Green, ethical, energy issues in the news

QrizB

2nd_time_buyer said:

QrizB said:

2nd_time_buyer said:

I read somewhere that hydrogen is three times the energy density of airline fuel. I am pretty sure that batteries will never be suitable for anything but very short haul flights. However, hydrogen has a lot more potential.

You need to be careful with comparisons. Yes, a tonne of hydrogen does contain 3x the energy of a tonne of aviation fuel. However a tonne of liquid hydrogen will occupy 13.5 cubic metres while a tonne of aviation fuel will only take up 1.3 cubic metres.

Oh. I hadn't realized that. That's a bit of a showstopper for most aviation then - which seems both weight and volume critical. So I guess there is no obvious carbon-free alternative for air transport them?

For short hops, battery electric might work out OK. For long-distance flights the front runner seems to be synthetic liquid fuels. Unless you think dirigibles are the future!

gefnew

Hi 
Or maybe this could help.
Manchester Airport first to get direct supply of sustainable jet fuel - BBC News

Martyn1981

QrizB said:

2nd_time_buyer said:

QrizB said:

2nd_time_buyer said:

I read somewhere that hydrogen is three times the energy density of airline fuel. I am pretty sure that batteries will never be suitable for anything but very short haul flights. However, hydrogen has a lot more potential.

You need to be careful with comparisons. Yes, a tonne of hydrogen does contain 3x the energy of a tonne of aviation fuel. However a tonne of liquid hydrogen will occupy 13.5 cubic metres while a tonne of aviation fuel will only take up 1.3 cubic metres.

Oh. I hadn't realized that. That's a bit of a showstopper for most aviation then - which seems both weight and volume critical. So I guess there is no obvious carbon-free alternative for air transport them?

For short hops, battery electric might work out OK. For long-distance flights the front runner seems to be synthetic liquid fuels. Unless you think dirigibles are the future!

There was an interesting interview with Elon about electric flight, I may have mentioned this before, but he said that flight should be possible when batts reach 400Wh/kg, and that would allow around 500 miles of travel. The next bit is obvious, but only after he said it, which is that a further 20% increase in energy density would allow about 1,000 miles of flight, since so much energy is needed to reach altitude, so doubling the distance doesn't double the energy consumption.

Regarding the energy density of hydrogen, I think that's one of the additional problems for the gas network, as under standard  mains pressure hydrogen has less energy, or to be more correct, there is less hydrogen gas, than methane gas. Lots of little problems to solve.

shinytop

EricMears said:

shinytop said:

I suppose the counter argument is that it's a waste to transport several hundred kilos of battery around in BEVs.      

Hard to believe !   A typical JCB roadgoing excavator usually carries around a couple of spare buckets and a few gallons of fuel without any great effort.  Quarry plant machines are usually able to shift tens of tonnes of stone as part of their normal function;  I can't see how an 'extra' half-tonne or so is going to have any great effect on their performance.  And in any case,  the batteries should be able to have the machines powered by a lightweight electric motor rather than a very heavy ICE and a fuel tank so the weight of batteries isn't all 'extra'

Fair point, I was just having another go at the excess weight and size of BEV cars, not the earth movers.

EricMears

shinytop said:

Fair point, I was just having another go at the excess weight and size of BEV cars, not the earth movers.

However,  in a TV interview I saw (not sure if it was his lordship or another company spokesman) the weight of batteries was cited as the main reason for going down the hydrogen route !  I thought at the time it was a strange argument.

Martyn1981

shinytop said:

EricMears said:

shinytop said:

I suppose the counter argument is that it's a waste to transport several hundred kilos of battery around in BEVs.      

Hard to believe !   A typical JCB roadgoing excavator usually carries around a couple of spare buckets and a few gallons of fuel without any great effort.  Quarry plant machines are usually able to shift tens of tonnes of stone as part of their normal function;  I can't see how an 'extra' half-tonne or so is going to have any great effect on their performance.  And in any case,  the batteries should be able to have the machines powered by a lightweight electric motor rather than a very heavy ICE and a fuel tank so the weight of batteries isn't all 'extra'

Fair point, I was just having another go at the excess weight and size of BEV cars, not the earth movers.

That's what I first thought going back a bit, but as Eric pointed out, the tanks needed to hold H2 are very large, strong and heavy due to the high pressures involved. I hadn't originally realised just how big they would need to be. In some HFCV's you end up with a 'transmission tunnel' again, if there's a tank running lengthwise, as well as the 1 or 2 crosswise. So you have to consider the weight of the tanks, and all the FC equipment, v's the reduced weight of the smaller battery pack (you still need a battery pack to act as a buffer for the FC, since it will be the smallest one possible due to the extremely high cost, so tends to be sized for average demand, not hard acceleration or steep hills).

Size wise, I think you mentioned this before on the BEV thread. I don't think BEV's are bigger, maybe I'm mistaken. They seem to be of a similar size to their competition, but tend to have more space inside, and greater storage space.

Now, I can't be certain this all transfers over directly from cars to heavy plant, but hopefully it's a reasonable guess, and it's probably ok for heavy plant to weigh a bit more, or even be shaped bigger/bulkier, since air resistance won't be an issue.

For trucks, I think BEV trucks are expected to weigh 1 or 2 tonnes more than an ICEV, and EU/US legislation looks like it will allow heavier max weight to compensate for this. When Nikola launched their H2FC truck back in 2016 they explained how weight saving was crucial for their trucks to be profitable, and that their Nikola One would be 1,000 to 2,000lbs lighter than a conventional diesel big rig, resulting in per mile costs of $0.97, v's $0.99 for a diesel. However, now that their conman CEO has left, their latest specs say that the truck will weigh 1,000 to 2,0000 pounds more than a diesel big rig (they've also reduced it's range by 50%, which presumably doubles its fuel cost).

So my assumptions about HFCV's was rocked, and this is probably why they have dropped out of favour as BEV costs fell. As to whether they are unsuitable for all heavy plant roles, I wouldn't be so sure yet, but its not looking great, perhaps some edge cases, but I also assume that low/specialised production rates will not help their cause.

gefnew

More Hydrogen news.
Chelveston energy park aims to power 100 lorries a day with hydrogen - BBC News

Coastalwatch

An interesting study concluding in the surprising, to me at least, that 1.5x excess generation alongside just three hours of storage would accommodate all but 200 hours of energy demand in any given year. Not sure how true it might be for the uk but that certainly is something for the country to aim fore by 2030 if nothing else.Alongside this would also be the development of other forms of generation and storage assets already being investigated.

When oversized is really the right size

Researchers recently published a paper in which they seek to understand how far we can go with wind and solar.

The research analyzes 39 years of hourly wind and solar generation data across 42 countries. An evaluation of “perfect” transmission without energy storage finds that the most reliable renewable electricity systems are wind-heavy and satisfy countries’ electricity demand in 72–91% of hours (or in 83–94% of hours by adding 12 hours of storage).

The research quantified the power, energy, and utilization rates of additional energy storage and demand management, (curtailment), as well as the benefits of regional aggregation. The models evaluated three levels of excess generation (1x, 1.5x, and 3x) and storage (none, 3 hours, and 12 hours).

Notably, the researchers concluded that wind and solar generation resources that were sized at 1.5x along with three hours of energy storage would meet all but 200 hours of demand scattered throughout any given year.

https://pv-magazine-usa.com/2021/11/01/when-oversized-is-really-the-right-size/?utm_source=USA+|+Newsletter&utm_campaign=3dbb7ee546-RSS_EMAIL_CAMPAIGN&utm_medium=email&utm_term=0_80e0d17bb8-3dbb7ee546-159341337

Martyn1981

Some positive news from COP26, but perhaps 10yrs too late since economics may already be leading, but any extra nudging can't be bad:

World leaders announce plan to make green tech cheaper than alternatives

A plan to coordinate the global introduction of clean technologies in order to rapidly drive down their cost has been agreed at the Cop26 summit by world leaders representing two-thirds of the world’s economy.

A global transition to green energy and vehicles is vital in tackling the climate crisis, and economies of scale mean that costs plummet as production increases – as already seen with solar panels and LED lightbulbs.

More than 40 nations said they would align standards and coordinate investments to speed up production and bring forward the “tipping point” at which green technologies are more affordable and accessible than fossil-fuelled alternatives. At that point, the green transition and cuts in climate emissions accelerate rapidly towards a net zero economy.

Among the countries signed up to the Breakthrough Agenda are the UK, US, China, India, the EU and Australia. The first five breakthroughs will be clean electricity, electric vehicles, green steel, hydrogen and sustainable farming. The aim is to make these affordable and available to all nations by 2030 and create 20m new jobs.

Coastalwatch

Martyn1981 said:

Some positive news from COP26, but perhaps 10yrs too late since economics may already be leading, but any extra nudging can't be bad:

World leaders announce plan to make green tech cheaper than alternatives

Among the countries signed up to the Breakthrough Agenda are the UK, US, China, India, the EU and Australia. The first five breakthroughs will be clean electricity, electric vehicles, green steel, hydrogen and sustainable farming. The aim is to make these affordable and available to all nations by 2030 and create 20m new jobs.

That's encouraging Mart, especially with the UK having signed up to it all including green steel. Does this possibly indicate that it would be hugely embarrassing for the Government if the proposed mine in Cumbria were to go ahead!