It sometimes seems that the news is packed with doom and gloom about our environment and climate change. Footage from around the world shows the destruction and devastation caused by extreme weather, and it appears to be getting worse by the day.
However, despite the depressing stories, there's still time to make a difference and slow down - or even reverse - the damage. But this can only happen if we embrace change and use renewable energy sources. It's time to stop relying on fossil fuel power plants!
At Heat Pump Gang, we firmly believe in sustainable energy sources. In this blog, we'll explore the advantages and disadvantages of one method that's often overlooked: geothermal energy.
Deep beneath the Earth's surface under your feet, the molten core is incredibly hot. Even though this is almost 2,000 miles down, the heat from the core affects the Earth’s crust and mantle.
This heat, called geothermal energy, comes from two main sources:
This heat travels upwards from the core, warming the rocks and fluids deep underground. In some places, hot springs, geysers, and steam vents are like nature's way of letting off steam, acting as a visible reminder of this hidden furnace.
We can now harness this heat for our own uses through geothermal power plants. These clever facilities use the Earth's heat in a few different ways, depending on what kind of geothermal resource is available:
These are the most common type, tapping into underground reservoirs of hot water. The hot water is brought to the surface through wells and can be used in two main ways:
In some areas, hot steam exists naturally underground. These plants simply capture the steam directly from wells and use it to spin turbines for electricity generation. This is a simpler process but less common than hydrothermal plants.
By using these different methods, geothermal power plants provide a clean and reliable source of electricity or heat.
For example, the Krafla geothermal power plant in Iceland (situated where tectonic plates meet on the mid-Atlantic ridge) uses heat from the Krafla volcano to produce a power output of 500 GWh of electricity per year!
Unlike fossil fuels, which are finite and take millions of years to regenerate, geothermal heat is constantly being replenished naturally. The Earth's core remains incredibly hot, and radioactive decay within the planet continues to add to this internal heat source. This ensures a reliable and long-lasting supply of clean energy for generations to come.
Geothermal power plants produce minimal greenhouse gas emissions, significantly reducing their contribution to climate change. This is because they primarily use steam or hot water to generate electricity*, releasing little to no harmful pollutants into the atmosphere. By choosing geothermal energy, we're opting for a greener future with cleaner air for everyone.
*The heat isn't just used for generating electricity; in Iceland, it's used to directly heat homes and greenhouses!
Unlike solar and wind power, which are dependent on weather conditions, geothermal plants can generate electricity twenty-four hours a day, 365 days a year, regardless of what the weather throws their way! This provides a stable and reliable source of baseload power that keeps our lights on and our homes comfortable year-round.
Geothermal power plants have a small land footprint compared to other renewable energy sources. This makes them ideal for locations with limited space or where preserving natural landscapes is a priority. Additionally, geothermal plants can often coexist with other land uses, such as agriculture or recreation, making them a versatile and space-saving solution.
Despite all these positives, geothermal energy production accounts for less than 0.3% of the UK's heat demand, probably because there aren't many of them around!
The UK currently has a single operational geothermal power plant (in Southampton), and a handful of others have been proposed or are under construction. Aside from this, there are small-scale projects, such as the one at the Eden Project.
We'll explain the possible reasons for this in the following section...
Geothermal energy is a fantastic renewable resource, but like most things, it does have some drawbacks to consider:
Unfortunately, geothermal power plants can't be built just anywhere. They need to be located near areas with accessible geothermal resources like hot springs, geysers, or reservoirs of hot water or steam. This limits its widespread adoption in areas lacking these features. In the UK, traditional mining areas are more likely to possess the right geology, and disused mines offer exciting potential for harnessing geothermal energy.
Drilling deep wells and building geothermal power plants can be expensive upfront. The exploration and drilling to find suitable geothermal resources can be a significant cost factor. Boreholes must reach depths of 2,000 to 5,000 metres in order to reach the geothermal reservoir!
Take a look: Ground Source Heat Pump Cost
While considered much cleaner than fossil fuels, geothermal plants aren't always entirely without environmental impact. There's a small chance of releasing relatively small amounts of greenhouse gases like hydrogen sulphide, carbon dioxide, or methane during the drilling process. Additionally, some geothermal plants use large amounts of water for cooling, which needs to be managed responsibly to avoid water scarcity concerns.
In rare cases, small earthquakes and surface instability can be triggered. This is usually related to the Enhanced Geothermal System, which uses similar techniques to Hydraulic fracturing (known as Fracking). Careful monitoring and responsible practices are crucial to minimise the risk of altering the Earth's structure on a local level.
While the Earth's heat source is vast, geothermal reservoirs in specific locations can become depleted over time if they're not managed sustainably. Careful planning and responsible extraction practices are essential to ensure the long-term viability of the resources.
As a renewable energy source, the geothermal plant potentially has a bright future in the UK, but only in certain areas where geothermal sources are located, and only if the government commits to funding a building program.
At present, it doesn't look likely that most of us will benefit from geothermal energy in the near future!
Even so, there is a way to reap the geothermal energy advantages without the need for large-scale power plants - sort of...
We're talking about ground source heat pumps!
Although sometimes referred to as the geothermal heat pump, ground source heat pumps could also be said to use solar power. Heat energy from the sun is stored beneath the Earth's surface, keeping the temperature relatively stable and constant all year round. Still, a heat pump also draws heat from the ground under our feet, some of which radiates upward from the molten core. This means we can call it geothermal energy without fear of contradiction.
Let's dig deeper (pun intended!) to see what it's all about...
Explore further: Heat Pumps And Solar Panels
Ground source heat pumps work in a similar way to a geothermal energy plant, transferring heat between your home and the ground to keep you comfortable year-round. They just do this on a much smaller scale:
Imagine the ground beneath your house as a giant thermal battery that stays at a relatively constant temperature throughout the year, cooler in summer and warmer in winter. A GSHP uses a network of pipes buried in your garden or a borehole drilled deep underground. A water-based solution circulates through these pipes, drawing in heat energy and transferring it to your home. A compressor squeezes the solution, increasing the heat dramatically (It’s all about physics!).
Dig deeper: What Is A Ground Source Heat Pump?
In the winter, when your house needs heat, the GSHP extracts heat from the ground (which is still warmer than the outside air). The ground loop fluid absorbs this heat and carries it back to your home. Inside, a heat exchanger transfers this thermal energy to the air or water in your heating system, keeping you warm.
Discover: Do Air Source Heat Pumps Work In Winter?
In the summer, the GSHP reverses its course. Now, the house is hot, and the ground is cooler. The GSHP acts like a fancy air conditioner, collecting heat from your home's air and transferring it to the cooler ground loop fluid. This heat is then deposited back into the earth, keeping your home comfortable and cool.
Pretty ingenious, right? But what are the real-world benefits of using a GSHP?
GSHPs offer a multitude of advantages over traditional heating and cooling systems:
By harnessing the Earth's natural, renewable source of energy, ground source heat pumps (or geothermal heat pumps) offer an energy-efficient, eco-friendly solution for year-round comfort in your home.
While upfront costs might be a consideration, the long-term savings, reduced environmental impact, and consistent comfort can make GSHPs a wise investment. Do your research, and consult a geothermal professional - like Heat Pump Gang! - and explore the potential of GSHPs to transform your home into a haven of sustainable comfort.
