|An artists impression of a grid-tied battery storage system. Photo credit: A123 Systems.|
By Anders Lorenzen
Renewable energy enthusiasts, myself included, are championing the idea that we can have a future energy system completely reliant on renewables. Opponents would say that renewables are too intermittent and until we get grid-scale energy storage, renewables are not going to work.
I would say that both have a point. The problem is not whether renewables can produce large amounts of capacity, we know they can. The problem is what we do with the excess energy produced during very windy or sunny weather. Grid operators can already adjust to such surges, using innovative computer forecasting technology.
But that is not enough.
I have often written about Denmark’s wind power achievements. Years of progressive policies mean that this Scandinavian country at times produces more electricity from wind power than it consumes, which is a great success story.
But the energy infrastructure system, even in one of Europe’s most modern and innovative energy systems, is still not able to fully integrate renewables. While policy makers have been focused on building renewable energy capacity, they have overlooked the infrastructure to go with it.
Denmark’s current wind power record stands at around 4.3 gigawatts (GW). On a normal working day electricity demand fluctuates between 4.8 – 5.5 GW, while at night it drops to below 3.0 GW. But Denmark’s wind power output can fluctuate fast. For instance, it can go from top capacity output to almost nothing or around 100 megawatts (MW) in hours. So without any storage Denmark need conventional power plants to maintain a steady supply and, unfortunately, such plants cannot be switched off completely when renewables are producing to maximum capacity. So there is still over-supply to deal with.
Luckily Denmark has good grid connections to Germany, Norway and Sweden so could in theory export excess energy to those countries, and they do. However, northern Germany also produces large quantities of energy through renewables and faces similar problems of storage and distribution during periods of peak production. As a result energy prices turn negative, caused by over-supply, and Denmark, more often than not ends up importing rather than exporting electricity from Germany. Norway, with its own efficient hydro-electric power capacity will only buy wind powered electricity from Denmark at low prices. The bottom line is that Denmark can’t always assume that during high wind power productivity they can export all that excess capacity to neighboring countries.
As the over-supply causes negative energy prices in Denmark (and Germany), it occasionally leads to situations where wind turbines have to be turned off, and where this is not possible (wind turbines constructed before 2009 can’t be switched off) suppliers are themselves charged for over-production of energy.
This could be good news for energy consumers but, of course, not for the sustainability of the wind energy industry itself and its continuing economic viability and need for investment.
If energy storage was widely available, instead of creating negative energy prices, that energy could be stored and used on days of low wind power productivity. In the long term, more power plants could confidently be switched off while knowing the lights would be kept on.
So here is the good news, 2015 actually looks like being the year when energy storage could make significant breakthroughs.
From Germany to Silicon Valley new startups working on grid- scale batteries are being set up and some are so far advanced in their development that they have started commercial distribution.
Now we just need the political backing to put as much effort into this much needed technology as there has been with renewables.