Comments on: Biofuels - the bad and the good! http://greenmonk.net/biofuels-the-bad-and-the-good/ Green from the roots up, Sustainable from the top down Tue, 06 Jan 2009 22:34:22 +0000 http://wordpress.org/?v=2.7 hourly 1 By: Phoebe Bright http://greenmonk.net/biofuels-the-bad-and-the-good/comment-page-1/#comment-3573 Phoebe Bright Fri, 18 Jul 2008 11:29:51 +0000 http://greenmonk.net/?p=200#comment-3573 Tom, 1. I guess it depends on the size of the tank and the temp/amount of hot air as to whether you get happy algae or cooked algae! 2. Your right. Just so long as it doesn't get hyped as capturing carbon. Like Brian's idea - reminds me of Zeri's closed loops systems. see http://www.zeri.org/case_studies_beer.htm Tom,

1. I guess it depends on the size of the tank and the temp/amount of hot air as to whether you get happy algae or cooked algae!

2. Your right. Just so long as it doesn’t get hyped as capturing carbon.

Like Brian’s idea - reminds me of Zeri’s closed loops systems. see http://www.zeri.org/case_studies_beer.htm

]]> By: Tom Raftery http://greenmonk.net/biofuels-the-bad-and-the-good/comment-page-1/#comment-3565 Tom Raftery Wed, 16 Jul 2008 08:27:21 +0000 http://greenmonk.net/?p=200#comment-3565 @Phoebe, thanks for the questions and apologies for the delayed response but am just back from hols and am catching up! 1. You are absolutely correct that it makes no difference where the CO2 is released but why would you need to expend energy to cool the gas to bubble it through the algae? Surely the CO2's heat would be used to heat water and thereby turn the heat into a benefit, not a cost. 2. You are again correct that the CO2 isn't locked up indefinitely this way. What turning it into a fuel does is reduce the amount of fossil fuel burned for transportation, so we get more energy for less CO2 released. But I agree that fundamentally we need to move totally off the carbon economy. This is a stepping stone, a short-term solution to help us get there. @Brian, see my comments to Phoebe above re sequestration. I love the idea though of wood-fired piggybacking! Excellent. @Phoebe, thanks for the questions and apologies for the delayed response but am just back from hols and am catching up!

1. You are absolutely correct that it makes no difference where the CO2 is released but why would you need to expend energy to cool the gas to bubble it through the algae? Surely the CO2’s heat would be used to heat water and thereby turn the heat into a benefit, not a cost.
2. You are again correct that the CO2 isn’t locked up indefinitely this way. What turning it into a fuel does is reduce the amount of fossil fuel burned for transportation, so we get more energy for less CO2 released. But I agree that fundamentally we need to move totally off the carbon economy. This is a stepping stone, a short-term solution to help us get there.

@Brian, see my comments to Phoebe above re sequestration. I love the idea though of wood-fired piggybacking! Excellent.

]]> By: Brian Miles http://greenmonk.net/biofuels-the-bad-and-the-good/comment-page-1/#comment-3549 Brian Miles Mon, 07 Jul 2008 15:24:09 +0000 http://greenmonk.net/?p=200#comment-3549 Regarding growing algae on power plant exhaust (I'm assuming coal or natural gas here), I'm no expert on CCS let alone the carbon cycle, but if you combust biofuels made from said algae, I don't think any CO2 is being sequestered in the end. Now you might be getting more energy per unit of CO2 emitted into the atmosphere, not to mention the convenience of a liquid fuel, but you're not keeping CO2 out of the atmosphere when all is said and done. You are in a sense piggybacking on the fossil carbon, which might not be a bad way, in the short- to medium-term, to reduce the carbon footprint of liquid fuels. Now if this algae process proves to be energetically and economically profitable for fossil fuel power plants, it would be interesting to try it on a wood-fired plant. Here you'd be piggybacking on "renewable" carbon, so you would be closing a loop, tapping a previously wasted byproduct of this form of centralized energy production. Regarding growing algae on power plant exhaust (I’m assuming coal or natural gas here), I’m no expert on CCS let alone the carbon cycle, but if you combust biofuels made from said algae, I don’t think any CO2 is being sequestered in the end. Now you might be getting more energy per unit of CO2 emitted into the atmosphere, not to mention the convenience of a liquid fuel, but you’re not keeping CO2 out of the atmosphere when all is said and done.

You are in a sense piggybacking on the fossil carbon, which might not be a bad way, in the short- to medium-term, to reduce the carbon footprint of liquid fuels. Now if this algae process proves to be energetically and economically profitable for fossil fuel power plants, it would be interesting to try it on a wood-fired plant. Here you’d be piggybacking on “renewable” carbon, so you would be closing a loop, tapping a previously wasted byproduct of this form of centralized energy production.

]]> By: Phoebe Bright http://greenmonk.net/biofuels-the-bad-and-the-good/comment-page-1/#comment-3542 Phoebe Bright Sat, 05 Jul 2008 11:59:02 +0000 http://greenmonk.net/?p=200#comment-3542 Tom, A couple of questions re the algae. 1. Is there much of a difference between bubbling the exhast gas through the algae and just growing the algae elsewhere? Where the CO2 is released makes no difference. I know the plants will take up more CO2 in a CO2 rich environment but I would guess that the extra energy required to cool the gas the bubble it through the algae would offset the simpler system of just putting the algae in a pond? 2. How is the algae locking up the CO2? Will it not be released again when the biofuel is used or when the remains are composted or fed to animals? Maybe it could go through a biochar system - that might lock it up. Tom, A couple of questions re the algae.
1. Is there much of a difference between bubbling the exhast gas through the algae and just growing the algae elsewhere? Where the CO2 is released makes no difference. I know the plants will take up more CO2 in a CO2 rich environment but I would guess that the extra energy required to cool the gas the bubble it through the algae would offset the simpler system of just putting the algae in a pond?
2. How is the algae locking up the CO2? Will it not be released again when the biofuel is used or when the remains are composted or fed to animals? Maybe it could go through a biochar system - that might lock it up.

]]> By: Jason Etheridge http://greenmonk.net/biofuels-the-bad-and-the-good/comment-page-1/#comment-3538 Jason Etheridge Fri, 04 Jul 2008 20:00:43 +0000 http://greenmonk.net/?p=200#comment-3538 Isn't the whole point of biofuels that, in theory, they're carbon neutral? That is, while burning them does produce CO2, it should produce no more than was incorporated during the life of the plants that made that fuel? Biofuels aren't inherently bad because they emit CO2 when burned. The problem is that the current production (e.g., ethanol from corn) isn't carbon neutral (fossil fuels are needed in the process), they're apparently more polluting than regular petrol, and (worst of all) they force up the price of food by creating a (subsidised) demand for food crops. An algae-based production method is ideal: biofuels can be produced that are truly carbon neutral. We can then have biofuels that are effective substitutes for use in aircraft and cars than can be delivered using the existing infrastructure, and don't require modification of engine design. The ideal solution, if its production can be scaled up to the required level. The bottom line is that there's no need to "get off the carbon economy", as long as the CO2 produced is an even exchange with what's incorporated. Isn’t the whole point of biofuels that, in theory, they’re carbon neutral? That is, while burning them does produce CO2, it should produce no more than was incorporated during the life of the plants that made that fuel?

Biofuels aren’t inherently bad because they emit CO2 when burned. The problem is that the current production (e.g., ethanol from corn) isn’t carbon neutral (fossil fuels are needed in the process), they’re apparently more polluting than regular petrol, and (worst of all) they force up the price of food by creating a (subsidised) demand for food crops.

An algae-based production method is ideal: biofuels can be produced that are truly carbon neutral. We can then have biofuels that are effective substitutes for use in aircraft and cars than can be delivered using the existing infrastructure, and don’t require modification of engine design. The ideal solution, if its production can be scaled up to the required level.

The bottom line is that there’s no need to “get off the carbon economy”, as long as the CO2 produced is an even exchange with what’s incorporated.

]]>