The Powerwall is the V8 of Energy-Storage… And Not in a Good Way

Have you ever stopped to think about whether the Powerwall is actually helping the push for CO2 reduction?

For many of us, choosing to go solar or purchase energy storage is more of a financial decision than one entirely focused on reducing emissions. However, it is an added bonus to know that in doing so you could helping lessen the impact of CO2 output.

For decades now, solar power has been hailed as a green, clean, energy reducing machine that is capable of eliminating fossil fuels in the long run.

So, when something like the Powerwall is announced, a product aimed expanding the usefulness of solar power, we automatically assume that it is equally capable of helping the environment.

The Unfortunate Truth About Technologies Like the Powerwall

Well, here is a very large, very bitter pill we must all collectively swallow.

It turns out home batteries, in their current state, actually increase CO2 emissions overall rather than reduce them.

Ok, so by now you must be thinking, why are you telling me this? Don’t you guys advocate for batteries and solar energy?

Despite this unfortunate truth, we still think that purchasing a battery system will only benefit the push for renewable energy in the long run (we will go into a little more depth on this in just a second).

We also think that choosing the battery unit with the lowest carbon footprint, is a better option.

Maybe it’s the smooth, very heavy, exterior shell that puts them in the red, but it turns out that Tesla is significantly less eco-friendly than its closest competition.

LG Chem, the thorn in Tesla’s Side

The reason that we have chosen to compare the Tesla’s eco-friendliness against the LG Chem RESU is because they both use Lithium Ion, High voltage battery system.

Beyond that, they are head to head as competitors in the residential energy storage sector and in a lot of ways are very similar.

In a past article we compared the 10 kWh battery pack from both companies, so we will do the same here for consistency’s sake.

The Real Cost Of Battery Manufacturing

Battery systems expel the most CO2 during the manufacturing process, be it due to mining the base materials required, assembling the unit, or shipping it to its destination.

The same goes for solar panels, however, solar systems are able to produce enough emission-free energy during their lifetime to negate their carbon footprint in a short time. For battery units, given that they don’t actually produce energy but instead strategically move it around, things are a little more complicated.

In fact, for any manufactured product the average carbon footprint equates to roughly 2kg of carbon for every 1kg of weight. However, for products that make use of many different minable metals and materials the ratio of carbon to mass is often higher.

For example, an iPhone produces 95kg of carbon during its lifetime and yet weighs only 129g –– of that 95kg, 85% is produced during manufacture.

The same goes for Lithium-Ion battery systems, which produce roughly 18kg of carbon for every 1kg of weight.

So, given that both companies haven’t released the exact figures relating to their footprint, we will have to compare this average to the weight of the two systems (both of which produce the same amount of power).

LG Chem RESU 10H CO2 = 76kg x 18kg of Carbon = 1.37 Tonnes of CO2
Tesla Powerwall 10kWh = 100kg x 18kg of Carbon = 1.8 Tonnes of C02

This is the first big reason that LG Chem outperforms the Tesla in a measure of eco-friendliness, simply, the Tesla is very large. This is actually surprising given that both systems have a similar capacity, yet the Tesla is only able to output 2.5 kW in comparison to LG’s 5 kW.

Round-Trip Efficiency Goes a Long Way

Once a battery has been manufactured, there is a carbon cost involved with actually running the unit as part of a solar system. This is because any electrical component has a round trip efficiency, meaning that electricity is lost even when it is merely being transported, inverted or stored.

Another example of this is the connect cost of your electricity bill which can make up 40% of your actual expense.

If a solar system did not have a battery unit, it would either send electricity to your home or to the grid, which would then help reduce CO2. By using a battery, the round trip efficiency of your system is reduced and therefore less clean energy is used.

However, it's important to remember that by doing so, you are able to use solar energy during peak times and when it is most expensive. This will save you money in the long run, and eventually put less pressure on the grid.

For now, however, batteries do cause a small increase in CO2 production, so how do our two batteries compare?

The LG Chem has a round trip efficiency of 95%, which is not bad. This means that 95% of the electricity that flows through it will be used, while 5% is lost during discharge and transportation.

The Tesla Powerwall, however, has a round trip efficiency of 92.5%. Over time, as this energy loss compounds, a few percentage points make a big difference.

For example for every kilogram of CO2 your system saves, your battery will contribute:

LG Chem RESU 10h: 5% x 1000g of CO2 = 50g of CO2
Tesla Powerwall: 7.5% x 1000g of CO2 = 75g of CO2

Overall, the Powerwall produces 1.5x more carbon when it is running. Over a ten year period, this could equate to a difference of hundreds of kilograms of CO2.


Home batteries will be able to reduce emissions in the future, but because it is a new industry, supply and demand have not balanced out in the right way, however, it won’t be long before they do.

If you are pragmatic, financially minded person then don’t worry; batteries are still able to produce a return on investment depending on price point.

If you want to give the power over to the grid, simply to maximise the eco-friendly nature of your energy consumption, then go ahead. In the process you’ll be handing over power for pennies on the dollar, all the while helping out energy providers.

We think the best choice is to purchase a battery system that will benefit you most greatly while taking into consideration which batteries output the most carbon which in this case is the LG Chem RESU.

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