In the third guest blog from Alstom Power, Christian Bohtz, Product manager gas power plant applications, Alstom Switzerland explains how solar and gas power can be used in tandem to great effect
Attempts to combat global warming are moving power generation towards an increasing role for renewable energies – C02 reduction is a priority for all. The Middle East has seen several countries introduce renewable targets of up to 20 per cent. The area has abundant open space and sunshine, making solar power central to power strategies in the region.
Solar power, however, is cyclical, the power it can generate during night time is minimal. An advantage is that solar power generation does create peaks at times of high requirement; it will generate the greatest power levels around midday when demand peaks. However, during times of weak sun, solar may struggle to meet demand and needs ‘back-up’ to ensure constant supply. Therefore, finding a suitable back up is the major question for any solar power station.
For the Middle East, an area rich in fossil fuels, and power stations extracting them, an effective answer lies in the Combined Cycle Power Plants (CCPPs) that are already utilising the region’s natural gas.
CCPPs offer a constant supply of power, but ALSO create CO2. Alstom Power has the ability to integrate a CCPP with a solar plant using equipment and infrastructure of the CCPP to generate solar power; an Integrated Solar Combined Cycle (ISCC) power plant. This allows operators to create a power plant that USES clean, low cost solar energy at peak times whilst a constant, assured flow of electricity is generated even when solar generation is limited, from natural gas production.
The ISCC approach utilises the components of a CCPP: no extra power block is needed, the steam turbine, generator, water steam cycle (WSC), plant infrastructure and grid access of the CCPP is in shared use with the solar field. The additional steam produced in a solar receiver through concentration of solar energy is integrated in the CCPP and expanded in the steam turbine, converting solar energy to electricity.
Consequently, initial installation costs are reduced as a full solar power plant doesn’t need to be installed. Generation costs of the solar power are significantly reduced and no back-up boilers are required to cover cloudy periods or sudden spikes in demand.
The efficiencies created by this combined, flexible approach are also significant. ISCCs can acheive efficiencies above 80 per cent and can boost energy production at peak times by 20 per cent through solar boost mode. Energy production levels can also be maintained at a constant level whilst lowering natural gas consumption to improve a plant’s environmental footprint.
Alstom is partnering with solar technology provider, BrightSource, to build ISCCs using the most efficient solar tower technology. One Brightsource project, the Ivanpah Solar Electric Generating System (ISEGS) in the Mojave Desert saw its first steam produced in 2012 and will be completed this year. The plant will power 140,000 homes during peak hours and will reduce CO2 emissions by more than 400,000 tons per year.
Integrated Solar Combined Cycles – CO2 reduction is a priority for all. However, renewable energies don’t currently supply constant energy. For instance, solar energy’s power generation capabilities are cyclical across the day – its output will peak at midday and reduce as the day matures. By integrating solar thermal technology with gas power stations, we can guarantee power continuity whilst reducing CO2 output.
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