A rarely mentioned problem with the use of hydrogen fuel cells for transportation is that their exhaust consists of low temperature water vapor, which in winter conditions would lay down a coating of black ice on roads, making them treacherous.

During the last eruption of Minnesota forest tent caterpillars (Malacosoma disstria), I noticed that the egg cases were composed of some kind of hard, light aerogel. Since the adults only live for a day or two, just long enough to reproduce, I thought that whatever the substance was, it must have been produced in the body of the caterpillar and stored and since their primary food is aspen (Populus tremuloides) leaves, the most likely source of the egg case polymer would have been a resin, namely lignin, and that modification of that resin may have been done by bacteria in the gut of the caterpillar. It's a marvelous substance, strong and light with tremendous glue strength. It would be worth investigating tent caterpillars to see what is going on.

Roger Pham is on the right track. He's thinking systematically. There is no magic bullet. We need to take a systems approach. As a retired farmer, I can relate there are some huge advantages to a perennial crop, especially one that requires minimal inputs, like perennial grass biomass: lower establishment costs, less machinery, less fuel, less fertilizer, low maintenance. The land also gains: carbon sequestration, soil building instead of soil erosion, reduced toxic run-off and siltation. It's a classic two-for. However, biomass based portable transportation-fuel production has to be combined with increased transportation efficiency. We can't continue burning fuel at the rate we have been, and projecting into the future present-day habits is not realistic. A third major paradigm shift that's needed is to decouple organic molecule synthesis from conversion into usable nutrients. For thousands of years we have depended on plants, primarily annuals, to accomplish both tasks. If we let plants synthesize carbohydrates and proteins, but take over the conversion process ourselves, perennial plant-based agriculture could produce more food on fewer acres with less inputs. Why feed alfalfa to a cow to get milk when its 18% protein content could be directly accessed more efficiently. This could be the greatest unanticipated side-effect of biofuel research.

I'm a retired native grass seed farmer, so perhaps I can help with understanding of perennial grass biomass. Miscanthus giganteus is a naturally occurring sterile hybrid of M. sinensis and M. sachariflorus. Its sterility is a real asset for biomass production, since it doesn't put any energy into seed production. This allows it to produce a large volume of biomass and carbon sequestration on very low nutrient inputs. Test plots at the University of Illinois, Urbana-Champaign produce 25 tonnes per hectare, without any fertilizer, tillage, or irrigation input, while sequestering 4 tonnes of carbon per year. This is a yield of almost 11 tons per acre, or more than twice the average corn crop in that area. M. giganteus grows to 12 feet tall and is harvested after full senescence, when all the leaves have dropped and only stalks are left. Switchgrass, Panicum virgatum, a native perennial and a crop I used to grow, produces about half as much biomass as M. giganteus. However, as I explained to the researchers, they were growing the wrong cultivar and should switch to a southern variety to trigger phenological sterility. Field trials in Quebec have shown that southern cultivars produce the highest biomass yield. Switchgrass is very cold tolerant and can stand being moved north. Switchgrass has the advantage of being a better soil stabilizer and wildlife habitat creater than M. giganteus and can be etablished from seed. M. giganteus has to be established from root stocks. These are both C4 photosynthesis pathway plants, which means they use a two-stage process, the second part of which operates at night. However, the chemistry requires ambient temperatures above 10 degrees C, which is why plantings in high elevation Wyoming won't work. It's too cold at night. The test plots at CoolPlanet are in southern California with year-round growing season, so biomass production can be very high, although irrigation would be required during the dry season, if the plantings are not on high water-table soils.

Since the original journal article is not available for free online, I have to go by this article. The key line is "Some 60-70% of the global increment of woody biomass would be needed to produce 20% of current global primary energy supply." I'm assuming this means that the 60-70% figure refers to annual growth, not existing total tree biomass, and that the 20% figure is for all energy, not just portable transportation fuels. However, biofuel development is primarily focused on portable transportation fuel, which would be a fraction of "global primary energy supply." Biofuel is not a major component of primary electricity production, where other sustainable technologies are more appropriate. The shift to shorter rotation harvest is already happening in the forestry industry, especially for non-saw lumber production. For pulp wood, which would be the appropriate analogue to biomass production, short rotation has become the norm. Research on hybrid poplar has shown the ability to produce equivalent total biomass at 20 year full tree harvest to old growth 70+ year trees. As a forest matures, most trees have to die, since available nutrients can only support a fixed total biomass, whether that be a large number of small plants, or a small number of large ones. Those trees that die, oxidize (rot) and release their stored carbon. Cellulose production, the primary feedstock for biofuels, is a low fertility demanding process for plants. Seed production from annual plants is what demands high fertility. Interplanting of nitrogen fixing alder bushes can provide sufficient fertility for short duration harvest cycles. The assumption that biomass harvest would require fossil fuel use is unwarranted. Harvest machinery can use biofuel. Also the assumption that future demand would be equivalent to present demand is unrealistic. Fossil fuel production will go down and efficiency must increase across the board, irrespective of biofuels.A corollary would be the belief in 1820 that steam power would never replace the sailing ship since a steam engine can't carry enough fuel to be viable. This was true for the inefficient single-conversion engine, but within a few years the development of the triple-conversion engine was so efficient it marked the death-knell of the age of sail. Linear transport should move to electrified rail, obviously. If automotive morphology were to keep pace with propulsion technology, the development of 100 mpg average fuel economy could become the new standard. If parallel plug-in hybrids were to become the norm, and two-thirds of miles driven were under stored electrical power, then the total need for portable transportation fuels, whether fossil or biofuel, would be a tiny fraction of the baseline scenario used for the study.

Let's decouple single-purpose travel, i.e. commuting, from general purpose. We presently use multi-purpose vehicles for both tasks. This has been made possible by inexpensive, energy-dense portable fuel. A BEV, at present stage of electricity storage development, does not fit in well with the multi-purpose vehicle paradigm, yet that is the vehicle morphology the industry has chosen, to date, resulting in high-cost, limited-range vehicles. If a BEV were designed as a single-purpose machine made to service the needs of commuting, it could be greatly simplified and reduced in size and cost. Since nearly 7/8ths of the time we drive alone, a narrow, three-wheel, enclosed, two-seat BEV "motorcycle" could fulfill the task of commuting and could be built at less than half the cost of a multi-purpose 5-seat car.

Alain, you hit the nail right on the head. This is what I have been hammering on in numerous postings. For 10,000 years we've used annual plants to produce food for us. In effect, they're small chemical factories synthesizing nutrients and concentrating them into a form we can use. However, annuals are essentially weeds, requiring soil disturbance and high fertility and maintenance. Perennials, on the other hand, are low disturbance/low fertility/low maintenance demanding plants. If we convert the sugars and proteins in their vegetative matter directly, without running it through an herbivore, we can increase food production per unit area while drastically reducing inputs: fertilizer, chemicals, fuel, water, tillage. University of Illinois Urbana-Champaign has field trials of miscanthus which produce four times as much biomass as grain corn with no tillage, fertilizer, or added water, while at the same time sequestering four tons of carbon per acre per year. Cellulose is a long-chain polymer of glucose, the form of sugar used by our bodies at the cellular level.

This push for high density habitation ignores the reality of human nature and our evolutionary history. If people actually wanted to live in such close proximity, they would do it. When given the opportunity and capability to spread out, they chose to do so. The fact that there is only one high density metro in the U.S., New York City, is an indication of the reality that we are tropical savanna animals, accustomed over thousands of years to life in small, widely dispersed family groups. That high density cities do exist at higher rates in other parts of the world is a function of poverty, high population, and lack of space.

This technology looks very promising, since it's able to convert both cellulose and hemicellulose and also uses lignin as part of the process. Lignin makes up about 25% of cellulosic biomass. Hybrid popple has received quite a lot of interest in Northern Minnesota. There are a number of plots around the region. Growing it is more similar to farming than traditional forestry. Commercially viable production can happen in as short as ten years. In traditional farm country, perennial grasses would be better. University of Illinois trials at Urbana-Champaign showed Miscanthus giganteus producing four times as much biomass as field corn without any fertilizer or irrigation input and at the same time sequestering four tons carbon per acre per year. Those who think that global warming will simply move the farming belt north are not taking into account soils. I'm a retired North Dakota farmer who produced native grass seed, much of which went to Canada for waterfowl dense nesting cover. Soil depth at my farm was 150 to 300 feet with 5 feet of A-Horizon (topsoil) and was mildly alkiline. At my land in Northern Minnesota in the Canadian Shield, soil depth is 30 feet, with a half-foot A-Horizon of acidic podsols. You can't easily move farming north simply because the growing season increases.

Lignin makes up about a fourth of the vegetative parts of plants, not just woody plants. It is the glue that binds the individual cells to each other. Lignin is a resin and could be the feedstock for a biochemical industry to replace petrochemicals. At a minimum, it works fine as boiler fuel.

This technology appears to have the potential for being applicable for on-farm use, thus obviating the need for transport of bulk materials to a distant processing center.

240 g/KwH in SAE units is 0.063 gal/hpH, putting this engine into diesel efficiency range, which is quite remarkable for such a small engine. And small is the operative word with dimensions of 19"H/16"L/13"W and a weight of 157 pounds as a genset. It would need water cooling, but the radiator would be tiny. An engine like this could be placed virtually anywhere, including under the floor, which is possible with its ability to be used horizontally. 30 KW (40 hp) is enough to maintain a compact car at constant highway speed with something left over for charging the batteries. When I had a scantool hooked to my Neon on a recent long trip, it showed 17 hp output at 65 mph on the flats and 30 hp climbing hills. In ordinary use, cars use a tiny fraction of their powerplant's full potential. As a retired farmer, I don't like the idea of systems without redundancy, which is what a pure BEV is. A small, get-home genset could keep our highways clear of stalled BEVs with dead batteries -- especially important during rush hours.

An addendum to the above on automotive morphology: If a shipping container is not placed on a trailer, but acts as its own "trailer," the overall height of the unit can be dropped by a meter, reducing frontal area significantly. Hydraulics can be used to raise the container to dock height. When not in use, the container is simply dropped on the ground, and all wheels and axles stay with the tractor. A system similar to this is used by some logging trucks hauling tree-length loads in northern Minnesota. The trailing axle is connected to the fifth wheel by a long tube, which collapses and rests on top of the fifth wheel when not hauling a load. When the tractor is dead-heading, there is no trailer on the road behind it.

Hub motors would allow for a complete rethinking of automotive morphology, especially for buses and trucks. It would allow for super efficient packaging, and, with trailing arm suspensions without transverse axles, low floor heights, lower height overall, and resultant reduced frontal area. For long distance transport, human and cargo, gensets could be more perfectly isolated from the passenger compartment. In a series hybrid system with variable power requirements being buffered through the battery pack while the genset runs at steady speed, the engine could be modeled after super-efficient marine style long-stroke, slow turning diesels, or OPOC HCCI. All wheels become drivers, making for excellent traction. If the standard semi-tractor rig is redesigned so that there is no trailer, per se, but a shipping container acting as its own trailer, grappled to the tractor's fifth wheel at the front, with a grappled on trailing axle assembly at the rear that always remains with the tractor, then hubmotors are only required by the tractor, while the trailer is an axle-less "dumb" unit.

Since the big agriculture shake-out in the mid 1980s, most farmers have switched over to the production methodology called Maximum Economic Yield (MEY), where the aim is not maximum production but maximum net return on investment. As a result of MEY, the practice of over-fertilizing a crop has declined dramatically. On-board farm machinery data monitoring and use of GIS has allowed farmers to control fertilizer use much more tightly than in the past. The aim is to apply only as much nitrogen as the plant uses over the growing season and leave minimum carry-over in the soil.

Re: "a shipping terminal is a very busy place and there's little time to spare for unloading the rear wheels from the back of the tractor unit" That's true. However, the whole process could be automated with hydraulics. Some years ago I rode on a logging truck hauling tree-length pulp wood. The "trailer," consisting of a long tube with the back axles attached, collapsed and folded up, the entire assembly resting on top of the fifth wheel when in transport position. The whole thing was handled with hydraulics. The driver did not have to get out of the cab. Something similar could be designed, automating the hook up process. Another advantage of such a system is the lower center of gravity. I once rolled a fully loaded grain truck when I backed one side into a big pot hole I couldn't see. It's no fun.

This technology shows just how critical the airflow under a vehicle is to its coefficient of drag. It's a good start. In the long term, what's needed is a complete rethink of the semi-tractor trailer. Except for bulk cargo, the shipping container has come to dominate long distance transport. A shipping container is a structural beam made to carry its own load. It does not require a trailer. If a semi tractor were to grapple on to the front of the container, with a trailing axle behind the container, the whole unit could be dropped by three feet, reducing frontal area by 25 square feet and also reducing the quantity of air flowing under the rig. Hydraulics could be used to raise the trailer to dock height. This would also reduce the number of moving parts requiring maintenance. The container would be left bare with its axles and wheels being "borrowed" from the tractor. In the next step, tractor locomotion could be shifted to a battery-buffered concept utilizing super-efficient, slow-turning, long stroke marine style diesels. Short-term high power demand would be handled by battery storage, with the diesel running continuously over a narrow power band. Drive would be by hub motors on all axles. Since the trailer's axles are provided by the tractor, this system would be workable without excessive increase in cost.

Attempting to reduce lignin content in plants is a big mistake. Lignin is what holds the plant together. With reduced lignin concentrations, a plant will have difficulty standing up, reducing growth and making harvest extremely difficult. Lignin should be recognized as a valuable product in itself and could be used as feedstock for a biochemical industry to replace petrochemicals.

Harvey D has a point. Non-subsistence farmers do not grow food in order to feed the world; farmers produce food and fiber as cash crops to generate an income to support their own families. In a capitalist system with private property rights they have the ability to choose for themselves what they want to grow. If farm production generates more net income as biofuel than as feed, then it would be the logical from the farmer's point of view to take that option. How many non-farmers would prefer a lower income option in their own lives? The main point I want to emphasize, however, is the need for a paradigm shift in agriculture: away from the pattern of the last 10,000 years in depending on annual plants and switching to perennial vegetative matter to produce feed, human and animal. This would reduce fertilizer and chemical requirements, reduce soil disturbance and resultant soil erosion, reduce on-farm capital investments and debt loads, while at the same time increasing production to meet the needs of an expanding human population. This Michigan State research has the significance of Norman Borlaug's Green Revolution. Borlaug is the single human being who has had the greatest effect on the daily lives of the greatest number of people in history. That's pretty significant.

As one of the few farmers who has actually grown switchgrass as a commercial crop, I've thought for a long time we need to be looking at ways to access cellulosic biomass directly. A field in perennial grass, like switchgrass, has very little soil erosion. In fact, quite the opposite happens. These perennial grasses build soil and sequester carbon by translocating nutrients into their below ground biomass, which far exceeds what is seen above ground. Instead of depending on annual plants, as we have done for the last 10,000 years, to act as miniature chemical factories synthesizing and concentrating nutrients in their seed heads or tubers, so that we can access those nutrients for ourselves and our animals, the better path would be to extract nutrients directly from the vegetative parts of plants, preferably from perennials. This is exactly what this research has accomplished. Let's not stop at processing leaf and stalk matter for animal feed. Let's find a way to do the same to create human feed. Then we'll be on the way to a huge paradigm shift in agriculture and get us away from soil disturbance and high fertility regimes that annual plant agriculture requires.

This technology would fit in well with what I call BBV, the Battery Buffered Vehicle. Some 15 years ago, I started seeing vehicle morphology as the greatest impediment to a paradigm shift in isotropic transportation. A big part of the problem was the need to size an engine for the needs of very infrequent, high power demanding events while operating the engine lightly loaded the majority of the time, resulting in lower efficiency. In my mind, a better solution would be to operate a small engine continuously, in its most efficient power band, buffering output through a battery pack to meet continuous low-duty power demand with short-duration high power spikes. Combine such a power source with hubmotors requiring no mechanical drivetrain, and the morphology of the vehicle can be changed to achieve highest usable interior space with the least exterior volume and mass. The genset could be placed anywhere, since it would be small and light; the battery pack, smaller than would be required by a pure BEV, can be enclosed in a torsion box floor forming part of the load bearing structure of the vehicle and reducing center of gravity. The result would be a vehicle offering more with less: higher efficiency at lower complexity and cost.

Re: "I think they have also shown that you can't convert a small conventional car into an EV and have any space left." This is exactly right. Switching to battery power will require a new automotive morphology, yet manufacturers keep recycling ICE based vehicle design. Perhaps they're afraid people want buy BEVs if they look radically different from what they're accustomed to. However, morphology is as important as batteries, if not more so, in switching to electric power. If the first generation of BEVs turn out to be duds, then the whole experiment will be set back a generation. I'm speaking in terms of the expectations of the general public, not enthusiasts.

Re: "...sub-optimal car performance during the extremely cold weather conditions in December 2009 and January 2010." My son spent 7 weeks in London during part of that winter. He said it was about like Minnesota autumn weather, but everybody was freaked out by the cold. If winter conditions that mild cause dissatisfaction in drivers of the Mini E, what will it be like in places that have real winter?

A topic that has not been sufficiently discussed is the impact of automotive morphology. We make excellent multi-purpose vehicles. What we don't make are single-purpose vehicles to satisfy 80% of private automotive useage: single occupant commuting. A narrow, two-seat, three-wheel commuter weighing under 1,000 pounds could achieve 100 mpg efficiency. Without the need for exotic technology, such a vehicle could be produced for half the cost of a standard sedan. In this post financial crash, Great Recession world, cost will be a major consideration for new vehicle purchase, more important than it was in the past. Americans won't switch to high efficiency vehicles if the cost is too high. Keep it under $10,000 and the transition will be fast. If it's over $30,000, the transition will slow to a crawl.

A modern economy cannot operate without transportation. Public transportation infrastructure has been the domain of government since the days of the Persian Royal Road 2,500 years ago. Afghanistan is a good example of a country with inadequate public transportation infrastructure. Professor of energetics Vaclav Smil has argued that diesel is the most important fuel in the world. Without it, the movement of goods stops. Petroleum based diesel will not always be with us, since it comes from a finite source that is running out. We need to plan for the future, and there is no way to do that without government input. I would hope that national freight transportation legislation focus closely on improving rail. Electricity is the easiest form of energy to produce sustainably, and rail can be completely electrified, unlike truck transport.