This isn't the usual Boiler Room fare, but I thought it might be of interest to the folks on this forum. Here is the link to a story that was published in the Worcester Telegram http://telegram.com/article/20101224/NEWS/12240450/1020. It describes a commercial wood plant being proposed for Springfield,Ma. First off, please note that this is commentary by one individual. He makes efficiency claims (23% efficiency.... worse than existing coal plants) which I haven't cross-checked. So it's possible that this information may be incomplete and/or inaccurate. Is anyone familiar with these things - is gasification incorporated into any of these commerical plants? And no one around here is shy, so I expect that there will be other comments and opinions about the subject and article as well ;-)
Gasification in Wood Power Plants?
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With electricity generation the major loss is in distribution.
I guess you can burn wood at very low efficiencies, not sure why you would, or wood.
As far as conversion wood should not be that different to coal, and then it goes from there.
Looking at the totality you would need to look at the harvesting of the wood vs extracting the coal. Best bet for CHP schemes is if you are using an otherwise waste product.
I guess you can burn wood at very low efficiencies, not sure why you would, or wood.
As far as conversion wood should not be that different to coal, and then it goes from there.
Looking at the totality you would need to look at the harvesting of the wood vs extracting the coal. Best bet for CHP schemes is if you are using an otherwise waste product.
I'm no expert but I'd say there is some missing info or the writer has an agenda.
Local power plant here modified their system so they could mix wood chips with coal to clean up emissions.
Local power plant here modified their system so they could mix wood chips with coal to clean up emissions.
I have no knowledge about the details of the MA plant that is the focus of the article, but I have noticed that the NIMBY syndrome seems to crop up for renewables nearly as much as for traditional generating plants.
Lots of people want any solution to be in someone else's back yard.
Lots of people want any solution to be in someone else's back yard.
I'm no engineer, but the article sounds about right. Coal fired power plants run in the range of 40% efficiency and wood is not economical to dry so it is burned with a high moisture content which leads to the 23% efficiency. Gasification is suited to small scale heat or running engines in some cases, but larger steam power boilers don't need or benefit from gasification technology.
Certainly the author has an agenda, and NIMBY is a big part of it. The part of the article that I found most humorous was the mention of non-economical renewables, especially "appropriately sited wind", I bet that means turbines in South Dakota, a high voltage line to the next county west of wherever the author is, and nothing to obstruct his view of his friendly local trees.
To his credit he did mention conservation and efficiency, but nobody seems willing to ride that horse since it threw Carter (who was right BTW). It's much easier to give pie in the sky answers like "solar and wind"
Certainly the author has an agenda, and NIMBY is a big part of it. The part of the article that I found most humorous was the mention of non-economical renewables, especially "appropriately sited wind", I bet that means turbines in South Dakota, a high voltage line to the next county west of wherever the author is, and nothing to obstruct his view of his friendly local trees.
To his credit he did mention conservation and efficiency, but nobody seems willing to ride that horse since it threw Carter (who was right BTW). It's much easier to give pie in the sky answers like "solar and wind"
I didn't read the article, my comments are based on the posted comments. Gasification is alive and well in commercial power plants. it's done different. There are a lot of approaches , I am not going to pretend that I could explain even one of them. These are Power boilers and do run extremely high steam pressures. Which requires high heat, there isn't any unburned fuel going up the stack. In a simple version -- a sloped grate wood chip burner or even a pellet burner they both gasifi for heating boilers, low pressure steam but usually hot water because of the storage potential, for on peak, demand.
They mix ground-up tires and wood in at least one power plant here in Michigan.
Jimmy Carter - blew billions into syn gas technology[ that was real money back then] -- not sure we got one usable thing from it. This is where the future is -- Nuclear fusion - room temp semiconductor. It's just not mine or any one else reading this. Sorry!!
They mix ground-up tires and wood in at least one power plant here in Michigan.
Jimmy Carter - blew billions into syn gas technology[ that was real money back then] -- not sure we got one usable thing from it. This is where the future is -- Nuclear fusion - room temp semiconductor. It's just not mine or any one else reading this. Sorry!!
benjamin said:
Try to locate a wind facility, at least here in the northeast, and opposition on "aesthetics" comes out of the woodwork. So apparently wind is only OK when someone else needs to behold the actual facility. My way of looking at it is this: ski slopes are not a natural phenomenon, and did not exist on any scale pre-WW II, and yet people have become completely accustomed to them. I'd rather look at wind turbines than have mountaintop removal coal mining going on elsewhere.
There are a couple of standard designs for Biomass Power Plants in New England. Realistically all the boilers "gasify" and then combust gases so the term gasifier isn't very specific. Important to note is that the power boilers burn wood chip not logs, The chips are usually 3 by 3 by 3 inches or smaller. They are green and have a high moisture content.
There are grate designs (usually moving), where a bed of burning wood sits on the bottom grate with a portion of the combustion air injected under the bed. Wood is broadcast roughly evenly over the grate where is partially burns and give off combustible gases. The gases then rise up the boiler where secondary combustion air is injected through a series of air ports (usually referred to a Over fire Air). In order to keep the NOx generation down, the combustion of the wood gas is "staged" by adding portions of the secondary air at different elevations. The entire boiler is lined with refractory. If you regard a gasifier as having two distinct sections, a grate design boiler doesn't have distinct sections so you may not regard it as a "gasifier". The other design that is used at some plants is a bubbling bed design. In this design the bottom of the boiler is a sand bed that is heated to gasification temperature. Air is injected under the bed at a high enough pressure that the sand acts like a fluid. Wood is broadcast into the sand and partially combusts giving off combustible gasses that then rise through the boiler and is treated like the grate boiler. Like the grate boiler everything happens in a one space so may not meet the definition of a gasifier. There are also some circulating fluid bed units in operation, but they too have only one distinct internal cavity.
There are some designs where a separate external gasifier is installed outside to the boiler combustion chamber with the combustible gases ducted to the boiler cavity. Chiptech out of burlington VT uses this design as it allows an easy retrofit of a liquid fuel boiler.
Some boiler designs are better then others, but economics drives the selection of equipment. They all can meet the air emission limits.
There is another technology of gasifiers that convert the wood into a fuel stream that can be burnt in a internal combustion engine, to date they are not yet commercial except for heavily subsidized applications (Nexterra makes one) The holy grail of wood power generation is a wood gasifier that can create fuel gas that is clean enough to send to a gas turbine combined cycle power plant which will potentially have a much higher efficiency. Unfortunately the economics of wood power generation generally limits the size of the wood fired plant to the wood available in a 50 to 75 miles radius, so the plant size is too small (20 to 40 MW) to be a good match for a combined cycle plant (500 to 100 MW).
The Manomet study in Mass was specifically tailored to give results that would oppose the proposed plants in western Mass. The efficiency required to meet RPS status are too high and there are no commercial plants in the world that can meet the required efficiencies on a year round basis.
There are grate designs (usually moving), where a bed of burning wood sits on the bottom grate with a portion of the combustion air injected under the bed. Wood is broadcast roughly evenly over the grate where is partially burns and give off combustible gases. The gases then rise up the boiler where secondary combustion air is injected through a series of air ports (usually referred to a Over fire Air). In order to keep the NOx generation down, the combustion of the wood gas is "staged" by adding portions of the secondary air at different elevations. The entire boiler is lined with refractory. If you regard a gasifier as having two distinct sections, a grate design boiler doesn't have distinct sections so you may not regard it as a "gasifier". The other design that is used at some plants is a bubbling bed design. In this design the bottom of the boiler is a sand bed that is heated to gasification temperature. Air is injected under the bed at a high enough pressure that the sand acts like a fluid. Wood is broadcast into the sand and partially combusts giving off combustible gasses that then rise through the boiler and is treated like the grate boiler. Like the grate boiler everything happens in a one space so may not meet the definition of a gasifier. There are also some circulating fluid bed units in operation, but they too have only one distinct internal cavity.
There are some designs where a separate external gasifier is installed outside to the boiler combustion chamber with the combustible gases ducted to the boiler cavity. Chiptech out of burlington VT uses this design as it allows an easy retrofit of a liquid fuel boiler.
Some boiler designs are better then others, but economics drives the selection of equipment. They all can meet the air emission limits.
There is another technology of gasifiers that convert the wood into a fuel stream that can be burnt in a internal combustion engine, to date they are not yet commercial except for heavily subsidized applications (Nexterra makes one) The holy grail of wood power generation is a wood gasifier that can create fuel gas that is clean enough to send to a gas turbine combined cycle power plant which will potentially have a much higher efficiency. Unfortunately the economics of wood power generation generally limits the size of the wood fired plant to the wood available in a 50 to 75 miles radius, so the plant size is too small (20 to 40 MW) to be a good match for a combined cycle plant (500 to 100 MW).
The Manomet study in Mass was specifically tailored to give results that would oppose the proposed plants in western Mass. The efficiency required to meet RPS status are too high and there are no commercial plants in the world that can meet the required efficiencies on a year round basis.
Peakbagger, Thanks for including the last 2 sentences! The Manomet study was a sham and even worse it is driving forestry policy in Mass. that will ruin sound forest management and a the use of a renewable resource.
Its funny how the folks taught that wood and coal are inefficient and wind is the answer but, do they count the day's that a wind turbine sits idle in their efficiency numbers. Wood energy is reliable and home grown energy source and has a place in our country's energy equation. Sorry I know I am preaching to the quire.
Its funny how the folks taught that wood and coal are inefficient and wind is the answer but, do they count the day's that a wind turbine sits idle in their efficiency numbers. Wood energy is reliable and home grown energy source and has a place in our country's energy equation. Sorry I know I am preaching to the quire.
http://biomassmagazine.com/articles/5181/bioenergy-expert-torrefaction-may-be-biggest-biomass-market
This seems to be the buzz lately for future biomass projects. Sounds promising.
This seems to be the buzz lately for future biomass projects. Sounds promising.
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