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The ecological challenges of Tesla’s Gigafactory and the Model 3

amosbatto

Member
Jul 8, 2017
10
2
Bolivia
I don't know I think when you say
"We will be using 100% sustainable energy through a combination of a 70 MW solar rooftop array and solar ground installations. "
it's pretty reasonable. Especially since that comment allows for an unlimited number of solar ground installations.
I'm predicting that the Gigafactory will consume between 3,229 and 4,688 GWh of electricity per year (or between 367 and 535 MJ on average).

The average capacity factor of utility scale PV solar in the US in 2016 was 0.2769. Looking through the EIA data for solar farms around Reno, Nevada, they seem to have capacity factors pretty close to the national average. There are places in Southern California that do much better, but the Gigafactory won't get that kind of sun.

With a capacity factor of 0.2769 the Gigafactory will need a solar array of between 1331 MW and 1932 MW in nameplate capacity. If Tesla wants a solar array that generates between 367 and 535 MJ in December when the average CF is 0.1550, then it will need an array between 2378 and 3452 MW in nameplate capacity. Because of the reduced solar irradiance in the winter, it is highly likely that the Gigafactory will be using a lot of dirty grid electricity from Nevada during the winter, which mostly comes from burning natural gas.

Telsa simply can't generate that much solar energy on the current acreage of the Gigafactory. Taking the average of the 6 largest solar farms in the US (which all get better sun than the Gigafactory), we get 0.333 GWh per acre per year. If we use that average on the 2864 acres of the Gigafactory we get 953 GWh per year, which is far less than the 3,229 to 4,688 GWh that will be needed. Also remember that the Gigafactory is located on hilly terrain which will block the sun in some parts and it will have parking lots and roads, so all 2864 acres will not be suitable for solar panels.

Of course Tesla can easily buy more land and better land for a solar farm in the region. The problem is the cost. Currently utility-scale PV solar costs roughly $1.1 million per MW of nameplate capacity, so Tesla will have to spend between $1464 and $2126 million to build a solar farm which is double the size of the biggest solar farm in the world. If the Gigafactory will have all its energy in December coming from onsite solar, then those costs balloon to between $2616 and $3798 million.

Another problem is the size and cost of the battery array to store the solar energy. Currently, Telsa charges $250 per kWh for the PowerPack. Let's guesstimate that the installation of a battery storage system will cost Tesla $150 per kWh. Since Tesla claims that it will be using 100% renewable energy, presumably it will need a full day's worth of electricity in its battery storage, so it will need between 8.8 and 12.8 GWh of battery storage. That means that Tesla will spend between $1327 and $1926 million on battery storage.

It is highly unlikely that Tesla will be spending this sort of money, so it won't be using 100% renewable energy. It is far more likely that it will have a 200 to 300 MW solar farm on the site of the Gigafactory and a small battery to smooth the solar output, but it will be buying power from the dirty Nevada grid for the rest of its needs.
 

SageBrush

REJECT Fascism
May 7, 2015
12,334
15,242
New Mexico
It is highly unlikely that Tesla will be spending this sort of money, so it won't be using 100% renewable energy. It is far more likely that it will have a 200 to 300 MW solar farm on the site of the Gigafactory and a small battery to smooth the solar output, but it will be buying power from the dirty Nevada grid for the rest of its needs.
I'm pretty sure Tesla has already said the intent is to be NET zero emissions. That is, they add clean energy to the grid in the same amount as they consume. During times of excess, other consumers use less NG; at night and when cloudy Tesla uses electricity that may be from fossil sources.

That is about a gazillion times better than any other car company in the world, so I am not about to whine that it is only net zero. In fact, it matches the NET zero PV install I have to cover our electricity for home and car. I presume from your criticism that you do better ?

Lastly, you have to include the opportunity cost of NOT installing clean energy. Grid electricity is not free, and it is subject to inflation and utility expenses and profits. How much do you think Tesla is paying for SolarCity panels ? Certainly not more than one penny a kWh, and perhaps half a penny. Beyond the sustainability goals of Tesla, clean energy is a financial no brainer for them. Just like it is for companies like Walmart.

This entire discussion devolves into 2.5 points:
  1. Efficiency is King
  2. Cover what remains with cheap, clean energy
  3. Use batteries to mitigate peak power charges
May I suggest a better use of your time ? Calculate the per car savings of Tesla Vs say GM based on embedded energy per car and purchase route.
 
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JeffK

Well-Known Member
Apr 27, 2016
6,997
6,653
Indianapolis
I'm predicting that the Gigafactory will consume between 3,229 and 4,688 GWh of electricity per year (or between 367 and 535 MJ on average).

The average capacity factor of utility scale PV solar in the US in 2016 was 0.2769. Looking through the EIA data for solar farms around Reno, Nevada, they seem to have capacity factors pretty close to the national average. There are places in Southern California that do much better, but the Gigafactory won't get that kind of sun.

With a capacity factor of 0.2769 the Gigafactory will need a solar array of between 1331 MW and 1932 MW in nameplate capacity. If Tesla wants a solar array that generates between 367 and 535 MJ in December when the average CF is 0.1550, then it will need an array between 2378 and 3452 MW in nameplate capacity. Because of the reduced solar irradiance in the winter, it is highly likely that the Gigafactory will be using a lot of dirty grid electricity from Nevada during the winter, which mostly comes from burning natural gas.

Telsa simply can't generate that much solar energy on the current acreage of the Gigafactory. Taking the average of the 6 largest solar farms in the US (which all get better sun than the Gigafactory), we get 0.333 GWh per acre per year. If we use that average on the 2864 acres of the Gigafactory we get 953 GWh per year, which is far less than the 3,229 to 4,688 GWh that will be needed. Also remember that the Gigafactory is located on hilly terrain which will block the sun in some parts and it will have parking lots and roads, so all 2864 acres will not be suitable for solar panels.

Of course Tesla can easily buy more land and better land for a solar farm in the region. The problem is the cost. Currently utility-scale PV solar costs roughly $1.1 million per MW of nameplate capacity, so Tesla will have to spend between $1464 and $2126 million to build a solar farm which is double the size of the biggest solar farm in the world. If the Gigafactory will have all its energy in December coming from onsite solar, then those costs balloon to between $2616 and $3798 million.

Another problem is the size and cost of the battery array to store the solar energy. Currently, Telsa charges $250 per kWh for the PowerPack. Let's guesstimate that the installation of a battery storage system will cost Tesla $150 per kWh. Since Tesla claims that it will be using 100% renewable energy, presumably it will need a full day's worth of electricity in its battery storage, so it will need between 8.8 and 12.8 GWh of battery storage. That means that Tesla will spend between $1327 and $1926 million on battery storage.

It is highly unlikely that Tesla will be spending this sort of money, so it won't be using 100% renewable energy. It is far more likely that it will have a 200 to 300 MW solar farm on the site of the Gigafactory and a small battery to smooth the solar output, but it will be buying power from the dirty Nevada grid for the rest of its needs.
It's cool that you're doing math and have given this a lot of thought, but you've missed my point entirely.

You're making assumptions about energy usage. They've done many things already to make the manufacturing process more efficient. You can hear about some of it in videos of the previous tours they've had. In addition, Nevada alone has over 1900 megawatts of renewable energy not counting Tesla's future 70 megawatts. Nevada just passed a local bill to increase their generation of renewable energy to 50% by 2030 and 80% by 2040.
 

techmaven

Active Member
Feb 27, 2013
3,618
9,711
I'm predicting that the Gigafactory will consume between 3,229 and 4,688 GWh of electricity per year (or between 367 and 535 MJ on average).

I'm starting to take a closer look at your calculation here, and I believe your values are completely meaningless. I remember going through this exercise about 2 years ago and found that the papers you are referencing. They aren't applicable, unfortunately. There are far too many input value assumptions that are wrong.

One of the biggest problems in your input assumption is that the production energy requirements are on a per kg basis, not per kWh. The specific energy of the cells used in the studies are a mismatch. Ellingsen's assumption is 27% lower than the Tesla/Panasonic original 18650 cell from 2012. That alone throws off a tremendous amount. Majeau-Bettez's assumption is 42% too low. And Tesla/Panasonic is currently using an even denser cell. Just from that, the energy required on a per kWh basis drops by 42% to 274 MJ/kWh. I haven't gone back through all their various erroneous assumptions, but likely your energy requirements are high by about an order of magnitude, if not more.

BTW, you need to address the paper by Dunn. She critiques the approaches used by predecessors like Majeau-Bettez and also compares against EPA's data. Unfortunately she is modeling LMO chemistry, but the critique still applies. She's modeling a cell with 148 Wh/kg specific energy and has 10.7 MJ/kWh of energy. Notter has 143 Wh/kg and 3.1 MJ/kWh. Majeau-Bettez's approach is 40 to 105 times higher. It's far higher than EPA's estimate too of around 28 MJ/kWh for 167 Wh/kg. Using the EPA figures, at 260 Wh/kg, that's 18 MJ/kWh, or 5 kWh to make 1 kWh of cells.

That's 525 GWh per year of electricity usage using EPA's data and only correcting for specific energy. Add in process improvements, and we're talking about far less than even that. Your calculations are likely around 10x, if not 15x too high.
 
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amosbatto

Member
Jul 8, 2017
10
2
Bolivia
I'm starting to take a closer look at your calculation here, and I believe your values are completely meaningless. I remember going through this exercise about 2 years ago and found that the papers you are referencing. They aren't applicable, unfortunately. There are far too many input value assumptions that are wrong.

One of the biggest problems in your input assumption is that the production energy requirements are on a per kg basis, not per kWh. The specific energy of the cells used in the studies are a mismatch. Ellingsen's assumption is 27% lower than the Tesla/Panasonic original 18650 cell from 2012. That alone throws off a tremendous amount. Majeau-Bettez's assumption is 42% too low. And Tesla/Panasonic is currently using an even denser cell. Just from that, the energy required on a per kWh basis drops by 42% to 274 MJ/kWh. I haven't gone back through all their various erroneous assumptions, but likely your energy requirements are high by about an order of magnitude, if not more.

BTW, you need to address the paper by Dunn. She critiques the approaches used by predecessors like Majeau-Bettez and also compares against EPA's data. Unfortunately she is modeling LMO chemistry, but the critique still applies. She's modeling a cell with 148 Wh/kg specific energy and has 10.7 MJ/kWh of energy. Notter has 143 Wh/kg and 3.1 MJ/kWh. Majeau-Bettez's approach is 40 to 105 times higher. It's far higher than EPA's estimate too of around 28 MJ/kWh for 167 Wh/kg. Using the EPA figures, at 260 Wh/kg, that's 18 MJ/kWh, or 5 kWh to make 1 kWh of cells.

That's 525 GWh per year of electricity usage using EPA's data and only correcting for specific energy. Add in process improvements, and we're talking about far less than even that. Your calculations are likely around 10x, if not 15x too high.
In the supplemental material of Dunn et al (2014, p.10, http://www.rsc.org/suppdata/ee/c4/c4ee03029j/c4ee03029j1.pdf) they estimate that a pioneer battery assembly plant will consume 780 MJ per kg of NMC battery and the Nth plant operating at full capacity will consume 4.5 MJ / kg. Certainly Dunn is right about the Nth plant using less energy, but I wasn't convinced by Dunn et al's estimate of 4.5 MJ / kg, because the GREET group at Argonne Nat. Lab. simply contacted the manufacturer of dry room equipment in 2011 and asked for an estimate of how much energy would be consumed per tonne of battery material (p. 32, https://greet.es.anl.gov/files/lib-lca), whereas Ellingsen et al (2014) used real plant data and arrived at 100 - 400 MJ / kg of battery cell. I also tend to distrust Dunn et al, because some of their estimates for other battery components are 1/10 of the estimates found in other LCA studies and the process-sum methodology often underestimates, whereas top-down is better at captured all associated processes to make a good.

I explained in my article why I think that all the existing LCA studies are underestimating the energy to produce lithium, nickel and cobalt (and probably copper as well), since they are based on brine operations with high lithium content in Chile and sulfide ores (that are often processed with cleaner energy in North America). The energy to produce these raw materials will likely increase in the future. However, the more I think about it, you are probably right that the Gigafactory will use much less than 100MJ / kg of battery in assembly. I doubt that it is as low as 4.5 MJ / kg, but 10 - 30 MJ / kg does seem possible if the Gigafactory is able to achieve an 80% energy reduction in the drying rooms and those drying rooms represent 60% of the total energy usage in the Gigafactory. The other thing is that I reread Ellingsen et al and they say that pack assembly has very low energy usage, so my guesstimate of 25 MJ / kg for pack assembly is wrong.

Based on that, let's redo the estimates as 10 - 30 MJ per kg in cell assembly and 1 - 2 MJ per kg in pack assembly, so you need 333 - 958 GWh per year (or 38 - 109 MW on average) at the Gigafactory. That would mean a solar array of 137 - 395 MW in nameplate capacity costing $137 - $395 million and battery storage of 0.9 - 2.6 GWh costing $137 - $394 million. Those totals would be doubled if wanting to operate at 100% renewable energy in the winter with onsite solar.

That level of energy consumption will be challenging with 100% onsite solar, but not impossible, especially if you are talking about net 100% renewable energy, so the Gigafactory sells solar energy during the summer and buys outside energy during the winter. Tesla still has to build the largest solar farm outside the prime solar radiation zones in the US and its panels will cost more than the CdTe panels used by almost all the large solar farms in the US. There is a reason why almost every US solar farm over 100 MW in size is located in southern California, Arizona and the southwest tip of Nevada where there is the best sun and they almost all use First Solar panels. The Panasonic/Tesla panels are not a good choice for $ per kW.

I understand your point about increasing energy density in batteries, but I don't understand your argument why MJ / kWh would be better than using MJ / kg for making estimates. We aren't sure about the rate of change for either of them. It is currently very hard to estimate anything based on either MJ / kWh or MJ / kg because of the dramatic improvements in the energy efficiency of drying rooms and using multiple production lines, so that equipment is always operating at maximum efficiency. We are also getting dramatic energy efficiency improvements by shipping materials directly from the refiners and recyclers so there is less transportation and less reprocessing of materials. However, these are one-time improvements in efficiency and they will not keep increasing in the future. In theory, the MJ / kg should be relatively stable in the future once all battery manufacturing moves to Gigafactory-style production whereas MJ / kWh will keep changing.

One of my frustrations is that EV advocates aren't demanding that Panasonic/Tesla, LG, Samsung and BYD share data about their battery factories. We can't resolve this debate about energy usage without hard data. If these companies want to claim that they are helping the environment, then they need to provide the data. Consumers and governments should demand more transparency from the battery industry. Whether you believe in EVs or not, it seems to me that it is in everyone's best interest to have good assessments of their environmental impact.

This debate about the MJ / kg of batteries and energy usage in the Gigafactory is ignoring the more fundamental questions which I raised in my article about whether we have the metal reserves to make 95 million BEVs every year and whether can we sustain the rising environmental costs per kg of mining so much lithium, nickel, cobalt and copper. Can we reduce the number of vehicles down to a sustainable level so that we avoid those rising environmental costs in metal mining? Can BEVs truly reduce the GHG emissions for the transportation sector by 90% or do we need to be focusing on other policies? It seems to me that these are the fundamental questions to be addressed if lithium-ion batteries are to be a fundamental part of Musk's vision for "sustainable transport".
 

techmaven

Active Member
Feb 27, 2013
3,618
9,711
My point was that the energy used to make a cell is roughly the same independent of the specific energy. Therefore, with a higher specific energy, the MJ per kWh changes, while the MJ per kg doesn’t change that much. So taking their MJ per kg and correcting based on specific energy gets a much closer end result.

There is also the issue of lithium carbonate versus lithium hydroxide. Musk had talked about getting the supply chain to stop the conversion of lithium raw materials to lithium carbonate to then convert to lithium hydroxide instead of just making lithium hydroxide directly. Definitely Tesla is looking to wring costs out of the supply chain which usually means reducing energy usage that also lowers emissions.

Your new calculations are within the ballpark of realistic onsite solar and wind production as well as their ability to buy renewable generation through renewable energy certificates. Of course, they will be making their own solar panels at a facility in Buffalo powered by hydro power at extremely cheap electricity rates (somewhere around 1.5 cents/kWh).

There is some interesting information in this lithium investing article:

Lithium Miner News For The Month Of June 2017 | Seeking Alpha

37628986-1497252327345514.png


Note that Tesla uses AC induction motors so no permanent magnet resource usage, but presumably higher copper usage. NCA also has far less cobalt usage. Tesla uses silicon but no manganese.

There is the issue of metal reserves to make 95 million cars of any powertrain. Or 1.5 billion smartphones. At least the operational lifespan of a BEV is likely 12-20 years and not 3-5 years as is the case for a smartphone. This isn’t unique to BEVs. Further, known reserves are just that... people have’t bothered to look for more raw material because the known reserves is good enough. There are mines and, in the case of lithium, other sources that are not yet viable due to lack of pricing or demand. You have to counter balance with the massive ongoing effort to find and extract oil which has a tremendous amount of environmental impact. At some point, recycling of battery cells will be viable or mandated. The constituent materials still exists in the cell, just the components have shifted in construction over the charge cycles where the internal resistance goes up and the cell can hold less and less charge.

The primary way to reduce overall light vehicle demand is to have more ride sharing and alternate ways to transport. Tesla/Musk is tackling this with autonomous driving and hyper loop.

I suspect that Tesla doesn’t want to talk about the LCA because they are making massive changes to the input data of the LCA. People will misinterpret the existing LCA and naturally dismiss the target LCA. Tesla’s LCA will definitely shift due to the simultaneous volume expansion and cost cutting, primarily through better processes and energy reduction. Unfortunately, most of the scientific papers are easily 5-20 years behind. Digging through some of them, you realize the basis of many of the calcualations are estimates of industrial processes done 15+ years ago with a completely different energy production mix. After Tesla gets to some steady state of a Gigafactory operation, I suspect Tesla will do a LCA... we should push them to publish one.
 
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SageBrush

REJECT Fascism
May 7, 2015
12,334
15,242
New Mexico
I've wondered before how many generations of Li based batteries can be expected before a different technology takes its place. If it is more than a few then recycling inputs become the asymptotic marginal value of interest.

OP: you have a few interesting biases, perhaps unintended, that you should be aware of and avoid:
  • 100% transition to Li-x battery based transport is not a pre-requisite target. Perhaps trains will run on lines. Perhaps trucks and buses will run on hydrogen
  • Sustainable means that the cycle of continuous and never-ending inputs of limited resources and outgoing pollution is broken. It does not mean that there are no initial inputs or initial pollution.
 

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