Mothballed Coal

[Mart]

There's also hemp, which can give two harvests pa in the UK. The product has loads of valueable uses, as well as the bio-mass potential.

Obviously a 6 month carbon cycle is great, but I've no idea if enough can be grown, or if the harvesting and transportation energy costs etc work out.

Bio-mass does provide an in built storage mechanism, and can demand follow, so potentially it has huge value in a RE future, but sadly also comes with a tonne of negatives too.

[Oldgreybeard]

Agree about hemp, some "species" can go from seed to flower in around 10 weeks now (not that I'd know anything at about them, you understand . . . )

[openspaceman]

The problem with burning trees is that it takes between 10 and 20 acres of managed woodland to provide enough energy to heat a single home through winter here. There are around 30 million homes in the UK, so that means we'd need around 300 million to 600 million acres of managed woodland just to heat them using trees as biomass (and ignoring all non-heating energy requirements. The UK has, in total, about 8 million acres of managed woodland, a massive shortfall, hence the need to import wood from North America.

Perhaps we can run some numbers on that, let's start with how much heat does the average of these 30 million homes need?

The space heating in my tiny 80m2 home is done entirely with wood, the solar gain from SW facing windows plus the activities of two septuagenarians and the waste from 6-8kWh of our electricity use at this time of year.

It is also part of the poorly insulated solid brick walls pre victorian stock.

Up till xmas I will burn 45ft3 (~1.25m3)of solid timber (none from managed woodland) but probably more in the next 5 months, let's say 4m3. That's typically the increment on under 1Ha of broadleaves. Maybe I can remember to update this in May.

[openspaceman]

I ask because way way back when Drax was switching to biomass there was talk of all the surrounding arable land being used to cultivate fast growing willow to supplement the boiler feed - sounded nuts at the time given that the fields in that area are comprised of excellent prime market garden soils with a good tilth and nutrient mix allowing a profusion of veg and salad growing business to thrive both in the open and under glass in that area.

I like burning willow when I can obtain it as its a nice clean wood, splits easy, burns warm and clean and dry's really fast, yet despite all these good aspects and the claims in the 90's that willow crops would be part of the energy mix answer you still seldom see willow available or being cultivated on mass? What happened to it ?

Moxi

I think you may be remembering the plans for ARBRE, a gasification to power plant that was fairly advanced when the plug was pulled. A chap, who I later did a bit of gig work for when he went into business installing commercial chip stoking boilers, was developing a low temperature dryers for them.

I think it was Yorkshire water that was on board as the willow Arable Short Rotation Coppice would have given them an outlet for their sewage solids which could not go on food crops.

They also shot themselves in the foot by stipulating harvesting could only take place in the winter months, for which there were good ecological and sustainabilty reasons plus it would make better use of the harvesting kit after the agricultural silage harvests but as the land for the willow was poorly drained...

I imagine with Drax they wanted to keep modifications from the coal system minimal and as there was always an intent to supply from abroad on cost grounds pellets became the choice, to increase the bulk density for shipping and because they could be crushed and blown into the furnaces just like coal.

[Tinbum]

I live near Drax and at one time, a few years ago, they were growing crops in the fields (like an elephant grass) for Drax. I also knew a lorry driver that said he was taking all sorts into there, even wheat. I understand the grasses were too hard on the machinery that was used to cut it up.

[openspaceman]

I live near Drax and at one time, a few years ago, they were growing crops in the fields (like an elephant grass) for Drax. I also knew a lorry driver that said he was taking all sorts into there, even wheat. I understand the grasses were too hard on the machinery that was used to cut it up.

I once swept the floor of a grain store and bagged the grain and chaff up, burned it in my pellet burner, it was okay but tended to leave a charred cake of sintered grains plus the street smelt of burned toast.

I can understand what you say about comminuting elephant grass, this is what I was trying to explain about getting the particle size small enough to be able to be blown in, the particles have to burn out completely in the time they reside in the staged air supply. Pellets made abroad on a very large scale and shipped here can be dealt with the same sort of crushers used to pulverise coal.

Commercial woodchip boilers use a size class of chip known as G50 and that is a distribution of sizes around 50mm.

[openspaceman]

BTW I did a few days for a Farmer, Rupert, whose land was crossed by the mainline to the now closed Didcot power station.

Any ASRC he grew would have had to be shipped back to the port near Bristol and then put on rail wagons. He had planted the willow on some fields but at that time had harvested it at a loss.

As we have seen with Drax the scale of biomass needed for the few GW of power produced is just not worth pursuing.

[Bugtownboy]

Perhaps the only profitable Willow culture is on the Somerset levels, but it’s not for biomass, rather as withy’s for basket, including coffin, making.

https://www.coatesenglishwillow.co.uk/

Coates are a long standing business, withy cultivation/harvesting on the levels is traditional and , perhaps, doesn’t displace other agriculture.

[Ken]

I dont see the problem with biomass.

There are something like 420 trees for every person on the planet.
There is a surplus of trees in Europe since the demise of news print.
If a tree dies naturally it falls over and decays producing CO2 but also methane which is much worse.

What is man doing that nature would not do anyway ?

I had some trees which had self seeded but had subsequently died and needed taking down for safety reasons. I used them for logs and mulch etc in the garden and hence nothing wasted.

I see fallen trees everywhere in my travels.

Whats the problem ?

[Oldgreybeard]

Timing is the BIG problem!

Burning a tree releases ALL the sequestered CO2 built up over decades in a very short space of time.

Leaving it to decay takes decades for just a bit of the CO2 to be released, and much of it is never really released at all (which is why we have beds of coal and reserves of underground oil and gas, as breakdown products sequestered from trees and plants that grew millions of years ago).

We need to start sequestering as much atmospheric CO2 as we can, as fast as we can. The oceans are doing their bit, but we need to do far more to reduce emissions and try and lock up CO2 in living things for a few decades, hopefully millennia.