Technology Status - NET Nowak Energie & Technologie AG

The following are areas where R&D can improve the techno-economic
performance of geothermal power:
● Plant refurbishment can increase the plant’s efficiency and availability,
taking account of the thermodynamic characteristics of the geothermal
fluid for any given site.
● Generating electricity from low-to-medium temperature geothermal
fluids and from the waste hot water coming from the separators in waterdominated
geothermal fields has made considerable progress. By
selecting suitable secondary fluids, binary systems have recently been
designed to utilise geothermal fluids temperatures of 85/90°C to 175°C.
For example, one company is exploring the use of the Kalina cycle, a
binary cycle that uses a mixture of ammonia and water as the working
fluid. This cycle has the potential to extract one-third more energy from
the geothermal fluid than a conventional cycle.
● More automation to decrease labour costs for O&M.
● Reservoir management aimed at increasing the production rate and
lifetime will thus improve the sustainability of the resource (e.g. injection,
re-injection, well stimulation). An example is the reservoir depletion
problem at The Geysers (USA) where reclaimed wastewater is
transported from several communities and injected into the reservoir.
This approach not only prolongs the life of the geothermal resource by
slowing the loss of the reservoir volume over time, but also provides a
solution to wastewater disposal problems.
● Expansion of the explored zone, which in general is less risky than
exploring a brand-new area.
● Development of more accurate and lower-cost methods for finding and
mapping geothermal resources. Recent accomplishments include
instrumentation that can operate in hotter environments, and more
accurate field survey procedures. Before drawing up a geothermal
exploration programme, all existing geological, geophysical and
geochemical data should be collected and integrated with any data
available from previous studies on water, mineral and oil resources in the
study area and adjacent areas. This information frequently plays an
important role in defining the objectives of the geothermal exploration
programme and leads to a significant reduction in costs and less financial
risk for project development. In general, only a small portion of an area’s
geothermal potential has been explored and exploited.
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