Green Conversion of Carbon Dioxide and Sustainable Fuel Synthesis
Round 1
Reviewer 1 Report
An useful review of opportunities to advancing carbon cycle controle - that might be taken further in future work
Author Response
Thank you very much for your time and your good comment on my submission.
Reviewer 2 Report
This is an interesting paper covering the field quite well, but I have problems with its organisation and section labelling. And its limited conclusions
'Carbon dioxide sequestration by microalgae'
This is the key section but it wanders off topic ( from lines 184- 202) to look at all approaches, comparing electro chemical and bio systems. It refocusses specifically on algal systems from line 230 and in detail from line 304 onwards- your main story.
I think you need to break up the text. 184-202 would, with some adjustment, make a good general introduction to the technology options and ways of assessing them , headed as such, and the rest would follow later as being algal CO2 conversion. Better use of Table 1 would also be good- at present as far as I can see it is just cited and then left free standing
The hydrogen section is wheeled in rather oddly, at the end. It really ought to come before the algal section. And the conclusion section is rather short. In the text (lines 123- 124) you make the important claim that
'A green fuel, unlike fossil fuel, does not emit more CO2 into the atmosphere since its burning, in the well-to-wheel cycle, creates a CO2 release equivalent to that required for its manufacture, closing the CO2 balance, making it a carbon-neutral fuel'
I am not sure it is necessarily true that the energy used in CO2 conversion processes is always
the same as is produced when the fuel is burnt. You says it's 'equivalent', making it carbon neutral. But as you point out later in the text, the various conversion processes all have different energy and hence carbon costs. As far as I can see, all you can says is that some are high and that for algal systems they may be lower but we don't have the data yet. So, reasonbly enough, at the end of the alglal section (319-320) you say
'To evaluate the atmospheric consequences of microalgae-based carbon se-questration, life cycle estimate schemes need to be developed'.
I think you need to round the paper off better by commenting a bit more on these issues. At moment you just assert that
'when compared to terrestrial plants, microalgae have better carbon dioxide tolerance, carbon absorption efficiency', [line 444]
Maybe so, but what about the other options you look including hydrogen?
Can anything more be said?
Author Response
This is an interesting paper covering the field quite well, but I have problems with its organisation and section labelling. And its limited conclusions
'Carbon dioxide sequestration by microalgae'
This is the key section but it wanders off topic ( from lines 184- 202) to look at all approaches, comparing electro chemical and bio systems. It refocusses specifically on algal systems from line 230 and in detail from line 304 onwards- your main story.
I think you need to break up the text. 184-202 would, with some adjustment, make a good general introduction to the technology options and ways of assessing them , headed as such, and the rest would follow later as being algal CO2 conversion. Better use of Table 1 would also be good- at present as far as I can see it is just cited and then left free standing
Response: Thanks for your point of view. We have changed the text as you requested.
The hydrogen section is wheeled in rather oddly, at the end. It really ought to come before the algal section. And the conclusion section is rather short. In the text (lines 123- 124) you make the important claim that
'A green fuel, unlike fossil fuel, does not emit more CO2 into the atmosphere since its burning, in the well-to-wheel cycle, creates a CO2 release equivalent to that required for its manufacture, closing the CO2 balance, making it a carbon-neutral fuel'
I am not sure it is necessarily true that the energy used in CO2 conversion processes is always the same as is produced when the fuel is burnt. You says it's 'equivalent', making it carbon neutral. But as you point out later in the text, the various conversion processes all have different energy and hence carbon costs. As far as I can see, all you can says is that some are high and that for algal systems they may be lower but we don't have the data yet. So, reasonbly enough, at the end of the alglal section (319-320) you say 'To evaluate the atmospheric consequences of microalgae-based carbon se-questration, life cycle estimate schemes need to be developed'.
I think you need to round the paper off better by commenting a bit more on these issues. At moment you just assert that 'when compared to terrestrial plants, microalgae have better carbon dioxide tolerance, carbon absorption efficiency', [line 444]
Response: Thanks for your point of view. We have modified the text as you requested
Maybe so, but what about the other options you look including hydrogen?
Can anything more be said?
Response: Thanks for your point of view. We have modified the text as you requested including conclusion.