I just came across this article in Science that points out how so little of our public research dollars go towards basic plant (agricultural) research. They claim that 2% of federal spending on research R&D goes to agricultural research. I am reminded of the general public bias out there which I noticed beginning as a graduate student when I decided to work on plants rather than animals or fungi or microbes. I've also been told by several faculty that their postdocs do quite well in a plant-specific search, but usually lose out to equivalent job candidates who study animals. Once I gave a talk and one of the faculty members afterwards mentioned that hearing my talk was the first time he actually found anything having to do with plants interesting. I was obviously flattered, but also appalled that so many people are so uninterested in plants.
Hey! Where does your food come from?? Ultimately, the answer is almost always plants. Who gobbles up CO2 and spits out oxygen for us to breathe?? Uh, plants. Does anyone wear cotton or linen anymore? They also come from plants. And your house is also likely made with wood (plants). Yep, plants make it possible for us to survive and thrive.
I know we are pretty animal focused (being animals ourselves), but I hope we can develop a better appreciation and understanding of plants. I know everyone wants a cure for cancer, but I would argue that funding basic research in plant biology is also crucial for our survival and health.
A new focus on Plant Science by McCormick & Tijian
Science 19 November 2010: Vol. 330 no. 6007 p. 1021
DOI: 10.1126/science.1198153
http://www.sciencemag.org/content/330/6007/1021.full.pdf
Wednesday, December 15, 2010
Thursday, December 9, 2010
Re: biofuel crops as habitat?
Just ran across this article in a new pub, Global Change Biology (GBC) Bioenergy which looked at how perennial feedstocks impact animal biodiversity. Perennial biomass feedstocks enhance avian diversity by Robertson et al. 2010 (DOI: 10.1111/j.1757-1707.2010.01080.x). [Note: sorry I will try to find "open" articles, but this is tough!! Please let me know if you want me to send pdf]
The authors looked at bird (and bird food=bugs) diversity and abundance in 3 kinds of habitat:
1) corn monoculture
2) switchgrass plot
3) mixed-grass prairie
This included surveying 20 sites of each type above, but just in the upper mid-west (Michigan).
The clear expectation is that corn (annual plant) would support the lowest bird diversity (this has already been shown). We also already know that mixed-grass prairie, which is largely what the midwest once was before modern agriculture, supports very high bird diversity and abundance. The big question is, what would the perennial switchgrass plot (switchgrass is native to N. America and is one of the mixed prairie grasses) be like in terms of supporting bird diversity and habitat?
It turns out that there was a greater diversity of birds with a larger patch (plot) size for both switchgrass & prairie, but not for corn. Also, the perennials (not corn) supported more arthropods (mainly insects), a key component in many birds' diets. Even though there was greater bird diversity overall in the mixed prairie habitat, the switchgrass plot was also pretty good.
Overall, this suggests that at least for some locations and for one species of cellulosic feedstock (switchgrass)--growing perennial energy crops can be managed to maintain habitat for native grassland birds.
The authors looked at bird (and bird food=bugs) diversity and abundance in 3 kinds of habitat:
1) corn monoculture
2) switchgrass plot
3) mixed-grass prairie
This included surveying 20 sites of each type above, but just in the upper mid-west (Michigan).
The clear expectation is that corn (annual plant) would support the lowest bird diversity (this has already been shown). We also already know that mixed-grass prairie, which is largely what the midwest once was before modern agriculture, supports very high bird diversity and abundance. The big question is, what would the perennial switchgrass plot (switchgrass is native to N. America and is one of the mixed prairie grasses) be like in terms of supporting bird diversity and habitat?
It turns out that there was a greater diversity of birds with a larger patch (plot) size for both switchgrass & prairie, but not for corn. Also, the perennials (not corn) supported more arthropods (mainly insects), a key component in many birds' diets. Even though there was greater bird diversity overall in the mixed prairie habitat, the switchgrass plot was also pretty good.
Overall, this suggests that at least for some locations and for one species of cellulosic feedstock (switchgrass)--growing perennial energy crops can be managed to maintain habitat for native grassland birds.
Monday, November 29, 2010
snapshot of the cellulosic energy grasses
Whenever I mention what I work on, nobody has ever heard of Miscanthus. Of course I consider my friends, family, & acquaintances to be pretty well-informed smart people, so this seemed a bit surprising. This lack of awareness about the incredible potential of Miscanthus & other crops as biofuel crops has been a big reason why I started this blog.
In order to simplify and clarify, I decided to make a brief list & descriptor (in no particular order) of the major energy crops, focusing on the perennial grasses. There are also non-grass cellulosic energy crops (such as poplar, willow, Jatropha and Agave--see previous blog post), which I will not go into here. Disclaimer: this is hardly an exhaustive description of all of these grasses, just what I choose to include...
1) Miscanthus (known sometimes as Elephant grass or Amur silver grass, this includes mainly the sterile hybrid Miscanthus x giganteus, but also relatives such as M. sinensis, M. sacchariflorus, M. floridulus). Tropical to temperate. Native to Asia & Africa.
Advantages: No fertilizer (nitrogen) input required, low degree of invasiveness (hybrid M. x giganteus is sterile), cold-tolerant, highly productive (see photo above!!), a carbon neutral source of fuel when life-cycle is considered, lots of natural variation in M. sinensis & M. sacchariflorus, can grow on marginal lands
Disadvantages: high initial planting costs (must plant rhizomes rather than seeds, due to sterility), M.x giganteus plants typically grown are all cuttings from a single genetic clone (greater genetic variation is typically favored), fairly high water needs during growing season--limits use in arid western U.S.
2) Switchgrass (commonly known as panic grass, Panicum virgatum) Native to North America.
Advantages: cold-tolerant, fairly drought-tolerant, relatively low fertilizer inputs needed, a carbon neutral source of fuel when life-cycle is considered, highly diverse, can grow on marginal lands
Disadvantages: roughly half as productive as Miscanthus in most climates, relatively high water needs during warm growing season (spring/summer) which limits use in much of the western U.S.
3) Maize (corn). Native to North America. Annual rather than perennial.
Advantages: well-established as an ethanol crop when using seeds, annual crops have some benefits, can use the stover (leaf tissue) as a byproduct of seed production for cellulosic ethanol production
Disadvantages: very high fertilizer and water input needs--leading to high carbon costs, not as prolific as dedicated cellulosic perennial grasses, growth for ethanol production competes with growth for food
4) Sugarcane (many species of Sachharum) Tropical to warm temperate climates, Native to South Asia. Brazil is the largest grower of sugarcane, where they generate ethanol as a by-product of sugar production. Brazil is self-sufficient in terms of fuel production due to this investment in sugarcane-based ethanol.
Advantages: high sugar content--sugar is directly fermented into ethanol,
Disadvantages: very water intensive, grows in tropical (warm) climates only thereby limiting its growth in the primarily temperate U.S., not typically grown for cellulosic biofuel production
5) Energy cane (sugarcane hybrids produced to make low sugar varieties).
Advantages: hybrids (crop behind person in above photo) often have increased vigour and are highly prolific, the energy cane varieties are bred to be more cold-tolerant than sugarcane which increases the growing range in the U.S., can potentially convert to ethanol in the same way as other cellulosic biofuel crops, can be more productive than sugarcane (producing more ethanol per unit of land)
Disadvantages: unless a "no sugar" variety is developed, separate conversions to ethanol are necessary (e.g., different process to convert sugar to ethanol vs. converting cellulose to ethanol), relatively high water needs, initial planting costs are high/intensive (established from cuttings rather than seeds), not cold-tolerant
6) Sweet sorghum (many varieties of Sorghum with high sugar content). Native to tropical and sub-tropical regions on all continents (except Antarctica)
Advantages: fairly high yield, relatively drought tolerant, direct conversion to ethanol from sugar (not typically cellulose)
Disadvantages: grown primarily for sugar conversion directly to ethanol rather than as a cellulosic form of ethanol production...but could be used for both (like energy cane), annual rather than perennial, high fertilizer needs, susceptible to pests, not cold tolerant
7) Native prairie (many species, primarily Switchgrass [Panicum virgatum], Indiangrass [Sorghastrum nutans], Eastern Gamagrass (Tripsacum dactyloides), Big Bluestem (Andropogon gerardii), Little Bluestem (Schizachyrium scoparium), and others)
Advantages: high biodiversity, excellent habitat for wildlife, renewable, requires no fertilizer or irrigation
Disadvantages: generates only a fraction of the productivity compared with dedicated energy crops
In order to simplify and clarify, I decided to make a brief list & descriptor (in no particular order) of the major energy crops, focusing on the perennial grasses. There are also non-grass cellulosic energy crops (such as poplar, willow, Jatropha and Agave--see previous blog post), which I will not go into here. Disclaimer: this is hardly an exhaustive description of all of these grasses, just what I choose to include...
1) Miscanthus (known sometimes as Elephant grass or Amur silver grass, this includes mainly the sterile hybrid Miscanthus x giganteus, but also relatives such as M. sinensis, M. sacchariflorus, M. floridulus). Tropical to temperate. Native to Asia & Africa.
Advantages: No fertilizer (nitrogen) input required, low degree of invasiveness (hybrid M. x giganteus is sterile), cold-tolerant, highly productive (see photo above!!), a carbon neutral source of fuel when life-cycle is considered, lots of natural variation in M. sinensis & M. sacchariflorus, can grow on marginal lands
Disadvantages: high initial planting costs (must plant rhizomes rather than seeds, due to sterility), M.x giganteus plants typically grown are all cuttings from a single genetic clone (greater genetic variation is typically favored), fairly high water needs during growing season--limits use in arid western U.S.
2) Switchgrass (commonly known as panic grass, Panicum virgatum) Native to North America.
Advantages: cold-tolerant, fairly drought-tolerant, relatively low fertilizer inputs needed, a carbon neutral source of fuel when life-cycle is considered, highly diverse, can grow on marginal landsDisadvantages: roughly half as productive as Miscanthus in most climates, relatively high water needs during warm growing season (spring/summer) which limits use in much of the western U.S.
3) Maize (corn). Native to North America. Annual rather than perennial.
Advantages: well-established as an ethanol crop when using seeds, annual crops have some benefits, can use the stover (leaf tissue) as a byproduct of seed production for cellulosic ethanol productionDisadvantages: very high fertilizer and water input needs--leading to high carbon costs, not as prolific as dedicated cellulosic perennial grasses, growth for ethanol production competes with growth for food
4) Sugarcane (many species of Sachharum) Tropical to warm temperate climates, Native to South Asia. Brazil is the largest grower of sugarcane, where they generate ethanol as a by-product of sugar production. Brazil is self-sufficient in terms of fuel production due to this investment in sugarcane-based ethanol.
Advantages: high sugar content--sugar is directly fermented into ethanol,Disadvantages: very water intensive, grows in tropical (warm) climates only thereby limiting its growth in the primarily temperate U.S., not typically grown for cellulosic biofuel production
5) Energy cane (sugarcane hybrids produced to make low sugar varieties).
Advantages: hybrids (crop behind person in above photo) often have increased vigour and are highly prolific, the energy cane varieties are bred to be more cold-tolerant than sugarcane which increases the growing range in the U.S., can potentially convert to ethanol in the same way as other cellulosic biofuel crops, can be more productive than sugarcane (producing more ethanol per unit of land)Disadvantages: unless a "no sugar" variety is developed, separate conversions to ethanol are necessary (e.g., different process to convert sugar to ethanol vs. converting cellulose to ethanol), relatively high water needs, initial planting costs are high/intensive (established from cuttings rather than seeds), not cold-tolerant
6) Sweet sorghum (many varieties of Sorghum with high sugar content). Native to tropical and sub-tropical regions on all continents (except Antarctica)
Advantages: fairly high yield, relatively drought tolerant, direct conversion to ethanol from sugar (not typically cellulose)Disadvantages: grown primarily for sugar conversion directly to ethanol rather than as a cellulosic form of ethanol production...but could be used for both (like energy cane), annual rather than perennial, high fertilizer needs, susceptible to pests, not cold tolerant
7) Native prairie (many species, primarily Switchgrass [Panicum virgatum], Indiangrass [Sorghastrum nutans], Eastern Gamagrass (Tripsacum dactyloides), Big Bluestem (Andropogon gerardii), Little Bluestem (Schizachyrium scoparium), and others)
Advantages: high biodiversity, excellent habitat for wildlife, renewable, requires no fertilizer or irrigationDisadvantages: generates only a fraction of the productivity compared with dedicated energy crops
Thursday, November 11, 2010
life-cycle analysis of greenhouse gas emissions
We already know that most of our energy comes from fossil fuels AND fossil fuels spew tons of greenhouse gases (GHG) that contribute to global warming, but are biofuels actually much better?? The answer is...it depends.
Energy analysts and economists are now looking at the entire life-cycle of producing fuels (which includes extraction of fuel, or planting to processing, transport, and the burning of fuels as emissions). Gasoline is usually used as the reference, and ideally, other forms of fuels emit LESS greenhouse gases than gasoline when the entire life cycle is taken into account.
In this 2009 life-cycle analysis of different types of fuels (http://www.pnas.org/content/106/6/2077.full), Hill et al. found that corn based ethanol produced as much or even more greenhouse gas emissions (including CO2, N2O, and CH4), than gasoline, a surprising result at first. But the GHG emissions differed in production of cor
n ethanol depending on the source of heat at the biorefinery (whether it was fueled by natural gas, coal, or corn stover--the left-over "leaf" part of a corn plant after the fruits are harvested).
As a bright point, cellulosic ethanol has significantly reduced levels of GHG emissions relative to either corn ethanol or gasoline, when the life-cycle of the fuel production is accounted for. Of note, however, is that the data used to estimate emissions for cellulosic biofuels is relatively limited as this form of ethanol production has not been done to scale.
Costs of GHG (A) and particulate matter: PM2.5 (B) emissions. Per liter and per gallon estimates are shown alongside total costs arising from production of an additional billion gallons of ethanol or an energy-equivalent volume of gasoline. (C) Combined costs of GHG and PM2.5. From PNAS article by Hill et al. 2009. http://www.pnas.org/content/106/6/2077.full
Why is corn-based ethanol not an improvement over gasoline with respect to fossil fuel emissions? The answer is that corn is a fairly intensive crop, it needs a lot of nitrogen fertilizers , and has higher fossil fuel input, all of which contribute to increased GHG emissions. Cellulosic ethanol production is better, when the life-cycle is accounted for, because it requires little to no fertilizer and lignin combustion from the cellulosic crops provides excess heat and power at the biorefinery, which displaces fossil fuel and electricity consumption.
While cellulosic biofuels are a large improvement over conventional forms of corn-ethanol and gasoline in terms of GHG emissions, there is rarely such thing as a golden ticket. That is, there are trade-offs to GHG reductions in terms of other forms of air pollution. From studies (http://dancingflames.org/dancingflames/EnvSci/Articles/EnvScipdffiles/EthanolPublicHealth.pdf, http://www.afdc.energy.gov/afdc/pdfs/technical_paper_feb09.pdf) looking at E85 blend fuels (85% ethanol blended with 15% gasoline) compared to straight gasoline, emissions are reduced for several greenhouse gases, but emissions INCREASE for other pollutants (such as ethanol, formaldehyde, and acetaldehyde). Both formaldehyde and acetaldehyde are nasty carcinogens, as classified by the U.S. EPA. Unburned ethanol can also oxidize to acetaledehyde, so these air pollutants (while not classified as greenhouse gases) have potential human health risks.
Like most things, there is no simple single solution. And it would be good to see ways to reduce both GHG emissions AND other forms of air pollution if we want to move forward with renewable fuel sources. Sorry, but the grass is not always cleaner.
Energy analysts and economists are now looking at the entire life-cycle of producing fuels (which includes extraction of fuel, or planting to processing, transport, and the burning of fuels as emissions). Gasoline is usually used as the reference, and ideally, other forms of fuels emit LESS greenhouse gases than gasoline when the entire life cycle is taken into account.
In this 2009 life-cycle analysis of different types of fuels (http://www.pnas.org/content/106/6/2077.full), Hill et al. found that corn based ethanol produced as much or even more greenhouse gas emissions (including CO2, N2O, and CH4), than gasoline, a surprising result at first. But the GHG emissions differed in production of cor
n ethanol depending on the source of heat at the biorefinery (whether it was fueled by natural gas, coal, or corn stover--the left-over "leaf" part of a corn plant after the fruits are harvested).As a bright point, cellulosic ethanol has significantly reduced levels of GHG emissions relative to either corn ethanol or gasoline, when the life-cycle of the fuel production is accounted for. Of note, however, is that the data used to estimate emissions for cellulosic biofuels is relatively limited as this form of ethanol production has not been done to scale.
Costs of GHG (A) and particulate matter: PM2.5 (B) emissions. Per liter and per gallon estimates are shown alongside total costs arising from production of an additional billion gallons of ethanol or an energy-equivalent volume of gasoline. (C) Combined costs of GHG and PM2.5. From PNAS article by Hill et al. 2009. http://www.pnas.org/content/106/6/2077.full
Why is corn-based ethanol not an improvement over gasoline with respect to fossil fuel emissions? The answer is that corn is a fairly intensive crop, it needs a lot of nitrogen fertilizers , and has higher fossil fuel input, all of which contribute to increased GHG emissions. Cellulosic ethanol production is better, when the life-cycle is accounted for, because it requires little to no fertilizer and lignin combustion from the cellulosic crops provides excess heat and power at the biorefinery, which displaces fossil fuel and electricity consumption.
While cellulosic biofuels are a large improvement over conventional forms of corn-ethanol and gasoline in terms of GHG emissions, there is rarely such thing as a golden ticket. That is, there are trade-offs to GHG reductions in terms of other forms of air pollution. From studies (http://dancingflames.org/dancingflames/EnvSci/Articles/EnvScipdffiles/EthanolPublicHealth.pdf, http://www.afdc.energy.gov/afdc/pdfs/technical_paper_feb09.pdf) looking at E85 blend fuels (85% ethanol blended with 15% gasoline) compared to straight gasoline, emissions are reduced for several greenhouse gases, but emissions INCREASE for other pollutants (such as ethanol, formaldehyde, and acetaldehyde). Both formaldehyde and acetaldehyde are nasty carcinogens, as classified by the U.S. EPA. Unburned ethanol can also oxidize to acetaledehyde, so these air pollutants (while not classified as greenhouse gases) have potential human health risks.
Like most things, there is no simple single solution. And it would be good to see ways to reduce both GHG emissions AND other forms of air pollution if we want to move forward with renewable fuel sources. Sorry, but the grass is not always cleaner.
Monday, November 1, 2010
Carbon-free energy
Globally, 87% of our energy comes from fossil fuels. These are dense sources of energy (see previous post on why oil tastes so good) & oil transports and stores well...but what about greenhouse gas emissions? Reams of evidence have demonstrated that greenhouse gases, such as CO2 (carbon dioxide), in excess, contribute to the overall warming of our planet. And fossil fuels produce A LOT of CO2. Another problem with fossil fuels is that they are a finite resource. Some estimates say that only ~100 years of oil resources remain (Source: World Energy Assessment 2000 & 2004/UNDP ). http://www.undp.org/energy/activities/wea/drafts-frame.html
Renewable energy sources (such as solar, wind, biomass, and geothermal), on the other hand, have very low CO2 output per kilowatt-hour of energy produced (See figure at http://www.sciencemag.org/cgi/reprint/329/5993/786.pdf). But given the amount of energy we currently use, is there enough renewable energy to meet this demand? The single largest potential comes from solar energy, where the total amount of solar energy available on earth's surface is several orders of magnitude greater than what we currently use, as a planet. And there is a good chance we could capture enough of that to generate the amount of power the world now consumes. One of the current challenges with solar, however, is energy storage. Sunlight does not shine in one solar panel 24/7, and we need more inexpensive, more efficient ways to store this energy when it is not being generated. There are many great leads to building better batteries out there..but I am not an engineer and will pass on further comment for now.
Biomass can be thought of as another source of solar energy, as plants convert sunlight into energy that is stored in the plant as sugar (via photosynthesis). Even though plant growth is seasonal, with an abundance of plant material (feedstock) at the end of the summer growing season, the leaves can be harvested and stored until energy is needed. A disadvantage of biomass, however, is that is requires resources such as water and land.
While there is much promise in renewables replacing fossil fuels, most experts agree that the best future outcome will include a number of different renewable energy sources and technologies.
Renewable energy sources (such as solar, wind, biomass, and geothermal), on the other hand, have very low CO2 output per kilowatt-hour of energy produced (See figure at http://www.sciencemag.org/cgi/reprint/329/5993/786.pdf). But given the amount of energy we currently use, is there enough renewable energy to meet this demand? The single largest potential comes from solar energy, where the total amount of solar energy available on earth's surface is several orders of magnitude greater than what we currently use, as a planet. And there is a good chance we could capture enough of that to generate the amount of power the world now consumes. One of the current challenges with solar, however, is energy storage. Sunlight does not shine in one solar panel 24/7, and we need more inexpensive, more efficient ways to store this energy when it is not being generated. There are many great leads to building better batteries out there..but I am not an engineer and will pass on further comment for now.
Biomass can be thought of as another source of solar energy, as plants convert sunlight into energy that is stored in the plant as sugar (via photosynthesis). Even though plant growth is seasonal, with an abundance of plant material (feedstock) at the end of the summer growing season, the leaves can be harvested and stored until energy is needed. A disadvantage of biomass, however, is that is requires resources such as water and land.
While there is much promise in renewables replacing fossil fuels, most experts agree that the best future outcome will include a number of different renewable energy sources and technologies.
Monday, October 25, 2010
Bioenergy crops in the desert??
There is some concern that bioenergy crops are more trouble than they're worth. They may produce a lot of biomass, but doesn't that come at a cost of lots of added fertilizer and water? Are fertile, midwestern climates the only suitable locations for growing crops, for food or fuel? For some plants, that may be true. But different plants are well-adapted to arid & semi-arid landscapes.
One group of plants with a fairly long history of cultivation includes various Agave species. Agave plants are succulents with a special type of photosynthesis (a process plants use to convert sunlight into energy) called CAM (Crassulacean acid metabolism) that increases water-use efficiency relative to most other plants. Traditionally, Agave varieties have many different uses: they have been used for production of fibers like sisal, for honey/sugar substitutes (agave nectar), and the flowers and stalks are edible. The most well-known use for agave is the fermentation & distillation of the sap to make mezcal, one type of which is tequila.
In addition to these uses, the leaves are also good sources of biomass that can be used as feedstock for conversion into biofuels. Although Agave farms may not produce as much biomass (in terms of tons per hectare) as Miscanthus or Sugarcane (see table below), Agave plants can be productive with as little as 12% of the water needed by these large grasses.
Table: Estimated productivity, rainfall, and nitrogen requirements of current or potential bioenergy crops (see article by Somerville et al. 2010. Science 329:790-792 for references).
| Crop | Average productivity (MT ha–1 year–1) | Ethanol yield (liter ha–1) | Seasonal water requirements (cm year–1) | Tolerance to drought | Nitrogen requirements (kg ha–1 year–1) |
| Corn | 3800 (total) | 50–80 | low | 90–120 | |
| Grain | 7 | 2900 | |||
| Stover | 3 | 900 | |||
| Sugarcane | 80 (wet) | 9950 (total) | 150–250 | moderate | 0–100 |
| Sugar | 11 | 6900 | |||
| Bagasse | 10 | 3000 | |||
| Miscanthus | 15–40 | 4600–12,400 | 75–120 | low | 0–15 |
| Poplar | 5–11 | 1500–3400 | 70–105 | moderate | 0–50 |
| Agave spp. | 10–34 | 3000–10,500 | 30–80 | high | 0–12 |
There is a lot of interest in producing energy sustainably in this country. Water is a particularly valuable resource, particularly in the western U.S. Using excessive irrigation or groundwater to grow crops in arid regions is not a responsible use of this resource. However, many plants, such as Agave, are naturally adapted to climates that experience little and/or erratic rainfall. By planting and harvesting climatically-appropriate energy crops, even the more extreme regions of this diverse country could become good producers of bioenergy.
Monday, October 18, 2010
Re: funding innovation
I recently attended the Philomathia Foundation Symposium at Berkeley on "Pathways to a Sustainable Energy Future," which had a number of amazing speakers. I was particularly impressed with Arun Majumdar, the director of ARPA-E (Advanced Research Projects Agency-Energy, sponsored by the Dept. of Energy. ARPA-E's mission is explicitly bold: to fund potentially revolutionary technologies that are too risky for industry to fund. Another mission is to re-assert the United States' technological leadership.
I naively assumed that the U.S. is already at the top of their game technologically, but Majumdar pointed out that the majority of the leading "green" energy companies (solar companies, electric car manufacturers, advanced rechargeable battery manufacturers) are foreign. This may be because, as Manumdar says, "The U.S. spends more on potato chips than on Energy R&D." It seems we are addicted to what is bad for us (see previous post on oil addiction). I agree that we should rediscover some national pride in ingenuity and technology and re-assert our technological leadership. Promising research results can have a high impact commercially, ideally in the form of smart, socially and environmentally responsible capitalism (a source for another blog post: the academic-industry partnership).
Even though it is probably not enough, I am really excited by the government's commitment to fund these "big ideas." Although it's considered risky, I think we live too much in a society that is scared to take risks, scared to innovate, because of the chance of failure. Sure, most of these ventures won't pan out, but even if just a single innovative, pie-in-the-sky idea works, it could make today's technology obsolete.
I naively assumed that the U.S. is already at the top of their game technologically, but Majumdar pointed out that the majority of the leading "green" energy companies (solar companies, electric car manufacturers, advanced rechargeable battery manufacturers) are foreign. This may be because, as Manumdar says, "The U.S. spends more on potato chips than on Energy R&D." It seems we are addicted to what is bad for us (see previous post on oil addiction). I agree that we should rediscover some national pride in ingenuity and technology and re-assert our technological leadership. Promising research results can have a high impact commercially, ideally in the form of smart, socially and environmentally responsible capitalism (a source for another blog post: the academic-industry partnership).
Even though it is probably not enough, I am really excited by the government's commitment to fund these "big ideas." Although it's considered risky, I think we live too much in a society that is scared to take risks, scared to innovate, because of the chance of failure. Sure, most of these ventures won't pan out, but even if just a single innovative, pie-in-the-sky idea works, it could make today's technology obsolete.
Monday, October 11, 2010
Coping with the "blend wall"
Part of the problem with biofuels gaining any momentum in our current car-driven, fossil fuel based economy is that our engines are built to run on gasoline..which can be blended with 10% ethanol. If the U.S. uses ~140 billion gallons of gasoline a year, then the demand for ethanol is about 14 billion gallons annually. Apparently we already produce about 12 billion gallons of corn ethanol per year (with even more capacity in idled biorefineries)...so we have basically reached what is referred to as the "blend wall," with no market for cellulosic ethanol.
How to cope with this dilemma?
One option would be to replace all corn-based ethanol plants with cellulosic biofuel pruduction plants, which would be an expensive, short-term fix, essentially tearing down something fully functional. And the "blend wall" problem would remain, with a maximum market of 14 billion gallons.
Another option is to increase the required amount of ethanol in blended fuels to 12% or 15%, something the EPA is considering. This is the most likely scenario, as it's technically and politically safest. But truthfully, this option will not do a whole lot to encourage use of biofuels in the long-term. I think of this option as a baby step, not covering much ground, but better than nothing.
A third, bolder option would be to make the leap to flex-fuel car engines, such as those that run on E85 ethanol (a fuel blend of 85% ethanol & 15% gasoline). Most of the cars in Brazil are built to run using some level of blended fuel, up to 100% ethanol. Since Brazil generates all of their own ethanol from sugarcane refineries, they have attractively achieved energy security (a topic for a future blog). Estimates of the cost of producing all future car engines to be flex-fuel lays around $100/car. If the average cost per new car in 2009 sold in the U.S. (according to the National Automobile Dealers Association) is $28,400, this minor change would amount to less than 1% of the value of the car. Although flex fuel contains its own controversies, it seems like a bold alternative way forward that would encourage both greater energy security and economic stability for the cellulosic biofuels market.
How to cope with this dilemma?
One option would be to replace all corn-based ethanol plants with cellulosic biofuel pruduction plants, which would be an expensive, short-term fix, essentially tearing down something fully functional. And the "blend wall" problem would remain, with a maximum market of 14 billion gallons.
Another option is to increase the required amount of ethanol in blended fuels to 12% or 15%, something the EPA is considering. This is the most likely scenario, as it's technically and politically safest. But truthfully, this option will not do a whole lot to encourage use of biofuels in the long-term. I think of this option as a baby step, not covering much ground, but better than nothing.
A third, bolder option would be to make the leap to flex-fuel car engines, such as those that run on E85 ethanol (a fuel blend of 85% ethanol & 15% gasoline). Most of the cars in Brazil are built to run using some level of blended fuel, up to 100% ethanol. Since Brazil generates all of their own ethanol from sugarcane refineries, they have attractively achieved energy security (a topic for a future blog). Estimates of the cost of producing all future car engines to be flex-fuel lays around $100/car. If the average cost per new car in 2009 sold in the U.S. (according to the National Automobile Dealers Association) is $28,400, this minor change would amount to less than 1% of the value of the car. Although flex fuel contains its own controversies, it seems like a bold alternative way forward that would encourage both greater energy security and economic stability for the cellulosic biofuels market.
Monday, October 4, 2010
Power density--why oil tastes so good..
As Americans, we are addicted to things that are bad for us. French fries, hot dogs, chips, sodas & cookies. All these foods contain loads of sugar & fat--essentially rich sources of energy for our bodies. The trouble is, we really don't need these rich sources of energy or "nutrients" in excess. One cheeseburger probably takes care of all of our daily caloric needs.
Same is true for oil. It is densely packed with energy. Nothing (other than coal and other petroleum products) comes even close to oil in terms of power density (the amount of energy produced per square meter of Earth's surface). Solar and wind facilities provide 1-2 orders of magnitude less power per square meter than oil, and biomass plants (based on corn ethanol) are even less dense...providing 1% (or less) of the energy per area compared to oil--see figure below from article in Science 329:780 (2010).
Source of data in figure: upper left and bottom--DOE; upper right--V. Smil, Energy Transitions, Praeger (2010)
Yikes! That's sobering news & tough to compete with. To soften the blow somewhat, it is worth pointing out that the full cost of energy should also include the cost of extraction, transport, storage, AND environmental risks (including CO2 output)...which is where renewables have the potential to come out ahead.
Can we learn anything from our unhealthy food addiction that can be applied to our unhealthy oil addiction? A good start is educating people on the scope of the problem, benefits & disadvantages to different forms of energy. But the truth is, most people do not want to change their lifestyles. An oft cited poll by The New York Times/CBS News (released 20 June 2010) found that although 90% of respondents agreed that "U.S. energy policy either needs fundamental changes or to be completely rebuilt," only 49% supported new taxes on gasoline to fund new and renewable energy. Seems to me that we should stop subsidizing oil and instead subsidize renewables, AND impose Greenhouse Gas taxes (on energy companies!!) that penalize for catastrophic environmental risks (such as drilling for oil) and emitting CO2 at any phase of the production. That might help level the playing field.
Same is true for oil. It is densely packed with energy. Nothing (other than coal and other petroleum products) comes even close to oil in terms of power density (the amount of energy produced per square meter of Earth's surface). Solar and wind facilities provide 1-2 orders of magnitude less power per square meter than oil, and biomass plants (based on corn ethanol) are even less dense...providing 1% (or less) of the energy per area compared to oil--see figure below from article in Science 329:780 (2010).
Source of data in figure: upper left and bottom--DOE; upper right--V. Smil, Energy Transitions, Praeger (2010)Yikes! That's sobering news & tough to compete with. To soften the blow somewhat, it is worth pointing out that the full cost of energy should also include the cost of extraction, transport, storage, AND environmental risks (including CO2 output)...which is where renewables have the potential to come out ahead.
Can we learn anything from our unhealthy food addiction that can be applied to our unhealthy oil addiction? A good start is educating people on the scope of the problem, benefits & disadvantages to different forms of energy. But the truth is, most people do not want to change their lifestyles. An oft cited poll by The New York Times/CBS News (released 20 June 2010) found that although 90% of respondents agreed that "U.S. energy policy either needs fundamental changes or to be completely rebuilt," only 49% supported new taxes on gasoline to fund new and renewable energy. Seems to me that we should stop subsidizing oil and instead subsidize renewables, AND impose Greenhouse Gas taxes (on energy companies!!) that penalize for catastrophic environmental risks (such as drilling for oil) and emitting CO2 at any phase of the production. That might help level the playing field.
Monday, September 27, 2010
Re: diversity mapping & clean energy
We live in an incredibly diverse country, in more ways than one. What I'm talking about, of course, is energy diversity.
I've been seeing lots of maps of the US, where the "potential" for various forms of clean energy forms are broken down by regions (county/zip codes/states). Obviously, regions like the desert SW are ideal for solar energy, while off-shore coastal breezes have high potential for producing wind energy, etc...
There is a cool interactive map tool in the NRDC website:
NRDC: Renewable Energy for America
where you can look up existing and planned sites for energy facilities, based on estimated "potential" for various energy forms (such as solar, wind, biomass).
Not surprisingly, the map for advanced biofuels is based on old data, old technology from first generation biofuels, and mainly includes crop residues (from corn, mostly, but also wheat, soybean, cotton, barley, and others). Not sure I would all that "advanced" biofuels..but I guess this is the best data we have until larger, more prolific grasses are grown to scale.
In truth, when I think about our country's potential for energy security, production of clean energy, and planning responsibly for our future, I find such maps hopeful. Speaking as someone with a background in ecology, I also think that we must embrace a diversity of solutions. There is rarely a single right answer to today's complex challenges. However, we are fortunate enough to live in an incredibly rich & diverse country--let's realize our potential and start producing cleaner forms of energy.
I've been seeing lots of maps of the US, where the "potential" for various forms of clean energy forms are broken down by regions (county/zip codes/states). Obviously, regions like the desert SW are ideal for solar energy, while off-shore coastal breezes have high potential for producing wind energy, etc...
There is a cool interactive map tool in the NRDC website:
NRDC: Renewable Energy for America
where you can look up existing and planned sites for energy facilities, based on estimated "potential" for various energy forms (such as solar, wind, biomass).
Not surprisingly, the map for advanced biofuels is based on old data, old technology from first generation biofuels, and mainly includes crop residues (from corn, mostly, but also wheat, soybean, cotton, barley, and others). Not sure I would all that "advanced" biofuels..but I guess this is the best data we have until larger, more prolific grasses are grown to scale.
In truth, when I think about our country's potential for energy security, production of clean energy, and planning responsibly for our future, I find such maps hopeful. Speaking as someone with a background in ecology, I also think that we must embrace a diversity of solutions. There is rarely a single right answer to today's complex challenges. However, we are fortunate enough to live in an incredibly rich & diverse country--let's realize our potential and start producing cleaner forms of energy.
Monday, August 2, 2010
Genome-schmenome
How is genomics helpful in the real world? I mean, really, what good does it do to anyone to know a bunch of strings of 4 letters (ie; ATGGTACCATG)?
Understanding how individual genes affect a particular trait (such as height or likelihood of developing heart disease) turns out to be very complex. Not only are many genes likely to be involved with any one trait, but they interact with each other AND with their environments. This makes predictions of functionality quite difficult.
Genomics is complex stuff, but it can still be incredibly informative. There are many useful applications of genomics to real-world problems.
One example includes criminology. Each individual has unique DNA (slightly different string of bases), though relatives will have more similar DNA than 2 random strangers. If there is DNA evidence from the scene of a crime that matches individual A, this provides fairly clear evidence that individual A was at least in the room (assuming that no laboratory experiments or mix-ups were made).
Another very different example of the utility of genomics, often employed in agriculture, is called "marker assisted selection" or "marker assisted breeding." In early agricultural history, humans would take the offspring from the "best" producers, such as those corn plants that made the largest, sweetest kernals or those goats that produced the most milk. Over many generations, this form of selection produced evolutionarily distinct products that suited the farmers. An example of this is the evolution of a branchy, small-seeded grain called teosinte into what is now known as modern maize (corn) which produces seeds over 100 times the size and weight of the teosinte ancestor's seeds.
This breeding strategy has been effective, but also has caveats. One is that it typically takes decades to produce a desirable final product, depending on the generation time. Another is that different traits may be preferred in different climates or by different farmers. Still another problem is that breeding for certain favored traits may cause other detrimental consequences at other particular traits.
Along comes genomics. Genomic data provides a unique blueprint of DNA code for all varieties of any organism one chooses to sequence. Statistical methods can link traits (such as big seeds) and particular genomic sequences. If we identify the genes or genetic regions associated with a desired phenotype, it is possible to then use this information for breeding desired traits. Seeds or seedlings can be "genotyped" (identified with genetic markers already shown to be linked to the trait of interest) and chosen for growing. For perennial plants or trees, this eliminates many years of the breeding process, since plants no longer have to be grown to maturity to assess their desirability. In addition, one can simultaneously select for many different traits in an individual or avoid undesirable side-effects, such as reduced fertility (as long as these traits were previously measured and linked to unique genetic markers).
Another bonus revealed by genomics is that organisms often find more than one way to make a particular trait. Imagine you have 100 corn plants with large seeds. Genomic information from each of these individuals reveals that there are 4-5 unique genetic signatures to "large seed" phenotypes. This information enables modern plant breeders to select for the desired trait in multiple ways, encouraging greater genetic diversity of desired cultivars.
Understanding how individual genes affect a particular trait (such as height or likelihood of developing heart disease) turns out to be very complex. Not only are many genes likely to be involved with any one trait, but they interact with each other AND with their environments. This makes predictions of functionality quite difficult.
Genomics is complex stuff, but it can still be incredibly informative. There are many useful applications of genomics to real-world problems.
One example includes criminology. Each individual has unique DNA (slightly different string of bases), though relatives will have more similar DNA than 2 random strangers. If there is DNA evidence from the scene of a crime that matches individual A, this provides fairly clear evidence that individual A was at least in the room (assuming that no laboratory experiments or mix-ups were made).
Another very different example of the utility of genomics, often employed in agriculture, is called "marker assisted selection" or "marker assisted breeding." In early agricultural history, humans would take the offspring from the "best" producers, such as those corn plants that made the largest, sweetest kernals or those goats that produced the most milk. Over many generations, this form of selection produced evolutionarily distinct products that suited the farmers. An example of this is the evolution of a branchy, small-seeded grain called teosinte into what is now known as modern maize (corn) which produces seeds over 100 times the size and weight of the teosinte ancestor's seeds.
This breeding strategy has been effective, but also has caveats. One is that it typically takes decades to produce a desirable final product, depending on the generation time. Another is that different traits may be preferred in different climates or by different farmers. Still another problem is that breeding for certain favored traits may cause other detrimental consequences at other particular traits.
Along comes genomics. Genomic data provides a unique blueprint of DNA code for all varieties of any organism one chooses to sequence. Statistical methods can link traits (such as big seeds) and particular genomic sequences. If we identify the genes or genetic regions associated with a desired phenotype, it is possible to then use this information for breeding desired traits. Seeds or seedlings can be "genotyped" (identified with genetic markers already shown to be linked to the trait of interest) and chosen for growing. For perennial plants or trees, this eliminates many years of the breeding process, since plants no longer have to be grown to maturity to assess their desirability. In addition, one can simultaneously select for many different traits in an individual or avoid undesirable side-effects, such as reduced fertility (as long as these traits were previously measured and linked to unique genetic markers).
Another bonus revealed by genomics is that organisms often find more than one way to make a particular trait. Imagine you have 100 corn plants with large seeds. Genomic information from each of these individuals reveals that there are 4-5 unique genetic signatures to "large seed" phenotypes. This information enables modern plant breeders to select for the desired trait in multiple ways, encouraging greater genetic diversity of desired cultivars.
Monday, July 26, 2010
Grass is greener
With all of the available information out there and the interest in global climate change and clean energy technology, why is it that so few people have heard of cellulosic biofuels? Perhaps because most people don’t know the meaning of “cellulosic” or “biofuels”? And what does “clean” really mean?
OK, so here are my own personal definitions of these terms:
1) Clean energy-a form of energy that is produced with net carbon output of zero, near-zero, or negative (meaning that more carbon is stored than is released into the environment).
2) Cellulosic-made from cellulose, a component of plant cell walls. Plants efficiently make energy (carbs) from sunlight. I like to think of cellulose, a complex carbohydrate consisting of a chain of glucose (sugar) molecules, as plants’ storage facility (like fat in animals) or a “battery” storing energy for later.
3) Biofuels-fuel produced from renewable biomass such as wood waste, perennial grasses (ie; Miscanthus, switchgrass, wheat straw, corn), algae, or trees
So cellulosic biofuels are made from the leafy/woody part of plants, as opposed to the most commonly produced form of ethanol (as of 2010) made from the grain of corn, which is NOT a very clean source of energy AND it diverts a food crop towards energy production. Cellulosic biofuels, on the other hand, while not yet produced at large scale, have enormous potential as a clean energy source. For example, giant perennial grasses such as Miscanthus (up 15 ft tall!!!) have numerous assets as a source of green energy:
1) They can grow on marginal lands and do not compete with land ideally suited for growing food.
2) They require minimal or no fertilizer input, partly by sequestering carbon and nitrogen in below-ground rhizomes. First generation energy crops, such as corn, on the other hand, typically rely on heavy application of synthetic fertilizers. Such fertilizers tend to leach into the soil and groundwater and can have devastating environmental consequences.
3) They promote efficient land use. A minimal amount of land can sustain an incredibly high biomass yield and perennial grasses and trees can be harvested continually for several years after an initial establishment phase.
4) Plants such as Miscanthus have been shown to provide a net carbon sink in the net life cycle of energy production.
5) Providing our own sources of domestic energy can provide new jobs and offer a source of energy security in times of increasing global instability.
While there is unlikely to be a single perfect green energy solution, investment in a diversity of available clean energy technologies, including wind, solar, geothermal, and advanced generation biofuels is a necessary part of our future.
In the U.S, we have the technology and land to produce clean energy in a sustainable, renewable manner, why do it any other way?
OK, so here are my own personal definitions of these terms:
1) Clean energy-a form of energy that is produced with net carbon output of zero, near-zero, or negative (meaning that more carbon is stored than is released into the environment).
2) Cellulosic-made from cellulose, a component of plant cell walls. Plants efficiently make energy (carbs) from sunlight. I like to think of cellulose, a complex carbohydrate consisting of a chain of glucose (sugar) molecules, as plants’ storage facility (like fat in animals) or a “battery” storing energy for later.
3) Biofuels-fuel produced from renewable biomass such as wood waste, perennial grasses (ie; Miscanthus, switchgrass, wheat straw, corn), algae, or trees
So cellulosic biofuels are made from the leafy/woody part of plants, as opposed to the most commonly produced form of ethanol (as of 2010) made from the grain of corn, which is NOT a very clean source of energy AND it diverts a food crop towards energy production. Cellulosic biofuels, on the other hand, while not yet produced at large scale, have enormous potential as a clean energy source. For example, giant perennial grasses such as Miscanthus (up 15 ft tall!!!) have numerous assets as a source of green energy:
1) They can grow on marginal lands and do not compete with land ideally suited for growing food.
2) They require minimal or no fertilizer input, partly by sequestering carbon and nitrogen in below-ground rhizomes. First generation energy crops, such as corn, on the other hand, typically rely on heavy application of synthetic fertilizers. Such fertilizers tend to leach into the soil and groundwater and can have devastating environmental consequences.
3) They promote efficient land use. A minimal amount of land can sustain an incredibly high biomass yield and perennial grasses and trees can be harvested continually for several years after an initial establishment phase.
4) Plants such as Miscanthus have been shown to provide a net carbon sink in the net life cycle of energy production.
5) Providing our own sources of domestic energy can provide new jobs and offer a source of energy security in times of increasing global instability.
While there is unlikely to be a single perfect green energy solution, investment in a diversity of available clean energy technologies, including wind, solar, geothermal, and advanced generation biofuels is a necessary part of our future.
In the U.S, we have the technology and land to produce clean energy in a sustainable, renewable manner, why do it any other way?
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