According to the executive summary of the Lawrence Berkeley National Laboratory study (see previous post), the US power sector emissions were already 52% lower in 2020 than projected in 2005 and therefor the US power sector has already gone halfway to zero emissions. This cheering message was shared far and wide.
Reading further than just the executive summary, the backpedaling begins. The author(s) acknowledge on the next page that 2020 is a special year and this could skew the result. There was a worldwide pandemic in 2020 that had a devastating effect on the economy. Less economic activity means less energy use, therefor a drop in emissions that would not be there if there wasn’t a pandemic. When they take 2019 as the final year (a year without the effects of the pandemic), then they find a decrease of 46%.
Okay, although that is less than 52%, it is still roughly half of the emissions.
The backpedaling continues however.
As I tried to explain tongue-in-cheek in previous post, part of this decrease is virtual. It is not an actual decrease, it is the difference between an IEA projection from 2005 (that was wrong in hindsight) and the reality in 2020. When the authors account for the actual decrease, then then they find that the decrease drops to 40% (page ii):
Just a couple pages into that study and that 52% number is going down pretty quickly…
Also here, the choice of end year might skew that number. If the author(s) take 2019 as final year (again, a year without the impact of COVID-19), they ultimately come to an actual decrease of 33% in emissions from 2005.
That is roughly one third of the 2005 emissions. The authors acknowledge this metric in the chapter “The Next Half: Review of the Scientific Literature”, but this 33% is not the number that is communicated to the public and policy makers…
Despite the lower actual emissions decrease than is communicated, the authors seem to stick to the “already halfway” narrative. This is how they view the zero emissions target versus the IEA reference case (page 16):
Their proposed target is reaching zero in 2035, so in another 15 years and this is consistent with the “already halfway” claim. They rightfully state that to reach this target, the US “must once again beat business-as-usual projections” and that this will pose challenges (things like long-term storage, synthetic fuels,… are mentioned). I think that there are also other challenges. Remember, the authors used a statistical trick to come to the 52% decrease in the first 15 years, so the US doesn’t start “halfway” into the following 15 years, but is more probably at one third and thus still two thirds to go…
The first 15 years also had the advantage that there was a gradual buildup of low emission capacity without (much) retirement of such installations. This luxury might not be there in the following 15 years. The lifespan of solar panels and windmills is 20 to 25 years, so the oldest solar/wind installations need to be replaced within the next 15 years. Basically, at least those that are build until 2010, maybe even 2015, are likely to be replaced in the next 15 years. Meaning the need to built extra (low emission) capacity to compensate for these retirements. Making it more difficult to reach the target in 15 years.
The same with nuclear power. The study acknowledges that nuclear power has an important role in reducing emissions and had a share of 20% of total generation in 2020. It is also stated that this share was close to what was projected in 2005. There was some good luck involved however: although some operating licenses expired in the period 2005 → 2020, these licenses were generally extended. That was good news for the 2005 projection, but these nuclear power plants will not be kept in service indefinitely. If these plants were already scheduled to be retired before 2020, then I guess they will not likely stay in service for the next 15 years. That means that this (low emission) capacity, that was partly responsible for getting a more favorable number, also will have to be replaced.
The US nuclear infrastructure is aging. Grouping the US nuclear reactors according to coming online date, I found that 48% of the nuclear reactors came into service in the 1970s, so these are now between 40 and 50 years old. The rest is not much younger: 46% of the nuclear reactors came into service in the 1980s. Only 6% of the reactors were put into service after the 1980s. There are bound to be quite some retirements in the next 15 years, especially now with politicians who are not exactly in favor of nuclear power.
Another challenge for the next 15 years is the evolution of the demand. The decrease in demand is one of the reasons that is given for the emissions decrease in the first 15 years. The electricity sector does not work in a vacuum (as acknowledged by the authors of the study). Other sectors like the transportation, households and industrial sector, are banking on higher levels of electrification to lower their own emissions. That probably means 2 or maybe 3 times the current demand that has to be generated, therefor the need to add even more (low emission) power sources to cope with the increased demand without increasing emissions.
There will be challenges ahead for sure. The emission decrease until 2020 was pretty easily framed, that second, ahem, “half” will surely be the tough one….
via Trust, yet verify
May 2, 2021