The path towards sustainability and the case for batteries

January 4, 2022

Sustainability is becoming increasingly important and people often ask themselves, are mobile batteries really sustainable? Isn’t the production of batteries much more polluting and what impact do the scarce raw materials in batteries have? To answer this question, we have done a Life Cycle Assessment (LCA) in which we take the production, user and end-of-life phases of our product into account and compare them with the alternative.

The Lifecycle Assessment

Different KPIs and measurements can be applied to different products and scenarios to measure and track sustainability. To gain a deeper understanding of why we chose the Life Cycle Assessment (LCA), we will take a closer look at what it is used for and how it is applied. The LCA can be used to look at the environmental sustainability of a product or process. More specifically it scrutinizes the environmental impact of a product, procedure, or activity during its life by quantitatively measuring the use of resources and the emissions. This tool can be used to gain a transparent insight into the eco balance and to demonstrate the potentials for improvement. This knowledge can in turn be a basis for the decision-making process of a company to improve their production process, material use, waste processes or the product design.

To apply this tool to an actual product, four steps must be taken:

  1. Definition of target and scope: The actual goal of the research, as well as the necessary decision-making criteria are determined. The framework and criteria for the actual research are decided on to give the research a clear direction.
  1. Status analysis: All the relevant data is collected. This includes the input, so all the resources used, as well as the output, which can include the consumption of energy sources, CO2 emissions etc.
  1. Impact assessment: The collected data about the emissions, waste and used resources are analyzed according to the impact categories and criteria, which were determined in step 1.
  2. Appraisal and interpretation:This is the last step of the LCA and includes the evaluation of the research and the actual results. By looking at the results, you can identify areas of improvement and identify the most important findings  (British Plastics Federation, 2021)[1].

While the LCA is an important tool to determine the environmental impact of a product, it should be seen as a theoretical evaluation based on energy and material flows. The underlying assumption of “cradle to grave” or in other words that all products will be disposed of at the end of their lives might not be applicable in all cases. Additionally, the social sustainability part is not considered in this model, since no data about people included in the processes is considered (Ayres, 1995)[2].

The research at Greener Power Solutions

As part of the way to sustainability, Greener Power Solutions wants to include all aspects of sustainability and as such also set up a strategy to further develop sustainable business practices. To keep track of these internal efforts, determine improvement points and to share our knowledge openly with anyone interested, our intern Friso Klemann has conducted a Life Cycle Assessment of the Greener mobile batteries in 2020 as part of his master thesis. In the following, we will share a short summary of his findings.

Before coming to the actual results of the research, the framework of the research must be acknowledged. The goal of the research was to compare the environmental impact of a 330 kWh, 285 kW Greener Power Solutions battery to a Diesel generator set concerning production, use, and end-of-life phase. The part of the analysis of the use phase was based on the battery being used as a peak shaving unit and seven different scenarios concerning the energy sources were chosen. Out of these seven scenarios four of the most realistic scenarios will be explored in this blog post to give an overview of the possibilities as some of the scenarios achieve very similar outcomes and this is meant as a short summary. For the comparative Life Cycle Assessment, the LCA software programme SimaPro was used. Additionally, all research results are included in a short infographic at the end of this blog post.

In the following the LCA for the three different phases (production, use, end-of-life) will be explored and during the use phase the distinction of the four different scenarios will be made.

Production phase:

In case of the mobile battery three components and one component group must be analyzed concerning their impact: the BMW i3 batteries, the transformers, the refrigerating containers, and the electronic equipment.

The batteries by BMW with a capacity of 42.2 kWh use the Nickel-Manganese-Cobalt-Dioxide (NMC) technology for the cathode and graphite for the anode and the environmental impact of these batteries were calculated based on the average values found during literature study, which results in 213.5 kg CO2 equivalent/kWh. Since the literature studies include both production and use in their assessment, half of this value will be assigned to the actual production, while the other half is added to the use phase.

Additionally, the used electricity to produce the batteries must be considered. With the average quantity of energy used during production in literature is 890.7 MJ/kWh, which comes up to 300.7 GJ when multiplied with the capacity of Greener batteries (336 kWh). However, the BMW factory in Leipzig, Germany, is powered by wind turbines, so we assume that the necessary electricity for production is delivered by this renewable energy.

The weight of the batteries, as well as the transformer, inverters and the refrigerating container are added for the total weight and together with the materials are put into the SimaPro program to calculate the environmental impact.

For the diesel generator the materials of its components, their weight and the energy used according to the producer’s information and literature study are considered. Based on a China-based production, the energy mix from China is used when calculating the energy use for a 200 kVA diesel generator. This results in the total of 190.188 GJ of natural gas and 56.352 GJ of electricity used for the production.

During the production phase the mobile battery has a Global Warming Potential 100 of in total 103,636. This GWP100 measures the impact with kilograms carbon dioxide, but also includes other greenhouse gases as for instance methane. The total GWP100 of a diesel genset is 53,086, so about half of the mobile battery. This is mostly due to the lithium-ion batteries of the mobile battery, which alone accounts for 46,114 kg CO2 eq.

Additionally, a mobile battery has more than three times the emissions of fine particulate matter formation (FPMF). The mobile battery here has a total of 299 FPMF in kg PM2.5, while the diesel genset results in 70.17 kg PM2.5.

GWP100 and FPMF of a mobile battery and diesel generator in the production phase
Mobile batteryDiesel generator
GWP100 (kg CO2 eq)103,63653,086
FMFP (kg PM2.5 eq)29970.17

Use phase

According to the manufacturer’s information on the mobile batteries, several assumptions are taken when determining the LCA of a mobile battery. One Greener battery of 330 kWh capacity contains eight BMW I3 batteries. After 200,000 kWh energy throughput these batteries’ capacity decreases by 30% and it is expected that his will happen after 10 years or a total of 4,850 charge cycles. Since the maximum allowed capacity degradation for Greener batteries is 30%, this will be the end of the lifetime for a battery and a total throughput of 1,600 MW will be used as the functional unit for the LCA.

To accurately research the environmental of mobile batteries during their use phase, the overall efficiency must be considered. The power input is not equal to the power output due to certain losses during processes such as the conversion, the actual storage inside the batteries and the cooling unit. Taken all these aspects into considerations the final efficiency of the battery is 92.67%.

Additionally, the battery is used in many different user cases, which differ in their environmental impact. For this summary four different scenarios will be explored:

User case 1: Power input by diesel generator

In this case the power to charge the battery is fully supplied by a diesel generator running on an optimum load of 80%. With a load of 80%, the efficiency of the genset will be 36.6%, so 1 kg of diesel fuel is converted into 15.45 MJ and together with the energy losses inside the batter for the whole lifetime this results in 6,215,798 MJ, which must be delivered by the genset to achieve 1,600 MW. This then results in 402,317 kg diesel fuel.

User case 2: Power input by grid

For this scenario, the electricity grid is assumed to be in the Netherlands and the power input of 6,215,798 MJ calculated for user case 1 is put into Sima Pro for the electricity grid.

User case 3: Power input by diesel generator and grid combined

In some cases, the available grid connection is too small and a combination of both the grid and the diesel genset is used to charge the battery. While the charging ratio can change according to the set-up, for this research data collected by Greener from a real set-up was used. Therefore, we assume a charging percentage of 67.94% by the grid and 32.06% by the genset, which translates into 1,173,059 kWh power input by the grid and 553,551 kWh power input by the genset.

User case 4: Power input by wind energy

This user case describes a fully sustainable energy source. This could also be solar energy instead of wind energy.

For the diesel generator, the lifetime is assumed to be 40,000 running hours and with a light load 60,000 running hours. Collected data on the efficiency of diesel generators has shown that their average load is at 12%, while the optimum load would be between 60% and 90%. With a power factor of 0.95, this would result in a total power output of 1,368,000 kWh during the lifetime of a diesel generator. This is less than the 1,600,000 kWh of a mobile battery and since the load will not be stable at 12%, we assume for this research that the 1,600,000 kWh can be achieved by one diesel generator. The efficiency of a load of 12% when comparing the collected data is an average of 22.1%, so 1 kg of diesel fuel is converted into 9.328 MJ. For 1,600,000 kWh, which equals 5,760,000 MJ, the diesel fuel needed therefore equals 617,468.57 kg.

For the mobile battery the GWP and FPMF for each user case is as follows:

GWP100 and FPMF of the different user cases of a mobile battery and of a diesel generator in the use phase
User caseGWP100 (kg CO2 eq)FMFP (kg PM2.5 eq)
1: Power input by diesel generator1,506,0614,342
2: Power input by grid1,027,836343
3: Power input by diesel generator and grid482,843 (genset) + 698,312 (grid) = 1,181,1551,392 (genset) + 233 (grid) = 1,625
4: Power input by wind energy26,46859
Diesel generator2,303,590 6,658

End-of-life phase:

For countries in the European Union, it is mandatory to recycle batteries according to the laws of the European Commission. For lithium-ion batteries, the minimum recycle quantity is 50%. However, since electric cars, as well as mobile batteries are new markets, the recycling market for both technologies are still in its development and limited information is available. For this research, we assume that the materials, which can be recovered are cobalt, nickel, manganese, copper and steel. These materials make up 55% of the weight of the mobile battery, while the other 45% consist of plastics, binder material, electrolyte, and graphite. They will be lost during the recycling; however, this could change in the future when new recycling methods are developed. Since the recycling part is so uncertain, these findings must be taken with a grain of salt.

For the diesel generator, the materials can be dismantled, sorted, and then recycled. All of the different materials, which are steel, cast steel, aluminium, copper and plastic, have different recycle rates. This means that during the process of recycling not 100% of the material can be retrieved and parts get lost.

Due to the recycling of both the mobile battery and the diesel generator, emissions can be saved and the GWP and FPMF have negative results. Keep in mind that for the recycling process electricity is necessary and this was subtracted during research.

GWP100 and FPMF of a mobile battery and diesel generator in the end-of-life phase
Mobile batteryDiesel generator
GWP100 (kg CO2 eq)-8,341-2,021.27
FMFP (kg PM2.5 eq)-78.6-16.93

Conclusion

While we can see that during the production phase, the diesel generator has a lower environmental impact than the mobile battery, the largest impact on the environment is measured during the use phase of both products. When looking at the results of the use phase, it becomes clear that the mobile battery has a large potential for reducing environmental impact and emissions, especially when being charged by a sustainable energy source. But even when comparing the mobile battery and the diesel generator in a less favorable scenario for the mobile battery, the savings are still high.

The user case most used by clients of Greener Power Solutions is user case three. In the table below the total results for this user case are presented.

Total GWP100 and FPMF of a mobile battery (based on user case 3) and diesel generator
Mobile battery (user case 3)Diesel generator
GWP100 (kg CO2 eq)103,6362,354,654.73
FMFP (kg PM2.5 eq)1,845.46,711.24

When using a combination of the electricity grid and a diesel genset to charge the battery, the GWP of the battery is 54% of the GWP of the genset and concerning the FMFP it is only around 28%. This proves that there is potential for a lower environmental impact of a mobile battery in every user case in comparison to a diesel generator even when accounting for the production. This potential is the most present in the user case of wind energy, which proves that a mobile battery can be an enabler for renewable energies.

Towards a more sustainable future

This analysis is only one step on the way towards a more sustainable future. As mentioned previously, sustainability is must more than just eco-friendly products. And looking towards the future we see that the user cases explored in this blog post are also just one part of what is possible: hydrogen generators, biofuel generators, Kitepower and other new energy sources can easily be combined with batteries in the future to further improve on the sustainability. With this blog post we hope to have given you a deeper understanding of the term sustainability and the environmental impact of Greener mobile batteries as an example.

Sources:

[1] Link to website:https://www.bpf.co.uk/sustainable_manufacturing/life-cycle-analysis-lca.aspx

[2] Link to document: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1061.3986&rep=rep1&type=pdf

Infographic with a summary of the lifecycle assessment

In this infographic, you can see a simple summary of results of the Life Cycle Assessment. Feel free to share this infographic if you found it helpful and please include attribution to greener.nl when sharing.

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