Here’s one we didn’t see coming:  Using the concrete slab on which your house is built as a 10 kWh storage unit at almost no additional cost.  How?  MIT researchers say to add carbon when it is poured.  The carbon creates its own electrode net.  It is not really a battery, but a capacitor instead—just a huge one.  In a capacitor, no electrochemistry is involved.   It just holds a separate positive and negative charge.  Usually, one thinks of capacitors as not delivering much energy.  But that’s different if it is as big as the slab foundation on a home or a big commercial building.  We have no idea how practical this discovery is or what it will cost, but it is not ready for prime time yet.  Read more about it here.