Battery 2nd Life Used as an ESS: Economic and Environmental Analysis Comparing Lead-Acid and Lithium-Ion on Different Real Scenario
Posted: 23 Jul 2019
Date Written: July 20, 2019
Electric Vehicles (EVs) are more environment and climate-friendly than Internal Combustion Engines vehicles (ICEVs), but disposal of batteries at the end of the automotive lifecycle has emerged as a growing environmental concern. Lithium-ion (Li-ion) batteries used in EVs contain metals, rare earth elements and toxic materials that adversely affect the environment and pose risk to human health. Scrap EV batteries should be recycled at dedicated facilities to recover valuable materials efficiently and safely, although they are not economically beneficial to recycle (recycling costs currently 1€/Kg). 1Kg of CO2 is saved per Kg of recycled battery, but recycling lithium costs five times as much as extracting virgin material. At the moment, only 5% of Li-ion batteries are recycled in Europe.
On the other hand, when EV batteries reach 70-80% of their SOH (State of Health) after about 8 years or 160.000km, they shall be replaced as they can suffer a drastic drop in capacity and in the vehicle's autonomy. However, even after that capacity loss, these batteries still have enough energy to be used for other purposes and can be reused instead of recycled, the benefit of which is practically nil nowadays. EV manufactures want to take advantage of this to reduce the sale price of the EVs opening new lines of research reusing these batteries as an ESS (Energy Storage System).
There are many applications that have demonstrated the technical feasibility of using EV batteries in energy stationary applications, but very few studies have detailed the economic benefit of these applications taking into account the real aging of the batteries.
This paper deeply analyses the economic feasibility and environmental impact to reuse these batteries as an ESS in five different real cases using a validated EV battery model and compare all of them with the use of Lead-Acid batteries and with the use of brand-new Li-ion batteries.
The research work was conducted using the power consumption profile of one hospital, one sewage plant, one hotel, one office building and one petrol station. Each of these energy consumptions was introduced in a Matlab/Simulink simulation battery model to determine the lifetime of the ESS in each case. Once the lifetime is known in each case, the ROI (Return of investment) is calculated and we can determine in which of these cases the use of second life batteries is more profitable. In addition, for each of these cases a completely LCA (Life Cycle Assessment) was performed using GaBi software to determine their environmental impact.
3. Results and Discussion
Li-ion batteries have some advantages over Lead-Acid batteries as they have higher energy density, are safer, are lighter, have higher working range at different temperatures and a longer lifecycle. Despite the advantages mentioned, Lead-Acid batteries are still cheaper than Li-ion ones.
This paper proves that reused EV batteries have better performance than the Lead-Acid batteries that were designed to be used as an ESS. Moreover, reused Li-ion batteries have a better economical return and a lower environmental impact due to avoiding a second extraction of material and delaying both the recycling of the old battery and the manufacturing of a new one.
The differences in the lifetime of the ESS in each case of study vary significantly depending on the DOD (Depth of Discharge).
Another important point is, that the negative environmental effects of batteries production are reduced as the battery lifetime extends. Therefore, in the cases that the batteries have less power demand, their lifetime will increase, and with this, the environmental impact will be lower.
Li-ion batteries have better performance than Lead-Acid as an ESS. The only point where lead batteries are still better is in price, but if batteries are reused, the balance is again tilted towards the Li-ion batteries.
Suggested Citation: Suggested Citation