Tech Talk - Of wood, coal, the UK and Bangladesh

Ice and snow have returned to the central part of Missouri, so the warm heat from the tile stove is again keeping us comfortable. For many folk, however, this is not an option and they rely on a centralized power station to supply the electricity that is a fundamental part of current Western life. Yet there are moves to use more wood, even there. In an earlier post I had written that Missouri S&T was switching from a coal:wood mix to a geothermal network which, with the use of natural gas, is expected to provide a net saving of about $1 million a year on the fuel bill. Price, while important to a university, is not, however, always the controlling factor when governments get involved.

The rising prices and obscurity of future government policy has stopped progress toward a wood-fired power station in Northumberland. A plan to replace coal with wood at Blyth has reached an impass, with RES ceasing work on the biofuel plant. The $500 million, 100 MW plant had been scheduled to come on line in about two-and-a-half years but has been stopped due to “ongoing uncertainty in UK energy policy.”

On the other hand the largest UK coal-fired power plant, at Drax in Yorkshire, is in process of changing from being a coal-based plant to one that burns wood. But not just any wood, for as David Rose notes the new fuel will be wood pellets, grown and processed in North Carolina and then shipped at an ultimate rate of 7 million tons a year to the UK. The current wholesale market price for power is around $83 per MW/hr relying heavily on coal, but the agreed price for the wood-powered electricity will rise to $174 per MW/hr, higher than that of either onshore wind or the new nuclear power coming on line. (Using $1.66 per English pound). Retail prices are somewhat higher.

Price may not be that critical in the UK, but it remains critical in poorer parts of the world, such as Bangladesh, where the nation needs to infuse power into a country that has, at the moment, only a single power plant. Yet this is not a move without criticism. A recent Op-Ed in the NYT, protested the intent of the government of Bangladesh to begin a program that will develop their coal reserves. The article comes after the government appointed a new minister for Power, Energy and Mineral Resource who has pledged a new coal policy “within the shortest possible time” and it is this (and the existing 2010 policy) which has irritated Joseph Allchin who wrote the opinion.

The major concern at present deals with the Rampal coal plant which will consume some 4.5 million tons of coal a year and generate 1,320 MW of electrical energy. The coal is presently anticipated to come from either Australia, South Africa or Indonesia and is intended to address the acute shortage of power in Bangladesh, with the government aiming to raise power generation from 5,000 MW in 2011, through 7,000 MW in 2013 to 22,000 MW by 2016, that being on its way to a capacity of 39,000 MW by 2030. By 2021 it is anticipated that 14 GW will be generated from coal-fired power, with domestic coal producing 6 GW, and imports powering 8 GW of capacity. The concern comes from the nearness of the coal-fired plant to the Sunderbans mangrove forest, and the threat which this poses. But given that millions of folk live within ten miles of coal-fired power plants around the world (the closest the plant will be) the dangers seem overhyped and unrealistic.

Figure 1. Relative location of the proposed power plant at Rampal and the Sunderbans (Yale)

A second power plant of similar size (1,200 MW) will be built at Matarbari although that will also rely on imported coal, at least initially (sourced from Indonesia, Mozambique, Australia or Canada) and

The government has also a plan to implement three mega coal-fired power plants at Moheshkhali each having capacity to generate 1200MW electricity under private sector or joint venture deals.

. Domestic coal production will require considerable growth in production, given that it was only at around 800,000 tons per year in 2011. The coal coming from the thick seams of the Barapukuria coal deposit has some 200 M tons of reserves, and is being won using longwall top caving, which simplistically involves undercutting the coal thickness with a shearer, and then allowing the overlying coal to fall into the mining opening.

Figure 2. Schematic showing the idea of Longwall top caving, there is a second conveyor at the back of the roof support to carry away the broken coal as it feeds down over the back of the support (University of Wollongong )

Bangladesh has struggled for years with less than half the country having access to electricity and with the rest of the population relying on biomass and waste to provide fuel for heating and cooking. But just to keep up with current demand it must increase natural gas supplies by 35% to overcome current shortages, and thus, to meet the demand for those without power they have chosen to go with the coal-fired option.

It will be interesting to see how the politics of this unfold, given the obvious benefits that will arise as more folk in Bangladesh are provided with electricity, with all the benefits that this entails, and which is being held up by those that one might have thought would have wished to see such progress.

In passing it might be noted that China approved an additional 15 coal mines with a total output of more than 100 million tons last year.

European weather, Danish and Scottish power supplies

Denmark would like to get rid of the idea of using coal for its power stations and would like to have the five largest cities in the country “coal free.” Because Denmark still uses conventional, currently coal-fired, power stations for power this requires that they be converted to burning biomass instead.

Converting to biomass from coal is predicted to reduce the country’s carbon dioxide emissions by between three and five percent. It has been estimated that the conversion to biomass will cost the state some 900 million kroner annually through the loss of levies on coal.

The process has begun at the Amager Power Station which now includes a unit that burns straw and wood pellets.

The renovation process has taken more than five years and cost DKK 1.9 billion. In return, we have reduced emissions by as much as 630,000 tons CO2 per year.

The straw comes from farmers in Zealand, where it is pelletized before being shipped to the plant, which will burn about 100,000 tons a year of straw and 300,000 tons of wood pellets that will be imported from neighboring countries. The power company that runs these power stations, Vattenfall, has the stated intention of being CO2 neutral by the year 2030.

One of the other suppliers, Dong Energy which supplies more than 50% of Danish energy, has been criticized in the past because it planned on building new coal-fired power plants at Griefswald in Germany and at Hunterston in Scotland.
The company dropped out of the German power station plan a year ago. And it now appears that it may have struck out in Scotland also. The Hunterston station was scheduled to burn a mixture of coal and wood pellets, and aimed to be a demonstration site for carbon capture.

The 1.6 gigawatt plant, proposed by Ayrshire Power, is seen as a test of the Scottish government’s energy policy, which is fiercely anti-nuclear and pro- renewables but which critics say ignores the realities of future demand for power.

If permission is granted, the site, at Hunterston, will be the first in the UK to have an experimental carbon capture and storage facility. The company claims that this will capture 90 per cent of carbon from the plant and reduce consumption by up to 25 per cent.

However, within the last month, it appears that this plan has also died with the issue of a new policy statement from the Government.

“There is no current need for an increase in overall thermal capacity,” the policy statement says. “A huge increase in the potential of renewable electricity has led to a downward revision in the estimated requirement for new-build thermal electricity generation plant.”

Environmental groups say this spells the end of the Hunterston project, as well as another hotly disputed power scheme – ScottishPower’s plan to convert an old coal plant at Cockenzie in East Lothian to gas. It also confirms there is no need for any new nuclear plants.

“This would seem to signal a death knell for new coal or gas power stations such as those proposed at Hunterston and at Cockenzie,” said Duncan McLaren, the chief executive of Friends of the Earth Scotland. He pointed out that, according to the new policy, Scotland would need just 2.5 gigawatts (GW) of power from fossil fuel plants in 2030. This could easily be met by cleaned-up electricity from refurbished plants at Longannet in Fife (2.4GW) and at Peterhead in Aberdeenshire (up to 1.6GW), he argued.

As a basic point of reference,

Scotland produced in 2008 48.217 TWh of electricity (Scotland 2 2008), equivalent to 5.5 GW continuous power output. Of this:
27% was from nuclear power stations, 29% coal & combined cycle, 10% from hydro power, 27 % from gas/oil plants, and 7% wind onshore from approximately 800 MW capacity.

Scotland has already seen one station brought on line the 44 MW station at Lockerbie, that burns only wood.

The CO2 neutral plant is the UK's largest dedicated wood burning plant . . . . . It will burn 475,000t of sustainable wood fuel a year, including 95,000t of short rotation coppice. It will save up to 140,000t of greenhouse gas emissions annually. . . . . . . . Wood can have high moisture content, including Small Round Wood (SRW, 52–58%) sawmill co-products (54–62%), and Short Rotation Coppice willow (SRC, 35–55%). Besides freshly cut and old wood, Stevens Croft can burn different grades of willow.

The power plant can reach full output even with high-moisture fuels. It will burn a maximum of 20% recycled wood (limited by Planning and IPPC), and a maximum of 20% SRC (targeted by grant conditions for end 2011). Moisture content range for the plant is between 46% and 58%, with a design blend of 53%.

The majority of the fuel comes from sources within 60 miles of the plant.

Now this isn’t where this post was supposed to end up. I had started writing it because of a report that Denmark was restarting mothballed coal-fired power plants to meet the demand for energy in this colder-than-normal winter. As the post evolved it showed that Denmark isn’t having much luck in finding other sources for power outside the country, but that Scotland is becoming more self-sufficient by, among other sources, increasing their use of wood, which is also in the Danish plan. However, at present, Denmark has had a remarkably stable supply of electricity from coal for the last decade, judging by their coal consumption. (Note that the plot below shows the BP data, there are other sources which report that Danish demand is higher (at 7.8 million tons in 2009) although the shape of the curve is the same.)

Coal use in Denmark (Export Energy Databrowser )

A review of the Nordic power balance earlier this year showed that Denmark should have been more than self-sufficient, even with a 1 in 10 severity winter. However, and this is the confirmation of the story that I began looking for, Dong Energy has had to recognize that this winter is more severe and has, in fact, had to reactivate coal-fired stations.

DONG Energy has today decided to temporarily bring back into service Unit 4 at 
Studstrup Power Station and Unit 5 at Asnæs Power Station with effect from 9 
December 2010 and 3 January 2011 respectively. At the same time, Unit 2 at 
Asnæs Power Station will be taken out of operation on 3 January 2011. It is 
DONG Energy's intention to take the two power station units out of operation 
again on 1 April 2011 and 1 May 2011 respectively and to recommence generation 
at Unit 2 at Asnæs Power Station on 1 May 2011. 



Cold weather, coupled with low water levels, in the reservoirs that supply the 
Norwegian hydroelectric plants has created great demand for generating capacity 
in the Nordic energy market. At the same time, the cold winter is putting 
pressure on supply of heat in Aarhus and the neighbouring municipalities. By 
bringing Unit 5 at Asnæs Power Station and Unit 4 at Studstrup Power Station 
back into service, DONG Energy will thus be contributing to securing the 
electricity supply and the heat supply.

On burning wood, coppicing and pollarding

The power plant on our campus is set up so that it can burn either coal, natural gas or wood feed stocks. At the present time the natural gas lines are blocked, since the trends of increasing price made it uneconomic to use within the boilers. However the plant uses around wood for 40% of the feed, and has for a number of years. It helps, both with pollution control, and with the overall plant economics (oftimes being cheaper per kwh generated). We are located adjacent to a national forest and thus there is a ready supply of material.

This practice is beginning to catch on, as Bloomberg notes:

Using biomass for power and heat -- mainly from poplar, willow and pine trees -- grew by 25 percent during the past two decades, according to the International Energy Agency, the Paris-based adviser to 28 oil-consuming nations such as the U.S.
Industrialized nations got 4 percent of their energy from biomass in 2006, the most recent data available from the IEA. That was the equivalent of 151 million tons of oil.

Chips of wood stumps and branches, heated to 400 degrees Celsius (750 degrees Fahrenheit) at the Novus furnace, are as efficient as coal and cheaper: European Union rules don’t require carbon-dioxide permits because the trees absorbed a like amount of the gas before harvest, making them carbon-neutral.

Now in relatively small quantities this is a viable program, and for domestic heating wood has long been a fall-back supply (we buy several cords each winter to burn in our tile stove).

It is particularly useful as a supply in those parts of the country where solar and wind energies are not going to be locally available as viable resources (long-term, long-distance transmission of generated power is an issue I’ll duck today).

However, before everyone rushes out to get a stove, furnace, or even a fireplace it is worth reminding folks of some historic facts (some of which Bloomberg also catches).
Generally you burn up a tree a whole lot faster than you can grow a new one. Out of that reality grew the European practice of coppicing where the young limbs of the tree are harvested back to just above the stump, and the stump thenn allowed to regrow limbs. (The practice dates back to before Henry VIII). Trees such as birch may, for example, be harvested every three or four years, while the basic root of the tree may survive for centuries..

Coppiced trees. (Source Hampshire County Council)

The alternative practice is known as pollarding where the tree is first allowed to grow to some height, and then the limbs are cut back. Because the growth then occurs at a later stage in the tree life, the trees will mature in a way that coppiced trees won’t though the production can come faster. It is used where livestock could come in and eat the coppiced limbs (Henry VIII passed laws about fencing the coppiced plantations, thereby enclosing parts of the forest). Both practices were common in Europe with their need for fuel and fencing material, oak and willow being commonly harvested this way, and the characteristic tree shapes are a feature of landscape portraits by artists such as Gainsborough , Knight and Price. It is a practice that, though laudatory for many reasons, has fallen into abeyance, since it is, among other things, very labor intensive. It is suggested that less than 3% of modern woodland is coppiced. There are some attempts to regenerate the industry.

Pollarded Trees (source Wikipedia

Short of these land management and wood harvesting techniques, wood can only be expected to supply a limited amount of fuel before it too runs out. Pelletizing the waste products from wood manufacture has created an industry that can, again, supply a limited market with fuel. Until recently the price has been relatively stable in comparison with other fuels.

Relative wood pellet cost (source New England Wood Pellet LLC)

An average household is anticipated to use some 2.67 tons of pellets a heating season, and they have advantages of being cleaner and simpler to operate than the wood that heats me at least three times (stacking, moving and burning).

Were the whole nation to turn to wood, however, then as happened in Europe in previous times, the cost of the fuel could well skyrocket. I have mentioned in earlier posts that King Edward I (Longshanks) tried to ban the burning of coal back around 1306, but the costs for wood were so much higher, that the ban was ineffectual, as were subsequent bans by monarchs such as Elizabeth 1. And even today one finds that there are those who would rather burn coal than wood. The stove that we have can be adapted (using two grates in about 2 minutes) to burn coal, however, as yet we have not examined that option.

The Bloomberg article notes that one supplier of pellets has already sold this years supply, and with 800,000 households (I suspect many, like us in more rural parts of the country) already using wood, overall supplies may also become tighter. And, in Europe RWE is building wood-fired power plants, and eighteen months ago a large-scale plant opened on Teeside in the UK.

This 30 MWe plant uses 300.000 tons of woodchips a year.

The wood for the station comes from four separate sources. Around 40% of the 300,000t a year total is recycled wood from UK Wood Recycling. This is received, stored and chipped on a nearby, separately owned site at Wilton. A further 20% comes to the site already chipped as offcuts from sawmills. SembCorp is working with the Forestry Commission to bring another 20% from north east forests in the form of small roundwood logs – items sometimes left on the forest floor after routine tree felling operations.

Finally, 20% comprises specially grown energy crops in the form of short rotation coppice willow. The company Greenergy is supplying the wood, to be grown by farmers and other landowners within a 50-mile radius of the site.

The new plant required the growth of around 7,500 acres of coppice in the area, an activity that is creating local wildlife havens.

As an example of the benefits available to local farmers is the case of the Corrigans near Middlesborough and the power plant. They have three 25 acre willow plantations, the first of which has just come to first harvest. Once dried it will be shipped to Wilton and bring in around $20,000. As the plants mature this harvest is expected to increase. There are other advantages

He said: "There has been a dramatic increase in insect and bird life especially snipe, woodcock, lapwings and reed bunting as well as pipistrelle and long eared bats and three species of owl.

So we have found a couple more words that you should probably add to your energy lexicon. And they provide not only fuel, but also jobs.