In recent months three different deep decarbonization scenarios have been produced from high-resolution grid integration models. In a new analysis at @TheBTI, my colleague @erikolsonn and I look at lessons they provide about what is needed:…

A thread: 1/19
The three models we examine are Princeton's Net Zero America (NZA) project (by @JesseJenkins et al), the @VibrantCE Zero By Fifty scenario, and results by a team of researchers led by Jim Williams at USF. 2/
All three take a deep-dive into how US could reach net-zero emissions by 2050, down to level of where each new generating facility might be located, where transmission lines would be built, and how electricity sources can meet hourly demand in different regions of the country 3/
Each study contains multiple scenarios looking at sensitivity to future technology prices, land use constraints, and other factors. For simplicity, we focus on their marker scenarios: E+ for NZA, the default Zero By Fifty scenario from Vibrant, and central from Williams et al 4/
Both NZA and Williams et al. use a combination of the EnergyPATHWAYS (EP) and RIO models to generate their scenarios (and thus have a lot of similarity in their results), while Vibrant uses their WIS:dom model. 5/
In our comparisons we focus on electricity generation, as it is a big part of the solution given widespread future electrification, but these models also tackle industrial heat, transport, agriculture, and other important sectors of the economy. 6/
When we compare generation over time, a few things stand out. First, overall electricity demand increases dramatically across all the models by 2050, by 2x in @VibrantCE, 2.5x for NZA, and 3x in Williams et al. 7/
Second, future gen looks quite different between the Vibrant WIS:dom model and the EP/RIO-based results from NZA and Williams et al. While variable renewables — wind and solar — supply the majority of generation in all three, Vibrant’s model sees a big expansion of nuclear. 8/
Third, while NZA and Williams et al. have some remaining gas generation in 2050 (some with CCS, some blended with H2 and offset by direct air capture), Vibrant has only a small amount of gas with CCS. 9/
In all three models variable renewables provide the bulk of future generation, ranging from 51% and 91% of total electricity generation by 2050 across the three models. However, in all three cases a sizable amount of clean firm generation (and much more firm capacity) remains 10/
The models largely move away from fossil fuels, and all agree that the priority should be replacing coal well before gas. Coal drops off a cliff, reaching zero by 2030 or 2035. Gas, by contrast, stays flat through 2030 or so before gradually declining. 11/
While gas generation declines gradually in all three models, the same is not true of gas capacity. Somewhat surprisingly, both NZA and Williams et al. actually have natural gas capacity at or above current levels through 2050, though capacity factors decline over time: 12/
So whats going on here? The US currently has a ton of natural gas capacity. Gas is in many ways a good compliment to renewables; its low capital costs and high operating costs make it well-suited to sitting idle and filling in the gaps when renewable generation is low. 13/
It also gets quite expensive in the models to try and fully replace gas with existing technologies – renewables, storage, and expanded transmission – at least in the near-term. 14/
Current tech can get us a long way toward power sector decarbonization, but if we ever want to fully decarbonize - and move away from our reliance on natural gas - we need things like grid-scale storage, advanced nuclear, gas with CCS, or hydrogen that are not mature today. 15/
We need to both accelerate deployment of current cost-effective clean energy resources and invest considerably more in future tech. As NZA report argues, “2020s is the decade to invest in maturing and improving a range of technologies that improve options for the long term.” 16/
Statements that “we have the technology we need and just need to build it” get it half right — we do need to build clean energy much more quickly than we are today. But we will need continued innovation in addition to this multi-decade buildout of clean energy. 17/
The future electricity mix is difficult to foresee perfectly, and history is a graveyard of failed energy model predictions. All models are wrong, as the saying goes, but some are useful. These deep decarbonization models give us a sense of what may be needed. 18/
We should take heed of where models agree: on importance of near-term renewables deployment, medium-term role of gas capacity to fill gaps, and role of clean firm generation and complementary tech to wean the power system off its dependence on natural gas in the longer term. 19/
(Also check out the cool interactive graphs in the article!)…
I should also mention that I start the article by criticizing @GlobalEcoGuy's statement that "any solution that doesn’t show up in the next 10–20 years is essentially no solution at all", I should point out that his views are more nuanced than that.

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More from @hausfath

20 Feb
There is some truth in Gates's suggestion that making new clean energy tech cheap for can be more important than deploying existing clean tech.

But it neglects the fact that a big part of making clean tech cheap is deployment: driving economies of scale and learning-by-doing.
We should recognize the need to do both: accelerate the deployment of existing clean tech to further drive down costs (particularly for more nascent clean tech like EVs that are on the cusp of cost-competitiveness with fossil alternatives) AND dramatically scale up RD&D.
The quote in the original post is from @yayitsrob's excellent interview in the @TheAtlantic this week:…
Read 5 tweets
18 Feb
Geoengineering is not a solution to climate change, and at best might be a "break the glass in case of emergency"-type bandaid to buy us time.

That said, I disagree with Bill here that small-scale research projects will "take the heat off" of the push for decarbonization. 1/5
Here is where I could see geoengineering playing a role: say, at some point in the future we have gotten our emissions under control, but climate sensitivity was high and we've locked in 2.5-3C warming even though we thought we would limit warming to 2C. 2/5
We discover some previously unknown planetary-scale climate feedback mechanism with hysteresis that will lead to substantial additional warming if temperatures remain >2.5C. We need to actively suck lots of CO2 from the atmosphere to get temperatures down to safe levels. 3/5
Read 5 tweets
17 Feb
There has been a lot of confusion over the drivers of the Texas blackouts. While more will become clear in the coming days, neither renewables nor insufficient gas capacity were the culprits. Rather, it was the lack of resiliency of to extreme cold conditions.

A thread: 1/9
Texas has seen an explosion of cheap wind power in recent years. Wind now produces around 20% of Texas' electricity. However, at the same time Texas has also been building a lot of gas capacity; gas generally works well with wind, able to quickly ramp up to fill in gaps. 2/
Because it is intermittent, the grid manager @ERCOT_ISO does not rely much on wind to meet extreme demand events such as the one we are experiencing right now. Rather, they have enough gas (and nuclear/coal) capacity on standby just in case high demand coincides with low wind. 3/
Read 9 tweets
15 Feb
Much of the US is experiencing extreme cold temperatures. But we should not read too much into this when it comes to climate change; its both not an unusual day for global temperatures, and there is not much evidence that climate change is making cold extremes more common.
We can see that while the US and part of Russia are exceptionally cold at the moment, other parts of the world have much warmer than average temperatures. A warming world is still one with regional weather variability!
At the same time, there has been a strong decrease in the number of extreme cold events in many parts of the world. Today's event feels so extreme in part because its become much rarer in recent decades. (@RARohde has a good graph of this, but I can't seem to dig it up)
Read 8 tweets
11 Feb
There has been a lot of discussion about negative emissions technologies (NETs) lately. While we need to be skeptical of assumed planetary-scale engineering and wary of moral hazard, we also need much greater RD&D funding to keep our options open. A quick thread: 1/10
Energy system models love NETs, particularly for very rapid mitigation scenarios like 1.5C (where the alternative is zero global emissions by 2040)! More problematically, they also like tons of NETs in 2C scenarios where NETs are less essential. 2/10
In model world the math is simple: very rapid mitigation is expensive today, particularly once you get outside the power sector, and technological advancement may make later NETs cheaper than near-term mitigation after a point. 3/10
Read 10 tweets
9 Feb
Quite the tour-de-force from @Sammy_Roth on what would actually be needed to get California to 100% clean energy by 2045 and the somewhat-telling unwillingness to build fast and big enough today:…

A few highlights: 1/9
In response to rolling blackouts this summer, CA is extending the life of its natural gas plants. At the same time, however, it is failing to invest in clean firm generation to ultimately replace the role that gas plays on the grid, "sowing the seeds for the next crisis” 2/9
The CPUC is planning to would make a relatively weak 2030 of 25% emission reductions as the basis for approving or rejecting new transmission lines, likely leading to a substantial underinvestment in the magnitude of transmission needed for deep decarbonization. 3/9
Read 10 tweets

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