In his February 15 column in Diario Estrategia, the academic and Director of the MCI in Energy and Environment at UAI highlighted SERC's contribution to the development of Solar Energy at the national level.
Column
Chile Can Lead the Development of Solar-Thermal Technologies by Adding Value to its Strategic Minerals: Lithium and Copper
The growing integration of NCRE sources into the country's energy matrix is recognized as one of Chile's main priorities to leverage its solar, wind, geothermal, and other potentials.
Monday, February 15, 2016 10:33
Lithium possesses a high thermal storage and transport capacity, and copper is an excellent heat conductor; therefore, the application of both materials in any thermal system, especially Solar-Thermal ones, would a priori be a significant contribution as they could improve efficiency, lower costs, and provide new added value to our strategic minerals, opening new markets for associated materials, products, and components.
It is well known that Chile possesses more than 60% of known Lithium reserves, is the world's leading Copper producer, and is endowed with one of the planet's highest solar energy or radiation potentials. Regarding materials, our country has declared Lithium a strategic mineral, and copper is also considered strategic due to its obvious importance to the national economy, contributing approximately 10% of our GDP according to figures from the Mining Council. Despite these encouraging data, our country must be careful to pursue sustainable development so as not to depend exclusively on market fluctuations. Sustainable development requires the transformation of its resources into other forms of wealth, such as buildings, machines, new materials, and human capital. Following this sustainability approach, certain evaluations can be made to determine if it is technically and economically viable to transform the country's lithium reserves and copper availability into competitive energy produced in the same region where these metals are obtained, favoring local communities and the region in general.
The growing integration of non-conventional renewable energy (NCRE) sources into the country's energy matrix is recognized as one of Chile's main priorities to leverage its solar, wind, geothermal, and other potentials. The Paris Climate Summit (COP 21) has highlighted the significant role that renewable energies will play in the world's energy future and, in Chile's specific case, it has been established that Solar energy will lead its development, creating important initiatives such as the CIFES-CORFO "Solar Strategic Program" (http://cifes.gob.cl/programas/programa-estrategico-solar/), the CONICYT "Solar Energy Research Center" (SERC-Chile, sercchile.cl/), and supporting the establishment of centers of excellence such as Fraunhofer and Laborelec.
One of the largest and most significant problems that these national initiatives, and countries in general, must solve is the intermittent nature of solar energy, which makes it difficult to match energy supply with demand. Particularly for concentrated solar power (CSP) or Solar-Thermal plants, Thermal Energy Storage (TES) is considered a key alternative that allows plants to operate when solar radiation is unavailable, increasing the plant's capacity factor from a range of 20% to 25% without a TES system, to 40% to 50% with 6 – 7.5 hours of TES. In fact, Chile is preparing to host a new solar thermal power plant with a capacity of 110 MW, which will feature an advanced storage system allowing it to operate with a capacity factor of 80% and generate electricity for up to 17.5 hours without sun. The main TES material in CSP plants, also used in some technologies as a Heat Transfer Fluid (HTF), is liquid or molten salt composed of 60% NaNO3 and 40% KNO3, also known as "solar salt," which is kept hot at temperatures above its melting point of 223 °C, and for which Chile is also the world's No. 1 producer. It should be noted that these TES and HTF materials can always be improved, and significant research efforts are already underway worldwide to develop more efficient new materials that allow for cost reductions. Firstly, the development of new materials with a lower melting point for use as TES and HTF is a key challenge, as this will prevent, for example, solidification blockages in pipelines below the melting temperature, energy self-consumption expenses, and other CAPEX and OPEX costs. In this context, some recent preliminary studies on thermal materials for CSP (http://www.mdpi.com/2071-1050/8/2/106/htm), such as those conducted by researchers Macarena Montané, Shahriyar Nasirov, and Raúl O’Ryan from Universidad Adolfo Ibáñez (UAI), which show that salt mixtures with lithium nitrate may be a potential alternative for resolving the risk of solar salt solidification in two-tank TES systems, potentially reducing the levelized cost of energy (LCOE) by up to 4% and improving system efficiency due to the high energy power of Lithium.
Furthermore, since materials with higher energy densities reduce the required amount of storage material, latent heat storage with solid-liquid phase change materials (PCM) has also been identified as a possible alternative to improve TES systems. These PCMs exhibit low thermal conductivity, which causes a decrease in the heat transfer rate and energy utilization efficiency. In particular, copper, which possesses high thermal conductivity, is considered one of the ideal and most promising materials for heat transfer. Some studies have already been conducted where, for example, copper foams [1] and copper-encapsulated PCMs [2] would be a good solution, but their manufacturing cost must still be reduced, as it currently makes their implementation economically unfeasible.
In conclusion, Lithium and Copper are very promising materials; we are on the right track to achieving outstanding development in the thermal and solar industry, but to reach a successful outcome, we must never abandon support and interest for innovation.
Gustavo Cáceres
Director of the MCI in Energy and Environment at UAI
