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17 November 2020

What is Geothermal Energy?

By Ben Strange, CEO Strada Global

To put it simply, it’s the heat beneath our feet. Did you know that at its core, the earth is roughly as hot as the surface of the sun? About 4,000 miles down, the earth’s molten core is over 6,000°C (or 10,800°F). That heat isn’t disappearing anytime soon – thanks to the continuous decay of naturally occurring radioactive elements which generate roughly 30 terawatts a year – almost double all human consumption.

If we could drill and recover just a fraction of the geothermal heat that the earth holds, there would be enough to supply the entire planet with clean and safe energy. 

A few more benefits for geothermal energy: it’s an inexhaustible energy source that’s emission free. It’s found everywhere in the world and is available all the time – what’s called ‘baseload’ energy – as opposed to other renewable energy sources like wind and solar which depend on certain conditions. 

The solution to the world’s clean energy needs is right beneath our feet. All we have to do is tap into it. 

 

How do we access geothermal energy?

 

The challenge that the geothermal energy industry has faced up until now is – how do we get down deep enough to access geothermal resources? Traditionally, drilling for geothermal has been slow, risky and costly, which has meant that geothermal projects haven’t had the uptake you’d expect for such an incredible renewable source of energy.

What the world needs is innovation in drilling technology that can access this constant energy under our feet – fast and cost-efficiently. And that’s where we come in. 

The best route to accessing real geothermal heat is by drilling deep, in hot, dry rock – which is our niche expertise here at Strada. To understand why our technology makes a difference, it’s helpful to understand the two main drilling methods that exist. Air percussion drilling has always been really good at drilling fast and into hard rocks. It’s quick and cost-effective, but it has a depth limitation. It’s only really been developed for depths down to 1000 metres. The deeper you go, the more air (or compression) you need, and the more fuel you need to use to get the hammer down. It’s not so much the driving force, it’s the cuttings – when you drill, that dirt needs to go somewhere and you have to push it back up the well. And that’s the limitation of air percussion. 

The opposite is true of the second main drilling method – mud rotary. Mud rotary drilling doesn’t theoretically have a depth limitation, except for loss of gauge, and the time and money it takes. It’s good at drilling large diameter wells where air percussion can struggle. It’s good at controlling wells, keeping the profile protected and it’s very good for lifting the cuttings back up to the surface, using aerated drilling muds that can gradually lift that dirt. 

Mud rotary drilling is great in soft rock or sediment. However, it starts to become very expensive when you hit hard rock. As an example, if you imagine drilling with a hand held drill into a wall of hard rock, the drill will heat up, you’ll lose size and the drill bit will eventually wear to pieces. It’s only when you put the drill bit on a percussion or on a hammer setting that you can drill through that wall much easier. Mud rotary drilling is extremely slow when you’re drilling in hard rock – which means more time and more costs for geothermal projects.


Our successful geothermal drilling technology


Our patented Fluid Hammer Operating System (FHOS) technology combines the advantages and safety aspects of the two leading drilling systems into one solution. It brings together the well control of the mud rotary system with the high penetration rates found in air hammer percussion systems and can be easily adapted to most drilling rigs. You can watch an animation of how it works here. It enables us to drill quickly and cost-efficiently in hard rock, unlocking the potential of geothermal energy, anywhere on the planet. 

There are a lot of new technologies being explored which all claim to revolutionise drilling, from rocket science to plasma, laser beams and sonic waves. The difference with Strada is that we don’t see our technology as revolutionary. It’s evolutionary. We’ve simply evolved it from combining the best drilling methods to date. We don’t have to do twenty years of testing to know that this is the solution, because there has already been a hundred years of testing on the technology behind us. 

 

ROP – Accessing geothermal energy fast

 

When it comes to how technology can impact on hard rock drilling times and cost, the answer lies in the ROP – rate of penetration. We can say that we are comfortably drilling an ROP of 30 foot an hour with our 12-inch hammer in hard rock right now. To put that into perspective, a mud rotary ROP in a similar hardness of granite can drop to as low as a couple of feet an hour. Our technology is built for hard rock, or very deep ground. That’s where we really add ultimate value in both time and cost savings. 

We believe that the value of our technology lies in the way that it can dramatically increase ROP in hard rock, reducing drilling costs substantially, and making geothermal energy a viable prospect in many more areas of the world.  

What we’re really excited about are deep wells, because it allows us to demonstrate the exponential benefits of our technology at depth. When a traditional mud rotary bit wears out – which is around every 20 metres – it takes a very long time to ‘trip’ the bit back up the well, replace the bit and ‘trip’ it back down again. Let’s call it a day. The deeper you are, the longer the ‘trip’ takes and the more your costs increase. 

Our hammers last 100-200 metres because of our patented technology. And that time saved, both in how fast we can drill and fewer trips, benefits us hugely the deeper the well gets. 

 

Why Strada is empowering change for geothermal energy

 

Our modus operandi here at Strada is to develop simple solutions to complicated problems. And that’s why we feel we are leading at the moment on hundreds of years of technology development, by combining the best parts of it. We’ve successfully drilled to 4,500 metres straight down into hot dry rock. We’ve also got the benefit of a dual circulation technique which can deliver whatever fluid you want – high enthalpy, low enthalpy – to constantly cool as we drill. 

In conclusion, geothermal energy isn’t new. It’s been used for millennia, and it’s still here, right beneath our feet, with the potential to easily supply the world’s energy needs.
There are some fantastic engineering companies across the world that, once you have that heat, can turn it into applications and harness the power of clean energy. 

The problem though has always been accessing geothermal energy. And that’s what we’re here to solve. 

At Strada, we believe that our technology can solve one of the biggest challenges facing the planet today – the search for clean, renewable energy. We feel we’ve developed, patented and successfully tested the solution to the barriers facing widespread geothermal development.

Our aim now is to back up our claims and get ‘beats’ on our hammer to prove to the industry and the world that this solution is suitable, it’s working and in action and it can be the next step to finally being able to access geothermal energy quickly and cost-efficiently, anywhere in the world.