First, the plan is considered “conservative” in that it is not making use of any new technologies. Those technologies will come, but any benefits are considered lagniappe.
The biggest savings comes from the fossil fuel industry itself:
…the global primary energy supply is 165 PWh/ year, and total fossil fuel supply is 134PWh/year1ab. 37% (61PWh) is consumed before making it to the end consumer. This includes the fossil fuel industries’ self-consumption during extraction/refining, and transformation losses during electricity generation. Another 27% (44PWh) is lost by inefficient end-uses such as internal combustion engine vehicles and natural gas furnaces. In total, only 36% (59PWh) of the primary energy supply produces useful work or heat for the economy.
So, rather than a starting point of 134 PWh/y, the replacement only needs to be 59 PWh/y. The report cites an analysis of the
U.S. Energy supply by Lawrence Livermore National Lab’s that independently validates their analysis. That ripples through the economics, for example, far less energy storage is needed. But, as you'll see...they have a few tricks up their sleeve.
Section 01 – The Grid
The normal 65 PWh/y for the U.S. grid, when subtracting out fossil fuel “losses”, becomes 26 PWh/y.
The model assumes inter-regional transmission capabilities and expects 32% curtailment (e.g., systems overbuilt by a third). Otherwise, the numbers look similar to an LCOE plot. Solar, wind, nuclear, hydro, and geothermal were all evaluated for power generation. Nuclear and geothermal assumed no new builds, guessing that is mostly because of the price of existing systems.
A blend of old technologies with lithium-ion was evaluated for energy storage. Sodium ion and metal-air were not considered as none had been commercialized while the report was being written. The plan calls for 6.5 TWh of 8-hr Lithium storage (+800%), 6.9 TWh of industrial thermal storage (+1500%), and 107 TWh of Hydrogen storage. About a 1.7d reserve, which with regional interconnects and being overbuilt sounds reasonable.
The hydrogen storage over ESS might be because of lithium mining concerns. Certainly when
studied Hydrogen typically loses to lithium. I suspect if sodium batteries are ready to go we can do away with a lot of the hydrogen storage.
Section 02 – EVs
No surprise, they use the Tesla Model 3 for efficiency numbers. The Model 3 is about 340 watts per mile, which seems about average efficiency. Some vehicles are a lot more efficient, for example, the Aptera only sips 100 watts per mile and with built-in panels might not ever need charging. So, their numbers do indeed seem conservative.
Surprisingly, they have data from their Class 8 trucks and found them 4.2x more efficient than their diesel brethren.
Section 3 - Heat Pumps
In their calculations they gave fossil fuels a 90% efficiency for heating, which is only possible with high-end systems; most are in the low 80s. So again conservative. They came up with heat pumps use 3x less energy than fossil fuels; which if you remember the earlier post on them doesn’t make sense for heat even with fossil fuel’s self-consumption losses. The reason for the much higher efficiency is they also factor in cooling, that is fossil fuels have an advantage for heat, but Carnot losses eat their lunch for cooling.
Section 04 - Electrify High Temperature Heat Delivery and Hydrogen Production
The plan takes into consideration that 55% of fossil fuel in the industrial sector are for processes that require high temperatures (>200C). Those temperatures are easily achieved electrically, but there are specialized low-cost techniques to bank heat rather than electrically via an ESS. The plan talks about a couple of them.
For Hydrogen, they are again conservative, but they went large.... really large. Hydrogen is indeed cheap to start up, but its round-trip efficiency is around 50%, so you have to overbuild your renewables a lot.
Previously I had only been thinking of hydrogen as a high-density fuel replacement where batteries don’t make sense (e.g., airplanes), but it turns out a substantial amount of hydrogen is needed for various chemical processes and is made from fossil fuels. By switching to electrolysis that can be replaced at a cost of 7.2 PWh/y, but replaces 8 PWh/y of fossil fuels.
They’re also making use of renewable availability. For example, hydrogen generation doesn’t need to run at night or on rainy days if there is sufficient storage for a few days. Techniques like this can greatly reduce the costs of ESSes.
Section 5 Sustainable fuel for Planes & Ships
According to the IEA, ocean shipping consumes 3.2PWh/year globally and aircraft 85B gallons/y of jet fuel. In total, synthesizing fuels for them requires +5 PWh/y, although they are sourcing the carbon from CO2 capture which increases the amount, again making it a conservative value. Interestingly, long-range/duration ships are recommended as 1 2 TWh for Ni/Mn based technology. Other ships would use 28 TWH of LFP. Short-range air travel would use 20 GWh of high nickel-based battery tech.
Section 06 Manufacturing the Sustainable Economy
This section looks at the costs to build the generation and storage needed to power a carbon-neutral system. In addition to the existing power, the report calculates an additional 4 PWh/y would be needed to manufacture the required batteries, solar panels, and wind turbines; a ~7% increase of global power production.
Investments
This section was quasi interesting to me in that ultimately it shows us saving money by making the switch. It also covers the expected new investments in exploration for key minerals and refining which I don’t recall seeing in other analyses. Finally, the investment sections also looks at setting up recycling for true life-cycle costs.
Land Area Required
I suspect this section made it in as land usage is often a criticism of renewables without examining how much land space is used by fossil fuels and associated equipment (e.g., mining, pipelines, refineries). As you can image, land use was fairly small over all.
Materials Required
This section looks fairly complete in that includes not only the devices (e.g., wind turbine), but also the concrete for support and wire for transmission. There were a number of materials being used today (e.g., Terbium) which are old-school and not really needed; some are quite exotic so it’s good they can be excluded from future designs.
While copper looked similar to prior estimates and was augmented with aluminum; nickel was quite low. It was only primarily in wind turbines and very little in batteries. Possibly it and lithium were greatly reduced due to the day-time hydrogen generation for storage.
Their analysis with material availability and mining shows that overall the discovery, mining, refining, and transport would decrease from current levels (primarily because those numbers are very high for fossil fuels).
This plot was interesting, there's a common misconception that the "global reserve" is all there is. It's not, it's just the tally as to what exists that is known and can be mined profitably. Because of new exploration and consumption, the number is always changing.
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