Biomass Energy and Agricultural Sustainability

Transcription

1 Biomass Energy and Agricultural Sustainability Stephen Kaffka Department of Plant Sciences University of California, Davis & California Biomass Collaborative May 28, 2008

2 coal use oil use Fuel consumption Biomass era ?????????? Year Expected duration of fossil fuels (0 to 3000 AD) (redrawn from P.E. Hodgson, 1999)

3 Overview: 1. Adding fuel production to agriculture s objectives 2. What do we mean by sustainability 3. Efficiency and sustainablity 4. Examples from California 5. Policy implications

4 The objectives of agriculture: 1. To provide an adequate food supply for a growing human population at a reasonable price. 2. To provide an increasingly high quality diet for all the world s people. 3. To maintain the income of farmers at levels comparable to that of the urban population 4. To maintain the natural resource base of agriculture. 5. To use non-renewable resources prudently. 6. To maintain and provide habitat and resources for other species, and to maintain the function of supporting natural ecosystems.

5 The end of oil? By 2025, every source of energy for transportation fuels will be needed ---VP for Research, Chevron

6 The objectives of agriculture: 1. To provide an adequate food supply for a growing human population at a reasonable price. 2. To provide an increasingly high quality diet for all the world s people. 3. To maintain the income of farmers at levels comparable to that of the urban population 4. To maintain the natural resource base of agriculture. 5. To use non-renewable resources prudently. 6. To maintain and provide habitat and resources for other species, and to maintain the function of supporting natural ecosystems. 7. To produce transportation fuels and other forms of surplus energy from crops and residues.

7 Energy Return On Investment: the ratio of energy in a L of biofuel to the nonrenewable energy required to make it. Source Older US Oil Current US Oil Corn Ethanol Brazilian sugar cane Biodiesel (soy) Cellulosic sources (mature technology) EROI 100:1 15:1 1.3:1 6-9:1 3:1 5-12:1 Data: various sources

8 Parity prices: Gasoline-crude oil-ethanol (based on Schmidhuber and Mueller/FAO, 2007) 120 Crude oil ($ bbl -1 ) Gasoline ($ L -1 ) sugarcane/brazil Palm oil Maize/US Mixed/EU BTL:synfuel

9 Uncertainties about the future of bioenergy production What will be the best feedstocks? What will be the best manufacturing technology? What will be the future public policies governing biofuel production and use? What will be the supply and price of oil and natural gas in the future?

10 What we call sustainable depends on the boundary conditions Equity Agroecological sustainability Economic efficiency Policy level Consumption Continuity of the resource base Production Farm Level Kruseman et al., 1996 Changes in natural resources Field level

11 What do we mean by agricultural sustainability? The debate over sustainability means discussing the implications of different choices when looking for compromise solutions between two pressures: 1. Economic pressure driving further intensification (higher rates of throughputs per acre and per hour of labor) 2. Ecological limitations or pressure to reduce the rate of throughput because lower input systems may have less local environmental impact. M. Giampietro, 2004

12 Cost of land and family labor

13 In discussing agricultural sustainability, we must use language clearly, and think about the meaning of our terms. A great deal of confusion exists around the use of this term. We must be careful to define our boundary conditions. Is agricultural sustainability a useful concept? Hansen, J. W. (1996). Agric. Systems, 50:

14 What do we mean by agricultural sustainability? A philosophy or ideology A set of strategies The capacity to fulfill a set of goals The ability to continue over time Hansen, 1996

15 Sustainability as a philosophy Sustainable agriculture is a philosophy and system of farming with roots in a set of values that reflect a state of empowerment, and ecological and social realities. -McRae, 1990

16 Sustainability by following a set of strategies: Example: Some argue that organic farming is synonymous with sustainability. If you follow the rules that define the organic farming label, and are certified, you are therefore sustainable.

17 Sustainability as the ability to fulfill a set of goals: A sustainable agriculture is one that, over the long term, enhances environmental quality and the resource base on which agriculture depends, provides for basic human food and fiber needs, is economically viable, and enhances the quality of life for farmers and society as a whole. American Society of Agronomy, 1989 At a minimum, this is not predictive

18 Proscriptive standards: Set of rules defining sustainability Does farming follow the rules? Yes No Agriculture is sustainable Agriculture is not sustainable

19 Proscriptive, narrative sustainability standards (The Cramer Report, The Netherlands) 1. The use of biomass must, on average, emit fewer greenhouse gases than fossil fuels (LCA) 2. The production of biomass must not endanger the food supply 3. Biomass production should not impair protected or vulnerable biodiversity 4. Production and processing must not reduce soil, air or water quality 5. Production of biomass must contribute to local prosperity 6. Production of biomass must contribute towards the well-being of employees and local populations.

20 If sustainability is determined by definition, then it is logically impossible to evaluate how sustainable farming practices actually are if adherence to a set of predetermined rules or standards is the criteria for evaluation. This circularity makes definitions of sustainability poor guides for research. Hanson, 1996

21 Useful ways to characterize sustainability for research at the field and farm scale Hanson, 1996 Element Literal Systemoriented Quantitative Predictive Stochastic Diagnostic Definition An ability to continue through time An objective property of a particular agricultural system whose components, boundaries and hierarchy are specified A continuous variable(s), permitting comparisons of alternative systems or approaches Focuses on the future, not the present or past Variability is a determinant of sustainability and a component of prediction Can be used to identify and prioritize constraints on a system that limits its sustainability

22 The ability to improve efficiency as an indicator of sustainability and basis for a sustainability standard Outputs Inputs Decreasing Constant Increasing Decreasing Indeterminant Unsustainable Unsustainable Constant Sustainable Sustainable Unsustainable Increasing Sustainable* Sustainable Indeterminant (Montieth, 1990)

23 Corn yields in Iowa and the USA as a whole ( ) y = 0,1916x + 10,033 R 2 = 0,7601 bushel/acre Iowa y = 0,4686x + 20,351 R 2 = 0, Nutrient Removal to Fertilizer Use USA Ratio for US Grain Corn N P K

24 Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels. In general, biofuels would provide greater benefits if their biomass feed stocks were produced: With low agricultural input (?) On land with low agricultural value (?) Could be converted to biofuel with little energy. _Hill, Tilman, et al., 2006, PNAS

25 De Wit, 1992, Agric. Sys. a feature of (agricultural) intensification is that it is not the improvement of one growing factor that is decisive, but the improvement of a number of them. This leads to positive interactions that result in the total effect of all these improvements being larger than the sum of the effects adopted separately.

26 Increasing returns to total factor productivity : The need for nutrients and water, expressed per unit surface area, increases with the yield level, but decreases when expressed per unit yield.

27 de Wit 1992 Increasing returns with fewer inputs: At the highest production levels, it is easier to manage inputs with good efficiency than at lower production levels. (Responses to inputs are better understood and managed).

28 De Wit, 1992 But while the need for energy, fertilizers, and biocides per unit product is lowest, (locally) environmental standards continue to be threatened and Cropping systems tend to become specialized, with fewer crops grown in the areas where it is most efficient to produce them.

29 Changes in California Agriculture since 1950 (Alston & Zilberman, 1998) Between 1949 and 1991, a 218 % increase in California s agricultural output has occurred, with only a 58 % increase in inputs of all kinds. This means that productivity doubled over those 42 years.

30 Growth in California s agricultural output (%) YEAR Field Crops Vegetables Fruits & Nuts Rate From , these rates fell by approximately 50% ---Alston and Zilberman, 2003

31 Biofuel Feed Stocks The most likely crops for shorter term use in CA are the ones used elsewhere: Corn, sorghum, (wheat and other small grains), oilseeds (canola, safflower, camelina, soybean(?) ) Sugar crops might be viable in the Imperial Valley (sugar cane + beet + sweet sorghum). In the longer run, cellulosic sources from crop residues like straw and stover and the production of perennial grasses for biomass may be viable in California. Many growers would like to reduce their input costs for fuel or stabilize its price.

32 Biofuel Feed Stocks The most likely crops for shorter term use in CA are the ones used elsewhere: Corn, sorghum, (wheat and other small grains, oilseeds (canola, safflower, camelina, ) Sugar crops might be viable in the IV (cane + beet + sweet sorghum). In the longer run, cellulosic sources from crop residues like straw and stover and the production of perennial grasses for biomass may be viable in California. ALL OF THESE CROPS AND CROP RESIDUES ARE PART OF CROP ROTATIONS AND CROPPING SYSTEMS

33 Imperial Valley Mexico

34 Desert Sky Farms, Imperial Valley, July harvest t/ha, 15.3 % sucrose, 22.6 t sugar/ha 75 cm

35 50 Imperial Valley ( ) Root yield (t/ac) root yield sugar % Sugar % Year 0

36 80 Imperial Valley mt/ha July Root yield (t/ac) April N rate (lb/ac)

37 Sugar beet yields in the Imperial Valley 80 Krantz & MacKenzie (1954) MacKenzie et al (1957) Loomis et al (1960) Hills et al (1980) Kaffka & Meister, 2004 Root yield (t/ac) N rate (lb/ac)

38 Imperial Valley Tile lines Salinity affecting sugarbeet stand establishment and crop growth

39 Relative salt tolerance of sugarbeet 100 Ayers and Westcot, 1979 Relative sugarbeet yield a = maximum ECe at which Y = 100% (7.0) b = rate of decline (5.9) Y = 100-b(EC e -a) ECe (ds/m)

40 Yield monitor and GPS in use at harvest Load cell GPS unit

41 IV , Sugar beet yield map (t/ac). Yield declined with increasing salinity N Head end

42 Returns over variable costs 44.3/$522 Sample locations 38/$ /$ /$ /-$ /-$ /-$349.5

43 Precision agriculture: Profit or loss (IV,2001) Strategy Reduce area farmed Farm entire field Difference Sugar sales ($/ha) 3, Profit or loss ($/ha) %, $83.55/t Farming less land is more profitable and resource use efficient

44 Drip irrigation Conservation tillage Biotechnology

45 Safflower and Residual Nitrogen Management Stephen Kaffka, Elias Bassil, Bob Hutmacher Plant Sciences, UC Davis

46 Residual Available Soil Moisture at Harvest (%) Soil Moisture Use and Soil Depth 1.1 m 2.2 m Soil Depth (ft) Capay soil Yolo soil (Henderson data) 3.3 m

47 Cotton Treatment (kg N ha -1 ) Safflower Seed Yield (kg ha -1 ) Pre-plant residual N, R 2 = 0.93 N applied to cotton, R 2 = 0.73 Safflower following many years of cotton fertilizer trials. No fertilizer N was added to safflower in this trial Pre-plant residual NO3-N (mg/kg)

48 Change in soil NO3-N during growth (mg/kg) kg N 230 kg N 50 Depth (cm) Pre-plant 250 Post harvest 300

49 Modeled and literature values for N 2 O emissions modeled data literature data crop modeled N 2 O measured N 2 O emission emission site (g N 2 O-N ha -1 yr -1 ) location (g N 2 O-N ha -1 yr -1 ) reference corn Field ± 0.7 Belgium 1.5 Goossens et al. (2001) Five Points 0.6 ± 0.3 Germany 2.1 Mogge et al. (1999) LTRAS 3.0 ± 0.1 Madison, USA Cates and Keeney (1987) Colorado, USA 4.0 Hutchinson and Mosier (1979) Costa Rica 7.1 Weitz et al. (2001) France 11.0 Jambert et al. (1997) cotton Five Points 3.6 ± 0.2 Australia Rochester (2003) Australia 1.2 Rochester et al. (1994) Pakistan 3.6 Mahmood et al. (2000) sunflower Field ± 0.7 Germany Flessa et al. (1995) tomato Five Points 4.4 ± 2.1 Northern China 5.5 He et al. (2007) LTRAS 4.2 ± 0.4 SAFS 2.1 ± 0.4 wheat Field ± 0.2 Germany Flessa et al. (1998) SAFS 1.9 ± 0.5 Germany 1.0 Kaiser and Heinemeier (1996) Germany 3.5 Kaiser et al. (1998) DeGryze et al., submitted,

50 More diverse crop rotations that use biofuel crops may have beneficial effects on agricultural sustainability. In California, crops like safflower and other oil seed crops can play beneficial roles in crop rotations. In the Midwest, where simplified corn/soybean rotations dominate, many agronomists have argued for the agroecological benefits of adding perennial grasses that could be used for biofuel production to crop rotations.

51 Kruseman et al., 1996 Equity Agroecological sustainability Economic efficiency Policy level Consumption Reproduction of the resource base Production Farm Level Changes in natural resources Field level

52 Social and global-scale objections to biofuels Food vs Fuel Land Use Change Agricultural intensification and its environmental consequences Free trade effects on local economies

53 Land clearing for crop production in the tropics

54 By producing biofuels on cropland, the demand for unplanted food crops must be met by producing it on land elsewhere. This displaced food production could lead to significant green house gas emissions and other environmental effects elsewhere from land conversion. These emissions are not compensated by carbon savings from biofuel use. Searchinger et al. 2008, Kammen et al., 2007

55 Some problems with assessing and valuing Land Use Change in remote locations Difficult to quantify and involves value judgments. Unreasonable to ascribe to biofuel production alone in many instances, because cropping systems have diverse, integrative effects. These will be site specific. Models used to estimate LUC were not designed for the purpose to which they are now applied. (Powerful economic forces and human well-being drive the conversion of land. Tropical LUC changes attributed to biofuel production may not be due to biofuel production at all). Not all conversion is destructive or the least bad alternative. Does not account for new crops, new cropping systems, new technology and their interaction. It s use for standards may preclude much beneficial development, especially, but not only in poor areas of the world, and may conflict with other legitimate public policy goals. For unique reasons, LUC will not apply to CA grown feed stocks.

56 Retired land in the western San Joaquin Valley

57 WSJV on left; ESJV on right About 25 miles south of Mendota

58 Within-valley (mid-term) solutions to the salinity/drainage problem Land-retirement Waste water treatment Evaporation ponds Modification of irrigation and drainage practices Reuse of drainage water Evaporation pond in the San Joaquin Valley

59

60 Kings Co Darker color = greater salinity D. Corwin

61 On a high SAR soil, using moderate EC w irrigation water (2 to 8 ds m -1 ), no infiltration and drainage problems have been observed where forages have been able to grow during the last seven years. Leaching and reclamation are occurring.

62 California has recently adopted a low carbon fuel standard that may require the use of biomass for transportation fuels, and related measures to reduce green house gas effects. The crops discussed are examples of those that would be good biofuel feedstocks. There is little surplus land and water for biofuel feedstock production in California. Lands in the WSJV coupled with drainage and other waste water use provide possible locations for biofuel feedstock production.

63 Biofuels in California Can (should) biofuels be produced in California? Yes For purpose-grown crops: where increasing returns to total factor productivity continue to occur. For crops and cellulosic feed stocks: where multiple environmental objectives can be satisfied simultaneously.

64 Can we produce biofuels in California from crops and crop residues? We should consider the sustainability of biofuel production from the start. We will know most about in-state conditions and can have the greatest confidence about our assumptions for CA feed stocks. This might provide an additional value for feed stocks produced within CA. CA should not export its pollution.

65 Biofuels and sustainability But, we should: Be humble, expect mistakes Go slow Use a light touch...try not to constrain innovation, be willing to make prudent tradeoffs Gradually increase sustainability requirements as knowledge and public consensus improves. Make sure the public agrees (legitimacy).