Climate Change and Electricity From Biomass
Posted by Dave Cohen on August 1, 2006 - 1:28pm
Topic: Alternative energy
Tags: biomass, carbon emissions, climate change, coal, degree-days, electric car, electric light rail, electricity, global warming, igcc, natural gas, power plants, streetcars [list all tags]
The time has come to put the ongoing biomass debate in a larger context. My thanks to many TOD participants for their informative comments. I usually work the "problem" side of climate change, peak oil and natural gas supply in North America. Here I intend to address the "solutions" side of the debate. It is important to remember that no solution is without its attendant problems.
This post is lengthy and complex because the larger picture requires that I talk about a number of different subjects: electricity generation and usage trends, the weather & climate, coal trends, natural gas trends, CO2 emissions as they relate to electricity demand and biomass for power generation. However, if you'll bear with me, a coherent picture emerges at the end. I will confine myself to the United States and not talk too much about oil.
Two recent deplorable developments and months of thought have inspired this post.
- The current liquid biofuels boom and bubble focusing mainly on corn ethanol as discussed by Robert Rapier here, here and now here. Is this the best way to use biomass? It is not and I agree with Jim Kunstler that we've got to make other arrangements for our future. The American cultural tendency is to maintain our happy motoring utopia at all costs. This tendency in turn underlies the misplaced enthusiasm for liquid biofuels.
- Two strong negative indicators appeared recently concerning the continuing fight to mitigate carbon dioxide (CO2) emissions and achieve some modicum of stability regarding anthropogenic climate change. The first is this report of a memo from the Intermountain Rural Electric Association (IREA) resurrecting an absurd plan to discredit climate change science and prepare the way for a coal-fired future without carbon sequestration. The second indicator is the new enthusiasm for geoengineering (realclimate.org, Gavin Schmid of NASA GISS). In this case, Nobel Prize winning chemist Paul Crutzen, who invented the excellent term Anthropocene, has suggested that we put sulfur into the lower atmosphere to spur the creation of sulfate aerosols. This would have a "global dimming" effect (like after the Pinatubo volcanic eruption) and hence cool the Earth. This is also absurd (see Gavin's story) and is tantamount to giving up the battle to mitigate climate change by reducing greenhouse gas emissions.
As promised, I will confine myself to the US except for the following chart from the Christian Science Monitor New coal plants bury 'Kyoto'.
COAL'S KNOCKOUT BLOW TO KYOTO:
By 2012, expected cuts in greenhouse-gas
emissions under the Kyoto treaty will be
swamped by emissions from a surge of new
coal-fired plants built in China, India,
and the United States
"Environmental optimists were assuming the world was going to switch to [natural] gas, but when you're short of gas you use your own coal," says Philip Andrews-Speed, a China energy expert at the University of Dundee, in Scotland. "What you're seeing with China and the others is the cheapness and security of coal just overwhelming the desire to be clean."As you can see, the problem is much bigger than American coal usage for generating electricity. Now that the context is established, I will talk about trends in the US while noting that we Americans have an obligation in this world to lead by example given that we use 25% of the liquid fuels and generate about the same percentage of CO2 emissions from fossil fuels. Also, I do not live in China and nor can I vote there.
Electricity Consumption and CO2 Emissions
I will be referencing a recent EIA report with the innocuous title US Carbon Dioxide Emissions from Energy Sources (requires Flash). See also the introduction to the report (June 28, 2006). Click on any of the figures below to enlarge them in a new window.
Figures 1 and 2
Figure 3
Figures 4 and 5
Guide to the Slides and Pertinent Data
- Figure 1 -- US Consumption of Residential Natural Gas, Electricity and Motor Gasoline. Electricity demand is outstripping gasoline and natural gas demand but prices remain stable. "Even though weather and population trends affect the demand ...". Even though?
- Figure 2 -- Carbon Dioxide Emissions by Fuel Type. While pretroleum fuel usage still generates the most emissions (2585 MMTons CO2) and is rising, natural gas is flat or slightly declining and coal (2136 MMTons CO2) also shows a steady rise.
- Figure 3 -- Electric Power Emissions by Source. Electric power emissions have risen an astonishing 30.9% since 1990 with coal responsible for 83 to 86% of total emissions. Natural gas, which powers about 19% of electricity generation (not in slide), creates only 12 to 13% of emissions over the last 5 years.
- Figure 4 -- Carbon Dioxide Emissions by End-Use Sector. In 1999, transportation emissions surpassed those generated by industry, which is flat since 1990. Emissions from the electric power sector show the most growth. Residential is rising 1.8%/year and commercial is rising 2.0%/year, greater than transportation at 1.4%/year.
- Figure 5 -- Residential Sector. Heating degree-days (winter) is flat but cooling degree-days (summer A/C) rose by over 13% from 2004 to 2005. While total emissions increased by 3.2%, electricity-related emissions rose by 4.9%. Population growth and greater electricity demand are the key factors affecting emissions growth.
Let's discuss this data. Most of it is self-explanatory, you can see the trends. Heating and cooling degree-days data is maintained by the National Climatic Data Center. "Degree day is a quantitative index demonstrated to reflect demand for energy to heat or cool houses and businesses". There don't seem to be easily obtainable national statistics for the period of interest here (1990 to 2005) but the problem is being worked on.
"Call it what you will -- trends, global warming -- the bottom line is we're much warmer lately"...We know that electricity usage has risen substantially between 1990 and 2005. What is the cause? As to the relationship to climate warming, we can not establish what that is yet. Naturally, the one data point (2004 to 2005) allows us to conclude nothing. The question is whether this is a statistically significant trend. Do warmer winters offset hotter summers? Are there more degree-days year-on-year for the period? Fewer heating degree-days in the winter could offset more cooling degree-days in the summer. If no significant trend can be identified, then increased electricity demand is probably due to increased population, larger residential and commerical buildings using central A/C & heating -- or both of these factors. However, I conjecture that climate warming is playing a role here but its true significance is unknown over the time period we care about (from 1990 to the present). All this requires further data analysis."We look at something called the number of National Cooling Degree Days," said [Jon] Davis [chief climatologist for Chesapeake Energy Corp]. "We're seeing a tremendous increase in cooling days. The weather variable in energy is going to get more and more (important) from this point on."
Coal and Natural Gas Power Generation Trends
As electricity demand increases over time, so should coal and natural gas consumption. However, Figure 1 indicates the natural gas consumption is only slightly higher over the 1990 to 2005 period, currently declining and does not reflect increased electricity demand over the period. In addition, the EIA's slide #3 (not shown) indicates that electricity prices are flat over the period indexed to constant dollars. What's going on? The answer must be coal.From the natural gas section of EIA's Annual Energy Outlook 2006 with Projections to 2030.
Figure 6
Currently, high natural gas prices discourage the construction of new natural-gas-fired electricity generation plants. As a result, only 130 gigawatts of new natural-gas-fired capacity is added from year-end 2004 through 2030, as compared with 154 gigawatts of new coal-fired capacity. Natural gas consumption in the electric power sector peaks at 7.5 trillion cubic feet in 2019, then starts falling as new coal-fired electricity generation increasingly displaces natural-gas fired generation. Natural gas use for electricity generation declines to 6.4 trillion cubic feet in 2030.Space restrictions prevent a thorough treatment of natural gas prices in this post. Suffice it to say that prices are high and have just spiked (NYMEX Henry Hub) to $8.21/Mcf (= MMbtu/Mcf, see below) as of this writing. A recent EIA gas update tells us why.
As a result of the record-setting heat and correspondingly higher power usage in many areas, natural gas spot prices increased at all market locations since last Wednesday, July 19. The Edison Electric Institute (EEI) reported yesterday that U.S. electricity demand reached an all-time record last week. According to EEI, domestic utilities delivered 96,314 gigawatt hours (GWh) during the week ending July 22, surpassing the previous record, which was set last year during the week ending July 23, 2005, by more than 1 percent. Price increases on the week varied widely, ranging between 49 cents and $1.11 per MMBtu.Consider the following table from EIA's annual natural gas prices report.
| Price Type | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 |
|---|---|---|---|---|---|---|
| Wellhead Price | 3.68 | 4.00 | 2.95 | 4.88 | 5.46 | 7.51 |
| Electric Power Price | 4.38 | 4.61 | 3.68 | 5.57 | 6.11 | 8.45 |
Note: Prices are in MMBTU: One million Btu’s is equal to approximately 1,000 cubic feet of natural gas (Mcf).
Electric Power Price: price of gas used by electricity generators (regulated utilities and non-regulated power producers) whose line of business is the generation of power.
Understanding Figure 6 is the key to what's going on. HO and I have done numerous posts on natural gas but I will do a quick summary here. I suggest you read back through some of them. Remember, using natural gas has very low CO2 emissions relative to coal. What happened is as follows. Starting in about 1996 and culminating in 2004, most new power plants were built using natural gas. Wellhead gas prices have more than doubled since 2000 due to tight supply and had increased previous to that since the mid-90's. Matters have not been helped any by extreme weather events (like this summer's heat wave) and especially the shut-ins in 2005 due to the hurricanes in the Gulf of Mexico. We are still in the hurricane season although the weather has been quiet so far. As if that wasn't bad enough, natural gas wells deplete rapidly and the shallow-water Gulf of Mexico is being used up. As a result, due to simple extraction economics rigs are leaving the Gulf. Given the lead times for adding additional electrical power generation, plans for building coal-fired plants started to hold sway; plans for natural gas generation have flattened out. However, around 2009 LNG imports from Qatar will boost imports and presumably make natural gas electricity generation affordable again. Meanwhile, coal is the power generation fuel of the present -- see Tracking New Coal-Fired Power Plants -- Coal’s Resurgence in Electric Power Generation (June 26, 2006, pdf). According to the EIA, the electricity fuel of the future will be natural gas again after LNG gets going. Meanwhile, our NETL source tells us that there are 153 proposed coal plants with an estimated 93 gigawatts of electricity generation. Here's the big picture from the link above:
>
Note how anticipated coal generating capacity starts growing in 2004 and reaches its peak in 2010. Note the large undecided category. This is probably due to uncertainty regarding future natural gas supply. And what about coal prices? Coal is still cheap. Relative to natural gas, they are low. In fact, the NYMEX Central Appalachian Coal Futures price is dropping! All this is a climate change disaster.
Biomass for Electrical Power Generation
Three detrimental things have happened as US electricity demand has risen year-on-year as it has since 1990 at a rate of 1.8%/year and 31% overall.- Natural gas prices have increased due to increasing scarcity of supply and growing demand.
- Plans to build coal-fired power plants increased.
- CO2 emissions have risen due primarily to the dependence on coal. This trend will get worse on our current path.
As Robert Rapier has told me (personal communication):
I don't know what the EROI [for BTL] will be, but they are partially burning the biomass. That will generate a lot of energy in which to make the liquid products. In my opinion, Fischer-Tropsch diesel is the best route. But this is a much more expensive option [regarding capital costs] than using biomass to generate electricity.Forget the corn ethanol. Forget the cellulosic ethanol too. In these cases, using BTL processes for liquid transportation fuels increases capital costs to levels that don't pay off much and substituting food stocks for transportation fuels does not replace a significant part of our gasoline usage in any case -- it makes no sense. What are the CO2 emissions for various biofuels strategies? Brazil has had some success with biofuels from sugar cane but they started subsidizing their production 20 years ago. What makes the biomass worth using is the energy yield from simply burning it. So, let's use the biomass for electricity generation directly in a sustainable manner. Then use the generated power to build nationwide electric rail or trolley in cities or electric cars. Here are some details.
As detailed in the EIA's study Biomass for Electricity Generation, there are four ways to use biomass.
Biomass for electricity generation is treated in four ways in NEMS: (1) new dedicated biomass or biomass gasification, (2) existing and new plants that co-fire biomass with coal, (3) existing plants that combust biomass directly in an open-loop process,18 and (4) biomass use in industrial cogeneration applications. Existing biomass plants are accounted for using information such as on-line years, efficiencies, heat rates, and retirement dates, obtained through EIA surveys of the electricity generation sector.Here I will restrict myself to option #1 though the co-generation strategies (#2, #4) are viable as well. Specifically, the EIA is talking about a closed-loop process using biomass integrated gasification combined cycle (BIGCC) technology where
A closed-loop process is defined as a process in which power is generated using feedstocks that are grown specifically for the purpose of energy production. Many varieties of energy crops are being considered, including hybrid willow, switchgrass, and hybrid poplar. If biomass is utilized in a closed-loop process, the entire process (planting, harvesting, transportation, and conversion to electricity) can be considered to be a small but positive net emitter of CO2. It is not precisely a net zero emission process in a life-cycle sense, because there are CO2 emissions associated with the harvesting, transportation, and feed preparation operations (such as moisture reduction, size reduction, and removal of impurities). However, those emissions are not the result of combustion of biomass but result instead from fuel consumption (mostly petroleum and natural gas) for harvesting, transportation, and feed preparation operations.The most important benefit of such a process is environmental; specifically the drastically reduced CO2 emissions. An obvious point bears repeating here: when referring to clean coal in IGCC electric power generation, the pollutants being considered are primarily sulfates (SO2) and nitrogen oxides (NO, NO2), not carbon dioxide. While it may be possible to sequester CO2 at IGCC power plants, this is currently a research matter. Why not reduce CO2 emissions at the source using biomass? I'm sure that the irony is not lost on readers here that just as the US has mounted a clean coal inititative, Crutzen suggests that we seed the lower atmosphere with sulfur to promote global dimming! As I tried to make clear above, natural gas (with sequestration) is not a supply-side option in the short term and perhaps further out given uncertainties about building recieving terminals in the US to support the LNG lifeline.
A long study A Biomass Blueprint to Meet 15% of OECD Electricity Demand By 2020 (large pdf) by the World Wildlife Fund (WWF) and the European Biomass Association (AEBIOM) goes into considerable detail about the proposal given by its title. Here's the introduction to the report. You can read all the report details. The logistical problems as viewed today in switching to electicity-based transportation are daunting. Here's what Wojciech Olejniczak, the Polish Minister of Agriculture and Rural Development, had to say about it:
Increasing energy prices result in deteriorating conditions for the whole economy, including agriculture. A very important element of [the] “professional” power industry, based on renewable energy resources, is overcoming the organisational, technical and technological barriers, which today make biomass less competitive than fossil fuels. Such possibilities already exist on the local markets, where biomass is easily accessible and is not connected with high transportation costs. Increases in renewable energy production will not only result in an improvement in the areas of environment protection and energy safety, but will also provide a great chance for agriculture.And from the report's authors:
Governments should also redirect their agricultural subsidies to support the development of a stable biomass fuel supply by allowing perennial woody and grass energy crops to benefit from incentive schemes and at realistic scales. This needs to be accompanied by the development and enforcement of best practice guidelines for for biomass production to maximise positive social and environmental impacts and minimise any negative effects. Bioenergy is a key technology to fight climate change and deliver economic and social benefits. Governments must act now to promote its world-wide development.Here I present a modest proposal for implementing the supply chain infrastructure for large BIGCC and localized electric power generation solutions. Where BIGCC plants are not an option, other Combined Cycle plants using biomass can be built. The US can pay for the transition by implementing both carbon and gasoline fuel taxes, as has been called for here at TOD. Carbon sequestration for existing coal-fired plants must be implemented as soon as possible and let us pray that it is feasible. Co-generation using biomass must be added into those plants to reduce the carbon burden. The carbon market can supply production of domestic stranded oil using CO2 EOR in suitable regions like the Permian Basin of west Texas and New Mexico. This has been demonstrated at Weyburn. This is only a stopgap measure to ease the transition. Current tax subsidies for fossil fuels must be phased out. The necessary transition will be long and painful. Sorry, there is no gain without pain. We must begin the work now.
In Conclusion...
If Hirsch, Skrebowsky, Simmons, Stuart and the rest of us are right about the oil depletion picture, oil consumption will actually start showing declines in the near future. Assuming a 2010 date for the peak and a slow squeeze scenario as shown by Hubbert Linerarizations, we might further assume a 2% year-on-year usage decline after that date. Concomitantly, CO2 from petroleum as shown in Figure 2 will decline at some comparable rate. However the picture for electricity consumption is that it may continue to grow at its current 1.8% rate (from 1990 to 2005), or even at a higher rate. The population problem can not be ignored in this context, nor can larger centrally heated or cooled residential & commercial spaces. We also can not dismiss the degree-days problem that is likely stressing our power grid beyond capacity -- this is happening now and may be due to climate warming in the present and may be exacerbated by increased warming in the future. Declining petroleum usage combined with generating a significant fraction of our electricity using biomass could mean reduced CO2 emissions in the United States in the future. As I alluded to above, increased electricity supply can support various transportation options like electric rail, cars and streetcars.
Welcome to the Future -- Click to Enlarge
However, US government policies (taxes and subsidies) must change if this scenario is to happen. Particularly, the two political parties and venture capitalists like Vinod Khosla must be made to understand that BTL processes are not the best way to use biomass in the future. This is a failed strategy to maintain "business as usual". That will not work. Climate change considerations as constructed by Jim Hansen must be taken into account. As we make the transition to biomass for electric power generation, the US can create jobs and wealth, export technology to Asia (China & India), mitigate climate change and take a large step toward avoiding a longer term calamitous future.



Biomass is bulky until peopel focus on use cases were the biomass is converted to and alternative form very close to where its created I don't see the sense in discussing it.
I use the scenario of the Georgia moonshiner the reason he makes moonshine from corn is its not cost effective to transport the corn from the mountian valleys to market so he converts basically onsite to a higher grade smaller format.
Biomass solutions must look at economies possible from distributed resources towards concentrated resources with minimal transport. Any other approach is relying on the existing oil/coal based factory to support production.
Consider corn.
One you need to distill so like the Georgia moon shiner you need access to some form of heat for distillation this can be solar power part of the biomass or popular or other brushy biomass used to fuel the distillation. The moonshiner used the abundant wood but in our case we could do a coupled biomass system with some optimized for burning.
Resulting ethanol can easily be moved via pipelines back to the main distribution center.
There's more but until I see someone work through conversion at the farm or better at the edge of the field to high grade
fuel using only local inputs I don't see the point.
Maybe a even better for biomass if you take a longer term view is artificial maybe salty peat bogs that are periodically drained.
I mention this because I've also researched running the oceans carbon cycle on a small scale you can readily get up conversion to krill which then form the equivalent of proto oil muck which can then be dried and refined. Salt water ponds allow the growth of wood eating bacteria and worms.
Also you can for example even look at electrical generation directly from a large muck pond via
http://news.bbc.co.uk/1/hi/sci/tech/3092754.stm
In any case managed muck ponds are very cost effective.
We routinely age wine and cheeses for years why not consider the same for biomass ?
I don't know what pisses me off not doing bio fuels or the fact that engineers are not even considering one the most basic aspects of a bio fuel system which is the initial biomass has to be converted as close to its production point as possible. This constraint drives most of the rest of the design. I find the absolute stupidity alarming. Either I'm way off base or there are a bunch of really dumb people in biofuels.
True, most biomass is quite bulky in its rough just-harvested form. But it can be made much less bulky by simple mechanical operations that can be set up at the point of harvest. The use of large tub grinders could convert the woody biomass into small chips with a far greater bulk density. Various compaction or bailing techniques could also be employed at the point of harvest.
I would venture that with proper chipping and compacting techniques, biomass could be given a bulk density perhaps a third to a half that of coal, and coal is transported tremendous distances.
I fully agree, though, that it is preferrable to have the operations as close to the biomass source as possible, but my main point is that there is still an economically favorable radius of operations for a biomass-to-energy system.
It all gets down to a big material handling problem.
Compaction takes energy we of course don't know off hand how much but I suspect its not cheap both in equipment costs and operation expenses to run this type of equipment.
After coming up with the concept of compacting biomass via a artificial muck pond or swamp I went looking for references surprisingly there seems to be no research on using pond muck as a carbon source. Now natural swamps are well know for there carbon rich deposits which burn when dried and peat is a well known source of fuel. Next with proper treatment algae blooms can be encouraged in a muck pond to add further biomass. They could be covered to collect methane also. So while the pond is filled it can act as a electric source and a methane source.
And again they can act is direct low level electric sources via bio batteries. Fresh vs Salt water muck ponds would also need investigation and those are just basic parameters that can be changed to influence the bacterial population of a muck pond you can play with oxygenation nutrients temp etc.
In colder climates composting on top of ponds covered with strong lids could be used to keep the temperature up plus using salt water ponds.
The concept would be to have a muck pond probably shaped as a long trench to allow easy access lined with clay concrete or plastic and potentially covered with plastic when not being filled. If these are done as long raised holding ponds down the lengths of a field the biomass harvester can simply deposit the biomass directly into the muck pond.
Lets estimate that it takes three years to fill the muck pond at the end of three years its drained with the rich effluent used to fertilize the field along with some of the muck. Next its allowed to dry and the concentrated carbon which is basically a cheap coal is sent to a CTL plant. And I say CTL because this process can be augmented with coal if needed. Residual ash is basically phosphate fertilizer since the biomass source is not important legumes can be rotated in to ensure nitrogen fixation and again the muck itself is incredibly rich.
Now if you want to do ethanol production also the crop can be harvested as normal and the peat can be used to close the cycle for distillation.
For energy sources we know they go oil->coal->peat so there is little or no reason to argue peat is not a valid and good energy source.
Can anyone argue against this scenario ?
Its really just a cheap bioreactor.
The energy consumption of various grinders, chippers, and balers in terms of energy per unit weight of material processed is well known. One can get that number merely by calling up any number of equipment suppliers.
If one is going to gasify the biomass or process it into ethanol, the biomass is going to have to go through at least one size-reduction step. So my point is simply: why not do that size reduction right at the point of harvest so as to also increase the bulk density of the biomass and save on transportation cost.
Harvesting pond muck is an interesting idea. As long as the concentration of organic matter is high enough and you can dewater and dry it without consuming a great deal of energy, it might have a positive energy return. It would work much better in warm rather than cool climates, particularly if you want to go with natural solar drying. Again, the economics of material handling is what can make or break such a scheme.
Building large open ponds or lagoons is relatively cheap and easy. Buidling large ponds with a transparent cover is neither cheap nor easy. Going with long narrow trenches would help ease some of theses construction difficulties.
What about harvesting water hyacinthes? These floating plants grow wild in Florida , grow incredibly fast, and tend to blanket whole ponds. They soak up nutrients like crazy, which is why there have been some demonstration projects using a water hyacinthe pond to treat domestic sewage. I happen to have a tiny koi pond by the side of my porch that is only about 5ft wide and 6 ft long. Each spring I buy two water hyacinthes for it, and by mid summer the pond is completely blanketed. In fact, I have to remove at least 2 - 3 plants each morning from mid-July through mid-September (this is in Delaware). The plants have a pretty high water content though, so dewatering and drying would be a major energy input. Just an idea.
Lets call them muck ditches I call them ditches now simply because it makes more sense to go with a long narrow pond I think then a large one.
Also there not quite ditches since they would need to be above the land level at least at some point to allow natural drainage similar to rice farming.
For northern climates you need to simply overfill the ditches with organic matter to get a composting zone which will maintain the temperature you don't need strong covers. The temperature should stay well above freezing.
At a guess, it sounds like a good idea for small scale and slow production ... but if you run the numbers for a commercial scale production plant it will start to look bad.
Can you really fill a pond over 3 years and then immediately start draining it? Or do you need to fill them, and let them stew (producing methane of course) for some number of years? How many ponds does a 100 million gallon per year plant need? If it can't do 100 million gallons, is it even a silver bb?
(in contrast, I'd expect the total cycle time for corn ethanol from grain delivery to shipment to be no more than a few weeks ... assuming they let the yeast work down to the last sugars)
If you don't start with a plant production number, what do you start with?
Now, currently the output of those ponds is fertilizer, and not waste in the sense of something that must be shipped at some cost to disposal. As I understand it, it can be sold.
If you are going to propose drying and conversion to liquid fuel, that is the step ton concentrate on. For that the numbers of interest are how many tons of psuedo-peat you need, what it costs to process it, and how much liquid fuel it produces.
Re: salt water. Usually has a lot of sulfate, at least if salt water = sea water. If you're waiting long enough to get significant methane generation you might also get significant sulfide generation, which on combustion turns back to sulfate, forming PM and acid rain. The sulfide may also have NIMBY odor issues (to be fair, H2S is also toxic). Then again, that might be trivial. Run the numbers and show us.
Man numbers are hard to come by. Generally people try not to initiate anarobic digestion :)
In any case my bust guess since references are slim is to start with areobic digestion with traditional composting methods this leads to a base of organic rich material as it accumulates water is added to induce anaerobic digestion and the composting region moves up the ditch. Anaerobic digestion is hell to find but agian we can point at rumen digestion and methane digesters to show its in the few week month rang. Same with composting. So I think all organic material introduced should be reduced well within a year. Again I can't find any references outside of methane digesters for animal waster where your actually overloading the system with organic material but we can assume its about the same.
Final answer is I don't really know the rates and I don't think anyone has really tried it but they seem to be reasonable. Since its a artificial peat swap compaction is on the order of 100:1 from bulk organic material.
This google search revealed there is scientific work in the area but its all behind paywalls.
http://www.google.com/search?hl=en&rls=GGGL,GGGL:2006-18,GGGL:en&sa=X&oi=spell&resnu m=0&ct=result&cd=1&q=rate+of+organic+material+breakdown+in+anaerobic+water&spell=1
There is of course the time lag between intial filling and
final draining thats on the order of years simply to accumulate organic material for some time. I think thats
the limiting factor not the biological digestion rates.
From this
http://aggie-horticulture.tamu.edu/extension/compost/intro.html
We learn that composting reduces organic matter bulk by 80%
so my estimate of 100:1 for a mixed aerobic/anarobic digestion is reasonable.
The energy content of peat is well known plus we get the methane also.
Finally this suggestion is not a lot different from fancy bioreactors just were fine with producing methane and carbon
to make syngas instead of trying to control the products to get ethanol.
The thing I'm most concerned with here is the "to liquids" step of the BTL process. I did some surfing and it looks like pyrolysis of wood and peat is the path to a liquid biofuel (biodiesel):
http://forestry.nacdnet.org/biomass/WoodBiomass.htm
Seven tons of oil from ten tons of biomass sounds pretty good ... but the question might be how pre-digesting, and then drying, to a pseudo-peat, changes that equation.
We do dig up natural peat bogs now for fuel.
The advantage here is since were creating the peat bog we control the surroundings by two means one the bog is actually above the natural water table allowing it to be drained like a holding pond. Next we have pre-lined our bog with a impermeable material probably clay or bricks or concrete. Next we can almost certainly do in-situ gasification. We are also loading the bog way beyond natural rates by introducing biomass from the surrounding fields.
It really the artificial nature of the bog that makes it worthwhile over natural peat bogs. Of course people drain natural bogs all the time also. Generally though there far from the population and can't compete with coal at least so far.
As a finally note the ash left over from gasification is a great fertilizer and can be spread back on the adjacent fields.
Well, of course. The real advantage of a peat farm (if it can be made to work) is that you only burn what you've accumulated in a year or however long it takes to make your peat, not burning tens of thousands of years of accumulated reduced carbon. The concern was that if you had a way of making peat valuable as fuel (directly, through BTL, whatever) we'll have the coal problem all over again, only we may end up destroying wetlands while we're at it.
As long as there is coal it more cost effective to mine coal then peat.
My artifical peat ditches differ dramatically from natural peat bogs.
First there charged with organic material from the surrounding
farmland that gives you say a 100-200:1 greater accumulation ratio than a natural peat bog. So in reality your getting if you fill for 3-5 years at least 300-1000 years of natural peat production plus your capturing the methane wich is a significant part of the overall energy probably 30-50%.
If for example you have 200 units of land you would fill a
artifical bog of say 1 unit. Its a volume problem since its related to the amount of organic material and the depth of the bog I'm guessing at leat 10-20 foot depth for the bog.
Needless to say the bog itself can be located on the least valuable land. I'm guessing to some extent but you can easily take the hay from a hundred acre farm and store it on a one acre plot piling it 20 feet high I find numbers like 9-15 dry tons per acre is common for biomass.
you have numbers like this for a round bale of hay
Hay Weight. 5 ft. 5 ft. 1200 lbs/bale So its about 1 ton
per 10 sq foot.
1 acre is 1 acre = 43560 sqft
divide by ten and that's
4,356 tons per acre storage.
And assume 10 tons per acre production gives
435 acres per 1 storage acre.
Man I'm good at back of the envelope calculations :)
You don't need to tightly bail the hay but it should compact
quickly under its own wet weight in the bog.
Except that the process is the same for peat production a artifical bog as I've described has a quite different energy profile from a natural bog.
Its the above multipliers that make it a viable energy source competitive with coal. In nature as far as I know there is generally no natural situation where a bog is flooded with organic material periodically except maybe if a river overflows into the bog area and it has a lot of organic material suspended. It would be intresting if this happens naturally somewhere on the planet maybe in the Amazon ?
I can provide data against some parts. Creating a bioreactor is yet another system needing management VS the "old" (ok present) system of taking out a dollar and buying energy. It will be hard to sell VS systems that capture sunlight or wind which have less management issues.
Next its allowed to dry and the concentrated carbon which is basically a cheap coal is sent to a CTL plant. ... Residual ash is basically phosphate fertilizer
If such is true, why do the rock dust as plant growth medium people see the better growth with rock dust, if plant growth was 'just' NPK? (Examples - remineralize the earth, www.thepeacock.com, and the azioth(sp) people)
The person(s) who come up with a system that can use 40 acres of biomass and is as easy as dumping material in one part and taking out the liquid carbon-hydrogen chemical/leftovers will become very wealthy making said devices. Most of the systems being offered up have market-protection in the form of massive costs to create and to provide an economic return need to draw in material from a wide area.
I estimated 100 acres gives a good yield that's not a industrial proposition but a reasonable sized farm. And my point is some good old fashioned basic science means you don't need massive costs or industrialization to get high grade liquid fuels from biomass just knowledge. Also they can be pulling in biomass from basically fallow fields planted with legumes and grass you don't need to grow high energy row crops. So this would come from resting fields.
Burt Rutan would laugh his head off at your comment I suspect. This is not rocket science :)
And yes said farmer would become reasonably wealthy and why not ?
Yea, that would be the part where the arceage becomes non-productive after a few years.
Feel free to show how what I've stated is not correct.
Burt Rutan would laugh his head off at your comment I suspect.
And somehow I don't think you have a clue about what Mr. Rutan would think or not think.
Assuming E100 cars would drive the typical 15K miles per year, at 15 mpg, that 1K gallons ... requiring 10 tons of biomass to be burned (just for the distillation step) for each and every car?
(actually, I HOPE I did that wrong)