Back in 2014, I posted a piece to Techso Mogro blog entitled, “Molten Salt an Answer to Renewable Energy Intermittency.” In it, I described how this inert and non-toxic material (a mixture of sodium and potassium nitrate) is an ideal energy storage and generating medium that makes solar capable of providing 24×7 on-demand power, solving the intermittency issue that operators of older forms of power generation always point to as the major flaw of the renewable energy model. Peak load, on-demand coal, and natural gas carbon-emitting thermal plants will no longer be needed by utilities that incorporate this zero-emission technology, a significant step in transitioning to a lower carbon footprint.
The State of South Australia has been working on a plan to become less carbon-dependent and lately has made some headline-grabbing strides in this effort. The first involved Elon Musk’s company, Tesla, with the installation of a 100-megawatt lithium-ion battery attached to a wind farm near Jamestown in the state’s north.
The second is the approval of the solar-thermal power plant near Port Augusta, to be built by SolarReserve, a California-based solar energy company. The facility covers an area of 5 square kilometers (2 square miles). Its central tower stands nearly 200 meters (650 feet) in height. The molten salt reservoir is over 30 meters (100 feet) tall. Its operation is simple. The sun reflects off thousands of heliostats each focusing the light on the receiver at the top of the central tower. The light heats the molten salt within the tower complex to 565 Celsius (nearly 1,050 Fahrenheit) degrees. The heat is transferred to water circulating through pipes in the system turning into steam which then drives conventional steam turbines attached to generators.
The advantages of the SolarReserve design become apparent when night falls because the very hot molten salt does not lose its heat load significantly throughout the darkness, and can reliably keep turning water into steam, and steam into electricity, generating continuous power up to 150 megawatts, enough to provide light, heat and air conditioning to 90,000 Australian homes.
The construction of the solar-thermal plant is to begin almost immediately and will mark the completion of South Australia’s move away from a reliance on coal power. In 2016, the state shuttered its Alinta Energy coal-powered thermal plant. This followed the ending of operations at the Leigh Creek coal mine in 2015.
South Australia has already met its 50% renewable energy target a decade ahead of schedule. When completed the plant will eliminate the equivalent of 200,000 tons of carbon dioxide emissions annually.
A lot has happened in a year and the IEA has once more updated its technology roadmap with a renewed focus on photovoltaics and solar thermal energy generation. Their prediction states, assuming continued technological progress and lowered production costs, that solar in all its forms could provide 27% of global electric energy by 2050. That would make it the largest source for electricity on the planet. The breakdown would be 16% photovoltaics and 11% solar thermal. To reach that number, however, the IEA states there must be a high price put on carbon.
In 2013 total solar photovoltaic electricity production equaled 36 Gigawatts installed. To hit 27% the world will have to create 200 Gigawatts capacity annually between 2025 and 2040. That’s only possible if carbon pricing penalizes fossil fuel energy sources.
And where will the energy be produced? Today China is the leader in photovoltaic energy production with the United States second. But the future is looking to places where solar energy is easier to harvest, south of the mid-latitudes and closer to the equator. These future solar energy produces will be the nations of Africa, the Indian subcontinent, and the Middle East.
Executive Director of the IEA, Maria van der Hoeven in releasing the IEA’s latest report stated, “The rapid cost decrease of photovoltaic modules and systems in the last few years has opened new perspectives for using solar energy as a major source of electricity in the coming years and decades….however, both technologies are very capital intensive: almost all expenditures are made upfront. Lowering the cost of capital is thus of primary importance for achieving the vision.”
Van der Hoeven went on to express the need for a clear and consistent policy on the part of government in support of renewables to reduce deployment risk and inspire confidence for investors. She pointed to “a record of policy incoherence, confusing signal or stop-and-go policy cycles” as being confusing to both investors and consumers and as a brake on development of new projects.
