FAQ – Corporate

Hybrixcel vision is to be a global leader in energy efficiency.

Hybrixcel welcomes academic and industrial partners to scale up and commercialize our projects and technology in the field of power generation mainly geothermal energy.

We may consider government funding options and investment from capital providers if the terms are right.

FAQ – Geothermal Energy

Until a century ago, the exploitation of geothermal resources was primarily for leisure purpose; hot springs and geothermal baths. It was at the beginning of the 20th century that active exploitation of geothermal resources for electricity supply purposes was inaugurated. Successful production of electricity from geothermal heat was first achieved in Larderello in Italy, in the early 1900s. Since this period, the production of geothermal electricity has steadily increased.

Geothermal energy is recognised to be a safe, reliable, environmentally benign energy, which produces renewable energy resources to generate electricity and/or heating and cooling while producing very low levels of greenhouse-gas (GHG) emissions.

As underlined in by the authors of the IPCC report (2010):

‘The natural replenishment of heat from earth processes and modern reservoir management techniques enable the sustainable use of geothermal energy as a low-emission, renewable resource. With appropriate resource management, the tapped heat from an active reservoir is continuously restored by natural heat production, conduction and convection from surrounding hotter regions, and the extracted geothermal fluids are replenished by natural recharge and by injection of the depleted (cooled) fluids.’

At present, geothermal production of heat and power is on-going in a number of geological environments where the temperatures and depths of the reservoirs vary accordingly. Many high-temperature (>180°C) hydrothermal systems are associated with recent volcanic activity and are found near plate tectonic boundaries, or at crustal and mantle hot spot anomalies. Intermediate- (100 to 180°C) and low-temperature (<100°C) systems are also found in continental settings with or without (in case of Enhanced Geothermal Systems: EGS) hydrothermal resources. Under appropriate conditions, high-, intermediate and low-temperature geothermal fields can be exploited for both power generation and the direct use of heat.

What are some of the evidence of geothermal energy? Some visible features of geothermal energy are volcanoes, hot springs, geysers, and fumaroles. Usually geothermal energy is deep underground. In many cases, there may be no visible evidence above ground to what exists below the surface. Geologists use many methods to find geothermal resources. They may;

  • study aerial photographs and geological maps,
  • analyze the chemistry of local water sources and the concentration of metals in the soil,
  • measure variations in gravity and magnetic fields,

Despite these scoping methods, the only way to be sure that there is a geothermal resource is by drilling wells to measure underground temperatures. The earth is a hot bed of geothermal energy. The most active geothermal resources are usually found along major plate boundaries where earthquakes and volcanoes are concentrated. Most of the geothermal activity in the world occurs in an area known as the “Ring of Fire.” The Ring of Fire is found at the tectonic plate margins along the Pacific Ocean and is bounded by Japan, the Philippines, the Aleutian Islands, North America, Central America, and South America.

There are two commonly used processes when creating electricity from geothermal sources. The first, conventional geothermal: flash or dry steam, is generally associated with higher temperature geothermal sources (>180°C). As the pressure of the subsurface environment is much greater than at the Earth’s surface, water can exist as a liquid/steam at very high temperatures.

Flash: The high temperature, high pressure water is brought to surface, where it is enters a low pressure chamber and ‘flashes’ into steam. The pressure created by this steam is channelled through a turbine, which spins to generate electrical power. Once the steam has exited the turbine, it is either released into the atmosphere as water vapour, or it cools back into liquid water and is injected back underground.

Dry Steam: dry steam power plants utilise straight-forwardly steam which is piped from production wells to the plant, then directed towards turbine blades. Conventional drysteam turbines require fluids of at least 150°C and are available with either atmospheric (backpressure) or condensing exhausts.

The second common method, binary geothermal: Kalina or Organic Rankine Cycle: ORC, is common with lower temperature geothermal resources. It operates on the same principle that when a liquid is heated into a vapour, the resulting pressure can drive a turbine. However, because the temperatures are often too low to ‘flash’ water in a binary system, the heat of water must be transferred to a separate liquid with a lower boiling temperature. The separate liquid is called a ‘working fluid’. When the hot geothermal water is brought to surface from deep underground, it is run through a ‘heat exchanger’ which transfers the heat from the geothermal water to the liquid working fluid. Because the working fluid boils at a low temperature, it vaporizes readily with less geothermal heat, and this vaporization produces enough pressure to drive a turbine. What makes a binary system unique is that it operates as a 2 closed-loops (hence, binary); neither the geothermal water nor the working fluid are exposed to the surface environment. All the water that is brought to surface is re-injected, and after vaporizing, the working fluid is cooled to its liquid state, so it may repeat the process. There are no-emissions in the binary geothermal cycle.

So far, geothermal technology development has focused on extracting naturally heated steam or hot water from natural hydrothermal reservoirs, and these technological systems for geothermal electricity production can be subdivided in three large categories, which are also linked to the temperature ranges:

1) 80°C<T<180°C (Medium Enthalpy resources): this range of temperature is appropriate for use with binary plants (Organic Rankine or Kalina cycle), with typical power in the range 0.1-10 MWe. These systems are also suitable for heat & power co-generation, typically for single edifice to small towns heating.

2) 180°C-390°C (High Enthalpy resources): temperatures in this range can be exploited with dry steam, flash and hybrid plants, with typical power in the range 10-100 MWe. These systems, characterised by high efficiency up to more than 40%, also allow heat cogeneration for large towns’ district heating. Above 200°C, these resources are generally limited to volcanic areas.

3) 390°C-600°C (Supercritical unconventional resources): temperatures in this range, limited to volcanic areas, generally involve superheated dry steam plants, with power per unit volume of fluid up to one order of magnitude larger than conventional resources.

However, geothermal energy has the potential to make a more significant contribution on a global scale through the development of the advanced technologies, especially the exploiting of hot rock resources using enhanced geothermal systems (EGS) techniques that would enable energy recovery from a much larger fraction of the accessible thermal energy in the Earth’s crust.

EGS (Enhanced Geothermal Systems), uses the high temperature of rocks with artificial water injection and, generally, with enhancement of permeability of the hot reservoir. An Enhanced Geothermal System is an underground reservoir that has been created or improved artificially.

As a renewable source of energy, geothermal is widely regarded as having major advantages over other energy sources in relation to climate impact and reliability.

The IEA underlined this point in its Geothermal Technology Roadmap:

‘Geothermal typically provides base-load generation, since it is generally immune from weather effects and does not show seasonal variation. Capacity factors of new geothermal power plants can reach 95%. The base-load characteristic of geothermal power distinguishes it from several other renewable technologies that produce variable power.’ (2011).

In addition, as stated by the IPCC report of 2010, ‘climate change is not expected to have any major impacts on the effectiveness of geothermal energy utilization, but the widespread deployment of geothermal energy could play a meaningful role in mitigating climate change.’

Geothermal energy has;

‘several significant characteristics that make it suitable for climate change mitigation. These include: global-wide distribution; indigenous resource; production independent of season; immune from weather effects and climate change impacts; effective for on and off grid developments and for provision of base-load power. In off-peak periods this base-load generation can also be used to recharge battery-powered vehicles, helping to mitigate CO2 emissions from fossil-fuelled transportation.’

Environmental and social impacts from geothermal use are site and technology specific and largely manageable. Overall, geothermal technologies are environmentally advantageous because there is no combustion process emitting carbon dioxide (CO2), with the only direct emissions coming from the underground fluids in the reservoir. Direct CO2 emissions for direct use applications are negligible and EGS power plants are likely to be designed with zero direct emissions.

Concerns on the consequences of exploiting geothermal resources have been cited at the local level, where natural phenomena, such as micro-earthquakes, may be influenced by the operation of geothermal fields. Induced seismic events have not been large enough to lead to human injury or relevant property damage, and proper management of this issue is a key factor in project development for EGS.

There are significant other benefits to be identified in terms of geothermal development. One particular benefit its local job creation, during the whole lifespan of a project.

No. If managed efficiently, the resource will not be depleted. Geothermal energy is a RENEWABLE form of energy. The long term sustainability of geothermal energy production has been demonstrated at the Lardarello (Italy) and Wairakei (New Zealand) geothermal fields which have been in production since 1913 and 1958 respectively. Although pressure and production declines have been observed at some plants, operators have been developing practices (such as the reinjection of waste water into the geothermal reservoir) in an effort to maintain the reservoir pressure.

A baseload power plant produces energy at a constant rate.  Because the energy is constant, its power output can remain consistent nearly 24 hours a day, giving geothermal energy a higher capacity factor than solar or wind power, which must wait for the sunlight or the wind, respectively.  This means a geothermal plant with a smaller capacity than a solar or wind plant can provide more actual, delivered electricity.