Energy Storage Advances Keep Coming
(3Bl Media/Justmeans) - One question that has been holding back the expansion of wind and solar energy is, “what happens when the wind doesn’t blow and the sun doesn’t shine?”
Traditional sources of energy: oil, gas and coal, are not just energy sources but they are also storage mediums. We take for granted that when you have gasoline in your tank or coal piled outside your power plant, you can use it whenever you want. But these two functions,” source and storage, do not necessarily come together. Flowing sources like sunshine or wind come without storage. The same is true for electricity.
This question has not gone unnoticed. Recently, the California Public Utilities Commission, who already has 4.5 GW of storage, announced authorization for an additional1.325 GW by 2020.
The Department of Energy has a database of energy storage projects, called the Energy Storage Exchange, containing several hundred case studies, ranging from flywheels to advanced lead acid batteries to open loop hydro storage to ice thermal which freezes water at night (when commercial rates are lower and efficiency is higher) and then uses that ice during hot days to reduce air conditioning load. There are a lot of different ways to store energy.
Battery technology is considered the Holy Grail. Electricity is a great energy source because it’s so versatile. It can be produced and used in so many ways, but storing it is expensive. If we could store it more efficiently, it would make everything easier. The DOE has stated a price goal of $100 per watt.
I have written about flow batteries, fluid tanks the size of swimming pools that can store energy for utilities very efficiently. Both Stanford and MIT have made significant progress in this area.
Another technology I’ve been watching is super capacitors. To understand this you have to look at energy versus power. When you make a battery, you either optimize the battery to have a lot of energy, meaning that it can store a great deal for a long time, but if you want a burst of power, for example as you would in an electric car, you would optimize for that burst capability. Those two things turn out to require different chemistries. So if you’re trying to make a battery for an electric vehicle which has a goal of several hundreds of miles, the requirement that it provide a burst of power, takes a lot of those miles right off the top. So what we’re starting to see now is the use of ultra capacitors, or super capacitors, that can be combined with batteries to provide that burst of power as well as storage, or the best of both worlds.
As we delve into this question of how to provide energy storage, and do it in a way that’s economical and effective, new innovations keep raising the bar of what can be done to make our energy system cleaner.