First, thanks to all who provided input for the renewable diesel essay. The comments were useful, and will help me to strengthen the chapter. Second, I had said that today I would comment on Benjamin Cole’s Seamless Transition to a Post-Fossil Economy. Frankly, I think other readers adequately addressed this, and even Benjamin realizes that a seamless transition is unlikely. So I will leave that one as is.
One of my major interests is storage systems for renewable energy options that would be characterized as intermittent. Solar and wind would fall into this category, and their intermittency really limits their ultimate potential. If wind turbines must be backed up by coal-fired power plants, it lessens the benefit. Therefore, the development of storage systems for intermittent sources of renewable energy is critical.
Previously, I wrote about Compressed Air Energy Storage (CAES). This is a system in which excess energy is used to pump compressed air into a storage cavern, which can then be bled off through a turbine when the wind is not blowing. There are clearly limitations to such a system. One must have access to both a good source of wind power, and a large, airtight cavern. This will limit CAES to specific niches.
However, this weekend I read about a system which, if successfully commercialize, would be more universally applicable. These ideas are to solar what CAES is to wind:
Groups Store Renewable Energy to Use on Rainy Days
First they frame the problem:
Scientists and engineers are struggling to find ways around a major obstacle to the growth of renewable energy: the fact that inexhaustible sources of energy, such as the sun and the wind, are undependable.
Solar power doesn’t work at night or on cloudy days. Wind is notoriously fickle, often dying down in the late afternoon just as electricity demand is peaking.
Then they cover the research under way:
The Department of Energy is researching ways to store energy at solar power plants that use thousands of mirrors to concentrate the sun’s rays on pipes filled with oil. The oil, heated to 750 degrees Fahrenheit, turns water into steam, which drives an electric power generator.
In one design from the Sandia National Laboratory in Albuquerque, N.M., excess heat is channeled into tanks of molten salt – a mixture of sodium, potassium and nitrogen that melts at 430 degrees Fahrenheit – where it can be stored for up to a week. The stored heat then can be transferred to a “heat exchanger” to boil water to make steam to run a generator at night or whenever necessary. Several power plants under construction in Spain plan to use this concept.
Another approach being tested at the University of Stuttgart in Germany would run pipes of fluid heated by the sun through a solid block of concrete. The concrete holds the heat for later use. To recover it, cold fluid is passed through the pipes, picking up heat on the way.
Molten salt is already used in some applications in the chemical industry to dampen temperature fluctuations in reactors. Even loss of power to a chemical plant would result in the reactor maintaining something close to reaction temperature, allowing a much quicker restart when power is restored. So, this is not pie-in-the-sky. These technologies are in use. I am glad to see that someone is attempting to use them to store solar energy, because I firmly believe it is the future.
In fact, I did a calculation this weekend for the book chapter I am writing that I believe demonstrates that there is no way we will be able to grow our way out of our petroleum dependence. The efficiency of photosynthesis is just too low to make that possible on the land we have available. So, in the long run it has to be solar, wind, and probably nuclear power.
Sounds nice in some respects — But I guess the question is how much above 430F you can get the salt mix … because 430F ain’t all that great, efficiency-wise.
Assuming that places hot enough to locate these molten salt deals can somehow get the turbine exhaust temperature down to 80F (with little or no water available), I get a Carnot efficiency — the maximum theoretically possible — of only 39% [Delta T/Thot = 350/890].
Am I missing something?
Good update on the stored energy thing, and it’s nice to hear of growing application.
But I’m going to respond to this:
Frankly, I think other readers adequately addressed this, and even Benjamin realizes that a seamless transition is unlikely. So I will leave that one as is.
by reminding you all of Kurt Cobb’s summary of peak oil uncertainty.
Perhaps there are some implied uncertainties with your (and all of our) probabilities … but just to name the worst case, we have all met peak oilers who will tell you at once:
– they have chosen a most likely peak oil scenario
– they cannot tell you the odds, let alone the uncertainty for that scenario
That is at its face irrational, at worst an example of cognitive dissonance, and all too common.
I don’t know, is this something you all know but choose not to emphasize?
Oh, maybe I meant to link this essay, thought they echo each other a bit.
1)wind/compressed air…don’t you lose a fair amount of energy due to wasted heat generated in the compression process?..or is there a practical way to recover and use part of it?
2)thermal storage…they say it can be stored “up to a week” but I’d be curious about what the loss curve looks like–after a week, is 90% of the original energy left, or only 20%, or what?
I have high hopes for solar thermal and some type of heat storage. Though I’ll admit I haven’t run any numbers. One thing frustrates me though. When people discuss the intermittency of wind and solar, they almost never mention changing our consumption habits to coincide with when energy is actually available. I think if we would just price electricity higher when demand is higher (or in the case of wind and solar, when supply is low), it would go a long way towards decreasing peak demand. I think it would also allow wind and solar to make up a larger percentage of our electricity supply.
I almost commented on conservation as well … but I figured I’d already taken things in one alternate direction 😉
FWIW, it seems to me that all of these surveys and studies reinforce conservation and/or efficiency as the least costly “alternative energy.”
Conservation and Certainty
We had an interesting discussion at Environmental Economics on the Economist’s carbon supply curve.
In terms of what’s certain in an uncertain world … apparently those things on the left side of that graph, those descending with negative costs … make money and reduce energy consumption today.
It seems in general that environmental and peak oil blogs get caught up in future-tech, and do not (IMO) spend an appropriate amount of time on solutions that have that kind of win-win today.
Well, I didn’t mean conservation, but a changing of the pattern of demand by altering the times of day when we use electricity.
For example, if electricity were priced higher at night when solar plants aren’t generating, then I’ll shift my usage to daylight hours. Or, if there is a time of day that has high demand and therefore higher prices, then I’ll avoid using electricity during that time. I think some places have something called time of use (TOU) pricing for electricity that does this. TOU is demand driven. For solar and wind, I think we need to add a supply driven component to the pricing.
Conservation is a separate issue, but even more important in my opinion. It’s often treated as an afterthought and even with disdain. But I guarantee you that if you price electricity high enough, people will find lots of ways to cut back.
Perhaps there are some implied uncertainties with your (and all of our) probabilities
That’s not it. Other readers covered the gist of what I would have said, and Benjamin himself said that he didn’t really mean “seamless” after all. So there was really nothing left to address.
Sometimes it’s hard to guess intent and context across the Internets.
Your answer just then almost implies to me a certainty, rather than a recognition of uncertainty … though from this distance I cannot be sure.
Have you looked at Nakamura’s research on direct photocatalysis of hydrogen out of water?
Currently well below 5% efficiency and storing hydrogen for long durations does pose big engineering challenges.
Howere, they claim a possible conversion efficiency of 40% (solar to hydrogen, no electricity conversion in between).
What about the Wind-to-hydrogen work currently ongoing at NREL, have you researched this technology, I know there still needs to be some signicant improvements in both the electrolyzers and the method to actually generate the electricity from hydrogen (i.e. fuel cell, ice??) What are your thoughts??
Your answer just then almost implies to me a certainty, rather than a recognition of uncertainty … though from this distance I cannot be sure.
I guess I am not following you. A certainty of what? That the transition will not be seamless? From my perspective, I already see seams. Our present ethanol adventure looks like a seam to me.
What about the Wind-to-hydrogen work currently ongoing at NREL, have you researched this technology
If you check out my previous article on CAES, you will see a link to David Bradley’s report on a number of options along those lines. The main problem with hydrogen is that you end up producing it a long way from where it is used, and storing and transporting hydrogen has some issues.
A certainty of our present is quite rational ;-), but it leaves unstated the confidence we might have in our projections.
Reminds me of the peak oil acronym, TEOTWAWKI.
The world, as we know it, is constantly ending and beginning again. The interesting thing IMO, as I mentioned in that past thread, is whether it will be perceived “in retrospect” by future folk, as “seamless.”
The path from my 4 kilobyte TRS-80 Model I, to the crazy duel core machine I type through today was quite seamless, but TEOTWAW[knew]I has gone away.
I think think some levels of energy transition may be perceived as seamless by the general public, though those paying close attention may see transitions as pivotal as … say the moment when they let just anybody on the internets.
So while I agree with you that change is all around us … acknowledging it somewhat begs the question of prediction and uncertainty.
Here is something practical:
“System Relies on Ice to Chill Buildings” By Colleen Long of the
Associated Press on Jul 16, 2007:
… some office towers and buildings have found a way to stay cool while keeping the AC to a minimum – by using an energy-saving system that relies on blocks of ice to pump chilly air through buildings.
The systems save companies money and reduce strain on the electrical grid in New York, where the city consumes more power on hot summer days than the entire nation of Chile.
… State officials say there are at least 3,000 ice-cooling systems worldwide.
… Because electricity is needed to make the ice, water is frozen in large silver tanks at night when power demands are low. The cool air emanating from the ice blocks is then piped throughout the building more or less like traditional air conditioning. At night the water is frozen again and the cycle repeats.
Ice storage can be used as the sole cooling system, or it can be combined with traditional systems to help ease the power demands during peak hours. …
In the basement, three main cooling rooms house chilling machines and 64 tanks that hold 800 gallons of water each. Credit Suisse has a traditional air conditioning system, but engineers use the more efficient system first.
Construction on the system took about four months, and company engineers say it is extremely efficient.
“The concept is the same, but when you make something mechanical, it can break, but a big block of ice four floors below grade level isn’t going to do anything but melt,” said Todd Coulard of Trane Energy Services. The company built the Credit Suisse system and is one of several that work with ice storage.
Ice storage at Credit Suisse lowers the facility’s peak energy use by 900 kilowatts, and reduces overall electric usage by 2.15 million kilowatt-hours annually …
… costs are considerable: Credit Suisse spent more than $3 million to renovate its cooling system; …
Hmm. According to this page, the Swiss paid 9 cents per kwh, back in 1999.
Perhaps their rates have gone up. Otherwise it would be a long payback period.
Energy storage must be the topic for the day. The NY Times gives us this:
Storing Sunshine
The ice storage idea is interesting. I’ve thought about using a swimming pool for heat storage. You could cool the pool down at night and then start extracting the cool energy at mid-day.
I am not sure how practical it would be on a large scale but I had heard of some people pairing a water pump with a wind turbine. When excess energy is generated they use that power to pump water from a low reservoir to a high reservoir. When the wind is not blowing, they run the water back down which turns a turbine to generate electricity.
Odograph: Credit Suisse is a Swiss bank, but the office in question is on Madison Square in Manhattan. KWhr saved is not the only economic benefit from the system.
Reducing peak hour consumption probably reaps an even more substantial reward from ConEd in the form of off-peak pricing. If you could get a total savings of $400K/yr, you would have a 7.5 year payback, which is OK but not great.
It is undoubtedly cheaper to put this kind of system into a new building than to retrofit it into an 80 year old land mark in the middle of a crowded city.
LOL, I thought I was doing due diligence by looking up the Swiss rate, but obviously my diligence should have been spent in another area!
Robert, it seems to me that long distance transmission, and demand management will handle wind intermittency for some years out.
By the time we get to the roughly 20% market share where storage might be necessary, PHEV’s will be here in force, and they will provide the storage needed, as a bonus benefit to the utility they provide to their owners.
At first they will buffer intermittency with scheduled charging at night, then graduate to dynamic charging when supply is peaking, then finally go to Vehicle to Grid, where they actually cover peak demand.
This seems likely to be the only storage needed, but there’s likely to be pumped storage as well. I suspect that the Northern Michigan Upper Peninsula could provide all we needed, using a system similar to that used at Ludington, MI.
Scientists and engineers are struggling to find ways around a major obstacle to the growth of renewable energy: the fact that inexhaustible sources of energy, such as the sun and the wind, are undependable.
Gravity Storage
Think cuckoo clocks. I’ve got a cuckoo clock that runs for a week after I pull an eight ounce weight to the top — the force of gravity pulls the weight down converting the energy I stored back into mechanical movement.
Now scale that up a million times or so: Imagine a huge tripod (perhaps 100 meters high) made of steel girders with a pulley at the top. When the wind is blowing and the wind turbines are generating surplus electricity, use that current to power an electric motor that pulls a ten-meter square block made of solid concrete to the top of the tripod. When the wind stops, gravity would pull the concrete block down powering a generator that would feed stored potential energy back into the grid in the form of electricity.
I can easily imagine such a tripod/concrete block next to each 140 meter high wind turbine we build, providing a vast and fairly low-cost energy storage system.
A one hundred meter pyramid next to each wind turbine wouldn’t be anynmore visually offensive than the wind turbine itself.
Best,
Gary Dikkers
I see that you made a prediction today Robert, at that most prediction-oriented site, TOD.
I don’t disagree with the broad strokes of your piece, because the central theme seems to be a statement of where we are now. It’s a description of our present, with rising quantities of oil demanded, and constraints to production.
History teaches us that the present is often a useful approximation of the near future. Things will evolve from the present incrementally, veering only slowly, or we’ll get hit by a black swan and everybody’s guesses will be right out the window.
As a quibble, I think we need to flip a few words to avoid a logical contradiction:
The bottom line is that I believe the world has now reached the point at which the symptoms of peak oil [will seem] to manifest themselves – even though I still do not believe we have reached a true production peak.
But of course I wouldn’t make the language of prediction too strong.
Even though the world looks much the same way to me today, I’ll probably wake up and hear of small changes and shifts tomorrow morning.
And of course, big changes are always possible.
I don’t disagree with the broad strokes of your piece, because the central theme seems to be a statement of where we are now.
But of course I made the original prediction over a year ago. If you look at the original piece, you will see that things have played out much as I thought. I also made a second prediction, which I thought was quite safe, but some at TOD thought was very dangerous: Oil will not reach $100 this year, and I put $1,000 on that.
The point of the piece is this: What happens if oil production peaks tomorrow? What are the impacts? If I list what I think they will be, they are mostly the same as if all the excess capacity disappeared, yet supply was still growing.
Think cuckoo clocks. I’ve got a cuckoo clock that runs for a week after I pull an eight ounce weight to the top — the force of gravity pulls the weight down converting the energy I stored back into mechanical movement.
Gary, I have a cuckoo clock as well, and have often wondered how to devise a system to capture energy as the cuckoo clock does. That’s an interesting suggesting. Let’s form a company. 🙂
Why not store renewable energy in the most desired way – liquid hydrocarbons ? Given a cheap and huge supply of energy, Fischer-Tropsch process and others of similar kind become economically viable …
The Drake Landing Solar Community south of Calgary uses borehole storage for seasonal thermal storage to provide district heating for a subdivision of 52 detached dwellings.
The SHPEGS project has a similar seasonal thermal storage concept and the most feasible scenario for this type of grand scale seasonal storage is probably going to be a paired open loop unconfined aquifer storage for seasonal heat and a closed antifreeze loop for sub-zero “cold” storage.
This is an interesting 1992 paper on unconfined aquifer thermal storage from Waterloo Centre for Groundwater Research and Oregon Graduate Institute of Science and Technology.
In my opinion, when many engineers with traditional training and experience with fossil fuel heat engines look at renewable power systems, they will tend to overlook the fundamental difference that the “fuel” is free but low-grade. Traditional Carnot efficiency calculations take on a different meaning in solar systems and the important factor is the power out over the infrastructure cost not the power out over the fuel input.
It’s amazing to me that the “green fuels” advocates are working with less than 1% solar conversion efficiency of photosynthesis, but many engineers will scoff at a solar thermal system with a design like SHPEGS that has a focus on base load generation, location independence and lowering the infrastructure investment of the solar collectors because the target heat gradient and Carnot efficicency is much lower than intermittent direct solar systems like PV, Solar Stirling and heliostat/SEGS style thermal systems.
The key to renewable system design is power out over the cost/energy to build the system and the long term maintenance. Carnot efficiency is part of the consideration, but base-load reliability, location independence and lowering the infrastructure investment are IMO the key factors to moving solar thermal from the novelty/peak load realm to the major energy source.
“But of course I made the original prediction over a year ago. If you look at the original piece, you will see that things have played out much as I thought.”
I suppose I can quote my year-ago self as well:
(odograph at TOD on February 11, 2006)
LOL, Halfin you are a true contrarian 😉
But I think the conservative bet is still a slow squeeze on oil/gas supplies, and that will produce a steady supply of techical types looking for a technical explanation. Whether the short-term driver is asian demand, industry underinvestment, or peak oil, is kind of moot from this standpoint.
Of course we all want to know if a game-changer is looming. This is our genetic programming at work. We must know the predictions … and so we go to any blog or tv channel that will supply them.
(Thanks everybody, including you Halfin)
So I guess I called it too … but I’ve also kept my … detachment, I guess.
I still don’t think it is necessary to be wedded to one of those explanations, and is probably bad for one’s future flexibility to become so.
LOL, I guess my meta-prediction was that people would still be going to blogs to look for predictions!
That is certainly true, with no increased certainty.
The hot oil technology also scales down well. As an example, the following outfit collects solarthermal energy via a hybrid greenhouse system.
The Solar Power Village
Large-scale cold store research is also ongoing in europe.
Storing wind power in cold stores
Fridges could save power for a rainy day
Night Wind: storage of wind energy in cold stores [PDF file]
Small-scale application mentioned in the following discussion of the Hydrogen Economy.
“Twenty Hydrogen Myths”: A physicist’s review
Small-scale, distributed applications can be as simple as variable air conditioning.
Talk of renewables is important, but let’s not ignore the elephant in the room: wasted surplus electricity and resources. Near 100% is from non-renewables but even renewables will have this problem. I’ll risk a guess that 100% of home photoelectric sold back to the grid is wasted, even during peaking hours (congratulations rich greenies, you just accomplished jack squat. But’cha got that feel-good green sales rate didn’t cha?). Gridpoint is probably familiar to readers of this blog.
Many might not be aware of the various utility-scale load balancing concepts which integrate with Gridpoint’s end-user distributed user solution.
Swinging To Peak [PDF file]
Ammonia and methanol co-production with running reserves peaking electricity.
“GREEN GAS” AS SNG (SYNTHETIC NATURAL GAS) A RENEWABLE FUEL WITH CONVENTIONAL QUALITY [PDF file]
How’s that Saudi-supplied LNG terminal on the bay’s horizon looking now? Compare apples with oily apples.
HIGH EFFICIENCY CO-PRODUCTION OF SUBSTITUTE NATURAL GAS (SNG) AND FISCHER-TROPSCH (FT) TRANSPORTATION FUELS FROM BIOMASS [PDF file]
Use of hydrogen (read: surplus off-peak and variable-sourced electricity) to drive reforming reactions. Also solves hydrogen storage distribution problem. Make the investment in hydrogen work harder for you. Can also use captured CO2 as an partial oxidizer for syn gas refining of biomass (read: coal).
Production of Substitute Natural Gas by Biomass Hydrogasification [PDF file]
HYDROGEN CONVERSION IN SUBSTITUTE NATURAL GAS BY BIOMASS HYDROGASIFICATION [PDF file]
Development of a Hydrogasification Process for Co-Production of Substitute Natural Gas (SNG) and Electric Power from Western Coals Description [PDF file]
American flavor (tastes like coal)
These options don’t store per se; they swing from one output to another for over-all lower demand and expanded economic opportunity. 100% fossil fuel displacement is easier when 100% is a lower hanging apple.
One last note. Pneumatic storage isn’t just for well-sited mega-million dollar utilities. Pneumatic is competitive with lead acid batteries on a small scale and can integrate well with an air-cycle (airliner-type ventillator) chiller. A hybrid system can use the compressor to store off-peak electricity while releasing this reversibly with the benefit of adiabatic cooling and high-velocity ductless ventillation. Even stores fresh air. Plug a tube into the wall next to your desk (you’ll find it next to the fiberoptic plug for your solar lighting lamp) and have efficient localized chilled breeze of fresh air on demand just like on an airplane.
Also, I haven’t seen much commentary on using the embodied energy of compressed and liquefied fuel gases. Considering the heat involved, overheating expanding pneumatic systems seems obvious to me as a way to extend the utility of say, a home CNG (line gas + plug-in electric-run ng compression upgrader) refueling station like the Honda Civic GX Phill appliance.
myPhill article [PDF file]
Bogger.com seemed to eat part of my post and spit it out on the internet all gross-like. As if the extra formatting work isn’t enough of a hassle.
“Many might not be aware of the various utility-scale load balancing concepts which integrate with Gridpoint’s end-user distributed user solution.”
The above “link” should have been and preceded by the following:
You have to be kidding me. Google must not want links to Gridpoint.
3rd try.
http://www.gridpoint.com/
http://www.gridpoint.com/curve/overview/
I have a cuckoo clock as well, and have often wondered how to devise a system to capture energy as the cuckoo clock does. That’s an interesting suggesting. Let’s form a company. 🙂
Sure, R&G’s Energy Storage Systems. We’ll tie up the market co-locating gravity storage pyramids at each of the thousands of wind turbines now being built in the U.S.
Who should we talk to about the IPO? 😉
Gary
Robert-
Actually, it depends on what day you ask me, whether I think it will be a seamless transition to a post-fossil world or not. I beleive it could actually move us to greater prosperity and a cleaner world, if done right.
There is so much potential for PHEVs and biofuels, it is wonderful. We clearly could radically reduce fossil consumption and reduce pollution, while obtaining higher living standards.
Will the price mechanism gently nudge us there? Will OPEC be nice? Or a rapid run-up in price?
Or will we have another glut, rendering this whole discussion moot?
My best bet is for a seamless transition, except if you happen to be poor, in which case it will be a trying decade ahead.
Remember, world fossil oil consumption rose only 0.7 percent in 2006, and may not rise this year at all. We may have already achieved Peak Demand. If so, we are wel on our way to a post-fossil economy (in which fossil fuels are important, but less so every year).
Who should we talk to about the IPO? 😉
I know a guy. Billionaire actually. 🙂 Actually, I also still have Mark Cuban’s contact information from when he e-mailed me last year. So, we can get the 2 billionaires in a bidding war.
You have to be kidding me. Google must not want links to Gridpoint.
Those links worked out fine for me. Thanks for posting them. The cold storage options are of great interest. I hadn’t really given them much thought before.
My best bet is for a seamless transition, except if you happen to be poor, in which case it will be a trying decade ahead.
Let’s keep in mind that a vast number of people worldwide are poor.
I don’t think the transition will be seamless for anyone. But right now, the solution is not even on the horizon.
Biofuels can’t replace petroleum – even in theory. Photosynthetic efficiency and available arable land are too low. I did a calculation for the diesel chapter I am working on. If you planted 100% of the arable land in rapeseed, and have it produce as it does in Europe, it could offset (on a gross, not net basis) about 30% of our petroleum usage. And rapeseed is one of the more prolific producers of vegetable oil. Solar efficiency is so much higher, and we needn’t use arable land. Lots of rooftops are available.
Robert, mechanical energy storage, like a cuckoo clock, is enormously expensive – at least an order of magnitude greater than alternatives like pumped storage, and idle PHEV storage.
What do you think of PHEV’s? To me, they seem like the clear path to follow.
Nick
Biofuels can’t replace petroleum – even in theory. Photosynthetic efficiency and available arable land are too low. I did a calculation for the diesel chapter I am working on. If you planted 100% of the arable land in rapeseed, and have it produce as it does in Europe, it could offset (on a gross, not net basis) about 30% of our petroleum usage. And rapeseed is one of the more prolific producers of vegetable oil. Solar efficiency is so much higher, and we needn’t use arable land. Lots of rooftops are available.
Well no and no.
First: We should not be thinking of dedicating any arable land for biofuel production. Period.
Feedstock for biofuel production would strictly be from the following:
1. Waste: ~87% of US landfill waste is organic.
2. Plant matter not currently put to effective use, such as forest residue (slash) currently harvested and burnt to reduce fire risk.
3. New, non-food production, such as algae. Due to the large area required this would need to be done at sea. A starting point would be to harvest the dead-zone (and clean-up the environment free of charge).
Second: Rapeseed-based biodiesel may not be the worst example, but it is close enough. What fraction of the total plant mass is seed? What fraction of the seed is oil? The overall fraction of the plant biomass that you end up using is just way to small. On top of that, you have to spend precious energy separating the seed from the rest of the plant and the oil from the seed. This is never going to work.
As a matter of principle we need to consider the most efficient form of photosynthesis, as measured in kg of biomass/m2.d: algae. Then we need to look at technology that can convert 100% of the available biomass into fuel with the minimum preprocessing, in other words, not biodiesel.
Now, if I was Big Oil, I’d start working on a technology that allows you to process some waste biomass with crude, so as to do the seamless integration/transition thing. Get familiar with the new feedstock. Optimize its processing. Start increasing the ratio of biomass to crude. We may never get off crude completely, but maybe we don’t need to…
Waste: ~87% of US landfill waste is organic.
Funny you mention that. I was just working on this today in my renewable diesel essay. The number I found was that 35% of the waste in developed countries is biomass, and North American and Europe have 500 million metric tons per year available. I pointed out that this needs to be utilized first.
What do you think of PHEV’s? To me, they seem like the clear path to follow.
Agree 100%, and I have endorsed them before. We have so much roof space that could be generating energy and charging PHEVs. I want to use a high efficiency solar cell on a rooftop for power rather than a very low efficiency crop using up arable land.
The number I found was that 35% of the waste in developed countries is biomass, and North American and Europe have 500 million metric tons per year available. I pointed out that this needs to be utilized first.
Source conflict? According to USEPA (quoted indirectly) Americans dump 232 tons of municipal solid waste a year. If you add up paper, food waste, wood and yard trimmings, the renewable (biomass) fraction is ~61%. Seeing as “other” includes rubber and textiles, the bulk of that would be organic (if not renewable). So subtracting metal and glass, the organic fraction is just over 87%.
Your number may include the 228 million tons per year of industrial waste the country also produces (7.6 billion tons of which 3% is solids). Hard to believe there is almost no renewables in industrial waste, though.
Speaking purely strategically, we should be aiming for as diverse a mix of transportation fuels as possible. Hence you should put PHEV on a rapid development path. For the same reason you should buy every drop of ethanol the Brazilians would be willing to sell – even if it is a drop in the ocean.
I am going to check my source tomorrow, and compare it with the one you just posted to see if I can determine the discrepancy. My source was a European agency.
Fair enough. Here’s the USEPA reference, a bit more current than the other one. The news gets even better: ~65% renewable and between 84 and 87% organic.
Note that paper by itself is almost 35%.
Of course, it’s never as simple as that. The numbers are “before recycling”. To subtract the effect of recycling, see Table 4. However, even after recycling I still get ~57% renewable and ~83% organic.
“… I did a calculation this weekend for the book chapter I am writing that I believe demonstrates that there is no way we will be able to grow our way out of our petroleum dependence. The efficiency of photosynthesis is just too low to make that possible on the land we have available.”
I have been thinking about this statement and here is my belated reply, which I might have previously posted here:
Let us just start with current consumption. According to the EIA the US used approximately 13,825,000 barrels a day of petroleum based fuels in 2005.
There are 42 gallons in a petroleum barrel (approximately 159 l). So in 365 days the US used about 800 Billion l of petroleum.
Taking gasoline (~725g/l) as about 3/5 of the total and diesel as 2/5 (~850 g/l), I get about 620 Billion Kg or 620 Million Tonnes of fuel.
Diesel is on the average C12H26 and Gas is ~C8H18. Averaged as C9H20 it would have a molecular weight of 9*12 + 20 = 128, so it would be 84% Carbon, and the 620 Million Tonnes of fuel would be ~525 MT of Carbon.
Now to get that much carbon from biological sources, most of it will be in the form of carbohydrates, which have molecular formula of HCOH. The oxygen atom is heavier (16) than the Carbon and Hydrogen (12+2) so carbohydrates (and most plant matter) are 40% Carbon.
To get 525 MT of Carbon in the form of carbohydrates requires 1.3 GT of plant matter.
Could it be done? ORNL published a report “Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply, April 2005” (PDF 8.5 MB)
From the “Executive Summary” of the report:
Looking at just forestland and agricultural land, the two largest potential biomass sources, this study found over 1.3 billion dry tons per year of biomass potential
Forestlands in the contiguous United States can produce 368 million dry tons annually. This projection includes 52 million dry tons of fuelwood harvested from forests, 145 million dry tons of residues from wood processing mills and pulp and paper mills, 47 million dry tons of urban wood residues including construction and demolition debris, 64 million dry tons of residues from logging and site clearing operations, and 60 million dry tons of biomass from fuel treatment operations to reduce fire hazards. All of these forest resources are sustainably available on an annual basis. For estimating the residue tonnage from logging and site clearing operations and fuel treatment thinnings, a number of important assumptions were made:
* all forestland areas not currently accessible by roads were excluded;
* all environmentally sensitive areas were excluded;
* equipment recovery limitations were considered; …
From agricultural lands, the United States can produce nearly 1 billion dry tons of biomass annually and still continue to meet food, feed, and export demands. This projection includes 428 million dry tons of annual crop residues, 377 million dry tons of perennial crops, 87 million dry tons of grains used for biofuels, and 106 million dry tons of animal manures, process residues, and other miscellaneous feedstocks. Important assumptions that were made include the following:
* yields of corn, wheat, and other small grains were increased by 50 percent;
* the residue-to-grain ratio for soybeans was increased to 2:1;
* harvest technology was capable of recovering 75 percent of annual crop residues (when removal is sustainable);
* all cropland was managed with no-till methods;
* 55 million acres of cropland, idle cropland, and cropland pasture were dedicated to the production of perennial bioenergy crops;
* all manure in excess of that which can applied on-farm for soil improvement under anticipated EPA restrictions was used for biofuel; and
* all other available residues were utilized.
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However the assumptions for bio-fuel production from agriculture make me very nervous. Do they represent soil mining that will leave us with depleted and unproductive land? Will increasing crop yields require additional applications of fertilizer and pesticide that could create their own problems? Would converting that much cropland into fuel production adversely affect food prices and harm people in poor countries?
Further, It would require an enormous input of energy to turn carbohydrates into alkane fuels. to make C12H24O12 into C12H26 requires the addition of 13 H2. The source of that H2 and the process heat required to drive the process, if it is not more bio-fuel or fossil fuel must be wind, solar or nuclear, and in large quantities. This is not to say that it is impossible — just that it would be an enormous task.
Note that paper by itself is almost 35%.
I have checked my source, and that’s what it says as well. It was paper that was 35%. My source was:
Municipal solid waste composition: for 7 OECD countries and 7 Asian cities
I have been thinking about this statement and here is my belated reply, which I might have previously posted here:
Thanks for that. It is good to have a sanity check.
“Solar efficiency is so much higher, and we needn’t use arable land. Lots of rooftops are available.”
And when the rooftop space runs out you can cover the biofuel crop fields with fresnel lens concentrating photovoltaic-thermal hybrid systems to capture the post-saturation light levels wasted by photosynthesis, as discussed in the Solar Power Village model.
fat man said: Do they represent soil mining that will leave us with depleted and unproductive land?
Of course you must know that in the original Sioux, the word “Iowa” actually means, “world’s largest, shallowest strip mine.”
Cheers,
Gary Dikkers
“Another approach being tested at the University of Stuttgart in Germany would run pipes of fluid heated by the sun through a solid block of concrete. The concrete holds the heat for later use. To recover it, cold fluid is passed through the pipes, picking up heat on the way.”
This technique has already been successfully used for years. I first saw it in the early 1980s in AK. A house outside of anchorage had been built with an attached greenhouse for passive solar heating. This turned out to be uncontrollable and resulted in 90+ degree tempatures inside the home. The owners ran pipes through the greenhouse and used water to bleed heed heat and store it in a brick cube in the basement. They used a heat exchanger to draw off that brick at night.