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will Biofuels and Biomass Feedstocks Come from?
It may look like waste, but to some people it's green power. Find out how California dairy farms
and restaurants like Jardinière are taking their leftover waste and transforming it into clean energy.
When it comes to biofuels we have a few choices and options - we can do it poorly, with short-run approaches with no potential to scale, poor trajectory, and adverse environmental impact, or we can do it right - with sustainable, long-term solutions that can meet our biofuel needs and our environmental needs. We do need strong regulation to ensure land use abuses do not happen. A recent report published by the Royal Society highlights some of the factors that need to be balanced - they note that some changes in land use (such as clearing tropical forest or adapting peatlands for crop cultivation) can do more harm than good. To counter these potential abuses, we have suggested each cellulosic facility be individually certified with a LEEDS (international certification program for "Leadership in Energy and Environmental Design", a green building rating system) like "CLAW" rating and countries that allow environmentally sensitive lands to be encroached be disqualified from these CLAW rated fuel markets. We think a good fuel has to meet the CLAW requirements:
- COST below gasoline
Cellulosic ethanol (and cellulosic biofuels at large) can meet these requirements. The Royal Society notes that the uncertainty of some biofuels do not obscure the main benefits of cellulosic fuels: "(1) biofuels from cereals, straw, beet and rapeseed are likely to reduce GHG emissions, though the estimated contribution varies over a wide range, from 10 to 80% (averaging about 50%) depending on crop, cropping practice and processing technologies; (2) biofuels from lignocellulose material are likely to show a twofold or more improvement in average abatement potential when compared with biofuels derived from food crops." Our research and data suggests that cellulosic ethanol can reduce emissions on a per-mile driven basis by 75-85%, with limited water usage for process and feedstock as illustrated later. Range, Coskata and other companies currently have small scale pilots projecting 75% less water use than corn ethanol, and energy in/out ratio between 7-10 (Energy returned on energy invested or EROI, even though we consider this a less important variable than carbon emissions per mile driven). The question that eventually comes to the forefront is land use and biomass production - how much will we need? What will it take? Is it scalable enough to make a meaningful positive impact? To be conservative, we assume CAFE standards in the US per current law though we expect by 2030 to have much higher CAFE and fleet standards (hopefully up near 54 miles per gallon (mpg) or 100% higher than 2007 averages), thus dramatically reducing the need for fuel and hence biomass. For, this to happen, we need a combination of factors, including lighter vehicles, more efficient engines, better aerodynamics, low cost hybrids and whatever else we can get the consumer to buy that increases mpg.
What do we believe? As we will cover in this paper, we believe that given reasonable assumptions on technologies, biofuel yields, and adoption of better agronomic practices, most of our biofuel needs can be met with fairly limited land usage. From a technology perspective, the advances and continuing research into thermochemical processes offers potential far exceeding that of standard biochemical approaches. From an agronomic perspective, a greater understanding about the benefits of crop rotations and conservation practices combined with an ability to use generally underutilized land offers us the ability to vastly increase our biofuel producing abilities without cultivating additional land. In particular, we think the potential for winter cover crops as a biofuel source has been greatly understated, and that even modest yield assumptions would allow them to meet a significant portion of our biofuel needs. In the long run, the combination of these multiple factors (an example of the innovation ecosystem at play) will allow us to sever our dependence on oil - for good. Hybrid vehicle technologies will help but not materially on a worldwide basis at current costs.
A note about evaluating alternatives - when looking at a potential solution, it's important not to evaluate a technology/approach in isolation; rather, we ought to compare it relative to other viable approaches to determine its actual feasibility. For example, every nuclear plant that we did not build over the last 50 years (due to environmental concerns) was almost certainly replaced by a coal plant, whose environmental footprint was significantly worse. We are in danger of doing it again, by going after pie-in the sky or uneconomic solutions to replace oil. That could lead to even more problems - the alternative (as a long run transportation fuel solution) may well be oil shales (Canada is moving aggressively in this direction), which are even worse environmentally. Letting the perfect be the enemy of the good is irrational - marginal analysis counts.
There are many approaches to production of feedstocks for biofuels. To make a material impact in replacing gasoline, major feedstocks need to collectively produce more than a hundred billion gallons annually in the US and preferably more than 150 billion gallons to replace gasoline. Replacing gasoline and replacing diesel involve different technologies and markets. The focus here is principally on gasoline replacement in America's cars and light trucks though we do briefly touch upon diesel feedstocks.
We believe that a sustainable biofuel needs yields of at least 2,000 gallons (ethanol equivalent) per acre (hopefully 3,000!) in the long run to meet the worlds oil replacement needs on a manageable amount of land (with the exception of winter cover crops that use no additional lands). We believe, as estimated in our papers elsewhere, that 2,500 gallons of ethanol equivalent per acre annually is a reasonable assumption. (Assuming corn grain yields of 140 to 170 bushels/acre that are typical of the mid-Western corn belt today, and 2.8 gallons of ethanol from a bushel of corn, the range in ethanol production from corn is only 392 to 476 gallons/acre.) Chemical and water inputs and the effect on biodiversity should be minimal, if any. Cost should be below that of oil. Feedstock production should not materially increase the land under annual cultivation nor affect food security materially but should enhance energy security, reduce poverty and increase rural incomes. None of the "food/feed crop" based biofuels (corn or sugar based) or classic biodiesel sources (vegetable oils) comes close to these targets. Is such a fantasy possible? Yes! Part I covers sources of biomass, Part II will cover agronomy practices for yield, biodiversity, water and chemical efficiency, and Part III discusses the rationale of yield assumptions that lead to 2,500 gallons per acre. Our calculations later show that if we can increase engine and automobile efficiency significantly at the same time, we will need no additional land for biofuels.
Currently there are two primary feedstocks for the production of renewable biofuels to replace gasoline (almost entirely ethanol) to replace gasoline - sugar from sugar cane (primarily used in Brazil) and starch from corn (the source of most US-based ethanol). In Asia and Africa, tapioca, potatoes and other starch crops are being used (sadly!). Amongst feedstocks, there has been significant discussion regarding both corn stalks and wheat straw. We are not huge fans of wheat straw or corn stalks, though they are possibilities. In our opinion, cellulosic ethanol plants need to reach production levels of 100m gallons per year per plant to achieve economies of scale (expensive fuels don't sell! A local conversion plant near the field and distributed supply would be ideal and we continue to investigate technologies that might make this possible). That would dictate feedstock needs of around 1,000,000 tons - per year, per plant In the short and medium term, at biomass yields of 10 tons/acre (by 2030 we expect about 20-25 tons/acre), 100,000 acres of land would be needed per cellulosic ethanol plant or 40,000 acres by 2030. With yields of approximately 2 tons/acre, the usage of either corn stalk or wheat straw would effectively quintuple land usage and substantially increase transportation distances and costs, hence our skepticism. In addition, there is value to plowing corn stalks and wheat straw under to minimize the need for commercial fertilizer. Winter cover crops like legumes and winter rye (no biomass optimized winter cover crops have been developed but grasses are a good candidate), grown on row crop lands during their idle period during winters, can yield 3-5 tons/acre with no additional land usage and may actually improve land ecology where row crops are grown anyway. In conjunction with winter cover crops, annual crop residue may become a viable supplement to winter cover crops annual/biomass yields per acre. To quote Prof Bransby, a renowned agronomist from Auburn University in a personal communication:
"Regarding water and fertilizer needs of cover crops: The answer is that no irrigation is needed, and fertilizer needs are about 30% of the fertilizer requirements of corn. Also, there are multiple benefits from cover crop/traditional crop rotations (compared to traditional crops with no cover crops), including better soil protection/less soil erosion, improved soil organic matter, better water holding capacity, suppression of crop pests, etc. Provided this is done with conservation tillage practices, there should be no serious negative environmental impacts." He states further: "It is reasonable to assume that winter cover crops can be grown on the same land that our summer traditional crops are grown, and summer cover crops can be grown on land where traditional winter crops (mainly winter wheat) are grown. As far as I know, most of this land is currently idle/fallow at the time when these cover crops would be grown. From the USDA National Agricultural Statistics website the 2007 acreage (in millions) for our major traditional crops is as follows: corn, 93; soybeans, 63; cotton, 11; sorghum, 8; winter wheat, 44; Total = 219. At a modest estimate of 3 tons/acre/year, this would provide 657 million tons of biomass annually. With research and genetic improvement, I believe the yield could be increased to 5 tons/acre within 10 years, for a total of 1.1 billion tons/year. Acreage for all annual crops is 317 million. For various reasons, it is unrealistic to assume that 100% of land in traditional crops could be planted to cover crops to produce biomass. Maybe 70%?"
our most likely scenario, we have chosen to use 50% of
the annual acreage of traditional annual crops for winter
cover crops and about 70% of forest waste in our estimates.
Each of these sources offers benefits. The DOE noted that
major primary sources for forest biomass would be logging
residues and fuel treatments, and that much of the forest
material we project to use "has been identified by
the Forest Service as needing to be removed to improve
forest health and to reduce fire hazard risks." With
regards to winter crops, our estimates suggest that any
feedstock transportation beyond about 50-75 miles (preferably
under 30 miles) will reduce its competitiveness, unless
the crop is very low cost (like winter cover crops), in
which case a maximum 100 mile radius might make sense.
Energy crops and winter cover crops will reduce the need
of substantial transport infrastructure for biomass and
answer critics' questions about infrastructure. If these
plants were distributed around the country it would substantially
reduced need for infrastructure. Smaller pipelines will
be needed if most of the biofuels are not concentrated
in the Midwest. Biomass crops will be widely distributed
and will minimize the need for this infrastructure.
What is the competitiveness of biomass vis a vis a oil? Since an air dry ton of biomass contains about 2.5 times the energy content of a barrel of oil (14.5 million btu vs. 5.8 million btu), $50/barrel oil could theoretically be competitive with $125/ton biomass. However, given the high cost and nascent nature of biomass processing, we believe a more conservative estimate is needed initially - as biomass processing costs decrease, we will see increases in the price of biomass (towards the 2.5 times oil price point) for farmers even as it remains competitive with oil. Today, we think a competitive feedstock cost based on current conversion efficiencies (which are subject to improvement), delivered to the factory, has to be below $50/ton of dry biomass (plus or minus 25% depending upon feedstock type) to compete with $50/barrel oil (which we are unlikely to see again without significant reduction in demand).
As per the pricing constraints above, we limit (in our estimates) potential incremental land using feedstocks to crops that yield over 10 tons/acre in the mid-term - effectively, "energy crops". The Royal Society's "Sustainable Biofuels" report notes the following:
"a significant advantage of developing and using dedicated crops and trees for biofuels is that the plans can be bred for purpose. This could involve development of higher carbon to nitrogen ratios, higher yields of biomass or oil, cell wall lignocellulose characteristics that make the feedstock more amenable for processing ... Several technologies are available to improve these traits, including traditional plant breeding, genomic approaches to screening natural variation and the use of genetic modification to produce transgenic plants. Research may also open up new sources of feedstocks from, for example, novel non-food oil crops, the use of organisms taken from the marine environment, or the direct production of hydrocarbons from plants or microbial systems."
We should also note that a number of "biomass densification" technologies are being investigated that may ultimately reduce biomass transportation costs even further but are currently in early research stages. For example, one approach is the production of "bio-oil" at small-scale localized biomass pyrolysis units. This bio-oil can then be transported to a centralized facility for conversion and up-grading to "biocrude" that can go into an existing refinery or used as-is for applications like home heating oil (Kior).
Source: David Bransby & Ceres .
The DOE Billion-Ton report confirms many of our conjectures. It notes: "It is assumed that significant amounts of land could shift to the production of perennial corps if a large market for bioenergy and biobased products emerges." It further notes that studies have shown that "if a farmgate price of about $40 per dry ton were offered to the farmers, perennial grass crops producing an average of 4.2 dry tons per acre (a level attainable today) would be competitive with current crops on about 42 million acres of cropland and CRP land." We do note that this report was published in 2005, and fuel and fertilizer costs have increased rapidly since then - updated research is needed. We also believe yields of 2-6 times these estimates are feasible by 2030.
Now to the numbers. How much biomass can we get to convert to biofuels without subsuming other uses for land and biomass? More than enough! There are four principal sources of biomass and biofuels we consider (1) energy crops on agricultural land and timberlands using crop rotation schemes that improve traditional row crop agriculture AND recover previously degraded lands (2) winter cover crops grown on current annual crop lands using the land during the winter season (or summer, in the case of winter wheat) when it is generally dormant (while improving land ecology) (3) excess non-merchantable forest material that is currently unused (about 226 million tons according to the US Department of Energy), and (4) organic municipal waste, industrial waste and municipal sewage.
For the US, the world's most oil intensive economy, our calculations show that a small dose of vision, two decades of agricultural development, and process technology that is in pilots today, with less than 5% of our annual crop and timberlands could more than supply our biofuels needs to replace most of our light-vehicle gasoline usage by 2030. The table below shows one of many possible scenarios - in the scenario below, we assume about 50% of the total annual crop acreage (317M acres) is used with winter cover crops; approximately 70% of excess forest waste identified by the DOE is used, and assume that waste-based (municipal organic waste, sewage, steel mill flue gases, industrial waste, etc) ethanol accounts for 10% of total demand by 2030 - resulting in dedicated energy crop usage of approximately 15M acres (The assumptions are covered in Appendix A).
While our projections above are based on our most likely scenario, other scenarios are possible. We project a range of scenarios using 50% or 70% of our annual crop lands for winter cover crops, using 50%, 70%, 100% of sustainable, harvestable forest waste, energy crop yields 12,18,24 tons/acre with and without usage of waste like municipal sewage and organic waste, and yields of 110 and 130 gallons ethanol equivalent fuel per dry ton. Early experimental data have shown that other biofuels may produce yields equivalent to 150 gallons of ethanol equivalent biofuels per ton (as opposed to the 110 projected in the table above), long before 2030; (based on data disclosed confidentially to us). In this (optimistic) scenario, ALL of our light-vehicle transportation needs would be met without using any additional devoted energy cropland! Going further, the USDA projects corn ethanol production of 9.3 billion gallons in 2008 - at 2.8 gallons per bushel and 150 bushels per acre, that suggests that 22M acres of corn crop is being devoted to corn ethanol today - 70% of this land could be "released" and reused for other purposes (we assume that all ethanol production by 2030 will be cellulosic). We have outlined six potential scenarios in Appendix A (a summary is provided here - scenario 1 is highlighted above).
We should also note the point about water usage - cellulosic ethanol has come under attack recently for excessive water usage, again without doing an apples-to-apples comparison with gasoline. Producing one gallon of gasoline uses 2-2.5 gallons of water ; producing one gallon of cellulosic ethanol (through the Range/Coskata processes) uses 1 gallon on water. Even account for the mileage discount of ethanol vs. gasoline (which we expect to decrease from 25% in 2020 to about 15% by 2030), the water usage of cellulosic ethanol is significantly lower than that of gasoline on a per mile driven basis! We assume that energy crops will grown as rainfed unirrigated crops.
Take Scenario 1: the key assumption here is recovering 3 tons/acre of biomass additionally per year from winter cover crops (growing to 4.6 tons/acre, or just over a 1.5% a year productivity increase). For conservation, we have not separately provided for summer annual crop biomass residue. Using crop residue plus winter crops will provide for higher yields and allow substantial biomass to be plowed back into the soil for sustainability. Based on point data reports on energy crop yields and detailed in part III, we assume that 24 tons/acre of energy crop yields can be achieved by 2030, starting at 7 tons/acre in 2008.. However, the net land use requirements are immaterially affected if yields are assumed to be 25% or 50% lower, since winter cover crops provide the bulk of the biomass. It should be noted that the 3 tons/acre of biomass from winter cover crops could be made up of actual winter cover crop yields and use of parts of the biomass (corn stover, wheat straw, etc) from annual food crop cultivation. And that's only the beginning - one of our investments is working to improve the mileage efficiency of the standard ICE (Internal Combustion Engine) by 50-100% for ethanol and gasoline dramatically reducing biomass needs! Increased CAFE standards will help too. Additional degraded land can be recovered if our 10 year by 10 year biomass crop rotation scheme is followed (described in Part II), though we have not modeled this. In combination with the other factors listed above, we are confident that our biomass needs will not be a limiting factor by 2030. Furthermore, they will neither encroach on land needed for food production, nor cause destruction of tropical rain forests that are vitally important resources for carbon sequestration and control of green house gases.
While gasoline is the primary focus of much of this research, a diesel replacement is also a vital goal. Today, an alternative fuel like "classic" biodiesel (diesel produced mostly from vegetable oil) can meet some needs, but its inability to scale and its vegetable oil source will prevent it from being a relevant scale replacement for petrodiesel in the long run - it lacks trajectory. And it creates a food versus fuel controversy. We are very negative on classic biodiesel (see our Biodiesel paper). The primary feedstocks for classic biodiesel are vegetable oils such as rape seed, soybean and palm oil, with sources such as jatropha being used in India and other parts of the world. Unfortunately, none of these sources has high enough yields per acre - soybean oil yield is around 40-50 gal/acre, rape seed around 110-130, and jatropha at 170-180, while palm oil reaches as 630-650 gal/acre . Jatropha does have the benefit of growing on non-food crop lands, limiting any food vs. fuel conflicts. Because food grains are well-optimized crops (with the exception of jatropha and algae), we don't expect vegetable oil yields to increase significantly over time (a 2X is projected for corn by 2015). As mentioned earlier, we believe that a sustainable biofuel needs yields of at least 2,000 gallons per acre (hopefully 3,000!) in the long run to produce the worlds oil replacement needs on a manageable amount of land. Unfortunately, none of the classic biodiesel sources comes close to these targets.
source that can achieve these minimum yields is algae,
which has not been optimized. However, there are many
challenges for producing diesel from algae. Growth can
be in open ponds or in enclosed bioreactors. Open ponds
are the simpler, more economic approach. Enclosed bioreactors
can be used to achieve higher yields but with increased
capital and operating costs and we are skeptical about
their economics. Methods such as the tools of synthetic
biology can be used to improve the productivity of algae;
however, these genetically engineered organisms are going
to be controversial in open oceans. Hence we are cautious
about investing in bioengineered algae. Our preferred
source to replace petrodiesel is to use cellulosic biomass
based "cellulosic diesel". Companies such as
our investments in Amyris, LS9, Kior, and others believe
they can produce diesel and jet fuel replacement at substantially
lower costs than food oil based diesel (below $1.75 per
gallon) while getting all the high yield benefits of cellulosic
biomass sources. At 2,500 gallons per acre and approximately
40 billion gallons of diesel usage (for on-road transportation
), we will need roughly an additional 16M acres to meet
our transportation diesel needs in the US.
II: Better Agronomy for Energy Crops
We have proposed the usage of a 10 year x 10 year energy
and row crop rotation. As row crops are grown in the usual
corn/soy rotation, lands lose topsoil and get degraded,
need increased fertilizer and water inputs and decline
in biodiversity. By growing no-till, deep rooted perennial
energy crops (like miscanthus or switchgrass - see below)
for ten years following a ten year row crop (i.e. - corn/soy)
cycle, the carbon content of the soil and its biodiversity
can be improved and the needs for inputs decreased. The
land can then be returned to row crop cultivation after
ten years of no-till energy crops. Currently unusable
degraded lands may even be reclaimed for agriculture using
these techniques over a few decades. A University of North
Dakota study highlights some of the benefits for food
crops. We expect similar or even greater benefits for
food crop/energy crop long cycle (ten year) rotations,
especially in soil carbon content: (1) Improved yields
-a crop grown in rotation with other crops will show significantly
higher yields than a crop grown continuously. (2) Disease
control- changing environmental conditions (by changing
crops) changes the effect of various diseases that may
set in with an individual crop, and crop rotation can
limit (and often eliminate) diseases that affect a specific
crop. (3) Carbon content - Energy crops in the rotation
can increase soil carbon content and reduce the impact
of top soil loss materially. (4).Better land: the study
notes farmers practicing crop rotations comment on improvements
in soil stability and friability. In addition, crop rotations
have the potential to increase the efficiency of water
usage (by rotation deep-rooted and more moderately-rooted
crops or rotation of perennials in long cycles with row
(ii) Another important crop practice is the idea of utilizing polyculture species instead of monocultures. This is particularly possible for energy crops as many processes can accept a mixture of biomass types. The Land Institute notes that polycultures (and the resulting plant diversity) have significant benefits - from the provision of an "internal supply of nitrogen, management of exotic and other harmful organisms, soil biodiversity, and overall resilience of the system." Further research shows that grasslands that suffer from overgrazing or drought tend to recover faster if there is greater biodiversity. The Australian Rural Industries Research and Development Corporation notes that "Polyculture is shown to offer the proverbial 'free lunch' by producing more from less." The report goes on to note that polycultures yield in greater amounts from smaller areas, and their yields are generally more stable than monocultures (with regards to income level and general risk). Furthermore, polycultures were found to be more efficient in gathering resources such as light, water, and soil nutrients. Other researchers have found similar potential in the yields and environmental benefits of polyculture crops. Though it is hard to extrapolate data from low production potential areas (where these studies were conducted) to the high production potential areas that are needed, we think this is an area that requires further exploration and study. These benefits are starting to gain recognition - Ceres Corporation has proposed an alternative approach they call polycultivation.
(iii) Perennial crops: As opposed to standard, annual crops which need to be replanted yearly, perennial crops (hopefully in polyculture prairies) will produce for multiple years before requiring replanting. As the Land Institute notes, the perennial plants provide significant advantages - from cover against wind and soil erosion, to improved soil quality over time. They note that "it has been shown that restoring former cropland to perennial vegetation can actually return much of the soil structure and function characteristic of original prairie ecosystems." The Royal Society notes that "the use of perennial crops and trees may reduce N2O emissions and provide large yields with the addition of nitrogen." Similarly, the DOE's Office of Science notes that "perennial grasses and other bioenergy crops have many significant environmental benefits over traditional row crops. Perennial energy crops provide a better environment for more-diverse wildlife habitation. Their extensive root systems increase nutrient capture, improve soil quality, sequester carbon, and reduce erosion." Plowing releases an enormous amount of carbon from the soil into the atmosphere. So, by simply eliminating tillage perennial energy crops sequester vast quantities of carbon, in addition to the carbon added to the soil in their roots. The NRDC (National Resources Defense Council) study, "Growing Energy" points out the advantages of a perennial crop (switchgrass) over most traditional row crops - "on average, switchgrass requires less fertilizer, herbicide, insecticide, and fungicide per ton of biomass than corn, wheat, and soybeans." In addition, the study shows the cultivating switchgrass reduces soil erosion and improves soil carbon. The advantage of increased soil-carbon is two-fold - a higher sequestration of carbon in the soil (and thus reducing carbon dioxide in the air), as well as an improvement of soil organic matter levels - truly a win-win scenario. Infact the NRDC shows that negative carbon emissions per mile driven are possible with biomass crop based fuels!
vs. Perennial Root Systems
The extensive roots of perennials and subsequent access to nutrients reduces the need for fertilizer (and thus farmer costs), while their evolution in naturally-occurring ecosystems has provided them with a greater resiliency to stresses such as droughts, diseases, and insects. Today, perennial grasses like switchgrass offer significant potential as energy crops. While this has been difficult for row crops, energy crops are most suited to perennial, polyculture cultivation.
Importantly, the usage of these crop practices around perennial, crop rotated energy crops will offer significant benefits to farmers themselves. One example of the usage of perennial crops is highlighted in a 2002 University of Illinois study - (along with other research by Ceres ) - on strictly economic terms, farmers are likely to be better off with miscanthus (a perennial grass) farming vs. a standard corn/soy rotation. The study in question pointed out that a 10 year rotation was likely to yield negative income (based on historical prices) for the corn/soy farmers (hence the need for subsidies) as opposed to a significant profit when growing the energy crop, with improving soils and reduced needs for water and fertilizer even during the row crop phase of the rotation. We do note that corn prices have changed significantly since this study, and results are probably different today. In light of this opportunity, companies like Bical (UK) have been setup to provide "renewable and profitable diversification for farmers and landowners." Today, it is Europe's largest miscanthus developer and commercial producer.
(iv) Improved Agronomic Practices: In addition to the changes highlighted here, the usage of better agronomic practices can also have a significant impact in raising yields. More than 85% of all corn grown in the US is non-irrigated, leading to efficient water usage. Elsewhere, the previously cited University of North Dakota study notes that practices like no-till or minimum till farming with crop rotations have been shown to reduce wind and water erosion. The NCGA (National Corn Grower's Association) notes that no-till farming is "a practice whose time has arrived." The CTIC (Conservation Tillage Information Center) notes that 20% of all corn surveyed is now grown utilizing no-till practices. These practices have bourn fruit - even as the corn harvest has increased rapidly over the past 20 years, farmers have reduced soil erosion by 44% using a combination of conservation tillage and other soil-caring practices. Energy crops will accelerate these trends dramatically because they make the farmer more money. Other benefits to conservation practices exist: Professor David Montgomery of the University of Washington notes that "No-till farming can build soil fertility even with intensive farming methods. It could prove to be a major benefit in a warming climate. By stirring crop residue into the soil surface, no-till farming can gradually increase organic matter in soil, as much as tripling its carbon content in less than 15 years."
Some concern has been raised about the risk of candidate biomass crops becoming invasive. We strongly oppose the use of species that are already invasive for production of biomass feedstocks, including plants like giant reed (Arundo donax), johnsongrass (Sorghum halapense) and water hiacynth (Eichhornia crassipes), since it is not necessary to use such species when others that have no record of being invasive are available. The current top priority candidate biomass crops include switchgrass (Panicum maximum), sugarcane and energy cane (Saccharum spp), high producing annual sorghums (Sorghum spp) and miscanthus (Miscanthus x giganteus). Switchgrass is native to North America, and is recommended for planting on Conservation Reserve Program (CRP) land where it occupies millions of acres and has shown no evidence of becoming invasive. Sugarcane and sorghum have been grown commercially on millions of acres throughout the world for over a century, also without evidence of becoming invasive. Miscanthus does not have as long an agricultural history, but has been under evaluation in Europe for over 2 decades where it is now in commercial production. Since it is similar to sugarcane, in that it does not produce seed, it is reasonable to assume that it is not invasive. The top priority woody species are hybrid poplar (Populus spp.) and willow (Salix spp), and these species have also shown no sign of becoming invasive.
As biomass crops are developed further, new genetic material
needs to be evaluated for its invasive potential prior
to being released. This will require development of procedures
to conduct such evaluation, as well as a regulation process
to prevent use of crops with clear invasive potential
from being cultivated on a commercial scale. It is assumed
that the recently formed Council for Sustainable Biomass
Production (www.csbp.org) will guide the development of
such a process, along with addressing several other environmental
issues related to the emerging cellulosic bioenergy industry.
Our most critical assumption with cellulosic biofuels is on land efficiency (tons of biomass per acre and hence gallons of fuels produced per acre - or more accurately, miles driven per acre) - we believe biomass yields per acre will improve 2-4 times from today's norms. The lack of genetic optimization and research on cultural practices, harvesting, storage and transport with would-be energy crops (like miscanthus, sorghum, switchgrass and others) means that there is significant potential for improvement. The Royal Societies report notes that miscanthus is " can be cultivated with low inputs in marginal land, but biomass yield is linked to inputs and may improvements will be required. As yet, there is little molecular understanding of the crop, its genetics and its agronomy and a number of additional issues, including the optimization of harvesting processes remain to be resolved." The application of advanced breeding methods like genetic engineering and marker assisted breeding, limiting water usage through drought resistant crops, and large-scale application of biotechnology (i.e., optimizing the process by which plants conduct photosynthesis, or reducing stress-based yield losses) will also contribute to increased yields with fewer inputs. More importantly, different energy crops are likely to be optimal for different climates- jatropha makes sense on degraded Indian land, but not in the American Midwest. Algae are discussed under Biodiesel energy crops. Rather than a single dominant energy crop, we are likely to see a variety of feedstocks that allow specialization to local conditions, mixes and needs while mitigating the risks.
reported examples and data points of biomass yields speak
to the feasibility of our estimates of yields between
18-24 tons per acre by 2030:
· Sugarcane ventures in Brazil (Allelyx is using GMO techniques, Canavalis is using more traditional plant breeding) are breeding energy cane that will likely result in a yield of 25 dry tons per acre/year of harvestable biomass. Similar progress is being made by USDA sugarcane geneticists in Louisiana.
· Megaflora Corp. has measured productivities of 28 dry tons per acre per year from crossing North American Hardwoods with the paulownia tree in North Carolina.
· Anagenesis Corp trees quotes "one acre can yield 48x times as much ethanol as an acre of corn".
· DOE estimates suggest that collecting existing biomass with only a small change in agricultural practices could generate 1.3 billion dry tons of biomass in the US (most of our biomass needs) and still be able to meet all food, feed, and export demands.
· High yield sorghum can be grown in 35 US States and produce yields as high as 25 dry tons per acre/year with low water usage
· Researchers at Texas A&M have developed new "freakishly tall sorghum plants" that reach heights of nearly 20 feet - more than double the height of regular sorghum and yielding double the amount of crop per acre. They use little water, and have been bred to prevent flowering (thus trapping more energy), and can be grown on marginal crop lands.
A wide variety of crops have potential as feedstocks for cellulosic ethanol. Bical notes that "The criteria for the ideal energy crop are high dry matter yield, perennial growth, and efficient use of nitrogen, water, other resources, and pest and disease resistance." The previously cited U of Illinois study compared corn, short-rotation coppice, and miscanthus versus a set of idealized criteria for energy crops and found miscanthus (and by extension, other C4 photosynthetic grasses) to meet most of the requirements (see charts below). Of particular interest to us is miscanthus that "partitions nutrients back to the roots in the fall just before harvesting". We figure crops that provided (and survived) energy for mammals in the prairies can now provide energy for humans!
Many of the advantages of miscanthus are also applicable to some of the other proposed feedstocks. The new, higher-yielding strains of sorghum developed at Texas A&M use less water than conventional sorghum (making them more drought-resistant), and are sterile (not flowering prevents the escape of energy) - their 20-feet heights mean that yields have effectively doubled. The table below (from Ceres) highlights the advantages and disadvantages of various feedstocks--however, it is notable that most non-cellulosic sources (example, vegetable oils) would fail on the vast majority of the criteria.
Examples abound of people in action on energy crops. Ceres has been attacking the problems from a multitude of angles, and is utilizing biotechnology in combination with better crop practices (such as those highlighted earlier). Firstly, they are attempting to increase the usable land available, by working on crops that can deal with problems such as drought tolerance (and recovery), heat tolerance, salt tolerance, and even cold germination. They are also working on increasing yields with plants that have shorter flowering times, greater photosynthetic efficiency, and greater shade tolerance Additionally, they are attempting to reduce the costs per acre by increasing the efficiency of nitrogen utilization, improving the efficiency of photosynthesis with lower nitrogen usage, increasing the biomass present in the root of the plant, and reducing costs through enzyme production while working to increase the gallons per acre that result from various feedstocks. They are also proposing better agronomy techniques like polycultivation (plots of monoculture crops interleaved together) as opposed to a polyculture (mixed crop cocktails). As a whole, the company is developing genetically modified, commercial energy crops, and expects to have proprietary commercial varieties ready for market in 2-3 years and transgenic varieties in 5-7 years. There are others with similar efforts.
the production of biofuels has come in for considerable
criticism from sources. While there has been a tendency
for much of this criticism to originate from sources with
a vested interest in bashing biofuels, there has been
significant attention to a recent article published by
Professor Timothy Searchinger in Science. In summary,
Professor Searchinger's article attempts to model the
effect of converting land from other purposes to feedstock
production for biofuels production and conclude that significant
greenhouse gas emissions are associated with this conversion.
As we've highlighted in the paper, we believe that we can replace most of our gasoline usage with biofuels within the next 25 years. However, we believe that there are a few areas of research focus that are vital to getting there. In addition, specific policy steps must be taken in order to help achieve these goals. While we disagree with some of the policy conclusions of the Royal Society report (next section), it does highlight issues key goals of research going forward.
While these are valuable areas of focus, we have highlighted specific practices and areas that we consider to be the most promising
development and research into the viability of winter
cover crops as long-term biomass sources
"avoid the unintended consequence of solving one
problem at the expense of exacerbating another;
While we agree with the idea of avoiding unintended consequences to the best of our abilities, we should not understate the problem at hand - our current oil usage is not sustainable on an environmental or economic basis; action has to be taken now, as opposed to at some future date. The principle of "primum nil nocere" (first, do no harm) is vital in individual medicine - it is less so when it comes to the planet at large. While the adoption time of new technologies has continued to increase rapidly (economists/econometrics use regressive data going forward - unlike technologists/entrepreneurs), replacing oil will still require substantial effort - and this is an effort that must start now. We recognize that there are risks with these approaches, but these are manageable technology risks, not market risks - furthermore, the risks of the status quo persist. From a policy perspective, we reiterate the question - what risks do we wish to take?
Our conclusions are surprising:
With biofuel yields of 110 gallons per dry ton of biomass
modest to little dedicated land is required. With yield
at 130 gallons/dry ton (or 65% of the maximum theoretical
yield of 198.4 gallon/ton), the land use issue becomes
minimal. If other well optimized chemical processes are
used as a guide, yields between 76-80% of theoretical
processes should be achievable, but were not assumed in
We have highlighted some of the feedstocks that (we believe) are likely to meet feedstock needs, but there are many other potential sources that have not yet been researched (or discovered!). In time, some feedstocks may prove to be more efficient than others, but local needs and transportation costs mean that cellulosic biofuels (utilizing local feedstocks) can be produced in many locations in the US and worldwide. The innovation ecosystem will ensure that over time, new ideas will continue to be developed- the better ideas will persist as more and more intelligent people, resources, and capital join the field, and the best ideas will eventually rise to the top. While some oil companies are starting to recognize and investigate the potential of biofuels, traditional oil interests (OPEC) will continue to fight this trend with the hundreds of billions of dollars at their disposal - state-owned oil companies control almost 80% of the world's oil resources. There is plenty of biomass available (computed here for the US but similar calculations are possible for other world geographies).
In the short term, we need to accelerate (not slow down) the deployment of biofuels. In order to prevent adverse outcomes we suggest implementation of the following policies (1) focus on non-food sources without additional land use such as winter cover crops, forest waste, and other organic waste sources (2) Aggressively pursue energy crop research and development including crop rotations, perennials, assessment of invasive species, land and water use etc (3) Prohibit the import of agricultural products from countries where deforestation rates don't decline to negotiated targets, either directly or through the WTO.
Biomass from energy crops can replace oil while improving traditional agriculture and biodiversity while reducing needs for chemicals and water for both the energy crops and the row crops that we use today. Far from being a food versus fuel battle that many tunnel visions critics have imagined, biomass based income may be one of the few fundamental economic tools we may have to solve poverty issues in Africa. Of course, biofuels can be produced as defined above or we can produce biomass on land from cut-down rain forests. They can be done well or done poorly. It behooves us to regulate each biofuels facility and qualify its feedstock sources as being eco-qualified (a LEEDS like rating for each biofuels factory!). Such regulation will cut off the abuses that will necessarily happen if we don't regulate them.
BIOFUELS: THINKING OUTSIDE THE BARREL - By: Vinod Khosla - Aug. 2006
BIODIESEL: GOOD, BETER, WORST OR WHY TRAJECTORY MATTERS - By: Vinod Khosla - May 2008
FOOD VERSUS FULE OR THE "SALVE FOR AFRICA"? - By: Vinod Khosla - Dec. 2006
BIOFUELS TRAJECTORY TO SUCCESS: THE INNOVATIONS ECOSYSTEM AT WORK - By: Vinod Khosla - Apr. 2008
ENERGY SECURITY AND OIL DEPENDENCE - Source: U.S. Senate - May 2006
PRAGMENTALISTS VS. ENVIRONMENTALISTS (PART I): PRIUS: GREEN OR GREENWASH? - By: Vinod Khosla - Mar. 2008
IMAGINING THE FUTURE OF GASOLINE: SEPARATING REALITY FROM BLUE-SKY DREAMING? - By: Vinod Khosla - Sept. 2006
A NEAR TERM ENERGY SOLUTION - By: Vinod Khosla - Sept: 2006
IS ETHANOL CONTROVERSIAL? SHOULD IT BE? - By: Vinod Khosla - Sept: 2006
Scenarios - Summary
We estimate that 150B gallons of cellulosic ethanol are
needed in 2030 to replace most light-vehicle gasoline
usage. How do we get there? The EIA energy outlook (published
BEFORE the recent energy bill passage) projects light-vehicle
usage of 11.15M barrels/day of oil equivalent in 2030
- or about 171B gallons annually. We assume a 20% discount
on this demand to reflect updated CAFE standards, and
an ethanol mileage discount of 15% - giving us equivalent
ethanol demand of 160B gallons (if every car was a Flex
Fuel Vehicle). We assume that by 2030, 90% of the fleet
consists of FFV's, leading to ethanol demand of 144B gallons
(we have thus used 150B gallons to be conservative). In
some scenarios, we exceed this projection without dedicated
crop land, and production numbers reflect that.