Green Optimistic

With the ascent of renewable energy sources, electric cars and a generally higher energy demand from consumers, energy utilities are now facing a crisis and at the same time a need to find solutions for temporarily storing the output of intermittent power sources, such as wind and solar.

Batteries are a no-brainer solution, but they’re expensive and need expensive maintenance once set up, which also raises the price per kilowatt served to the end customer.

In such a crisis, one cheap and efficient solution would be pumped hydro. The scenario is simple: energy is used to pump water uphill, and then energy is generated on-demand, when the grid needs it by letting water flow downstream onto a turbine.

However, pumped hydro has its drawbacks, as it only can be installed in select places and needs special permits.

A new solution comes from a small company called Energy Cache, whose founder, Aaron Fyke – an MIT graduate – wants to use gravel instead of water in a system that’s much alike pumped hydro, but that has several advantages over it.

Just like all successful businesses, Fyke started his in a garage, by assembling a set of buckets, motors and pulleys to store and regenerate electricity. The idea caught several investors, like Nat Goldhaber from Clatemont Creek Ventures, Bill Gross and even Bill Gates, who helped building a prototype whose scale is closer to the commercial version and is capable of storing 50 kWh of electricity.

Fyke says his gravel-based energy storing system is more efficient and 40% cheaper than pumped hydro, and can be installed virtually anywhere there’s a hill and can be scaled up to virtually any size. The commercial unit will be under 1 MW but will have a high response speed when the grid operator will demand energy to be released.

Here’s how it works:

As I said, brilliant ideas do get born in garages from people with vision and persistence. And if those ideas are also funded by big people thinking even bigger, then brilliant companies get born to implement simple technologies that nobody had thought of before… I wish I had it.

I’d have one suggestion: I think the system would store much more energy if they put heavier stuff in there or made the buckets bigger. However, gravel is dead-cheap and I don’t think there’s practical need for anything else.