Mexico Needs Options for Renewable Energy Storage

Renewable energies, such as wind and solar, are considered an option if the world wants to collectively lower its CO2 emissions. Not only do renewables offer an outlook toward a sustainable future, in countries such as Mexico they have proven to be quite competitive in terms of pricing, as well. One technical problem remains to be solved. Sun and wind are simply not available 24/7, which means long-term storage is needed to bridge the gaps. If Mexico wishes to adapt renewables as a significant portion of its energy mix, it will have to make choices on this front as well, even though no ideal solution exists.

Green Tech Media (GTM) reported that currently, energy is stored in lithium-ion batteries as much as 99 percent. While this is not an ineffective option, lithium-ion batteries are expensive if a large-scale operation wishes to store energy for many hours. Mining the resources for this is an intensive process, as well. Now that renewables are becoming widely adopted, the storage issue needs to be addressed properly. The most promising options include a mixture of new and old technology according to GTM, including pumped hydro, stacked blocks, liquid air, underground compressed air and flow batteries.

One development to note is that NREL projected the cost for lithium batteries will go down further. The only uncertainty remains in how much the price will drop. If the existing go-to option will become cheaper, large investments in alternatives will likely remain. What is more, BloombergNEF reported that battery capacity will likely more than double in the next decade.

Pumped hydro developments could be interesting as they do not need any further technological advancements. It is a rather old technology originating in the 1950s adapted to modern needs. One could hardly call it irrelevant as it accounts for 95 percent of today’s grid storage in the US, according to GTM. The concept uses gravity to move water from a higher ground to a low reservoir, where water descends when electricity is needed. Hydro plants are massive in size and disrupt surrounding ecosystems significantly, however. Luckily, modern applications of pumped hydro can be constructed on isolated reservoirs.

Liquid air is another option discussed by Energias Renovables and GTM. This technology uses low temperature liquids, also known as cryogenic liquids, to store energy in. Highview Power is a startup deeply involved in this project and currently is trying out the application in a UK power plant. Furthermore, the Washington State Department of Commerce's Clean Energy Fund announced in 2019 that it issued a grant to help Tacoma Power partner with Praxair to build a liquid air energy storage plant.

Another viable option can be found in flow batteries. This technology circulates liquid electrolytes to charge or discharge electrons via a redox reaction. While enthusiastically promoted by scientists working on the application, it has not proven to be a commercial wildcard as of yet. In fact, GTM reported that most of the investment regarding mergers and acquisitions comes from “bankruptcy-induced fire sales.”

Many more potential options to build upon exist. It is impossible to predict which technologies will be boosted by the market and which ones will fade into obscurity. Nonetheless, if renewable energy producers want the world to forget about fossil fuels, storage will need further development in order to showcase an undeniably efficient solution.