Attn home builders /renovators. Climate change commission to ban natural gas

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#2714863 28-May-2021 19:35

Wood burners are more-or-less carbon neutral as long as the trees are replanted. The main issue is smog in urban areas, which generally have much more reliable electricity.

There's a general slow growth of wind farms, and solar is probably going to pick up a bit sooner or later.

Scott3

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#2714895 28-May-2021 21:05

Fred99:

Scott3:

I'm agree that it could be done, but if the main end purpose is to produce heat for hot water & cooking, I can't see the point.

Sure. But power to fuel can be used for energy storage - and for applications where the low energy density of batteries isn't going to work very well.

Hydrogen ain't great for energy storage either.

You either need to cryogenic temperatures, crazy high pressures, or huge volumes.

The firstgas document assumes that hydrogen can be stored in high volumes in underground features to cover seasonal demand etc, but dosn't give much detail. I don't really know much about the viability of this, but I don't think this is a mature technology they are counting on.

Also if using hydrogen as a battery (power -> hydrogen from electrolysis -> compressed for storage -> fuel cell -> inverter - > AC power) is approx 35%. (source: https://www.nrel.gov/docs/fy19osti/73520.pdf). In my mind that's quite bad, so only suitable for applications where batteries absolutely aren't workable, like long haul aviation.

For comparison holding back water in a hydro scheme would be 100% efficient, batteries can be around 95%, and pumped hydro is typically 70% - 80% (with some claiming 87%)

Government is funding a study into onslow pumped hydro scheme. - Needs a carbon price many times higher than current to be justified, but would be a more efficient way to solve the dry year reserve storage issue.

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#2714921 29-May-2021 02:04

Holding back water is actually >100% efficient, as the higher lake levels mean that you get more energy out of the withheld water than simply using it immediately.

For the most part, hydrogen is simply another "new tech will fix everything in 15 years so we don't need to do anything now" pie-in-the-sky.

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#2714938 29-May-2021 08:19

Scott3:

Hydrogen ain't great for energy storage either.

Sure.

"Power to fuel" can get around that problem by using hydrogen as a feedstock to produce easier to store gaseous fuels, or liquid fuels.

If that was going to be used for all transport down to private motor cars, then a weak link in the chain is the terrible efficiency of internal combustion engines.

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#2714943 29-May-2021 08:28

SomeoneSomewhere:

Holding back water is actually >100% efficient, as the higher lake levels mean that you get more energy out of the withheld water than simply using it immediately.

For the most part, hydrogen is simply another "new tech will fix everything in 15 years so we don't need to do anything now" pie-in-the-sky.

Higher lake levels will also be "pie in the sky" in NZ. If building many bigger / higher dams is part of the equation, then it won't be happening.

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#2715296 29-May-2021 18:22

No, I mean that if you use the water as soon as it appears behind the dam, you're keeping the lake at the lower end of its control range. If you let it back up and sit nearer the top of the dam, you get a bit more energy out of each cubic meter because it falls further.

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#2715327 29-May-2021 20:14

Pretty in depth piece on the gas sector in stuff today:

https://www.stuff.co.nz/business/125169780/gas-in-nz-its-tough-parting-with-an-old-flame

In short, it say's we have enough gas in proven and probable reserved for another 9 years at current use rates, but use rates are likely to decline (i.e. closure of the oil refinery which uses 5% of our natural gas), Plus about 150% of that where the certainty is below "probable". Also there will be some more drilling under existing permits. Conclusion was that the gas will likely last to 2050, but may get more expensive.

Analysis omits the reason for the Methnex shutdown - In short the electricity sector seems likely to experience a dry year concurrent with a shortage of natural gas (due to issues with extraction rates). Methanex has sold a bunch of their allocation / rights to power generators, and is shutting down to free up that gas.

An interesting point made Methnex is so big, that if it is shut down, it could potentially kill the incentive to invest in / maintain production from gasfields, and in a worse case situation could see no gas for huntly power generation in 2026.

Says the following on hydrogen:

"But it would probably be fair to say the jury is out on whether it will become a mainstream fuel, at least in anything like the timeframe discussed by First Gas.

The large inherent inefficiency of converting water into hydrogen and oxygen, and then back again when hydrogen is burnt, can only be reduced to a degree and never avoided."

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#2715328 29-May-2021 20:17

it's ok i have no gas appliances other than the emergency use BBQ, camping burner, and now illegal gas heater. but i know other people have gas everything

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#2715335 29-May-2021 21:20

Batman:

it's ok i have no gas appliances other than the emergency use BBQ, camping burner, and now illegal gas heater. but i know other people have gas everything

Cost structure of natural gas in NZ kind of incentive's the all or nothing approach (especially before heat pumps were common place).

Much cheaper kWh rate, but hefty connection fee, means you need to use a lot to be in the win.

The last place I lived in with gas (4 adults) roughly broke even using natural gas for hot water & cooking.

If we had space heating, clothes dryer etc on gas too, we would have been well in the win.

Further contributing, if one moves enough load to gas, they are likely to qualify for low user power plan's where power is like 30c/kWh (rather than 17c/kWh in my area), further increasing the differential between 7c/kWh gas and power.

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#2715390 30-May-2021 09:13

Scott3:

Cost structure of natural gas in NZ kind of incentive's the all or nothing approach (especially before heat pumps were common place).

Much cheaper kWh rate, but hefty connection fee, means you need to use a lot to be in the win.

This is because gas connection fees, unlike electricity line charges, accurately reflect actual costs.

The cost of connecting a house to the gas or to the electricity network is just about fixed: the variable factor depending on consumption is tiny - the capital costs of the network are the same regardless of how much you consume (within very broad limits), it costs the same to read your meter, it costs the same to send a service team out, etc.
Gas tariffs reflect this in a high daily connection charge and no volume based "pipe charges".
Electricity tariffs have a lower daily connection charge and collect a significant proportion of the distribution network costs through volume-dependent line charges. This is from the economic point of view a nasty kludge that only works because distribution networks are monopolies. The reasons are political, and go back to the 1990s: some lines companies tried to set cost-reflecting tariffs where line charges were almost all fixed, but there was an immediate outcry that this removed all incentive to save energy and 'think of the poor Old Age Pensioners trying to be thrifty'.
This is how NZ's energy policies (used to?) get determined. Sigh

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#2715847 30-May-2021 21:32

mattwnz:

I just saw a new home have diesel central heating installed.

Largest house I have ever been in has diesel underfloor heating - its also offgrid.

I was so disappointed when i found out.

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#2715849 30-May-2021 21:41

Scott3:

Government is funding a study into onslow pumped hydro scheme. - Needs a carbon price many times higher than current to be justified, but would be a more efficient way to solve the dry year reserve storage issue.

I am a fan of pumped hydro.
Typically pumped hydro is just designed for peaking supply as countries where it is typically used is where nuclear provides the base supply and they can use the excess overnight to recharge/pump.

However in our case, I think its a really good way to store solar power. Even at 80% efficiency.

This in turn can keep lake levels higher.

Does anyone know if the electricity market has a mechanism for prioritising the use of wind & solar before hydro, and geothermal / coal / gas as the last resort?
Other than bidding price?

Hydrogen is probably a good idea even at 30% efficiency when its used for vehicles.
In some European countries they are trialing a catenary pantograph system for trucks on uphill sections of motorway where they switch to electricity to get over the hill. I like that idea as building on the uphill sections at the beginning would make the biggest difference and the biggest cost saving for users. Havent found out if they decided it worked yet.

Ray Taylor

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SomeoneSomewhere

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#2715904 30-May-2021 23:00

The issue with hydrogen is that, for less money and a bit of a weight penalty, you can use lithium and get 85% efficiency.

For the most part, any uphill sections with enough traffic to justify the investment could probably be done on rail anyway.

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#2715913 31-May-2021 00:39

raytaylor:

Largest house I have ever been in has diesel underfloor heating - its also offgrid.

I was so disappointed when i found out.

Pretty typical to have Fossil fuel and/or solid fuel for off grid houses.

Go back a decade, and it basically wasn't economically viable to build an off grid power system (other than micro hydro) to handle any significant heating loads (without regularly running a generator). Stove-top, oven, hot water (booster if solar thermal), space heating, clothes dryer all had to be done by burning something.

Situation has got a lot better, but still not really viable to do hot water & space heating.

People have a view of "off grid" as self sufficient, but often you are highly dependent on LPG or diesel. In general being "on grid" is a lot less green than being on the grid in NZ. That said some people do make a lot of use of wood grown on site.

Usually houses go off gird because the location would be crazy expensive to connect to the grid. If it is going to cost $150k to connect to the grid, a $50k solar / battery system, plus a $10k diesel back up gen-set, and a $15k diesel fired central heating system sharing the same bulk tank as the genset might be quite attractive. No power bills ever, Genny only needs to run for unusual demands (lots of guests, long rainy period in winter etc). Much better to burn the diesel directly in a boiler than to use the gen set to make power and use that to run electric heaters....

Must say I was quite surprised when I stayed in a (luxury) batch at the foot of Ruapehu. That place (on grid) had diesel fired underfloor heating, LPG Hot water / cook top, Electric spa pool heater, oven, drying room heater & heat pump for the lounge (which also had underfloor heating). Didn't expect to see LPG (2x45kg) and diesel at the same modern place. - As a side note lines charges are super expensive in this area, and they used to (might still be) charge based on your demand at the times the network is most stressed, so big incentive for not electric heating / cooking in this area.

raytaylor:

I am a fan of pumped hydro.
Typically pumped hydro is just designed for peaking supply as countries where it is typically used is where nuclear provides the base supply and they can use the excess overnight to recharge/pump.

However in our case, I think its a really good way to store solar power. Even at 80% efficiency.

This in turn can keep lake levels higher.

Does anyone know if the electricity market has a mechanism for prioritising the use of wind & solar before hydro, and geothermal / coal / gas as the last resort?
Other than bidding price?

Hydrogen is probably a good idea even at 30% efficiency when its used for vehicles.
In some European countries they are trialing a catenary pantograph system for trucks on uphill sections of motorway where they switch to electricity to get over the hill. I like that idea as building on the uphill sections at the beginning would make the biggest difference and the biggest cost saving for users. Havent found out if they decided it worked yet.

We have so much hydro in NZ, we don't really need to pump to deal with daily demand surges. Just ramp up and down the plants that have more than a few hours of storage behind them.

If Onslow ever gets built it will be something really special. They are talking 5000 GWh. nz annual 25,000 times as much as the largest battery bank in the world (Tesla battery plant in Horns dale). Enough stored energy to power 1/8th of the country for the year!

Should note that while Onslow could do daily peaking it's main purpose would be to provide dry year reserves without needing fossel fuels.

Personally I think overbuilding renewable generation, plus keeping something like huntly coal to provide coverage for say 1:25 or 1:50 year return period events would be nearly as good at much lower cost. (that overbuilt renewable would be needed for onslow too - need green energy to fill it - no point burning coal to fill it...).

RE prioritizing Wind / solar dispatch. bidding price covers this fine. They just bid in at zero in the stack, so almost all way's get dispatched (market works so that everybody gets paid the clearing price, not their bid price, so if you bid zero, you would get paid the bid to the most expensive generation that actually got dispatched that trading period).

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#2715916 31-May-2021 00:44

A woodburner with a wetback and thermal solar panels to heat hot water is a pretty common solution to at least some of the off-grid issues, or at least was a few years back. But you'll still almost invariably find gas hobs and maybe ovens because the peak power used for cooking is pretty substantial.

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