Comparing battery technologies

Until recently lead acid batteries have been the major player in the energy storage industry, particularly for off grid installations but they have serious limitations in terms of requiring customer maintenance and of course they are made from toxic materials.

Recently, Tesla’s lithium ion batteries have received a lot of attention due to their advertised low price and excellent marketing, however the lithium ion batteries are now receiving attention due to their fire risk on the release of embodied energy. Lithium ion batteries have a smaller operating range than most other batteries and won’t operate efficiently above 35 – 40°C. Also, lithium is a toxic material and is in limited supply and at this stage can’t be recycled effectively.

There are some new technologies coming onto the market, such as Redflow’s zinc bromide, Aquion’s sodium ion salt water batteries, improved lead acid and many variations of lithium battery. These each have advantages and disadvantages, both in terms of performance and size.
Depth of Discharge (DOD)


A common way of comparing batteries is by talking about number of cycles and depth of discharge (DOD). These are very fluid figures as there are so many variables to be taken into account.

Some of the newer batteries are claiming a large number of cycles and a large DOD but in fact these figures are being claimed with no proof as the technologies haven’t been in the marketplace long enough to determine the effect of real life operating conditions. Indeed a number of batteries have already disappeared from the marketplace as they have not lived up to advertised operating claims.

Battery Operating Temperatures
Also, a lot of battery testing is done in factories, at temperatures of 25°C. When batteries are used at higher or lower temperatures the DOD and number of cycles will reduce. This is particularly relevant for lead acid and lithium ion technologies. For example a lead acid battery being operated at 30°C will have its life reduced by up to half compared to if it is operated at 20°C. The lifetime will be reduced by half again if a lead acid battery is operated at 40°C.
 

 

Cycles
The more you discharge a battery (high DOD), the fewer cycles you get out of the battery with a reduced lifetime of the battery. Larger batteries, like the FIAMM SoNick battery are likely to have a lower DOD on a daily basis, so are likely to last longer, while smaller batteries like the lithium ion batteries are more likely to discharge completely on a daily basis, thus reducing their overall lifetime.

Degradation
Many batteries will degrade over their lifetime which means you may need to install more capacity than you would need upfront to allow for this degradation. Lithium ion batteries can degrade down to 50 – 60% capacity over 10 years while lead acid may degrade even lower to 30-50% depending on their operating condition.  FIAMM SoNick and Redflow batteries don’t degrade so will remain at 100% capacity over their lifetime.  This degradation means you may not be able to add extra capacity to an existing system after a couple of years.

Recyclability
Something else that needs to be considered is the end of life of batteries. At this point in time lithium ion batteries are not recyclable and it is questionable whether recycling programs will be set up in the future without government subsidies. For commercial battery recycling programs to operate it must be economical for the recycler and this occurs when there are enough components in the battery to make it economical. Unfortunately there is little cobalt, nickel or copper in most lithium ion batteries which reduces their value to recyclers. Also there are many varieties of chemical components and system complexities which are constantly changing and this will make it difficult to set up lithium ion recycling facilities.

Lead acid has up until now been recyclable, however some of the newer sealed gel batteries have the plates doped which means they are no longer recyclable.

SoNick batteries are 100% recyclable and all components of the battery are accounted for in the recycling process.

Total cost of ownership
When comparing batteries it is important to take into account total cost of ownership from initial purchase, through maintenance to end of life. What may appear to be a cheaper battery option when first considered may in fact be a much more expensive option over the life of a battery when other factors are taken into account.

When comparing battery costs you need to consider not only battery purchase price but installation costs and time. If a battery takes 10 hours to install as do many lead acid and some lithium ion installations this will add extra costs as opposed to sodium nickel chloride batteries or other plug and play installations.

If a battery is subject to gassing, as lead acid batteries are and to a lesser extent lithium ion batteries are they will need to be housed in an area where the gassing can’t start a fire. This again can add to costs of the battery installation.

Some batteries require maintenance over their lifetimes and this will add extra costs, especially in a commercial installation where people need to be employed to do this maintenance. This particularly applies to lead acid batteries which need their fluids topped up and corrosion monitored. Redflow batteries will need their pump replaced every 5 – 10 years and their plates and bromide solution will also need replacing. This is one area where lithium ion batteries don’t have major problems. FIAMM SoNick batteries are 100% maintenance free.

The operating temperature of a battery can make a big difference to its overall cost. If a battery needs to be kept in an air conditioned environment this will add operating costs over its lifetime. This can also be a safety component as lithium ion batteries; in particular, can catch fire if they get too hot. There are many safeguards built into lithium ion batteries to prevent this happening but a fire can occur in the vicinity of the battery and not be caused by the battery itself and a lithium ion battery may still go into thermal runaway if it gets overheated, no matter what the cause of the heat is.

Expected degradation, recommended depth of discharge, round trip efficiency and expected lifetime of battery are other factors that need to be taken into account when considering the “total cost of ownership” of a battery.

The FIAMM SoNick battery definitely comes out as one of the leaders in the industry when all these factors are taken into account.

 

As can be seen there is a large degree of misunderstanding about what battery storage can achieve, and what different technologies are best applied for households depending on their needs. You must do your homework and get anything you are told verified by several independent sources to confirm accuracy.

Unfortunately as there are currently no standards in Australia for batteries, other than lead acid people can say anything they like without recourse. Organisations like the Energy Storage Council and the Clean Energy Council are working on battery standards to provide tighter control on what can be claimed in the energy storage industry which will make it easier for consumers to understand what they are being offered.

If you would like to know more about getting information on our safe, reliable and recyclable sodium nickel chloride battery storage for your own home, business or micro-grid visit us at http://quantum.GridEdge.com.au

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