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
This is, of course, problematic if the aim is to ensure that particular targets (such as well-below 2C) are met; betting that a "backstop" technology that does not exist today at any meaningful scale will save the day is a hell of a moral hazard. 4/10
Many models go completely overboard with CCS, seeing a future resurgence of coal and a large part of global primary energy occurring with carbon capture. For example, here is what the MESSAGE SSP2-1.9 scenario shows: 5/10
These modeled worlds of planetary-scale engineering (with, say, three times the land area of India devoted to bioenergy with carbon capture and storage) are pretty hard to imagine from the vantage of today, where we are struggling to get our act together on basic mitigation. 6/10
At the same time, there will be a real need for NETs, even if its not as the scale that some modelers dream of. There will be a long tail of hard-to-decarbonize sectors (agriculture, aviation, polymers, industrial heat) where NETs can cost-effectively offset limited emissions. 7/
Perhaps more importantly, one of the most pernicious aspects of climate change is that left to its own devices its effectively permanent (at least in human-relevant timescales). Even if we get all our emissions down to zero the Earth will just stop warming; it won't cool down. 8/
This means that if we ever want to return to a cooler climate after we reach zero emissions, we will need to actively remove CO2 from the atmosphere. Its not hard to imagine massive efforts in the 22nd century to reverse the damage of the 21st. 9/10
So lets continue to fund research and deployment of NETs to help drive down costs and drive future innovation. But lets be very careful to make sure we treat NETs as a compliment to rather than a replacement for mitigation. 10/10

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More from @hausfath

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: latimes.com/business/story…

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
2 Feb
The National Academy of Sciences has a great new report on accelerating decarbonization of the US energy system, taking a deep look at what is needed to put us on track for net-zero by 2050. A few major takeaways: nap.edu/resource/25932… 1/5
1) Clean energy needs to scale up dramatically by 2030. This will require record-setting deployment of solar and wind technologies, get rid of all coal and some gas-fired power plants, and preserving operating nuclear plants and hydroelectric facilities where possible. 2/5
2) Zero-emission vehicles as 50% of new sales by 2030, prioritize heat pumps in homes and buildings (mandatory for most new construction) while increasing efficiency, start decarbonizing industrial processes/heat with low-carbon alternatives (hydrogen, CCS, adv nuclear) 3/5
Read 5 tweets
1 Feb
Ten years ago I made a bet with @BigJoeBastardi; he thought that the world would cool, while I projected it would warm. We settled on a paid dinner for me each year 0.1C above the prior decade avg (2001-2010) and for him each year 0.1C below, using UAH.

He now owes me 5 dinners
I had originally suggested a $10k bet, based on the past warming trend continuing, as I outlined here: rankexploits.com/musings/2011/b…
Joe countered in the comments that he was not willing to wager $10k, but was happy to make a bet around dinners. He suggested using UAH satellite troposphere data instead of surface temperature data, and making it relative to the prior decade's average:
Read 6 tweets
29 Jan
Meeting Paris Agreement climate targets will involve building a lot of big clean energy projects extremely quickly. We need to streamline permitting, remove barriers, and take the power away from NIMBYies to gum up the works if we want any hope of a rapid energy transition
We are talking about some large-scale land use changes happening in a 30-year timeframe; here is what the region around St. Louis might look like in 2050, for example:
Similarly, we will require a huge amount of new transmission to help balance out generation and demand in a high renewable future:
Read 5 tweets
28 Jan
A lot of time is wasted in oft-superficial debased about whether renewables or nuclear will be the key to decarbonization.

The reality is that both will play a key role in reaching our ambitious climate goals. Some new results by @VibrantCE show how.

A thread 1/10
Some of the most cutting edge research on how to integrate clean energy into the grid is done by @DrChrisClack and his team at @VibrantCE. They have done perhaps more than any other group in analyzing the important role that variable renewables can play.
They find – as do most others who build similar models – that wind and solar will be biggest driver of near-term power sector decarbonization. However, they do so using the huge amount of gas capacity we have to fill in the gaps. Heres capacity in their new zero-by-2050 scenario:
Read 11 tweets
28 Jan
Theres lots to be excited about with the new Biden climate EOs. But at the same time meaningful, durable climate policy will also require legislation.

In a new @TheBTI report we take a deep dive into policies that are both impactful and could become law: s3.us-east-2.amazonaws.com/uploads.thebre…
On the energy side some big ones are supercharging DOE loan authorizations to support early-stage clean energy companies, more funding for geothermal/carbon removal/small modular nuclear, grid modernization through a nationwide "supergrid", and extending support for renewables.
On the transport side, we argue for investing in expanded EV charging infrastructure and investments in ports and airports to reduce emissions, deal with maintenance backlogs and adapt to future climate changes:
Read 6 tweets

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