Posted on 17 June 2016 by Guest Author

This is a re-post from Leo Hickman at Carbon Brief

Bioenergy with carbon capture and storage – better known by the acronym “BECCS” – has come to be seen as one of the most viable and cost-effective negative emissions technologies.

Even though they have yet to be demonstrated at a commercial scale, negative emissions technologies – typically BECCS – are now included by climate scientists in the majority of modelled “pathways” showing how the world can avoid the internationally agreed limit of staying “well below” 2C of global warming since the pre-industrial era.

Put simply, without deploying BECCS at a global scale from mid-century onwards, most modellers think we will likely breach this limit by the end of this century.

But where did the idea for this “saviour” technology come from? Who came up with it? Who then developed and promoted the concept?

Continuing our week-long series of articles on negative emissions, Carbon Brief has looked back over the past two decades and pieced together the seminal moments – the conferences, the conversations, the papers – which saw BECCS develop into one of the key assumed options for avoiding dangerous climate change.

The interactive timeline above shows these moments in sequential order. But Carbon Brief has also spoken to the scientists who were instrumental to the concept first taking hold…

Beginnings of BECCS

In April 2001, a PhD student from Sweden travelled to the University of Cambridge to present his latest unpublished work to the 12th Global Warming International Conference and Expo. Kenneth Möllersten, who was studying at the Royal Institute of Technology in Stockholm, had spent much of the past 12 months thinking about how the Swedish paper industry might be able to financially benefit from the Kyoto carbon emissions trading system through capturing its factory emissions and sequestering them underground.

Kenneth Möllersten

Sitting in the audience at Möllersten’s talk was a scientist called Michael Obersteiner based at Austria’s International Institute for Applied Systems Analysis (IIASA). Obersteiner approached Möllersten afterwards.

“He was quite excited and wanted to collaborate, so we decided that we should try to do something together,” says Möllersten, who now works as a senior scientific advisor for the Swedish Energy Agency.

A few weeks later, the two men picked up the conversation over the phone, explains Obersteiner:

“Kenneth called me one day and asked if he would get double carbon credits for emissions avoided from a pulp and paper mill using CCS [carbon capture and storage]. At that time, I was very annoyed that 450 parts per million [CO2 atmospheric concentration] was the accepted climate target simply because the integrated assessment models (IAMs) could not project below that. At that time, with the insight that, in principle, there was the possibility to use an industrial process to generate negative emissions on large scale, we got excited and wrote a paper in two weeks.”

Paper in Science

Michael Obersteiner. Credit: IISD

The short, yet influential paper that Möllersten and Obersteiner ended up writing, along with a diverse group of other scientists, was published in the high-profile journal Science the following September. Titled, “Managing climate risk“, it was the first time that the concept and potential of BECCS – even though it wasn’t named as such – was raised in a peer-reviewed paper. (“Initially, we were calling the concept BCRD – Biomass-energy with Carbon Removal and Disposal,” remembers Möllersten.)

The paper makes some eye-catching claims:

“Technologies that can rapidly remove GHGs from the atmosphere will play an important role, particularly if unforeseen catastrophic damages are expected to significantly decrease human welfare and natural capital. Terrestrial sinks are limited by land requirements and saturation, and concerns about permanence limit their attractiveness. However, biomass energy can be used both to produce carbon neutral energy carriers, e.g., electricity and hydrogen, and at the same time offer a permanent CO2 sink by capturing carbon from the biomass at the conversion facility and permanently storing it in geological formations…The cumulative carbon emissions reduction in the 21st century may exceed 500 gigatons of carbon, which represents more than 35% of the total emissions of the reference scenarios, and could lead, in cases of low shares of fossil fuel consumption, to net removal of carbon from the atmosphere (negative emissions) before the end of this century. The long-run potential of such a permanent sink technology is large enough to neutralize historical fossil fuel emissions and satisfy a significant part of global energy and raw material demand.”

But Obersteiner says the paper has, subsequently, been misinterpreted by some: “I think I am the inventor of the term BECCS as a tool to allow for ambitious climate targets. But the BECCS concept was unfortunately misused for regular [emissions pathway] scenarios and not in a risk management sense.” 

He adds: “The argument of the 2001 paper was to use BECCS as a backstop technology in case we got bad news from the climate system (e.g. signs of abrupt climate change, unpleasant carbon cycle feedback). Thus, the strategy should be to plan climate mitigation for a still ambitious climate target without BECCS, but still prepare for it in terms of large scale afforestation and regeneration to be prepared for the backstop, if needed. All of the integrated assessment models (IAMs) are deterministic [ie, have a single outcome per model] and do not allow for risk management thinking.”

Sweden’s paper mills

Möllersten says the first spark for the idea of BECCS came to him in 2000 when he was preparing to give a presentation at the 5th biannual Greenhouse Gas Control Technologies (GHGT) conference in Cairns, Australia. Working the idea through with Jinyue Yan, his PhD supervisor, Möllersten claims today that he “cannot remember the exact moment when we thought about this”, but he can recall the background:

“The way it started for me was when I started doing the work for my PhD. My focus was on looking at the pulp and paper industry as a very important industrial branch in the Swedish energy system. What measures could be taken to achieve cost effective emission reductions or CO2 emission reductions? Having worked on this topic for a while, looking at the most conventional measures, my professor and I noticed that there was a lot of work going on in this rather new and exciting area that was called “carbon capture and storage”. We also noticed that, as far as we could see, all that work was focused on emissions from fossil use. We simply decided to investigate what CCS could mean in the context of pulp and paper mills. When we did this work, we were looking at energy systems with a negative CO2 balance. For me, personally, it felt exciting to see that.”

Next came the calculations, says Möllersten:

“We defined some fundamental power cycles that could be utilised in the pulp mill. We looked at various power cycles and integrated fuel to capture into those power cycles and to get preliminary performance data. Then we tried to estimate costs. That was done during the year 2000. In early 2001, we had something to present and that is the material that I brought to Cambridge. Before I met Michael, I was looking at the pulp mill and how you could get two or three commodities out of it – electricity, industrial heat and negative emissions, which I hadn’t heard anyone else talk about it. When I was preparing to write the paper for that Cambridge conference, I did some academic literature surveys and I could only find two or three papers that had considered power cycles or energy cycles with biomass and CCS. [Möllersten says that because the 1998 book mentioned in the timeline above wasn’t peer-reviewed, it didn’t show up in his search.] They were mostly about co-firing of fossil use and biomass. Adding CCS to fossil use you get near zero emissions, but you can’t really get to zero.

What I did was to take this a step further and test the idea on a purely biomass-based system and acknowledge the fact that a negative emission is good, and that it should be rewarded in some way. When I wrote the paper for my conference in Cambridge and later on for the World Resource Review journal [see timeline above], I was trying to look at some kind of model that rewarded the pulp mill for negative emissions. I realised when I wrote that paper I didn’t fundamentally understand how an emissions system rating would work, but that doesn’t really matter. The principle that you could create an incentive for a power producer, or an industry, to generate negative emissions by allowing them to sell an emission code, or something like that, that still holds.”

Möllersten had a specific application in mind for his theoretical idea, but it was Obersteiner, he says, who took this germ and developed it into a climate mitigation risk strategy for their Science paper:

“It’s just one page or so, but there was a lot of work behind it. I saw quite extensive emailing back and forth from the majority of the names that were in that paper discussing how to present the idea. Mainly, the notion was of having to manage planetary risk; to be able to respond if and when it is realised that conventional technologies might not be considered sufficient. Then you can implement BECCS as a kind of risk management tool. My impression is that group of people worked very well together to try to present that concept in a compact way based on robust science.”

Keith and Rhodes

But at broadly the same time that Möllersten, Obersteiner and their colleagues were developing the fledgling idea of BECCS over in Europe, two scientists based at Carnegie Mellon University – a private research university in Pittsburgh, Pennsylvania – were also thinking along similar lines.

David Keith

In 2000, David Keith was an assistant professor at the university’s department of engineering and public policy. Along with a PhD student called James Rhodes, he, too, had begun to flesh out some early thinking about the potential of achieving negative emissions through the combination of bioenergy and CCS.

“I had been thinking about CCS and biofuels for quite a while,” says Keith (who also presented a paper at the GHGT-5 conference in Cairns in 2000). “I’d say the idea was in the air. I started to give some talks about the combination of biomass and CCS in the late 90s. At that point, as I recall, we were thinking about biomass that implied negative emissions. What I don’t remember is when I first started to draw a cost line for biomass on plots of electricity cost vs carbon price – the biomass line starts high and slopes down.”

James Rhodes

Keith has trawled through his archives for Carbon Brief, but says he can only find a single Powerpoint presentation from 2000 which mentions biomass with CCC: “I remember that we were talking about it in the Carnegie Mellon’s Center for Integrated Study of the Human Dimensions of Global Change in 1999 or 2000, but don’t have any slides in a readable format. I have an email to Jamie Rhodes sent on 7 November 2000. That’s the first mention of biomass and capture in an email with him.”

Rhodes, who is now a private consultant and inventor based in California, says this chimes with his memory, too:

“My recollection is that David and I began discussing BECCS in the fall of 2000, shortly after I entered graduate school that September. From my perspective, the concept initially came up during discussions of several possible research topics for my thesis work. However, my sense was that the topic had been discussed as a potentially interesting area of enquiry among several faculty members well before that time. I was not exposed to those earlier discussions. An initial framework for analysis emerged fairly quickly during those early discussions with David, and it grew to became a cornerstone of my doctoral research. The bulk of my analysis on BECCS was developed from late 2000 into early 2002. The analytic framework was developed in the winter of 2000 and throughout the following spring. The core model was developed over the summer of 2001 and refined throughout the fall and winter.

This work comprised the research component of my qualifying exams in early 2002, and a portion of this was featured in the paper we submitted to the GHGT-6 conference in Japan (and reflected in our 2002/2003 paper). [See timeline above.] The work was further developed in a 2005 paper in Biomass and Bioenergy and in my doctoral thesis. [Again, see timeline above.] I do remember when Obersteiner and Möllersten published their Science piece in late 2001. I believe it was the first evidence I’d seen that others were actively engaged in technology assessments in this area. I recall my impression of it being both a solid piece of analysis and a useful validation for the approach we were developing at the time.”

Rhodes says he can’t recall when the term “BECCS” first came to be used:

“I don’t know the origin of the term as it is currently used. My recollection is that during the period of my early research we used a number of labels, descriptions and acronyms, which varied over time and across concepts and technological pathways. For example, in my notes the shorthand “BE-CCS” may have referred to bio-energy with CCS (contrasted with fossil energy with CCS), to bio-ethanol with CCS, or both.  I don’t recall off-hand when the broader research community coalesced around the term BECCS.”

‘Crude engineering analysis’

In April 2001 – the same month Möllersten was giving his talk in Cambridge – Keith expressed his thinking to date in an editorial commentary for the journal Climatic Change. He argued that an “integrated analysis is needed to account for the strong linkages between the use of sinks and the use of biomass energy, linkages that are inadequately addressed in most estimates of the cost of CO2 mitigation”. The article went on to undertake a “crude engineering analysis” of using “biomass to produce electricity in a power plant that captures the CO2 and sequesters it in geological formations”. He concluded:

“Such a plant would be about 17 $/GJ and the net carbon emissions would be −55 kg/GJ (emissions are negative because the system sequesters carbon from the biomass). The current average producer cost of electricity is about 8 $/GJ and the US average carbon intensity of electric production is 47 kg/GJ, therefore the carbon mitigation cost is ∼90 $/tC. Again, a 100 $/tC tax would favour this option over remote sequestration.”

But Keith also used the article to raise concerns about the large scale use of bioenergy for climate mitigation: “It is my expectation that measured use of biomass that focuses on arresting or reversing some of the environmental damage wrought by recent exploitation – for example, by halting and reversing global deforestation and by improving denuded soils – will provide environmental and social benefits, but that large scale use of cropped biomass for energy will not.” 

Over the following years, as the timeline above shows, BECCS’ prominence grew in the academic literature and conference schedules – not least through the efforts of these pioneering scientists. For example, Keith admits that he “spent a fair amount of time pushing to get BECCS into the Intergovernmental Panel on Climate Change (IPCC)special report on CCS “with some success”, which was published in September, 2005.

Integrated assessment models

Detlef van Vuuren

But a key tipping point in the story of BECCS came when climate scientists started to increasingly include it in their modelling for sub-2C emissions pathway scenarios, often to the point that they grew reliant on it.

“Model teams picked up BECCS around 2005,” says Detlef van Vuuren, a senior researcher at the PBL Netherlands Environmental Assessment Agency and who has been a key figure behind many of the low-carbon emissions scenarios used by the IPCC. He says:

“Among the first were Christian Azar’s team from Sweden (modelling CO2 only) and my own work with IMAGE [integrated assessment modelling]. The latter was, in fact, one of the first publications making BECCS known at a larger scale. Up to around 2005, the lowest scenarios in the literature were looking at 450ppm CO2 only, i.e. 550ppm CO2eq. That was assumed to be consistent with 2C. However, at that time, people started to point out that, with new insights on climate sensitivity, the distribution of the estimates would provide a 50% chance at best of limiting temperature rise to 2C. So new scenarios providing a better chance of 2C would be needed. We published a set of mitigation scenarios using IMAGE looking at a wide range of options, including BECCS, with scenarios going from 2.6 W/m2 up to 5-6 W/m2 [two of the four representative concentration pathways, or RCPs, used by the IPCC; RCP2.6 is the scenario viewed as offering the best chance of staying below 2C].

The paper attracted interest as it was the first multi-gas model looking at such low greenhouse gas forcing targets. The work was published in 2007 in Climatic Change. However, it became even more well known during the IPCC expert meeting on new mitigation scenarios in Noordwijkerhout in 2007. The two lowest multigas scenarios in the literature at that time were from that IMAGE climatic change paper, i.e. a 2.9 W/m2 scenario without negative emissions and a 2.6 W/m2 scenario with negative emissions. At the meeting, that scenario was selected for subsequent research for the IPCC regarding climate impacts (RCP2.6). In subsequent years, most other teams started to look into the question of how to reproduce the IMAGE forcing scenario – adding negative emissions also to these system, by AR5 [the IPCC’s fifth assessment report published in 2014] resulting in 114 scenarios similar to RCP2.6 with the far majority including negative emissions.”

In little more than a decade, BECCS had gone from being a highly theoretical proposal for Sweden’s paper mills to earn carbon credits to being a key negative emissions technology underpinning the modelling, promoted by the IPCC, showing how the world could avoid dangerous climate change this century.

As a result, Van Vuuren now believes that climate scientists and policymakers stand at a crucial crossroads: