Geothermal’s attributes – namely its widespread distribution, availability of over 97 per cent, small environmental footprint, and low emissions – are desirable for a sustainable energy future. But the use of geothermal energy is generally limited to highly fractured, fluid rich, high temperature resources near the surface. An untapped resource exists given that 90 per cent of the earth’s mass exceeds 1,000° Celsius.

For geothermal, it is not so much a technical deficit as it is an attention deficit that is holding its production back. We need only apply existing technology found in the oil patch, hard-rock mining, space, defence, and – most importantly – electronics. These lateral transfers of knowledge then need to be concentrated into 25 centimere diameter holes.

The path to commercialisation

Because geothermal is a low density energy, and is dispersed at depth in relatively hard rock, there are four basic problems on its path to commercialisation. While one of these problems is common to all power systems, the other three are distinct downhole challenges unique to geothermal.

Challenges

1. Generating efficient electricity

At the surface, the challenge is generating electricity as efficiently as possible from a low temperature heat source. Oil, gas and coal-fired power plants generate temperatures exceeding 500° Celsius.

Power generation is a function of temperature differential. Most of the developed geothermal resources are around 200° Celsius. Increasing efficiencies of low temperature systems is a power engineering challenge whose need is not confined to geothermal.

Below-surface challenges

Below the surface there are multiple challenges. Temperature, pressure and caustic fluids wreak havoc. Geothermal professionals have identified three broad areas; drilling, pumping systems, and reservoir management.

2. Drilling and well development

Drilling and well development can exceed 60 per cent of project costs. Unlike oil and gas, geothermal involves drilling into hard rock – many a diamond-tipped drill bit has been sacrificed in the name of geothermal. Drilling costs are a function of both surface and subsurface factors. Access, site development, workforce availability, and commodity costs vary from location to location.

Australia’s government is showing decisive leadership by tackling this technological challenge with its $50 million drilling program. As a nation, Australia is rich with hard-rock professionals who are taking their mining expertise and turning it towards geothermal. For a country with less than 1megawatt of geothermal power on line, there are over 40 geothermal companies actively developing resources around the country.

Globally, Australia is punching above its weight when it comes to geothermal. It is for this reason that Australia is a key partner with Iceland and the United States in the International Geothermal Partnership for Technology.

3. Pumping systems

On the pumping system front, the industry needs solutions that can surpass the limits of line shaft pumps or the limitations of existing electric submersible pumps. To that end, the Foundation for Geothermal Innovation is developing the Global Geothermal Challenge.

An incentive to be launched in 2010, the Foundation will award a $10.84 million ($US10 million) prize to the team that can design and commercialise a temperature hardened downhole pump. The five-year competition has already drawn the interest of major pump companies like Baker Hughes Centrilift and The Woods Group.

4. Reservoir management

The last challenge is geothermal reservoir management. Today, managing several hundred hectares of subsurface heat through five 25 centimetre holes is less a science then an art and for the industry to succeed it simply must practise. As more resources come on line and plant operators are given more time to stimulate, monitor and manage their reservoir field’s productivity will increase.

The future in Earth’s depths

Humanity has long been intrigued with the idea of going deep into the sea or to outer space. Deploying a thin narrow device to great depth within the Earth has garnered less attention.

Geothermal energy is not sexy. But it is prolific. And by borrowing some of the technical know-how from the minerals sector, the oil and gas industry, and the marine and space industries we can create the tools and systems to tap a ubiquitous clean energy.