In this article, it will be explained why energy storage companies are racing against Tesla for the filling the emerging gap in the infrastructure required for the new electrical grid system. It will be discussed why Battery storage power stations (BSPS) are the holy grail to renewable integration in grid systems.
Problems with the existing grid
A power grid infrastructure of today was designed and conceived in an age, when input from intermittent sources like renewable energy wasn’t an option. The power generation was centralized rather than desperate . In most cases, a major power plant far away from the city was used to cater for the demand. Some supplementary units aided this method.
This infrastructure has its own problems. Centralized power generation means greater line losses, heat energy wastage (no Combine Heat and Power), and low security of supply.
The other major problem with such system is maintaining a certain level of power in the grid. If the demand rose higher than supply than the grid frequency would drop. On the other hand if there was more generation that being used, than grid frequency would increase. Grid management companies keep a close eye on supply and demand. In many cases, rise in demand is anticipated based on societal behaviour patterns for e.g. energy usage during match days. This information is passed on the generation plants which ramp up or scale down their production based on the feedback from the grid.
In some countries like UK, it is possible to observe live parameters such as total demand, current grid frequency, total generation by energy source through websites such as National grid UK.
On this particular link, not only total energy demand in UK can be observed but also the amount generated by Wind, Coal, Nuclear and CCGT (Combine Cycle Gas Turbine) can be viewed separately
With Kyoto protocol, there has been a push towards low carbon economy and renewable energy sources are high on government’s agenda. To accommodate renewables with a grid structure that is old poses a problem itself. Solar farms for instance can cause energy spikes on days when cloud cover is patchy. Substations can become energy importers to energy exporters in a matter of seconds.
Is there a solution that can eliminate all these listed problems?
The answer is simply battery energy power stations or very large scale batteries. With the advancement in battery technology, efficient utility scale batteries are now a reality. Energy buffering systems will help the grid immensely. The second to second management of grid frequency, will slowly phase out as more energy storage becomes available to the system, particularly one that can provide energy instantaneously. For this reason, battery storage is thus more superior compared to other forms such as pump storage, which feedback time is higher. They can provide power at full load within 20 mille-second. Electro chemical energy storage technology was not available at a large scale mainly because of costs. However, recent research has altered this impediment.
What large scale batteries are available?
There are many different battery chemistries within the flow battery configuration. The largest installed flow battery is a Vanadium Redox battery that has a capacity of 8 MWh and is located in China, 60 Km North of Beijing. Currently Vanadium batteries cost in the range of $700-$800 for every kWh including all components that connect it to the grid. This is likely to drop to $500/kWh in the future and even lower to $300 /Kwh if recycled vanadium is used as electrolyte. The other type of flow battery which has shown promise is of Iron Chromium chemistry. The largest one of this kind was installed in May 2014 in Turlock, California, USA. The total capacity of this system is 1 MWh. The Iron Chromium battery according to research by MIT is 1/6th of the cost of flow batteries with Vanadium in their chemistry.
Yet another type of flow battery being developed is the Magnesium -Antimony liquid metal battery. In the video below, MIT professor Donald Sadoway elaborates some of the virtues of this battery technology:
With the price of Lithium Ion cells also dropping, these batteries are now comparable in price to flow batteries and have some unique advantages. A report on energy storage was carried out by financial advisory and asset management firm Lazard. It showed that the levelized cost of lithium Ion battery was in fact in many cases lower than flow battery. Because of their solid-state nature, Li-ion batteries make an overall more reliable system. Li-ion batteries also offer a superior energy density and therefore occupy less space and are portable.
An example of large scale lithium -ion battery is the 400 MWh Southern California Edison project (due to be completed by 2021). This battery storage will be able to furnish an extremely healthy 100 MW of power for 4 hours.
There are many Islands around the world, which are either dependent on supply of diesel fuel. Harsh weather can often hinder supplies. Even in cases where Islands are connected to mainland through grid systems, it is likely for grid to fail. An example of this is the Isle of Arran in Scotland which saw power outage for days after a snow storm in the winter of 2014. Battery storage power stations for Island communities are extremely useful, particularly those which have ample renewable resources.
A 250 Mwh battery storage power station is under construction in Indonesia that will be able to provide power to over 500 villages.
How large scale batteries will benefit utilities?
With more and more renewables getting integrated in the system, the spikes in power supply are more frequent.
Through battery storage power stations the following advantages will be gained:
- Energy storage when renewables energy is high (high wind, sunny day)
- Energy supply when renewable energy drops
- Smoothen energy in the grid because of spike generated through demand
- Make a more reliable system in terms of energy security
- Reducing the load and need of peaking plants which are expensive to run
- Allowing more renewables to be integrated to the grid