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100 Tesla Gigafactories would allow 100% sustainable energy

#energy #energymanagement #energyefficiency #sustainableenergy #batteries #consulting


During an interview, a couple of years ago, Tesla’s CEO stated that according to internal calculation 100 Gigafactories would be enough to "transition the whole world to sustainable energy”. Even though the exact calculation is not available, this post tries to understand a possible way to look at numbers; the premise is that those kinds of high-level views represent very strategic insights useful in several domains.

The idea is to start from the total worldwide energy supply, isolate the electricity consumption and understand the percentage of that electricity needing battery-storage capacity – that will also be recharged through renewable sources. The previous post “Our 100 W metabolic consumption and the 10,000 W one of our civilization“, went through the world’s total yearly primary energy sources (TPES) of 157,000 TWh/year and obtained the final electricity consumption of about 27,000 TWh/yr. That can be considered the starting point of this calculation even though there will be adjustments and considerations later on.

The analysis wants to figure out the need of storage-capacity based on a daily usage, meaning that batteries will be supposed to be drained and recharged -- by renewable sources -- on a daily basis. Dividing the initial 27,000 TWh/yr by 365 days it results in about 64 TWh/day of electricity consumed daily. Not all electricity needs to be stored; a big part can be directly used. Assuming the share of energy directly used to be 50%, the remaining 34 TWh/day would need battery-storage capacity. That assumption seems coherent with the average 2-person household consumption of 20 KWh/day (energy-intensive countries) and a typical utilization as per the picture below:

Source: https://www.solarchoice.net.au/blog/can-you-go-off-grid-solar-energy-storage

About 15-20% of the electricity currently produced at power-plants is used for internal production processes and lost along grid-lines; that loss is comparable to internal losses of current batteries. There are basically few benefits with respect to internal losses when it comes to batteries compared to the current grid. Therefore, 34 TWh/day remains the starting point of the next step.

The analysis focuses on installed capacity or, capacity to be manufactured; that includes ramp-up (till the world is taken off the grid completely) and replacement time (batteries needing to be replaced). For sake of simplicity we can assume both time-periods above to be about 20 years, that is, the capacity needed for the ramp-up will be comparable to the one for replacement. That assumption may be more accurate for the replacement time than for the ramp-up -- which seems optimistic. Anyway, a scenario where it is “full-throttle” is assumed and where everybody is convinced that taking the world off the grid is the solution to go and everybody is working in order to achieve that. Therefore, with those assumptions, 34 TWh/day divided by 20 years results in 1.7 TWh/day to be produced through the 100 Gigafactories each year.

It would be possible to supply 1.7 TWh/year with 100 Gigafactory if each one of them produced about 17 GWh/yr of battery-capacity per year. That number would seem more than obtainable considering that Tesla may intend to produce up to 150 GWh/year of battery-capacity at the current Gigafactory – about 1.5 MM cars/year with 100 kWh battery pack each. However, the calculation is missing an important component related to automotive: a transition to renewable sources is likely to imply a complete transition of the automotive industry to electric vehicles. Therefore, the calculation must include also that additional manufacturing output on top of the current electricity need. There are currently about 1.5 Bil cars in the world and considering a complete conversion to electric through the current production capacity of about 100MM cars/year, it means 100MM/year * 85 kWh (assumed avg battery pack similar to the current Model 3’s one) = 8,500 GWh/year of additional annual battery capacity to be produced for the automotive industry every year -- the small percentage already produced is neglected. The reader should note that it would take about 15 years to replace 1.5 Bil cars with a replacement rate of 100 MM per year; that is similar to the 20 year period already considered for the initial component and that is why the whole 8,500 GWh/year is included in the calculation. Dividing that number by 100 Gigafactories, it results in 85 GWh/year per factory.

Therefore, each one of the factories would need to produce about 85 GWh/year of battery capacity for the automotive industry and about 17 GWh/year of battery capacity for all other needs. 85 GWh for the automotive business may seem too high when compared with the 17 GWh for all the rest, however, there are a couple of assumptions determining that. The average Model 3’s battery pack of 85 kWh represents the energy capacity for about 10 average driving days rather than only one – daily capacity was the assumption used for all other uses. Assuming that on average people drive for 15,000 km per year, and considering Model 3’s autonomy of 450 km (thanks to the 85 kWh), it results in about 10 driving days of autonomy on average. Therefore, the actual daily usage would require only 8.5 GWh capacity to be produced but, because of the real use and consumption of a vehicle, we need ranges of 400+ km or about 10 driving days. On the contrary, for the electric capacity (non-automotive) it was considered only 50% of it to need storage – directly consuming the other 50% -- otherwise, each Gigafactory would need to produce 17 GWh * 2 = 34 GWh. Therefore, if it was only for total consumption, 34 GWh would be about 4x with respect to 8.5 GWh and it would justify a little better the calculation. Anyway, even though the analysis is dealing with high-level numbers, it has to represent as much as possible real life, therefore, 85 GWh and 17 GWh are the numbers to consider.

To conclude, adding up 85 and 17 GWh/year the results is about 100 GWh/year. While the existing Gigafactory is supposed to arrive at a production output of 150 GWh/year, that should not imply that 50 GWh/year represents production-capacity in excess. If the current annual energy consumption growth of about 2 - 2.5% is compounded for 20 years, it would require exactly those additional 50 GWh/year in 20 years. Moreover, while the calculation includes all the industries that could be currently technologically converted to electric like the automotive industry and the whole electric energy consumption (domestic, commercial and industrial), it would be possible to create other scenarios where few remaining industries are moved to electric (e.g. aviation …). However, at the moment it seems acceptable to consider those extra 50 GWh/year to be used for the extra energy-need once the compounding of the current 2 - 2.5% growth rate is included in the calculation.


Tesla's CEO video (minute 1:25)



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