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  Reply # 2033495 11-Jun-2018 09:08
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frankv:

Aredwood: F
NZ also doesn't have anywhere near enough hydro storage to properly use large scale solar. Storage is only in the region of a few weeks to a month of generation capacity. Meaning a big storm can easily fill the lakes. While a dry year can still cause a winter power shortage, even if the lakes were full in April.

We would need hydro storage equivalent to around 6 months of demand for large scale solar to be useful. We would probably need a lake of similar size to Lake Superior in the USA for that to happen.

And is solar still economic to install if grid power cost around 10c per unit? How about 5c per unit? And if you give subsidies to solar, is that actually the best way of reducing carbon emissions? Is such money better spent on say subsidies for buying EVs?

Either way, something needs to change. As high power prices are a subsidy for fossil fuels. As they are cheaper in comparison. And are also an unnecessary extra cost on EV charging.


Does that still apply if you have an alternative like wind generation? Wind increase during winter, when electricity demand increases.


I don't see EVs as an alternative to solar to reduce emissions. I see EVs and home solar and PowerWall as to symbiotic technologies which, for the energy consumer, multiply the cost savings available from each separate technology. Batteries allow time-shifting of consumption away from time of generation. So a home solar generation system charges batteries which can then be used for energy at peak load times. And, given sufficient solar generation, to also supply power to charge your car for use the next day.


 



The big problem with both solar and wind is that you can't command them to output power when you choose. And they can't be used to provide reserve capacity. Also bear in mind that there is a lot of run of river hydro and geothermal generation in NZ also. If you run them at less than max capacity, you are just throwing away energy, in the form of spilled water or steam. So lake fed hydro is far more valuable than other sources of power. As the only other sources of large scale energy generation with storage are fossil fuel generation.

Home batteries are extremely expensive, as each time you put the battery through a charge and discharge cycle, it's lifetime reduces. This means that the equivalent power cost for electricity delivered from a home battery can be as high as 50c per unit. Even if the power used to charge the battery was completely free.

Agree that solar and EVs can both be done at the same time. But if subsidies are going to be paid, then they should only be used for what would give the biggest emissions reduction. This is a big problem with solar. As getting solar installed reduces the amount of lines fees that you pay. But because solar doesn't reduce peak demand, the cost to supply your house doesn't reduce. So lines fees have to increase. And low income people are forced to pay the bulk of those increases.





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  Reply # 2033530 11-Jun-2018 10:38
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debo:

 

Can you prove a source for this.  When  I was at tech, I was taught that thermal stations did not like the thermal shock of being turned on and off twice per day. It vastly reduced their life expectancy.  Instead, they were run at constant capacity, and hydro provide for peak power, as their turbines did not mind being varied through out the day.  

 

 

I don't have a link that states it in plain English, however in our free electrical market the cheapest generation possible at any given time supplies the load and off peak we are a wash with cheaper options than coal.

 

The Genesis website states that all the units can be used for peak loads. https://www.genesisenergy.co.nz/assets

 

The 2015 Genesis annual report says that thermal generation was only used for 11 days in June because the purchasing team could buy cheaper power elsewhere to meet peak demand for customers.

 

In the 2000's they were talking about shutting Huntly down entirely.

 

Here is a good link if you want to see the instantaneous mix of thermal/hydro/wind etc.

 

https://www.transpower.co.nz/power-system-live-data

 

Suspect you were a tech in the days when the purpose of the Electrical system was to support the economic and social wellbeing of the country.


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  Reply # 2033559 11-Jun-2018 11:33
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frednz: Sure, at the moment, the use of coal for electricity generation may not have a lot to do with EV battery recharging. But, what I had in mind when I said "if the demand on the electricity network becomes too great" was, what is going to happen when EV numbers grow substantially in the future? Will NZ be able to withdraw the use of coal for the generation of electricity if EV numbers grow as predicted?

 

Even if you have to use coal (which I hope we don't), there are 2 key advantages over oil:

 

1) Total CO2 is lower per KM so while not great, it is less bad (bearing in mind that petrol CO2 emissions are usually very understated because they are tail pipe emissions and don't include the CO2 from oil production, refining and delivery - a  lot of electricity is used in refining ironically).

 

2) It is a domestic fuel source which is good for trade balance, local employment, security of energy etc.

 

frednz: The topic of how the grid might be able to handle a large increase in the number of EVs is discussed in this article:

 

http://www.infometrics.co.nz/big-ev-fleet-can-new-zealands-grid-handle/ 

 

The fundamental message of the linked article is true however in that we'll need to plan some generation upgrades (with a population growing as rapidly as ours we need to irrespective of EV charging), however in terms of the grid, not so much. I contains typical scaremongering tactics revealed in the statement "if everyone plugs their EV's in a the same time...". Everyone has a kettle and "if" everyone plugged their kettles in at the same time we'd load to grid up to max, but that simply doesn't happen due to human nature. Mostly EV's charge at night, when there is surplus capacity on the grid as shown here https://www.transpower.co.nz/power-system-live-data

 

Additionally, with hardware that already exists in the UK, EV charging can be controlled by the power company to slow it down when power demand is high and ramp it up when demand is low (the reward for the EV owner is cheaper power rates). They're building the equipment necessary for EV's to return power to the grid at peak times, negating the need for grid level battery storage.


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  Reply # 2033617 11-Jun-2018 12:34
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Interesting technology.  Almost sounds to good to be true.

 

Some observations: -

 

1) As I read it's using CO2 from the atmosphere to make hydrocarbons which are then burnt again.  I wouldn't call this removing C02 as much as continuously recycling it.  Still much better than burning more oil.

 

2) There are obviously significant advantages in a 'carbon neutral' fluid energy source:  Energy density, rapid 'charging' and compatibility with existing networks.

 

3) Would still contribute to urban pollution.

 

4) Needs clean energy - possibly solar - to power the fuel production process.

 

5) Need energy to move the fuel around.  Unless you can make it into diesel, that won't be a carbon neutral fuel for long haul.





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  Reply # 2033644 11-Jun-2018 13:04
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shk292:

 

I'd love to see more big hydro projects - clean power with the by-product of fantastic recreational facilities for sailing, fishing etc.  But these days there always seems to be a unique breed of snail, or some other reason why they can't be built.

 

 

The downside of hydro electricity is that there's a lot *less* recreational facilities for whitewater kayaking and rafting and tramping. And, in the North Island, a lot of either productive pastures or forest drowned. And, as you point out, loss of habitat for some species which depends on fast-running water. These species, of course, contribute to NZ's reputation as the only place where a whole lot of unique wildlife can be seen, which is of course a major attraction for tourists.

 

I wonder about the economics; is a billion dollar dam better than 50,000 homes set up for solar?

 

 


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  Reply # 2033647 11-Jun-2018 13:07
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The two major areas where this would be game-changing would be aviation fuel, as someone mentioned above, and plastics.

 

Extracting CO2 from the air and using it to make plastic instead of using fossil hydrocarbons is actually removing and sequestering CO2.

 

We can use plastic without using up fossil fuels, and when we dispose of it (tidily in landfill) we are sequestering it safely away.


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  Reply # 2033721 11-Jun-2018 15:14
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shk292:

 

The most likely application is aviation fuel.  It's unlikely we'll ever achieve the energy density in a battery to replace jet fuel in an airliner or helicopter (with useful endurance), but this could provide a low carbon alternative

 

 

Not so unlikely.In fact hybrid airliners will soon be going into production.Boeing Airbus and Siemens to mention a few are backing this tech.

 

 

 

https://www.economist.com/science-and-technology/2017/11/30/small-hybrid-electric-airliners-ready-for-take-off

 

 

 

 


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  Reply # 2033916 11-Jun-2018 20:42
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frankv:

shk292:


I'd love to see more big hydro projects - clean power with the by-product of fantastic recreational facilities for sailing, fishing etc.  But these days there always seems to be a unique breed of snail, or some other reason why they can't be built.



The downside of hydro electricity is that there's a lot *less* recreational facilities for whitewater kayaking and rafting and tramping. And, in the North Island, a lot of either productive pastures or forest drowned. And, as you point out, loss of habitat for some species which depends on fast-running water. These species, of course, contribute to NZ's reputation as the only place where a whole lot of unique wildlife can be seen, which is of course a major attraction for tourists.


I wonder about the economics; is a billion dollar dam better than 50,000 homes set up for solar?


 



The Hydro dam is definitely better. Considering that the 50,000 homes on solar can't provide any peak time generation or offset peak time load. And the environmental costs of building a dam are one off costs. In 50 years and most likely in 100 years time. That dam will still be generating power, providing extremely low cost power that is 100% renewable. Solar systems will never last that long, due to the complex electronics in the inverters.

Consider also that most of the large dams were built before anyone cared about carbon emissions. Yet it was still judged as cheaper and better to build a hydro dam than coal burning power stations. Despite plenty of coal being available in the South Island.





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  Reply # 2033968 11-Jun-2018 21:31
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Arguably dams provide far more recreational value than they take away. Karapiro and Ruataniwha host the Maadi Cup regatta which is one of the largest secondary school sporting events in the southern hemisphere. Hydro lakes along the South and North Island hydro schemes provide fantastic kayaking, sailing, boating, fishing and swimming. White water sports are great in NZ but participation is tiny compared to sports on large bodies of water and not sure there's any shortage of rivers to suit. The land area flooded by dams is tiny compared to the area covered by wilderness as the hydro lakes are generally long narrow flooded valleys.


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  Reply # 2034062 12-Jun-2018 07:08
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Aredwood:

The Hydro dam is definitely better. Considering that the 50,000 homes on solar can't provide any peak time generation or offset peak time load. And the environmental costs of building a dam are one off costs. In 50 years and most likely in 100 years time. That dam will still be generating power, providing extremely low cost power that is 100% renewable. Solar systems will never last that long, due to the complex electronics in the inverters.

 

Solar does remove 50,000 homes from the peak demand though... I'm figuring 50,000 homes * $20,000 to get the whole PowerWall+solar package. And dam generators do require maintenance. Presumably there's some limit to the life of a dam due to silting up of the lake.

 

The environmental costs of a dam aren't one-off... they're annual. Tourists won't come to NZ to see a hydro dam or its lake. Every year, the drowned land doesn't produce anything (except electricity, indirectly). Only the construction costs are one-off.

 


Consider also that most of the large dams were built before anyone cared about carbon emissions. Yet it was still judged as cheaper and better to build a hydro dam than coal burning power stations. Despite plenty of coal being available in the South Island.

 

True. OTOH, the best dam sites have already been used. Each subsequent dam will have diminishing returns.

 

 


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  Reply # 2034145 12-Jun-2018 09:09
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frankv:

 

Solar does remove 50,000 homes from the peak demand though... I'm figuring 50,000 homes * $20,000 to get the whole PowerWall+solar package. And dam generators do require maintenance. Presumably there's some limit to the life of a dam due to silting up of the lake.

 

The environmental costs of a dam aren't one-off... they're annual. Tourists won't come to NZ to see a hydro dam or its lake. Every year, the drowned land doesn't produce anything (except electricity, indirectly). Only the construction costs are one-off.

 

 

Fairly sure Tekapo does well selling postcards of Lake Pukaki, :)

 

If you have access to dam storage, large scale pumped hydro is still cheaper that Lithium Batteries, ( and probably has a longer lifespan)

 

Dams do silt up, but it doesn't reduce their output , but it does reduce the amount of water stored...


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  Reply # 2034167 12-Jun-2018 09:24
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frankv:

 

The environmental costs of a dam aren't one-off... they're annual. Tourists won't come to NZ to see a hydro dam or its lake. Every year, the drowned land doesn't produce anything (except electricity, indirectly). Only the construction costs are one-off.

 

 

A hydro lake can be damn useful for various recreational activities.

 

For example: Fishing, boating, sailing, paddling, water-skiing, swimming, diving. 

 

 





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  Reply # 2034176 12-Jun-2018 09:41
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Since you are also including Powerwalls. You also need to allow for their replacement. They are unlikely to last more than 10 years, when they are being cycled daily. And when I got quotes for solar + batteries for my own home, battery cost was around 2/3 of the total cost. So over a 50 year period, you will have to spend another 1.3 billion replacing those Powerwalls as they wear out.

And for a powerwall to be able to reduce peak demand, it has to be charged first. But solar only outputs around 10% of its rated capacity on overcast days. And since overcast days in winter are colder than sunny days, more power would be used for heating and hot water. So the Powerwalls are unlikely to be fully charged.

And if hydro dams are really that bad, should we drain and demolish all of the existing hydro dams? If not, why is a new dam so much worse than an existing dam? And what about if a dam gets created by an earthquake? Should such a dam be removed or left in place? That actually happened in the Kaikoura earthquake.

I'm not completely anti solar. I have solar hot water and a very small PV system on my own house. And I will consider upgrading the PV system after I get heatpumps installed. But such a system won't reduce my peak load.





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  Reply # 2034396 12-Jun-2018 13:44
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frankv:

 

The downside of hydro electricity is that there's a lot *less* recreational facilities for whitewater kayaking and rafting and tramping. And, in the North Island, a lot of either productive pastures or forest drowned. And, as you point out, loss of habitat for some species which depends on fast-running water. These species, of course, contribute to NZ's reputation as the only place where a whole lot of unique wildlife can be seen, which is of course a major attraction for tourists.

 

I wonder about the economics; is a billion dollar dam better than 50,000 homes set up for solar?

 

 

 

 

They submerged two of the world's largest geysers under Lake Ohakuri in 1961.

 

I wonder if the geysers would still be there if we drained the lake.

 

https://en.wikipedia.org/wiki/Lake_Ohakuri


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  Reply # 2034430 12-Jun-2018 14:23
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elbrownos:

 

They submerged two of the world's largest geysers under Lake Ohakuri in 1961.

 

I wonder if the geysers would still be there if we drained the lake.

 

https://en.wikipedia.org/wiki/Lake_Ohakuri

 

 

Although at the time the Electricity Department described them as "a few dirty pools and gurgling geysers" :)


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