.-based startup Dandelion Energy has designed a home-adapted drill that only requires seven feet of space to drill down the 300 to 500 feet needed to reach the 55 degree temperatures. In the winter, the ground loops more heat stored in the ground into your home. In the summer, it returns heat from your home to the ground. The company has received a $30 million cash infusion from Bill Gates-backed Breakthrough Energy Ventures.
THASSALIA - Using Ocean’s Thermal Energy
ENGIE has inaugurated Europe’s first-ever marine geothermal power station in France. Built at the Marseille-Fos Port, the power station Thassalia will use the sea’s thermal energy to produce space heating, water heating and air conditioning services for local buildings spread over an area of around 500,000m2 — reducing greenhouse gas emissions by 70%.
TARGEO - Discovering Geothermal’s Commercial Potential
Engie-subsidiary Storengy has launched its targeo project that provides building-specific, regional analyses to identify the economic potential of geothermal energy. The solution leverages data processing to evaluate the underground and geothermal potential — measuring the characteristics of buildings and their demand, as well as the existing infrastructures. In addition, the Targeo team also has dedicated further investments to support the local implementation of CO2 targets through geothermal natural resources.