"Net Zero"

[mikeey84]

One thing to consider is that a widespread shift to hydrogen use might be associated with an increasing number of reports of 'big bangs' on the 6 o'clock News!

Whilst hydrogen is a smaller molecule, and therefore leaks a bit more than natural gas, it also disperses much more readily, and therefore is less likely to build up into explosive levels than natural gas

 

[JohnW2]

About 250-300 kwh per tonne apparently ...

That would presumably lead to some more pretty mind-boggling figures - maybe around 10 TWh to deal with just a few Gt of 'carbon'

CO2 compression uses about a third of that, so in suitable strata, the gas could be pumped in directly. CO2 is pretty soluble, so you wouldn't even need to displace all of the water, and if it's impermeable to gas, as gas fields would be, its not going anywhere

I must say that I've never heard of that one, although I suppose it's fairly logical.

Kind Regards, John

 

[JohnW2]

Whilst hydrogen is a smaller molecule, and therefore leaks a bit more than natural gas, it also disperses much more readily, and therefore is less likely to build up into explosive levels than natural gas

All true, but I was thinking more of hydrogen storage than simply 'leaks'.

It's also not only a matter of explosive mixtures and 'bangs' - as they discovered back in 1937 (I think), even when it doesn't explode, hydrogen can sure burn

Kind Regards, John

 

[flameport]

hydrogen as a replacement for natural gas,

That will never happen. It's promoted entirely by the fossil fuel industry as a solution so they can continue to sell gas, oil and other fossil fuels just as they have always done.

The idea is that if we can capture carbon at source,

CCS is the same - an excuse to continue using fossil fuels by magically removing the carbon. At absolute best, it will be a very expensive way of removing a proportion of the CO2, which can then be stored somewhere where it hopefully will remain for ever. Plenty of CO2 will still be emitted into the atmosphere.
The correct idea is to stop using fossil fuels.

Hydrogen production, as long as it's produced by a Green source it should be zero carbon and only produce H2O/Water as a byproduct.

If hydrogen is used in a fuel cell, it creates electricity and water.
Burning hydrogen is a total bust, as it's burned in air, which contains a very substantial amount of nitrogen. The result is nitrous oxides, a serious air pollutant and health hazard.
Both use cases are extremely inefficient and therefore expensive.

a widespread shift to hydrogen use might be associated with an increasing number of reports of 'big bangs' on the 6 o'clock News!

No question about it, it certainly would result in large numbers of deadly explosions on a regular basis.
Hydrogen is entirely different from natural gas or other gases commonly used as fuels today.

hydrogen is a smaller molecule, and therefore leaks a bit more than natural gas, it also disperses much more readily, and therefore is less likely to build up into explosive levels than natural gas

Hydrogen has a very wide flammability range, from around 4% to 75% when mixed with air.
This is vast compared to other gases and fuels, such as natural gas which is only flammable in mixtures between 5% and 15%. Above that, it won't burn.
The same applies to other fuels such as petrol which is only flammable between about 1.2% to 7.5%.

 

[mikeey84]

The correct idea is to stop using fossil fuels.

I dont disagree with you at all

 

[Munroast]

The correct idea is to stop using fossil fuels.

Absolutely, that is our very first priority.

Everything about carbon capture surrounding burning fossil fuels is just an utter nonsense, I heavily suspect it is the fossil fuel companies who are suggesting this idea in a bid to carry on selling fossil fuels.

As far as I know generating energy from renewables is already considerably cheaper than generating from fossil fuels where carbon capture is used, so it is a pointless road to go down.

 

[StephenStephen]

...going to the original question of the thread, a search engine will lead you directly to a number of simple and clear definitions of what is meant by net zero, but it's harder to find a credible plan in place to achieve it, https://www.gov.uk/government/publications/net-zero-strategy

https://www.nationalgrid.com/stories/energy-explained/what-is-net-zero

 

[RandomGrinch]

I am more than willing to be argued against, but the whole idea of being 'Net Zero' seems messy to me.
Yes, we should stop using fossil fuels, and we should use renewables.
But how do you manufacture the infrastructure for renewable energy production without using fossil fuels?

Taking solar PV as an example, the big manufacturers of panels are based in China; I would be interested to know the carbon (Dioxide!) footprint of a Chinese panel installed in the UK.
Also, the efficiency of new solar panels constantly improves with advancing technology, whilst the efficiency of those panels in use, declines as the panels age.
It may not be long before it pays to replace first generation panels with newer models - how easily can these panels be recycled, or are we facing a waste mountain?
An interesting (US) perspective here:

The Dark Side of Solar Power

Solar energy is a rapidly growing market, which should be good news for the environment. Unfortunately there’s a catch. The replacement rate of solar panels is faster than expected and given the current very high recycling costs, there’s a real danger that all used panels will go straight to...

hbr.org

With wind turbines, there was a popular myth that a turbine couldn't recover the amount of energy it used to manufacture it, within its lifetime.
Recent calculations suggest that with ideal conditions, this energy can be recovered within six months.
But even then, many of the epoxies, plastics and lubricants used in the production of the turbine are derived from fossil fuel origins, and are difficult (if not currently impossible) to produce in a better way.
...and as mentioned earlier - they can use a lot of concrete too!

A small and probably outdated article from IEEE Spectrum here:

To Get Wind Power You Need Oil

Each wind turbine embodies a whole lot of petrochemicals and fossil-fuel energy

spectrum.ieee.org

 

[JohnW2]

...going to the original question of the thread, a search engine will lead you directly to a number of simple and clear definitions of what is meant by net zero

Looking back, it still seems to me that my 'original' question' was clear enough but, like eric, you seem to have interpreted my question as being about the definition of 'net zero', so I have to wonder if I perhaps wasn't actually as clear as I thought I had been!

The chosen definition of "net zero" is obviously an important issue, not the least because it might exclude some actual 'emissions' (e.g. 'unavoidable' ones - as below). However, regardless of that issue, my actual question was, given that total elimination of literally all 'emissions' of CO2 into the atmosphere could obviously never be achieved, what was 'on the other side of the equation' other than 'planting trees and capturing/storing carbon'.

Since you have provided links to a couple of things .....

https://www.gov.uk/government/publications/net-zero-strategy

I'm familiar with that document but, unless I'm missing something, it does nothing to provide a definition of "net zero" beyond a fairly literal meaning of the term. The initial chapter with the promising-sounding title of "What is net zero and why do we need to act" merely says:

The science could not be clearer: by the middle of this century the world has to reduce emissions to as close to zero as possible, with the small amount of remaining emissions absorbed through natural carbon sinks like forests, and new technologies like carbon capture. If we can achieve this, global emissions of greenhouse gases will be ‘net zero’.

The main problem there being that it leaves the reader having to decide what exactly is meant by 'emmisions'.

https://www.nationalgrid.com/stories/energy-explained/what-is-net-zero

This one starts off much the same as the government one, initially saying ....

We’ve all heard the term net zero, but what exactly does it mean? Put simply, net zero refers to the balance between the amount of greenhouse gas produced and the amount removed from the atmosphere. We reach net zero when the amount we add is no more than the amount taken away.

The words are different, but the meaning of "the amount of greenhouse gas produced" is as vague as the "emissions" of the government document.

However, at the end of the page, it addresses this issue to some extent, when it says (with my emboldening) :

Real zero would mean stopping all emissions, which isn’t realistically attainable across all sectors of our lives and industry. Even with best efforts to reduce them, there will still be some emissions.
Net zero looks at emissions overall, allowing for the removal of any unavoidable emissions, such as those from aviation or manufacturing. Removing greenhouse gases could be via nature, as trees take CO2 from the atmosphere, or through new technology or changing industrial processes.

This seems very confusing (at least to me). I initially thought (and still wonder) whether it was a typo, and that they meant "avoidable emissions" (since it would seem strange to suggest that emissions from aviation and manufacturing were "unavoidable"), but then I saw the commas around the middle clause, and therefore wondered if they perhaps meant:
"Net zero looks at emissions overall, such as those from aviation or manufacturing (allowing for the removal of any unavoidable emissions)"
... but, even then, their "overall" would seem confusing (to me)!

Whatever, whoever wrote all that doesn't seem to understand the meaning of "net". "Net" surely means "net", and has no implications as regards whether one is talking about avoidable or unavoidable emissions, or both? The 'net' emission is surely the difference between the amount put into the atmosphere and the amount taken out of it, and that remains the case whether one is talking about avoidable emissions, unavoidable emissions or both?

Of particular relevance is the fact that if it is our hope that we will one day achieve a situation in which atmospheric CO2 does not increase any further (or even declines) then it surely will be necessary that true total 'emission' (both avoidable and unavoidable) must become the same (or less) than the total amount removed from the atmosphere (i.e. true (overall) 'net emissions' must become zero or negative), isn't it?

[ In passing, everyone seems to talk about trees as if they were the main natural remover of CO2 from the atmosphere, but I thought it was the case that we now believe than algae in the oceans are more important biological removers of CO2 from (and 'putters' of oxygen into) the atmosphere, and also that geological removal of CO2 and dissolution of CO2 in the oceans are also major factors? ]

Kind Regards, John

 

[chivers67]

Hi Flameport, I meant burning it purely with oxygen rather than "Air". Obviously this would be impractical in households but doing it this way on a commercial level to produce Heat/Electricity would be a way forward?

 

[Notch7]

Maybe we need to breed cows to fart oxygen instead of methane.

 

[flameport]

burning it purely with oxygen rather than "Air"

That works in theory.

In reality, it's just adding huge extra costs and complexity to an already massively expensive and inefficient process, as now you need to create, store and distribute oxygen as well as hydrogen.

 

[RandomGrinch]

Maybe we need to breed cows to fart oxygen instead of methane.

 

[chivers67]

That works in theory.

In reality, it's just adding huge extra costs and complexity to an already massively expensive and inefficient process, as now you need to create, store and distribute oxygen as well as hydrogen.

If the process of using electrolysis is used it creates both gases from Anode & cathode - as you are no doubt already aware of. it's becoming more and more efficient with all types of processes being designed, with polymer electrolytes and all sorts of break through technology.

Rome wasn't built in a day.

 

[JohnW2]

I am more than willing to be argued against, but the whole idea of being 'Net Zero' seems messy to me. Yes, we should stop using fossil fuels, and we should use renewables. But how do you manufacture the infrastructure for renewable energy production without using fossil fuels?

For what it's worth, I agree. It's far more complicated than one might first think - particularly since, as I have suggested above (and despite what some people have said), even the meaning of "Net Zero" does not seem to be clearly defined.

Kind Regards, John