4 months ago

Climate Action 2014-2015


THE CRESCENT DUNES PROJECT: CONCENTRATING SOLAR POWER WITH THERMAL ENERGY STORAGE By Daniel Thompson, Director of Development, SolarReserve Headquartered in Santa Monica, California, SolarReserve is a leading developer of large scale solar power projects and advanced solar thermal technology. With more than 5,000MW of projects under development, and more than US$1.8 billion of projects under construction and in operation including the flagship Crescent Dunes project, SolarReserve is a global leader in the development of solar power projects that can fully replace conventional coal, oil, natural gas, diesel and nuclear power stations. Its team has collectively built more than 15,000MW of projects across all power generation technologies and financed more than US$15 billion of projects. GAME-CHANGING TECHNOLOGY Long held as the holy grail of renewable energy, energy storage enables an intermittent resource – the sun – to be utilized at a scale and in a way that was never before cost-effectively possible. SolarReserve’s Concentrating Solar Power (CSP) with thermal energy storage technology utilises more than 10,000 heliostats (made up of an array of individual mirrors) that continuously track the sun across the sky and reflect the sun onto the top of a tall tower which holds the receiver. SolarReserve’s heliostat tracking technology was originally developed as part of the International Space Station (ISS), which orbits the earth 15 times a day and is required to continually realign its solar panels to capture energy from the sun to keep the ISS’s power systems operational. The accuracy of the tracking technology is critical to ensuring energy reflected by the heliostats is collected through the molten salt in the receiver and not spilled and wasted. Molten salt is pumped through the receiver from a cold tank, heating the salt from the reflected sunlight from 288 to 565 degrees C, where it is pumped into a heavily insulated hot tank and is able to be stored almost indefinitely. As electricity is needed, molten salt is dispatched from the hot tank through a heat exchanger to create superheated steam which then powers a conventional steam turbine. The molten salt is then returned to the cold tank where the process is repeated. The molten salt, which acts as both the heat transfer fluid and the energy storage medium, is maintained in a molten state for the entire 30 year life of the plant, never needs to be topped up and being a nitrate blend is able to be utilised as high grade fertiliser when the plant is eventually decommissioned. SolarReserve’s Concentrating Solar Power with molten salt energy storage process The de-coupling of energy collection and electricity generation enables SolarReserve’s CSP with molten salt energy storage technology to provide firm, reliable and dispatchable electricity – day or night. The technology enjoys 58

all the benefits of renewable energy – free fuel, zero emissions, low operation and maintenance costs, long-term certainty on electricity cost – together with all the benefits of a conventional power station – dispatchable, reliable, proven, and grid-friendly technology. The technology is highly customisable through the sizing of the steam turbine generator that is installed, enabling the same plant to operate as a peaking plant delivering a large amount of energy for a short period of time, a mid-merit plant generating less energy over a longer period of time, or as a base load power station. Unlike conventional steam power stations which incur higher maintenance costs for starting and stopping the power station due to thermal fatigue issues with their large boilers, SolarReserve’s technology does not utilise a boiler and is more flexible and better equipped for more frequent starting and stopping of the power station. CRESCENT DUNES – NEXT GENERATION SOLAR BECOMES A REALITY SolarReserve is currently commissioning the 110MW Crescent Dunes project in Nevada, USA, utilising its world leading SolarReserve’s technology is highly customizable in size and dispatch profile CSP with thermal energy storage technology. The project incorporates 10 hours (at full capacity) of molten salt thermal energy storage enabling the power station to operate for up to 16 hours at 110MW during summer, and 12 hours in winter due to the different seasonal solar resource. The project is contracted to supply NV Energy, Nevada’s largest utility, with a firm and reliable block of power from 12PM to 12AM for the next 25 years. NV Energy is the dominant electricity supplier in Nevada, supplying Las Vegas and Reno, which have high evening air conditioning and lighting demand that could not reliably be met with intermittent renewable energy sources. The Crescent Dunes project utilises 10,347 heliostats that are 115 square metres each, combining to provide more than 1.2 million square metres of mirrors reflecting energy from the sun onto the receiver. The receiver and tower stand 200m tall, and are located adjacent to the hot and cold molten salt tanks that each can hold 31,000 tons of molten salt. The site is approximately 2.8km wide covering an area of 630 hectares in the Nevada desert. The project is expected to deliver 500,000MWh of electricity each year, twice the generation of an equivalentsized photovoltaic (PV) project. The project has created more than 4,300 direct, indirect and induced jobs during construction and will create 45 fulltime roles to operate and maintain the plant. Unlike other renewable energy technologies, the vast majority of the construction of the Crescent Dunes plant has been completed using locally sourced equipment and locally sourced labour, injecting more than US$700 million into the local economy. The once booming mining town of Tonopah, 20 miles from the plant, has been revitalised from the investment, jobs and tax benefits delivered by the Crescent Dunes project. Crescent Dunes CSP with molten salt thermal energy storage project 59