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  Reply # 2137120 30-Nov-2018 11:26
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tdgeek: Call nonsense? Maybe you should read first. This is about carbon capture. Carbon capture means capturing carbon if that’s not clear. Hence zero emissions

 

The whole thing smells to me of pseudo-science (and that it's on the Herald's site doesn't improve its credibility ;) ) and a wilfully? credulous politician.

 

If you convert natural gas (hydrocarbons) into CO2 and water, you get the maximum amount of energy out of the conversion, because CO2 and water have very low entropies. If you're going to produce methanol (ummm, don't we already have a gas-to-methanol plant at Waitara? And while that was great for New Plymouth, it was terrible for NZ) or fertiliser (presumably hydrocarbons), then either you extract less energy in the conversion, or you have to put some energy into converting the CO2 and water into methanol or fertiliser. And Thermodynamics says that no conversion is 100% efficient. Finally, of course, the methanol is going to be burnt at some point. At which point, all that CO2 goes into the atmosphere anyway. But maybe the carbon in the fertiliser would be sequesterd by plants which won't be harvested?

 

Similarly, if you're going to produce compressed CO2, somewhere you have to get the energy to compress it. And then you still have to find some way to get rid of it. Fundamentally, there's no particular reason why the CO2 generated by a gas- or coal-fired power station couldn't be captured and compressed. But it's obviously not cost-efficient (short-term, ignoring the climate change costs) when compared to just releasing it to the atmosphere, otherwise it *would* be collected and converted to methanol or fertiliser or whatever. Obviously there's not a great market for CO2. And I don't see why it would be any different for this new process.

 

 


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  Reply # 2137130 30-Nov-2018 11:50
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Rikkitic:

 

I don't know what is involved in wave generation, or what the problems with that are, but I would think just on general principles that if anything like the level of investment devoted to fossil fuel generation was applied to that, it would probably become a viable alternative very soon. There is no lack of wave energy around New Zealand.

 

 

I suspect the problem is that the energy is not particularly well concetrated. You would need a lot of construction around the coastline, or perhaps floating offshore. And then you need lots of transmisison lines to move the electricity to where it's needed. From Wikipedia:

 

 

Example: Consider moderate ocean swells, in deep water, a few km off a coastline, with a wave height of 3 m and a wave energy period of 8 seconds. Using the formula to solve for power, we get

 

 

P ≈ 0.5 kW m 3 ⋅ s ( 3 ⋅ m ) 2 ( 8 ⋅ s ) ≈ 36 kW m , {\displaystyle P\approx 0.5{\frac {\text{kW}}{{\text{m}}^{3}\cdot {\text{s}}}}(3\cdot {\text{m}})^{2}(8\cdot {\text{s}})\approx 36{\frac {\text{kW}}{\text{m}}},}

 

 

meaning there are 36 kilowatts of power potential per meter of wave crest.

 

 

I've highlighted the key problem... shallow water, close to a coastline is not as good, so you have significant engineering problems in capturing that power and transmitting it to shore. Efficiencies are only about 20% with current technology. So you would need 1500m of power station to get about a megawatt. Contrast that with Manapouri at 800MW.

 

Tidal power seems to me to be a better option; place turbines underwater at narrow entrances to large areas of water; harbour mouths or the entrance to Marlborough (e.g. Tory Channel, French Pass) or Fiordland sounds.

 

 


 
 
 
 


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  Reply # 2137132 30-Nov-2018 11:55
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SaltyNZ:

 

Without wanting to be too hyperbolic about it, @TwoSeven has a point. The reason you burn the fuel is that that releases energy. If you then have to capture and store the exhaust somewhere, that costs you energy, which was the point of burning the fuel in the first place. In the long run, the economics favour not burning fuel rather than burning it and trying to clean up afterwards. We would do better to concentrate on renewables than get side-tracked by what is still unclear as a long term answer. After all, even if carbon sequestration works, the fossil fuels are still going to run out.

 

 

Using energy isn't an issue per se.  The issue is using energy generated by releasing CO2 depending on where the energy comes from.  So if you have a country where all of the electricity comes from renewables .. why not.





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  Reply # 2137135 30-Nov-2018 12:08
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frankv:

 

Rikkitic:

 

I don't know what is involved in wave generation, or what the problems with that are, but I would think just on general principles that if anything like the level of investment devoted to fossil fuel generation was applied to that, it would probably become a viable alternative very soon. There is no lack of wave energy around New Zealand.

 

 

I suspect the problem is that the energy is not particularly well concetrated. You would need a lot of construction around the coastline, or perhaps floating offshore. And then you need lots of transmisison lines to move the electricity to where it's needed. From Wikipedia:

 

 

Example: Consider moderate ocean swells, in deep water, a few km off a coastline, with a wave height of 3 m and a wave energy period of 8 seconds. Using the formula to solve for power, we get

 

P ≈ 0.5 kW m 3 ⋅ s ( 3 ⋅ m ) 2 ( 8 ⋅ s ) ≈ 36 kW m , {\displaystyle P\approx 0.5{\frac {\text{kW}}{{\text{m}}^{3}\cdot {\text{s}}}}(3\cdot {\text{m}})^{2}(8\cdot {\text{s}})\approx 36{\frac {\text{kW}}{\text{m}}},}

 

meaning there are 36 kilowatts of power potential per meter of wave crest.

 

 

I've highlighted the key problem... shallow water, close to a coastline is not as good, so you have significant engineering problems in capturing that power and transmitting it to shore. Efficiencies are only about 20% with current technology. So you would need 1500m of power station to get about a megawatt. Contrast that with Manapouri at 800MW.

 

Tidal power seems to me to be a better option; place turbines underwater at narrow entrances to large areas of water; harbour mouths or the entrance to Marlborough (e.g. Tory Channel, French Pass) or Fiordland sounds.

 

 

Waves harvesting: The short version is it's an engineering nightmare.  Salt water, (violently) moving parts and electricity. Achievable but also expensive. 

 

It's also a regulatory nightmare.  Try getting permission to put a structure in the coastal environment in NZ.  As well as amenity objections (visual pollution, interference with recreation etc) there are genuine environmental issues.  Harvesting wave energy will change the adjacent coast physically and ecologically.  Ironically wave generation might protect coastlines from some of the effects of climate change.  Where waves are associated with wind, it may be cheaper to just harvest the wind.

 

Tidal generation: there is a lot of talk, but little action.  Tides are possibly the most predictable natural phenomena on earth.   I'm not sure what the barriers are?  A lot of the places that would suit tidal generation are important scenic areas and/or shipping routes.  They also tend to be away from large centres of population.  The Kaipara tidal energy proposal was appealing because it was close to Auckland.





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  Reply # 2137160 30-Nov-2018 12:48
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tdgeek:

Thanks for the detailed post, much appreciated. What is your opinion on this http://www2.nzherald.co.nz/the-country/news/article.cfm?c_id=16&objectid=12166840


 



As far as I can see they are still basically storing C02, giving it to someone else and saying ‘dont use it for a while’.

As I pointed out before, its science - when you combust a hydrocarbon and air (by whatever mechanism) the output is C02 + water,

As far as I understand the allam cycle - the air is substituted. Some of the C02 is used for part of the refinement process, but at the end there is still enough produced that it has to be disposed of in some way.

As an example of how C02 can find its way into the environment, I understand that the fizz in ones soda drink is likely produced from the manufacture of LC02 (liquid C02) which I would suggest is delaying the release of it into the environment until the bottle is opened. By that time, one only sees the effect of opening one bottle, even though it is likely a lot more are produced.




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  Reply # 2137602 1-Dec-2018 01:47
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MikeB4:

 

Hydro power  is not with out risk and enviromental impact.

 

 

If hydro power generation is so bad, why are we not demolishing the hydro dams and building coal fired generation to replace the hydro? There are large coal reserves in NZ, so obtaining the necessary coal is not a problem.

 

 

 

tdgeek:

 

Where else can we add more hydro, including man made lakes? Benmore is only 75 sq km

 

 

 

 

Easiest would be to revive the original proposal to raise Lake Manapouri by 30M, this proposal dates back to 1959. It would cause lake Manapouri to merge with Lake Te Anau. I can't find any information on what the surface area of the new "great lake" would be. But Im sure that it would be significantly larger. And the extra water depth would also mean a very large increase in storage capacity. Plus the higher water level will mean that more electricity could be generated by the Manapouri power station, without that station needing to use any extra water. Due to higher water pressure being fed to the turbines.

 

Yes, I get that there are arguments against more hydro generation. But those arguments still valid today? Taking into account current knowledge in relation to CO2 emissions. If we assume that the claim that the world will experience uncontrolled warming in 10 years, unless major carbon emissions reductions are achieved, is true. Then the natural environment around Lake Manapouri is going to be destroyed anyway. So why not just go ahead, raise the lake and lower carbon emissions.

 

Even if global warming is a complete scam, raising Lake Manapouri would be a very cheap way of getting more generation capacity, as well as improving NZ electricity security of supply. As you don't need to build any new actual generators to do so.

 

Then there is the project Aqua hydro power scheme also. That alone had a proposed generation capacity that is higher than the remaining Huntly coal generators. Also notable, is that the Manapouri hydro power station was already fully operational before construction began on the Huntly coal power station. If the Manapouri hydro scheme had been built to it's original proposed capacity, There is a chance that the Huntly power station may have never been built.

 

And in 2015, Genesis Energy announced that it would be withdrawing the Huntly coal generators from service. As due to recent (at the time) construction of new geothermal generation. Huntly was losing money. It was only due to swaption agreements between Genesis, and other major power companies that saved the Huntly power station from closure. If those agreements hadn't been signed, the coal generators would either be permanently closed already, or very close to it.

 

Yet now, Genesis Energy has announced that they are temporally recertifying a 3rd (out of the original 4) Huntly Coal Generator. Although they say that they won't be able to operate all 3 coal generators at the same time. But having 3 available will mean more redundancy from outages.

 

If more large scale Hydro generation had been built, then almost certainly the Huntly coal generators would have long since closed down. I fully blame stupid environmentalists for the fact that coal is still used to generate electricity in NZ today. As they campaign to stop the construction of new hydro generation. Yet they are indirectly ensuring that fossil fuels not only continue to be burnt for baseload generation. But also ensure that the owners of fossil fuel generation continue to make large profits. And I haven't even started on higher power prices causing people to switch from electricity to gas for their energy needs. Here is a recent example. https://www.geekzone.co.nz/forums.asp?forumid=141&topicid=243040

 

SaltyNZ:

 

MikeB4:

 

With the reserves of natural gas NZ has investment into new power generation from NG would not seem prudent. Maybe the investment would be better spent on wind or solar production.

 

 

 

 

Agreed. If we were to, say, swap out the coal boilers with NG boilers at Huntly then it might be worthwhile in the short term because NG is much lower emission (and also has less contaminants) than coal. But other than that, renewables are now the cheapest generation technologies. And that trend will only continue.

 

 

The Huntly coal generators can already operate on Natural gas, And have always been able to do so. Although there is also the newer units - 5 and 6. Which are natural gas only.






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  Reply # 2137609 1-Dec-2018 07:48
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I agree fully. Its not like we will build 25 rectangular lakes everywhere and be eyesores. And and the environmentalists who favour pollution, ridiculous. If we raise lakes we still have lakes. We lose some natural land, but whats the % of land lost compared to what 5 million of us have taken so we drive cars, live, work, and play? Benmore is 75 square miles. Thats not a lot. 

 

Its a small price to pay to remove coal burners, maybe stabilise electricity prices, allow room for EV's to continue the drive to reduce air pollution. 


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  Reply # 2137712 1-Dec-2018 10:21
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Totally agree Aredwood - if Climate Change really is the imminent disaster it's being made out to be, then we need to take steps that are not necessarily risk-free or impact-free.  More hydro, accepting that a species or two of snail might be killed.  Tidal power, accepting that Hone Harawira won't be happy and traditional food-gathering might be disrupted.  More nuclear also an option.

 

 


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  Reply # 2137851 1-Dec-2018 18:07
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I would suggest that To build a hydro dam, one has to permanently destroy a huge area of ground. Its not a small area like some have suggested in previous posts, nor is it a matter of raising the level of existing lakes as if nothing adverse would happen.

Human made hydro lakes bascally take an area of ground and destroy it. I would suggest the eco system takes hundreds of years (or possibly longer) for It to adapt. Natural lakes which have their levels increased basically do something similar, they destroy the natural eco system that had developed around something over millions of years.

I would suggest that the technology was good at the time. But this is the 21st century, not the 20th.

For example, i think the size of lake tekapo is roughly like 80 os sq km and the power output is about 180MW so that would make it around 2 1/4MW per sq km at a rough guess.

My question to you is how much power would be generated from 80km2 of solar power arrays. And what damage does that do to the environment in the long term. I would also ask is it possible to use the land for dual purpose?




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  Reply # 2137857 1-Dec-2018 18:18
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shk292:

Totally agree Aredwood - if Climate Change really is the imminent disaster it's being made out to be, then we need to take steps that are not necessarily risk-free or impact-free.  More hydro, accepting that a species or two of snail might be killed.  Tidal power, accepting that Hone Harawira won't be happy and traditional food-gathering might be disrupted.  More nuclear also an option.


 



I would suggest this is a common fallacy.

The argument has the logic - global warming will cause damage, therefore it is ok to cause damage (or probably even more damage) in an attempt to avoid it.

I find that the argument is often refers to known older technologies and sometimes [carefully] avoids the possibiliy that modern technology exists or that current process/regulation can be changed.







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  Reply # 2137877 1-Dec-2018 19:14
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I don't know how much more "dual use" you can get than a hydro lake, which is also scenically magnificent and a recreational resource for fishing, sailing kayaking etc.

 

Compare that to "modern technology" such as wind turbines or hectares of solar panels - as well as being a blight on the landscape, they exclude any other land use.  I also question their longevity compared to hydro-electric schemes, some of which are already 50 years old.

 

I'm not saying we shouldn't have a mix of systems, but hydro is proven tech with a lot of benefits


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  Reply # 2137878 1-Dec-2018 19:16
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Hydro Dams impact in various ways. They impact the stability if the surrounding land. They impact ground water upstream and down stream. Their impact Flora and Fauna both up and downstream. They can have an impact on downstream arable land. They can alter and impact aquifers. Then there is a seismic risk and a risk due to weather extremes resulting from climate change.




Mike
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The views stated in my posts are my personal views and not that of any other organisation.

 

Using empathy takes no energy and can gain so much. Try it.

 

 


gzt

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  Reply # 2137882 1-Dec-2018 19:31
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Is there anything to be gained by upgrading existing hydro electrical generation plant? Almost everything is higher output since 1960s.

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  Reply # 2137888 1-Dec-2018 19:53
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MikeB4: Hydro Dams impact in various ways. They impact the stability if the surrounding land. They impact ground water upstream and down stream. Their impact Flora and Fauna both up and downstream. They can have an impact on downstream arable land. They can alter and impact aquifers. Then there is a seismic risk and a risk due to weather extremes resulting from climate change.

 

Yep, so we may have to choose between some slightly dubious mild environmental impacts and a species-ending climate catastrophe.  Let me think about that and get back to you...


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  Reply # 2137896 1-Dec-2018 20:08
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shk292:

MikeB4: Hydro Dams impact in various ways. They impact the stability if the surrounding land. They impact ground water upstream and down stream. Their impact Flora and Fauna both up and downstream. They can have an impact on downstream arable land. They can alter and impact aquifers. Then there is a seismic risk and a risk due to weather extremes resulting from climate change.


Yep, so we may have to choose between some slightly dubious mild environmental impacts and a species-ending climate catastrophe.  Let me think about that and get back to you...



There are alternatives that have less impact. The mess we are in now illustrates clearly why we need to look at low impact and not repeat mistakes of the past.




Mike
Retired IT Manager. 
The views stated in my posts are my personal views and not that of any other organisation.

 

Using empathy takes no energy and can gain so much. Try it.

 

 


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