Energy Storage R&D Key to Renewables
Global investment in renewable energy has surged in recent years, with increases of 37% in 2010 and 17% in 2011, and a total dollar figure of $257 billion last year, according to a U.N. report. Though solar just overtook wind as the most heavily invested renewable energy source worldwide, Midwest wind development has grown rapidly in the last 10+ years.
Despite this growth and success within renewable energy industries, wind and solar will remain “alternative” energy sources until we can effectively deal with one crucial problem: energy storage.
Wind speeds vary and the sun sets, making wind and solar energy difficult to manage at high levels in an electricity grid that has large and constant levels of demand.
The solution for this is not a new concept: store excess energy that is produced when we don’t need it, and release it when demand is high but supply is low. However, technological and economical barriers have prevented means to achieve high levels of storage capacity from coming to market.
Batteries are the classic example of storing energy for later use, and lithium-ion batteries now exist in everything from electronics to hybrid cars and buses. But these batteries currently have an extremely low energy density compared to other materials, meaning that they pack a weak punch given their size and weight, are fairly expensive at larger scales, and are not really feasible when we’re talking about supplying a whole energy grid.
There has been much work on the idea of using plug-in hybrid electric vehicles (PHEV) and battery electric vehicles (BEV) to take up excess energy from the grid, and even return energy to the grid when needed. But there are smart grid application issues, auto manufacturer concerns and privacy matters involved with this approach, not to mention the time and effort it would take to replace our vehicle fleet with PHEVs and BEVs.
Pumped hydro-storage (PHS) and compressed air storage are also technologies that have garnered attention in recent years. PHS can work when wind turbines or solar panels are coupled with hydroelectric dams and generators, but is limited geographically and not widely applicable in some areas. Compressed air storage has made progress crossing over to energy generation thanks to University of Minnesota research, but it's in very early stages of development and has yet to prove it can grow to large-scale applications.
One technology that I find extremely fascinating when it comes to energy storage is artificial photosynthesis. It’s not particularly new, but MIT professor Daniel Nocera’s recently released “artificial leaf” technology takes this concept one step closer to broad market-level application.
The idea is simple and happens as part of the photosynthesis process in every plant in the world: use sunlight to break down water into hydrogen and oxygen. The hydrogen can then be used as raw material for chemical processes to make ammonia, methanol, hydrogen peroxide, polymers and solvents, and in refineries to remove the sulfur present in crude oil (as it currently is in large quantities), or to burn for energy like natural gas. But regarding energy storage, the hydrogen can be used to power hydrogen fuel cells. These cells can store unused solar energy and release it into the grid when needed.
A short, simple, informative video about how hydrogen fuel cells work to generate electricity. And the only byproducts are water, oxygen and heat!
While artificial photosynthesis has been accomplished in the past, it has used expensive and rare materials like platinum. Nocera’s artificial leaf replaces these materials with abundant and cheap nickel, cobalt and zinc, making the technology much more feasible to build and distribute, especially in remote rural areas and developing countries.
There is no guarantee that the artificial leaf will become the savior of the energy storage dilemma that underlies solar energy, and Nocera’s technology is currently applicable only on small scales. In fact, no technology has yet emerged to take the lead as a widely applicable energy storage solution to help bring wind and solar from dominant renewable energy sources to dominant energy sources period.
But it took 20 years of research and testing to significantly increase the performance and reduce the costs of lithium-ion batteries to the point where they could be widely used, and a leading battery maker just announced another breakthrough in the technology. This is why the focus now regarding energy storage technologies has to be on research and development. Policymakers need to keep R&D funds going to public and private research institutions like the University of Minnesota and MIT to ensure that down the road we have rigorously researched, tested and developed technologies that work at large scales on our energy grid.
Bill Gates said “we always overestimate the change that will occur in the next two years and underestimate the change that will occur in the next ten.” Renewable energy sources like wind and solar aren’t currently bursting at the seams to take over every aspect of our energy needs, and coal and natural gas plants aren’t going away anytime soon. But investigating and developing energy storage technologies now means that we will be better prepared to integrate larger amounts of renewable energy into our grid in the future.