Is alkalinity addition by wastewater treatment facilities CDR?

[Josh Perfetto]

Hi,

What do people think about the additionality and validity of CDR credits in this scenario:

A wastewater treatment facility was previously treating wastewater with magnesium hydroxide to meet outfall pH requirements as is a common practice. Let us assume this was preventing some CO2 from being released from water in the facility or after discharge, and/or alkalinity in discharge later equilibrated with air causing additional CO2 to be stored. However as the carbon footprint of the magnesium hydroxide was very high, this was a net positive process.

Then a CDR company comes along and provides the facility carbon-neutral magnesium hydroxide. The facility continues business-as-usual (no increase in Mg(OH)2 usage), just using this alternate material. The CDR/wastewater partnership does some MRV to ensure the above assumption actually happened, and then claims CDR credits for this removal.

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Is this CDR? My first instinct was that it is not CDR but rather decarbonization of the wastewater facility, as the facility is otherwise doing what it always had, so it would be a quality offset, but not CDR. But now I'm almost convinced of the opposite. The argument for that:

The wastewater facility was well positioned to be a CDR facility but hadn't put the pieces together until the partnership with the CDR company happened and along came their carbon-neutral Mg(OH)2. Said differently, the wastewater facility was always a CDR facility, just a crappy one because its removal efficiency was negative. Now the partnership can offer CDR services because of the much better LCA, and there's the co-benefit of helping the wastewater side of the business meet its outfall pH requirements. It is not fair to say the wastewater facility can never be a CDR facility just because of its historical use of magnesium hydroxide to treat wastewater. The wastewater facility is not the source of the CO2 in the water it treats, and there was never a regulatory requirement to remove it.

Thoughts?

-Josh

[Greg Rau]

Thanks Josh. The short answer IMHO is that someone should get emissions reduction credit for making or using zero-emissions Mg(OH)2 under otherwise BAU. On the other hand, if you up the application of zero emissions Mg(OH)2 to WW above BAU, then any additional CO2 removed as a consequence here should count as CDR. This is something that my company is doing, and we are not alone in adding alkalinity to WW for CDR. A note of caution - there is probably no such thing as zero-emissions Mg(OH)2 (yet) since some fossil energy is still required to produce, transport and/or distribute the stuff. This has to be substracted from any gross CDR achieved to get net CDR and credits. 

Greg

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[Chris Van Arsdale]

Well, definitions of CDR are always a bit in the eye of the beholder.

Personal opinion: I would probably treat this as "Avoided Emissions" up to the net neutral point, then "CDR" past that (in the LCA analysis). While the CO2 benefit from each is similar, the labeling is different for a variety of reasons, including how investment budgets are allocated. Many AE technologies don't scale to net-negative CDR (e.g. point source capture), whereas OAE would, so investors would probably treat it as CDR-catalytic.

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[Mike Robinson]

+1 

Emissions reduction credit vs BAU for reducing the CI of making Mg(OH)2.  CDR to the extent that the alkalinity can be shown to mineralize environmental CO2 (subject to adequate MRV, of course).

But this is also a problem of scope.  The wastewater facility would recognize the Mg(OH)2 manufacturing emissions as Scope 3 and the factory making it would see that as Scope 1.  Do they both get to claim the emissions reduction credit on their carbon footprint reports?  For that matter, does the Mg(OH)2 factory get to claim credit for CDR in their Scope 3? 

[Josh Perfetto]

Thanks for the opinions guys. My interest in this scenario was that if it was viewed as CDR, it could really help kick-start and scale the OAE and low-carbon alkalinity production industry(ies). No one would object to the facility changing to a lower-carbon supplier and this could spread much faster, whereas if the facility starts to increase alkalinity addition above baseline, then some people don't tike it and the social aspects get much harder.

But if it is not CDR and just some decarbonization offset, then I don't think many people would be interested in buying it, certainly not at the price low-carbon alkalinity would need. That is kindof a shame, because the impacts to atmospheric CO2 would be exactly the same whatever we call this business-as-usual credit.

-Josh

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