Fri, 12 June, 2020
Due to the increasing penetration of variable renewable energy resources, such as solar PV and wind, grid security and stability is becoming one of the challenges in transitioning to a secure and low-carbon energy future. GeoSmart aims to transform geothermal plants into flexible sources of power, allowing them to respond quickly to the changes in power demand and increase grid stability and reliability.
The project’s main aim is meeting the different flexibility needs of operating geothermal power plants with low enthalpy and high enthalpy sources at demonstration level. In addition to this, the evaluation of future scenarios, including the synergistic effects of geothermal with other renewable energy resources such as biomass and solar thermal, is one of the objectives of GeoSmart to offer an insight on hybrid power plant opportunities and make informed future energy investment decisions.
Advantages of Hybridisation
Compared to equivalent stand-alone power plants, cost effective power generation is possible with hybrid power plants. Since the infrastructure can be shared, the need for a land, grid infrastructure, and transmission lines are eliminated. Therefore, the investment costs are minimised meaning that greater capital utilisation is achievable with hybridisation.
Hybridisation can play a key role to convert weakness into strengths. For example, the efficiency of geothermal power plants drops significantly during hot summer months, while the solar insolation is at maximum. Introducing a hybrid geothermal concentrated solar thermal system, the effect of seasonal variations in temperature can be eliminated if the solar heat is utilised in geothermal power generation. In addition to this, the maximum temperature available in geothermal plants is notably lower than with concentrated solar or other thermal plants, and accounts for lower thermal efficiencies compared its counterparts. This weakness can be converted into a strength if the low temperature geothermal source can be utilised as a heat sink for the high temperature resource.
Hybridisation at Kizildere site (Turkey)
Geothermal is commonly described as the most location-specific energy source due to its limited availability in tectonically active areas. Therefore, hybridisation of geothermal becomes a site-specific phenomenon, as well. GeoSmart is exploring the potential of hybridisation of the high enthalpy site at Kizildere-1 with a locally available biomass source; olive residue. Olive residue is a solid by-product of olive oil production and possesses a calorific value around 4800 kcal/kg. Specifically, the olive oil production is quite common in Western Turkey and even the Kizildere power plant is surrounded with olive trees. In order to exploit the potential co-existence of two renewable resources, geothermal and biomass, GeoSmart is aiming to develop a hybrid scenario that is also using an alternative power cycle; sCO2. Supercritical CO2 cycles, generally abbreviated as sCO2, are next generation thermodynamic cycles that are currently under development. sCO2 cycles can offer competitive efficiencies, have a small footprint, can be ramped up and down rapidly, and therefore supports flexible operation.
The studies to combine the synergetic effect of geothermal, biomass and next generation cycles are still in progress.
Article courtesy - METU