I’ve done posts on wind and solar, now it’s the turn of Biomass. Get comfortable – this is a long one. I had intended to have this ready weeks ago, but every time I thought I had covered all I wanted, something else popped up. To be honest it’s doing my head in…
Although most of you will have heard of Biomass, it’s fair to say that it currently plays second fiddle to wind & solar in the grand scheme of things. The term “Biomass” seems to cover quite a range of power generation technologies, but all are supposed to be either carbon neutral or, less environmentally damaging than oil /coal / gas.
Over the last few years lots of Biomass electricity generating plants have sprung up, mostly small scale. However a couple of larger ones have made the headlines recently – Tilbury near London, which suffered a serious fire in a storage area in February this year, and Drax which is in the process of changing over from the existing coal fired units. They have little choice in the matter, thanks to the EU Large Combustion Plants Directive, which is sounding the death knell for most of our coal fired stations, and will lead to a significant reduction in the UK’s generating capacity in just over 4 months time. Funny how this doesn’t seem to have prevented Germany hastily building a fleet of new coal plants, but that’s another story…
There is a 10 minute film on the Drax site which (apparently) explains in more detail, but it won’t play or download properly. The part that does, talks about an infinite source of raw materials, which would be fine if the world had even a fraction of the capacity to grow that much, and still feed an ever growing population. The website goes on to say how they intend their supply chain to be as environmentally friendly as possible, and invites UK farmers and growers to get involved, but I understand that a lot of the feedstock is coming from the US. This will involve dozens if not hundreds of ship movements each year, ships that are usually powered by bunker fuel, the dirtiest form of heavy oil around. Most of our coal is already imported, so I fail to see how this is going to make much difference to our emissions. It will also do little to end our reliance on overseas supplies!
Not surprisingly government incentives play a part in this as the following wording on their site suggests: (my bolding)
Drax has the capability to produce up to 12.5% of its output from sustainable biomass, but is ready to become a predominantly biomass fuelled generator, given an appropriate level of regulatory support.
But when I started searching for further information I soon found links referring to several new plants being cancelled, due to reductions in the tariffs payable. Now doesn’t this sound just like the complaints currently emanating from the wind & solar camps? Most bizarrely of all, the favourite Green campaigners are now saying that electricity from burning trees is dirtier than coal.
“Burning imported trees is worse for the climate than burning coal – it’s absurd that the Government is spending millions of pounds subsidising it.”
Forgive me while I roll around the floor laughing uncontrollably!
For more debunking of the claims of reduced CO2 emissions (compared to coal, since the CO2 emissions of biomass are higher), check this article by the economist Matt Ridley. There are links within his post giving more detail of the chemistry involved, which I can just about follow, but it’s been over 40 years since I last saw the inside of a chemistry lab!
So far I’ve only looked at large plants, but there are many smaller ones burning a variety of feedstock, such as straw, chicken shit, and waste/scrap wood. These would (presumably) be OK with the FoE mob, but they know very little about the operation of such sites. Thanks to some information sent to me, I have gained a useful insight as to what goes on “behind the scenes”
For a wood burning site there are 3 types of feedstock:
Grade “A” – which is virgin timber
Grade “B” – which is principally chipboard, MDF, pallets etc
Grade “C” – which is all the old scrap wood which normally has to go to landfill.
Virgin timber costs (typically) £110/ton, “B” is £65/ton, and “C” is free to the stations, because it would otherwise cost the disposal contractors £65/ton at the landfill site, so they pay the power station £40/ton to take it off their hands! Free fuel AND a nice little cash bonus – what could be better? As the saying goes: “And there’s more” – which I’ll come to in a moment…
Now to the practicalities – it will hopefully be apparent that the way these various feed stocks burn is quite different. Fresh timber will be of fairly consistent quality and the boilers can be expected to operate reliably and controllably. Grade “B” less so due to the variety of material present. But, like most things, it’s a trade-off between cost and output. However I’m told that Grade “C” is a nightmare to use, and can lead to all sorts of difficulties controlling the boiler, to say nothing of the increased maintenance because of clinker build up in the boiler tubes. This means a reduction in heat transfer and consequently less steam available to drive the turbine. It also means more frequent downtime for cleaning etc.
If anyone is thinking ahead at this point I’m told that these plants are referred to by the industry as “Profit Centres” so you can guess what it leads to. Many use a mixture of Grade “B” & “C” to try and keep things under control, whilst keeping the fuel bills down. This is still far from satisfactory, and I wonder what the long term view is. I posed the question “What happens after 20 years?” in my earlier post, and can’t help thinking the companies are only out to make a quick buck, and to hell with the future…
Another aspect of poor quality fuel is emissions. MDF and chipboard contain many extras compared to virgin wood, and these produce lots of “nasties” when burnt. In order to meet government standards, high temperatures (over 850C) have to be maintained in the boiler combustion chamber to destroy dioxins and furans, which have long term health implications as they can build up in the body and can’t be removed. Some very sophisticated monitoring – CME (short for Continuous Emission Monitoring) – is employed, along with off-site laboratory analysis of the ash, to ensure strict limits are not exceeded. This information is automatically sent to the Environment Agency. In the event that something does go wrong various contingency plans are designed to limit the discharges until normal operation is resumed, or the plant is shut down. It’s obvious this will be far more likely to happen when using poor fuel, and since a predetermined number of such events are allowed each year, there must be an incentive to push the boundaries.
Did I say “And there’s more”? Oh yes there is…
You may also have heard the term “CHP” or Combined Heat & Power. It is a way of getting the most from whatever fuel is used, and normally involves waste heat being pumped round local communities to provide domestic heating and hot water. This is no small undertaking, and is best applied to brand new developments where each town has its own power station and the pipework is laid during construction. I don’t know of any examples in the UK – Milton Keynes would have been an ideal location, but Warble Gloaming wasn’t on the agenda when it was started back in the 70’s. But this doesn’t stop us consumers being milked for every last penny in the name of saving the planet. It turns out that if a Biomass plant uses a minimum of 90% “renewable” material, and the waste heat is employed to dry and pre-heat it, they can class themselves as a CHP station. Very handy as they can then claim THREE times the rate for the Renewable Obligation Certificate payments they get! This is all agreed between the the Government and the Environment Agency, for nothing more than Political reasons, to show the (Sheeplike) electorate they are pursuing their Green Policy agenda…
Is your blood pressure rising? Mine certainly is. However we are not done yet.
There is a further twist in the saga: something called a “TRIAD”. This is not a shady bunch of Chinese gangsters, but an additional payment made to the Power Industry by the National Grid. I’m told it works like this:
In the winter months when there are massive “predictable” power surges, for example between 4 & 7 PM on a Friday, the National Grid contact contact the generators asking for Maximum Power Output, in addition to normal full load capacity. This is known as a “TRIAD”. The stations shut down all non-essential equipment to maximise output. The extra production is paid for in an very cunning way. National Grid choose a day not known by the Power Industry to make a payment of £350,000 as a one off, during the Winter months ONLY. If they pick a day when power generation of that particular plant exceeds normal output by at least 5% the payment is made to that Power Station, if they happen to pick a day when it is shut down or has plant issues, the payment is not made. It is a bit like “Russian Roulette”. The National Grid get extra power for no payment during this period and Power Stations are so greedy they want the TRIAD payment, so they pull out all the stops to produce it, hoping to pick the right day.
This particular aspect applies to all generating stations, but it doesn’t appear to be well known.
There is undoubtedly further material on the topic, but I can’t keep dragging this post out any longer – apart, that is, from one story that is just breaking. It concerns the wind industry, and another sneaky way to milk the tariffs. Guido spotted it at The Spectator, and you can read it here.