Widespread use of solar energy is hobbled by two fundamental factors: storage and cost. If environmental cost is not considered, which typically are hard to assess, the cost of solar energy still remains one of the single largest hurdles hindering the implementation of photovoltaic as a mainstream power source. But in recent years solar power is rapidly approaching the grid-parity-where the cost of electricity generated from solar power equals or less than that from conventional, longstanding grid sources such as natural gas, nuclear and fossil fuel power plants. This has been made possible by the improvement in solar cell technology such as introduction of the thin film solar cells.
The governments around the world on the other hand, in order to provide impetus for the growth of renewable energy, are coming up with policies such as feed in tariffs, financial incentives and subsidies that could help reduce the PV cost and further brings it closer to the grid-parity.
Storage of the energy is also a major stumbling block for the solar energy system usage. However this could be a thing of the past with a inspiring new storage technology invented by an MIT professor Donald Sadoway. The Liquid Metal Battery, which is made out of liquid metal, is a silent, emission free, scalable and cheap to make battery, which could solve the intermittent problems that have prevented the adoption of wind and solar power into the mainstream and bridge the missing link to renewable energy. This battery is capable of containing large amounts of energy, which would allow renewable energy to be stored and therefore contribute much more effectively to grid-level power demands and as well be effective supplier of energy as nuclear and coal. In his TED talk he explains "today there is simply no battery technology capable of meeting the demanding performance requirements of the grid--namely uncommonly high power, long service lifetime and super-low cost. The invention could possibly find a long lasting solution to the energy storage problem.
His research is not based on the paradigm of search for the coolest to make battery and then hopefully chased down the cost down the curve cost by making plenty and plenty of products. Instead he began his research looking for something that would immediately meet the pricing point of the electricity market. As a result he researched for earth abundant materials that uses simple manufacturing technique and is cost effective.
Sadoway in order to get fresh perspective sought inspiration beyond electricity storage and instead looked into aluminum processing that catalyzed his idea. The cells that enable its processing are extremely similar to normal batteries, but with a few key differences. They operate at a very high temperature, making the aluminum product liquid, and use molten salt rather than a salt solution as the electrolyte. This combination allows extremely high current to be sent through them. Sadoway borrowed the idea of using liquid metal and molten salt, and applied it to energy storage.
They finally settled on high-temperature (700 °C) magnesium–antimony liquid metal stationary storage battery comprising a negative electrode of Mg (magnesium), a molten salt electrolyte (MgCl2–KCl–NaCl), and a positive electrode of Sb (antimony). Because of the density differences and immiscibility of the contiguous salt and metal phases they stratify into three distinct layers. During discharge, at the negative electrode Mg is oxidized to Mg2+ (Mg → Mg2+ + 2e−), which dissolves into the electrolyte while the electrons are released into the external circuit. Simultaneously, at the positive electrode Mg2+ ions in the electrolyte are reduced to Mg (Mg2+ + 2e− → Mg-Sb), which is deposited into the Sb electrode to form a liquid metal alloy (Mg−Sb) with attendant electron consumption from the external circuit .The reverse reactions occur when the battery is charged. Charging and discharging of the battery are accompanied by volumetric changes in the liquid electrodes.
The invention is groundbreaking advancement in how people going to view renewable energy in the near future and will be necessary for energy storage when combined with Wind and Solar energy. It could help spur the development of micro grid through the harvest of the renewable energies hence would help share electricity in a peer-to-peer basis across an internet-like micro-energy grid that can extend across regions especially in developing countries where there is insufficient grid connection in the rural areas. The energy from the renewable sources could be made and used by many local sources, each according to its unique environment, each connected to all the others like the Internet itself, which would more efficient and democratic model for the rural communities which are still not connected to the national grid due to the unwieldy fragility of one massive grid for all.
In conclusion, with the extensive advancement in storage technology such as Liquid Metal Battery, molten salt storage system and flywheel storage system micro-generation could probably become the future for our energy. Smart appliances (that shut themselves down temporarily, or power themselves up, when commands are transmitted down the local power lines) will greatly mitigate the requirement for grid-level energy storage. With between 2–10% market penetrations of smart appliances we will start to see meaningful reductions in the cost of producing and distributing electricity.
We can create a more sustainable, cleaner and safer world by making wiser energy choices.
Robert Alan Silverstein
TED http://www.ted.com/talks/donald_sadoway_the_missing_link_to_renewable_energy.html
David J. Bradwell, Donald R. Sadoway et al Jurnal of American chemical society
Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States
