Source: LA Times. 1-Apr-2015. 'Traffic crawls along the northbound 405 Freeway in Westwood during rush hour

Source: LA Times. 1-Apr-2015. 'Traffic crawls along the northbound 405 Freeway in Westwood during rush hour

The intense Political and Media scrutiny on Boundary Dam over the last 2 weeks has focused on the financial and technical aspects of project commissioning.

With that focus the original purpose of Boundary Dam (to sequester carbon dioxide!) has taken something of a back seat. So and since a change is as good as a rest, we thought this week would be a good opportunity to look at the carbon question. 

It has been noted that "this project takes 250,000 cars off the road".  Putting emissions in terms of cars makes it easy to visualize but hard to be specific. So and for this post at least, we'll stick to the intensely dull - but accurate - 'kilograms of carbon dioxide emitted when one megawatt hour of electricity is generated'. 
At present coal-fired generation in Saskatchewan emits about 1,110 kilograms of carbon dioxide per megawatt hour and SaskPower states that Boundary Dam will reduce that to 140 kilograms. That, BTW, is about a third of the carbon emissions of a gas-fired power station.

Impressive. But is 140 kilograms for real?  

No.

 

 

So what does SaskPower do with the Carbon Dioxide it captures?
Critical to understanding the true emissions rate is understanding what happens to the captured carbon. The name 'Carbon Capture and Sequestration' might lead one to believe that the carbon dioxide disappears, never to be seen again, into an indestructible, perma-sealed, carbon crypt deep in the bowels of the earth.
Nice idea but not quite - actually not by a long shot.

Enter the oil industry.

Only 350,000 tonnes (about 1 percent) of the 30 million tonnes captured is permanently stored below ground (see the Aquistore reference in this blog): the remaining 29,650,000 tonnes is being sold to an oil company for Enhanced Oil Recovery (EOR).

The process of using carbon dioxide for EOR is quite simple in concept. It is captured and then, under high pressure, pumped into old oil fields. In the case of Boundary Dam the oil field is Weyburn which is about 60 kilometres to the north-west of Estevan. The carbon dioxide, once in the oil field, combines with crude oil and, in doing so, makes the oil flow more easily. The combined oil/carbon dioxide mix is then pumped to the surface.  

Source: California CCS Coalition

Source: California CCS Coalition

While it is underground the oil/carbon dioxide mix is under great pressure. When it reaches the surface it is very much like opening a can of pop: the pressure is suddenly released, the crude oil fizzes and most of the stored carbon dioxide is released to the atmosphere.

 

In fact the amount lost is about 30 percent of the total that is originally pumped into the oil field. 
(see page 8 of this industry-funded study).  

 

 

..and what about the energy required to capture the carbon in the first place?

Source: The Halifax Chronicle Herald. 'Pipes and tanks snake around a carbon capture and storage facility at the Boundary Dam Power Station'.

Source: The Halifax Chronicle Herald. 'Pipes and tanks snake around a carbon capture and storage facility at the Boundary Dam Power Station'.

The complex system of pumps, compressors, heat exchangers etc. within the carbon capture facility needs loads of electricity to make it work. In fact the carbon capture process uses about a quarter of all the electricity generated by the coal-fired power station at Boundary Dam.   In other words the 'useful' electricity which can be used by industry and homes (760,000 megawatt hours) is much less than the total amount of electricity generated at Boundary Dam (1 million megawatt hours).  

The point is that the total carbon emissions of the facility needs to be divided by the lower amount of 'useful' electricity and not by the higher amount of total electricity. 

 

 

PUTTING IT ALL TOGETHER

Carbon emissions:  So the total annual carbon emissions to the atmosphere, from the Boundary Dam carbon capture scheme, consists of two parts. 

The first is the 110,000 tonnes of carbon dioxide which is never captured in the first place because the capture process is only 90 percent efficient.

The second, and much larger component is the 300,000 tonnes lost to the atmosphere during the processing of the crude oil/carbon dioxide mix pumped out of the Weyburn oil field.
(Funny this is never mentioned by the project proponents?!)

Carbon emission rate:  Dividing total emissions by the amount of 'useful' electricity generated - and not by the TOTAL electricity generated - gives the true carbon emissions per unit of electricity.

As noted: the total 'useful' electricity generated (i.e. after subtracting all the power which is needed by the carbon capture process) is 760,000 megawatt hours annually. In other words 410,000 tonnes divided by 760,000 megawatt hours or 540 kilograms per megawatt hour of generation.

 

 

CONCLUSION

SaskPower claims, that Boundary Dam carbon capture will reduce carbon dioxide emissions from 1,110 kilograms per megawatt hour to 140 kilograms, are not supported by the evidence. The true emission rate appears to be closer to 540 kilograms.

This latter amount is almost 4 times higher than the 140 kilograms claimed by SaskPower. It also exceeds the 420 kilogram level mandated for coal-fired power stations in the new federal regulations ('The Reduction of Carbon Dioxide Emissions from Coal-fired Generation of Electricity Regulations’ which entered into force on 1 July.)

A critic of this analysis might claim that the fate of carbon dioxide, after it has been sold to Cenovus, is not SaskPower's concern. That argument fails because, in the increasingly carbon constrained world in which we operate, carbon emissions are a real financial liability. Unless ownership of that liability is explicitly defined the liability associated with non-permanent storage will almost certainly rest with SaskPower. In other words: SaskPower has just created a multi-million dollar carbon liability for itself - and hence for electricity ratepayers (i.e. you!). 

In a CBC interview, just after Boundary Dam was commissioned in October of last year, SaskPower's then-CEO Rob Watson said that what happens to Boundary Dam's carbon, after it is sold to Cenovus, was not his concern.  

Perhaps it should have been. 


Posted
AuthorJames Glennie