Opportunities for avoidance of land-use change through substitution of soya bean meal and cereals in European livestock diets with bioethanol coproducts
R. M. Weightman, tel. +44 1954 267 666, fax +44 1954 267 659, e-mail: Richard.firstname.lastname@example.org
An analysis is presented which quantifies the potential for distillers dried grains with solubles (DDGS, a coproduct of wheat bioethanol production) to replace soya bean meal (SBM) and cereals in livestock rations. A major proportion of the SBM imported into Europe as a protein-rich feedstuff for livestock comes from South America, where land-use change (LUC) is associated with high carbon emissions. Production of DDGS can therefore reduce LUC in South America by substitution of SBM in animal feed. The analysis indicates that a single bioethanol distillery processing 1 million tonnes of wheat, and producing ca. 330 000 tonnes of DDGS per annum, would substitute at least 136 493 tonnes of whole soya beans grown on 47 725 ha of land, and save greenhouse gas emissions equivalent to 0.63 million tonnes CO2 per annum. By growing sugar beet and wheat in an average ratio of 0.06 : 0.94 on 1 ha of land in Europe, the net area of agricultural land required to produce feed ingredients equivalent to 6.08 t of sugar beet pulp (SBP) and 1.72 t of DDGS associated with 2363 L of bioethanol, is reduced to 0.40 ha. This accounts for 0.42 ha of soya that is not required when DDGS displaces SBM, and 0.18 ha of wheat that is not required when DDGS and SBP displace wheat in livestock rations.
Greenhouse gas emissions (GHG) reduction is the main driver for biofuels development in the European Union (EU) with a target originally set in the Biofuels Directive (2003/30/EC) of a 5.75% inclusion of biofuel by volume in the road transport mix by 2010 (EU, 2003). In recognition of sourcing biofuels in a sustainable way, the Renewable Energy Directive (RED; 2009/28/EC) specifies the level of GHG savings to be expected. Guidelines are available in the RED (Annex V) which state default values for various biofuel supply chains to be used for reporting, in the absence of specific data from individual fuel suppliers (EU, 2009).
Following initial broad support for biofuels, Searchinger et al. (2008) raised important questions over the indirect land-use change (ILUC) associated with biofuel production, suggesting that using cereal grains such as maize in the United States, would lead to conversion of land elsewhere in the world in order to grow the food crops which had been displaced. If this conversion of land took place on high carbon stock land (for instance forest or permanent pasture) then their conversion to crop land would be associated with release of significant quantities of carbon into the atmosphere which would negate the potential GHG savings associated with any biofuel. Searchinger's analysis led to the so-called ‘Gallagher review’ in the United Kingdom, which led to a reduction in the 2010 target for the inclusion of biofuel in road transport fuel to 3.5% (Gallagher, 2008).
An economically important coproduct of bioethanol production from cereals, accounting for around one-third of the dry matter of the initial grain in the case of wheat, is distillers dried grains and solubles (DDGS), a protein-rich animal feed containing ca. 33 g crude protein 100 g−1 (Smith et al., 2006; Cottrill et al., 2007). In response to Searchinger's analysis, Croezen & Brouwer (2008) suggested that wheat (W-) DDGS produced in Europe would substitute locally produced wheat and maize, but also soya bean meal (SBM) originating in South America. Other protein-rich coproducts include vinasse (up to 35 g 100 g−1; Stemme et al., 2005) originating from spent yeast cells and unfermented sugars during production of bioethanol from beet sugar. This fraction is often added back to the sugar beet pulp (SBP) to give a feed which has a crude protein content in the range 10.6–13.5 g 100 g−1 (Ministry of Agriculture Fisheries & Food, 1975). For convenience in this paper, the SBP and vinasse have been considered together as a single product.
Soya beans are grown principally for the defatted SBM, with the oil as a secondary product (LMC International Ltd., 2006; Steinfeld et al., 2006). Dros (2004) forecasted the continued expansion of soya cropping in South America under a ‘business as usual scenario’ with soya cropping encroaching on both natural habitats and existing pastures, while pushing cattle ranchers into forest areas. Lapola et al. (2010) have described soya expansion replacing pasture in Brazil, with a resultant effect of pushing the boundaries of pasture into existing Amazonian forest. Therefore, given the environmental costs of soya bean production associated with extensive deforestation (Dros, 2004; Gasparri et al., 2008; Gasparri & Grau, 2009) as well as conversion of habitats such as cerrado and pasture (Sampaio et al., 2007; Morton et al., 2006; Zak et al., 2008) the displacement of SBM by W-DDGS and other protein-rich coproducts means that bioethanol production could be seen as one mechanism by which to avoid damaging land use. In this context, the potential benefits of bioethanol coproducts in Europe have not been thoroughly quantified, although Özdemir et al. (2009) have described the potential to avoid deforestation in Brazil based on the substitution of SBM with rapeseed meal. In addition to reducing the pressure on LUC in South America through substitution of soya, additional substitution of a proportion of the cereals in the diet by DDGS and by SBP, will at the same time remove some of the risk of ILUC from using cereals for biofuel production.
The value of coproduct credits, which can be used in the calculation of GHG savings from bioethanol production, are estimated using a proportional allocation method and have been discussed by Punter et al. (2004) and Edwards et al. (2006). In the European Joint Research Centre (JRC) (2007) report, the proportional allocation of SBM by wheat DDGS was based on a theoretical substitution ratio of 0.78 t SBM t DDGS−1, a value derived from the relative protein contents of 49 g 100 g−1 for SBM and 38.5 g 100 g−1 for W-DDGS. For SBP with vinasses added, it is assumed that 1 MJ dry SBP replaces 0.83 MJ of dry wheat grain based on their similar protein contents (JRC, 2007). In commercial practice; however, the achievement of full substitution of soya with coproducts will also be influenced by the inclusion levels of the coproduct in the diet for different species (Bremer et al., 2010), and limited by competition with other commodities available as cheaper ingredients in a least cost ration formulation (LCRF) system.
While proportional allocation is not proposed as a methodology for calculation of coproduct credits within the RED, determination of an appropriate substitution ratio is very relevant to quantifying the amount of SBM which will be displaced by bioethanol coproducts, and hence to what extent ILUC might be mitigated by biofuel production in Europe.
In order to test the hypothesis of Croezen & Brouwer (2008), it was therefore necessary to clarify and quantify certain elements of the SBM supply chain into the EU27 particularly (i) the proportion of substitution of DDGS for SBM in typical livestock diets, (ii) the proportion of EU27 SBM imports which are supplied by South American soya, (iii) the types of habitat which are being used for the production of SBM in the countries of origin within South America, (iv) the carbon stocks associated with those habitats, and (v) assumptions about the allocation of carbon stock loss to soya cropping following LUC.
The aim of the present study was to consider each of these elements, and to build an additional calculation of a coproduct credit based on avoidance of LUC, soya production and hence carbon emissions in South America, which could be allocated as a saving to W-DDGS produced in the EU, and to consider the implications for substitution of cereal grains and by-products by both DDGS and SBP.
Quantification of soya imports into EU27 and countries of origin
Volumes of annual soya imports into the EU27 for two commodity groups relating to soya were collated for the period 1999 to 2008 from the Eurostat database (http://epp.eurostat.ec.europa.eu; accessed on September 29, 2009) and classified as follows:
- 1Whole soya beans (excluding those for sowing),
- 2SBM: Oilcake and other solid residues, whether or not ground or in the form of pellets, resulting from the extraction of soya bean oil.
The volumes of SBM were converted to whole soya bean equivalents (WSBe). Typical soya bean seed oil content is 20% (Weiss, 1983; Robinson, 1987) and therefore assuming a SBM yield of 80% from whole soya beans, the WSBe was estimated as 1/0.8 or 1.25 times the weight of SBM imported. Soya bean imports as total WSBe were therefore estimated as follows:
Wheat, sugar beet and soya bean yields, production and areas harvested were collated from the FAO statistical database, FAOStat (http://faostat.fao.org; accessed on March 4, 2010). Soya was identified using the FAO classification ‘Soybeans’.
Allocation of habitat undergoing deforestation and estimation of carbon stocks
Descriptions and areas of habitats undergoing deforestation in three South American Countries (Argentina, Brazil and Paraguay) to 2020 were taken from the scenarios described by Dros (2004). These habitats were linked to climate region classifications for soil organic carbon stocks to 30 cm depth as defined in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 4, Agriculture Forestry and Other Land Use (IPCC, 2006; table 2.3), except in the case of Atlantic Forest, Chaco and Yungas Forests in Argentina, where data for soils to 20 cm depth (Gasparri et al., 2008) were used and in the case of cerrado soils to 40 cm depth in Brazil (Corbeels et al., 2006) were used. Aboveground biomass estimates in the selected habitats were collated from values given by IPCC (2006; table 4.7) and the carbon in aboveground biomass for each habitat type was then estimated using a default value of 0.47 for the fraction of carbon in the biomass (IPCC, 2006; table 4.1). Root carbon stocks were estimated from the aboveground biomass, using ratios of belowground to aboveground biomass given by IPCC (2006; table 4.4). The total carbon stock per hectare of land was then estimated as the sum of the soil, root and aboveground carbon.
Estimation of carbon losses following deforestation
Following deforestation, it was assumed that all root and aboveground carbon was lost. The soil carbon was assumed to reduce to a constant after 20 years, based on a stock change factor for long term cultivated tropical soils, using values of 0.48 for moist/wet soils and 0.58 for dry soils (IPCC, 2006; table 5.5). The difference between the initial (i.e. total) and the final soil carbon values represent the soil carbon loss. The total carbon loss (soil+root+aboveground vegetation) was allocated to the subsequent cropping activities, and annualized over 20 years. The annualized losses for each habitat expressed as CO2e ha−1 were estimated from the carbon values, using a multiplier of 3.67.
Proportion of substitution of SBM by W-DDGS in livestock diets
In order to estimate the typical inclusion levels and substitution ratios of DDGS for SBM in commercial practice, a LCRF approach was used (data presented in Supporting Information Table S1) using ingredient prices in October 2009. For each livestock grouping studied, test diets including W-DDGS were compared with a control diet with no W-DDGS, and containing a typical amount of SBM. For pigs, the control diet contained 132 g SBM kg−1, and a number of runs were created, each representing a weighted average of 11 pig feeds representing both home-mix and compound diets, with maximum W-DDGS levels (in parentheses) set for different body weights and diet types as follows: 15–30 kg (50 g kg−1), 30–65 kg (100 g kg−1), 65 kg finishers (150 g kg−1), lactating sows (200 g kg−1), sows (250 g kg−1). For a typical diet containing W-DDGS introduced at 62 g kg−1, the substitution ratio was 0.35 t SBM t DDGS−1. For ruminants, the control diet contained 71 g SBM kg−1, and two runs were created, each representing a weighted average of 20 dairy, calf, beef and sheep feeds. The average ruminant test diet incorporated W-DDGS at an inclusion level of 45 g kg−1, determined by setting the W-DDGS price at the same level used in the pig test diets, and the substitution ratio was 0.26 t SBM t−1 DDGS. The LCRF takes into account the levels of digestible essential amino acids and energy concentrations in the case of nonruminants and metabolizable protein in the case of ruminants, as well as the digestibility of other key ingredients including phosphorus and micro-nutrients. For poultry diets incorporation rates of 65 g kg−1 were used, based on the example reported by Lywood et al. (2009) with a substitution ratio of 0.56 t SBM t−1 W-DDGS.
Potential inclusion rates of W-DDGS differ both between livestock categories (pigs, poultry and ruminants) and types of livestock within categories. In order to estimate the impact of W-DDGS on SBM use as a whole, the relative numbers of livestock units (LSU; reflecting the feed requirements of each individual animal category) in the EU27 in 2007 were collated from Eurostat. By combining the proportions of LSU for pigs, poultry and ruminants with the typical inclusion rates for W-DDGS for each livestock type, weighted average inclusion rates and substitution ratios for EU livestock diets were calculated.
The above scenario reflects the commercial position at the time of the study. In order to estimate the impact of W-DDGS on SBM in a future scenario, an assumption was made that W-DDGS would be included in more nonruminant than ruminant diets. It was also assumed that higher inclusion levels of W-DDGS, and higher substitution rates of SBM would be achieved in the future. The amounts of compound diets produced in Europe in 2007 were collated from the European Feed Manufacturers Association (FEFAC, 2009), and the potential substitution rates taken from Lywood et al. (2009). By combining the volumes of the different diet types produced in Europe with the typical inclusion rates for W-DDGS for each livestock type, weighted average inclusion rates and substitution ratios for future EU livestock diets were calculated.
Allocation of carbon losses following deforestation and soya cropping to DDGS and bioethanol production
Using the individual estimates of carbon losses associated with soya production collated above, the following approach was taken to allocate these as credits for W-DDGS production, where W-DDGS displaces SBM from EU livestock diets:
- 1Carbon emissions (t C ha−1) in the key South American countries (Argentina, Brazil and Paraguay) supplying the EU27, following deforestation attributed to subsequent soya cropping were expressed as t CO2e ha−1,
- 2The emissions in terms of CO2e/ha were expressed per tonne of soya, based on national yields of soya per hectare,
- 3The emissions in terms of t CO2e t WSBe−1 were reduced pro rata, according to the proportions of soya imported into Europe from Argentina, Brazil and Paraguay,
- 4The emissions of CO2e associated with soya production were expressed as a credit per tonne of W-DDGS, based on the average substitution ratio of DDGS for SBM estimated from LCRF across livestock types, and the proportion of livestock diets in Europe,
- 5The credit calculated in (4) was reduced by a factor of 0.2 based on mass of products, to account for the fact that some soya beans would still need to be grown to supply oil for existing markets,
- 6The credit in g CO2e kg DDGS−1 was expressed per kg of ethanol, based on a ratio of 1.14 kg DDGS (fresh weight basis) per kg ethanol from a UK wheat-bioethanol distillery (Renewable Fuels Agency, 2008) and also expressed per MJ of energy, based on the energy content of ethanol (26.72 MJ kg−1).
Results and Discussion
The EU27 imported 15.2 Mt of soya beans and 23.6 Mt of SBM in 2007 (Table 1), equivalent to an original production of ca. 45 Mt of whole soya beans per annum in the countries of origin. Three South American countries, Argentina (Ar), Brazil (Br) and Paraguay (Pr) account for the majority (0.89) of the soya imports into the EU27. Conversely, when the production of soya beans in these countries is examined, it is seen that 0.39, 0.25 and 0.18 of the total soya beans produced in Ar, Br and Pr, respectively, are exported to supply the EU market (Table 2).
Table 1. Imports of whole soya beans and soya bean meal (SBM) into the EU27 by country of origin in 2007, converted to total WSBe
|Argentina||312 895||14 642 501||18 303 126||18 616 020||0.420|
|Brazil||9 492 855||8 515 963||10 644 953||20 137 808||0.450|
|Canada||797 744||6079||7598||805 342||0.018|
|China||21 378||25 745||32 181||53 560||0.001|
|Norway||0||155 168||193 960||193 960||0.004|
|Paraguay||1 046 466||1174||1467||1 047 933||0.023|
|Russia||0||14 494||18 118||18 118||<0.001|
|Ukraine||143 678||0||0||143 678||0.003|
|USA||3 275 657||150 447||188 059||3 463 715||0.078|
|Uruguay||79 261||2100||2625||81 886||0.002|
|Others||40 482||30 374||37 968||78 450||0.002|
|Total||15 210 424||23 551 222||29 439 028||44 649 452||1.000|
Table 2. Production, areas harvested and yields of soya beans in 2007, and proportion of each countries total production supplying the EU27 market
|Argentina||47 482 784||0.392||15 981 264||2.97|
|Brazil||57 857 200||0.348||20 565 300||2.81|
|Canada||2 695 700||0.299||1 171 500||2.30|
|China||13 800 147||0.004||8 900 068||1.55|
|India||10 968 000||0.001||8 880 000||1.24|
|Paraguay||5 856 000||0.179||2 429 000||2.41|
|Russian Federation||651 840||0.028||709 900||0.92|
|Ukraine||722 600||0.199||583 100||1.24|
|USA||72 860 400||0.048||25 960 000||2.81|
|Uruguay||779 920||0.105||366 535||2.13|
Dros (2004) predicted the continued expansion of soya in four key South American producing countries assuming a ‘business as usual’ scenario, including expansion of the global production for soya beans to 300 Mt, and a continual increase in soya bean yields based on historic trends. Excluding Bolivia (which was included in Dros' analysis but currently does not export to the EU27) the areas and types of habitat predicted to be deforested in Ar, Br and Pr are shown in Table 3.
Table 3. Habitat types and areas subject to land use change associated with expansion of soya 2004–2020 forecasted by Dros (2004)
|Argentina||Atlantic Forest||300||18 750||0.06|
|Transition and rainforest||3600||225 000||0.27|
|Paraguay||Atlantic Forest||1000||62 500||0.53|
|Total|| ||20 450||1 278 125|| |
The assumptions made in the present study rely heavily on figures from Dros (2004) forecasting an increase in soya production driven by external demand. These figures are broadly corroborated by other sources e.g. LMC (2006) who forecast 221 million tonnes supply of SBM equivalent to 278 Mt of WSBe by 2020, the Food and Agricultural Policy Research Institute (FAPRI) (2009) who forecast production of 295 Mt of soya in 2018 (applying an annual growth rate of 2% the estimate reaches 307 Mt by 2020), and the Organisation for Economic Co-operation and Development (OECD) (2009) who forecast 407 million tonnes of oilseeds by 2018, which assuming soybeans account for 74% of total oilseed production (based on soya bean, rapeseed and sunflower production in 2007; FAOStat) gives an expected world production of 301 million tonnes of soya beans in 2018, and ca. 312 Mt by 2020.
Given that world soya bean production is therefore expected to increase from 214 Mt in 2005 (FAOStat) to ca. 300 Mt, an average increase of 5.7 Mt yr−1 implies an increase in the world area sown to soya of ca. 2.4 Mha yr−1 (allowing for an annual yield increase of 0.02 t ha−1 yr−1 based on yield trends over the last decade; FAOStat). In this context the estimates from Dros (2004) for annual soya expansion in Ar, Br and Pr of 1.2 Mha yr−1 (Table 3) appear realistic. Similarly, based on historical production trends between 1998 and 2007 (FAOStat), the average annual increase in the area of soya harvested has been 0.96, 0.91 and 0.15 Mha yr−1 for Ar, Br and Pr, respectively (total 2.02 Mha yr−1). Therefore given that both historic trends in expansion of soya area and forecasted soya production increases broadly support the continued demand for land presented by Dros (2004), these figures were used to estimate the effects of LUC from deforestation and conversion of cerrado.
The carbon stocks associated with the various habitat types are shown in Tables 4–6 (soil, aboveground and root carbon, respectively). In each case, a high and low estimate is given from IPCC figures, and either a mid-point value chosen for further calculations, or where available, specific values from Gasparri et al. (2008) and Corbeels et al. (2006) have been used. Based on the losses of carbon from soil (using a stock change factor) and assuming all aboveground and root carbon lost, the annualized emissions are shown in Table 7. Based on the carbon loss for each habitat type and the proportion of each habitat within each country (Table 3), the 20-year annualized emissions could be allocated to each country studied (Table 8). Using the yields of soya (Table 2), annualized carbon losses were then converted to emissions per tonne of soya as WSBe produced by each of the three countries, and using the proportion of EU27 imports coming from each of the three countries (Table 2). Finally an average figure for total CO2 emissions associated with deforestation and expressed per tonne of soya entering the EU27 could be estimated. However, it is acknowledged that while SBM is the major product from soya beans, by reducing soya production, there would also be a parallel loss of the soya oil which currently supplies world markets, principally for food use and to a lesser extent biodiesel. This potential deficit in vegetable oil from South America might therefore have to be supplied from other crops e.g. oilseed rape, groundnut, sunflower and palm, each with differing yields of oil per unit area and different effects on LUC. Lapola et al. (2010) have suggested as an alternative to soya biodiesel, that palm oil production would be associated with the smallest LUC. It is not possible to state categorically which cropping systems would expand in response to a reduction soya oil, therefore for simplicity it was decided to reduce the coproduct credit by 0.2 (based on the oil content of soya beans by mass) reflecting the fact that a replacement vegetable oil would need to be supplied somewhere in the world and this could easily be in South America. This analysis gives a GHG emissions balance associated with soya imported into the EU27 of 4.62 t CO2e t WSBe−1 (Table 8). A further reduction in the coproduct credit could also arise from considering the oil content of soya bean on an energy or economic basis, rather than by mass. Modelling the demands for, and relative prices of commodities, was beyond the scope of this paper and may be worthy of further study.
Table 5. Estimates of aboveground carbon in five different habitat types in Argentina, Brazil and Paraguay
|Argentina||Atlantic Forest||280||210||303||0.50||152||Gasparri et al. (2008)|
|Chaco||280||210||96||0.50||48||Gasparri et al. (2008)|
|Yungas||280||210||233||0.50||117||Gasparri et al. (2008)|
|Brazil||Cerrado||90||40||37||0.47||17||Corbeels et al. (2006)|
|Transition and rainforest||400||120||300||0.47||141||Tropical rainforest|
|Paraguay||Atlantic Forest||280||210||220||0.47||103||Subtropical humid forest*|
|Chaco||410||200||210||0.47||99||Subtropical dry forest*|
Table 6. Estimates of root carbon in five different habitat types in Argentina, Brazil and Paraguay, estimated from aboveground carbon and the ratio of belowground biomass to aboveground biomass (R)
|Argentina||Atlantic Forest||0.24||0.20||0.20||30.0||Gasparri et al. (2008)|
|Chaco||0.24||0.20||0.23||11.0||Gasparri et al. (2008)|
|Yungas||0.24||0.20||0.19||22.1||Gasparri et al. (2008)|
|Brazil||Cerrado||0.40||0.40||0.40||7.0||Corbeels et al. (2006)|
|Transition and rainforest||0.37||0.37||0.37||52.2||Tropical rainforest|
|Paraguay||Atlantic Forest||0.33||0.22||0.24||24.8||Subtropical humid forest†|
|Chaco||0.28||0.27||0.28||27.1||Subtropical dry forest†|
Table 7. Estimated total carbon losses following change in land use of five different habitat types in Argentina, Brazil and Paraguay
|Transition and rainforest||45.2||238||874||43.7|
Table 8. Estimated total carbon losses (as CO2 equivalents) associated with land-use change expressed per tonne of soya, from Argentina, Brazil and Paraguay, for whole soya bean equivalents (WSBe) imported into the EU27
|Chaco||12.0|| || || || |
|Yungas||1.2|| || || || |
|Transition and rainforest||11.9|| || || || |
|Paraguay||Atlantic Forest||15.4||28.0||11.61||0.19|| |
|Chaco||12.6|| || || || |
Before these carbon emissions associated with soya can be attributed as a credit to DDGS, the proportion of SBM which will be substituted by W-DDGS across the European livestock industry needs to be estimated. In practice, the amount of soya which is displaced depends on the other protein-rich ingredients available for ration formulation, their relative prices, the composition of up to 20 nutrients (including the different fiber fractions and essential amino acids), and limits set on maximum inclusion for W-DDGS and other ingredients in diets for the different livestock types. Özdemir et al. (2009) stated that DDGS will principally replace cereals and not oilseed meals because of the low protein content of DDGS. However, Özdemir et al. appear to classify DDGS alongside low protein (60–150 g kg−1) feeding stuffs, whereas the protein content of DDGS is nearer 350 g kg−1, and Lywood et al. (2009) show that the digestible crude protein content of DDGS is slightly higher than that of rapeseed meal across the three major livestock categories. In reality DDGS is likely to replace a mixture of both cereals and oilseeds (Croezen & Brouwer, 2008). In order to model current scenarios, a pragmatic approach was therefore taken by examining the introduction of W-DDGS into different UK livestock diets containing SBM. The inclusion levels under the current scenario in Table 9 may appear conservative. Undoubtedly, the production of W-DDGS on a large scale from an EU bioethanol industry will increase the amount of W-DDGS in the market, but its use will be determined by the availability and price of other feeds against which it competes. In the case of the livestock types and diets above, it would be possible to force more W-DDGS into the diet to simulate this effect, but in reality, the effect of forcing more W-DDGS into the diet would be to lower the SBM : W-DDGS substitution ratio. This is because feed materials other than soya e.g. barley together with other high protein materials such as rapeseed meal, would be forced out of the diet in order to maintain the correct levels of essential nutrients. It is not possible to say precisely in which livestock diets the displaced ingredients will ultimately be found, because of the dynamic effects of the price availabilities of the other feed materials.
Table 9. Calculation of coproduct credit allocation to DDGS and wheat-bioethanol based on current and future substitution ratios in EU livestock rations
| Average|| || ||0.33||0.41||1912||2180||82|
|Future high usage scenario|
| Average|| || ||0.60||0.76||3495||3984||149|
By combining these inclusion limits and substitution ratios with the production volumes of compound feeds per livestock type in the EU27, it was possible to calculate a weighted average substitution ratio across livestock types (0.33; Table 9). Combining this average substitution ratio with the carbon cost per tonne of WSBe from Table 8, it was possible to estimate a coproduct credit of 1912 g CO2e kg W-DDGS−1, or 82 g CO2e MJ bioethanol−1 (Table 9). This is a factor of 1.8 greater than the GHG savings from wheat bioethanol of 45 g CO2e MJ−1 stated in the RED (EU, 2009). It should be noted that the aim of the present analysis was not to revisit the estimation of GHG emissions associated with the whole supply chain (growing, transport, production and processing components) for bioethanol from wheat and sugar beet, as these have been adequately described elsewhere (JRC, 2008) and are now incorporated into sustainability and reporting guidelines (EU, 2009). Rather the aim was to quantify a coproduct credit based on substitution of soya with W-DDGS which is additional to the net savings used as current default values for wheat bioethanol.
The inclusion limits for all livestock categories are expected to increase in the future, as larger volumes of more consistent W-DDGS are produced by the biofuels industry, and confidence is gained from further nutritional research. However at the present time, inexperience and variability of DDGS from traditional (nonbiofuel) coproducts has tended to limit inclusion levels. In order to consider future potential, an additional scenario was studied using the same methodology as above, but using the higher substitution ratios (Lywood et al., 2009), an assumption of greater usage of DDGS in nonruminant livestock diets (based on the current proportions of compound feed manufactured in Europe) and acceptance of higher inclusion levels of W-DDGS in the diet. Such a scenario assumes that as the biofuels industry develops in Europe, and more nutritional research is carried out on bioethanol coproducts, this will give greater confidence to the animal feed industry, and more W-DDGS will be incorporated into rations. Using this future scenario gave a coproduct credit of 3495 g CO2e kg W-DDGS−1 (Table 9).
An important observation resulting from the use of LCRF is that other feed ingredients and in particular cereal grains and milling coproducts and some oilseeds, are also substituted from the diet by DDGS in addition to SBM (Table S1). Similarly, SBP can also be considered to displace wheat from certain animal diets (Lywood et al., 2009). Thus the use of bioethanol coproducts can release land which might otherwise be used to produce livestock feeds, thereby reducing the impact of ILUC. Table 10 shows different scenarios for net land area required to grow 1 ha of bioethanol feedstock crops (wheat and sugar beet) in Europe, taking account of land made available for other uses because of the use of the major bioethanol coproducts, W-DDGS and SBP. It can be seen that using the average relative proportions of wheat and sugar beet found in the rotation (0.94, 0.06; FAO Statistics 2006–2008 for EU27) the bioethanol coproducts from 1 ha of land will displace cereals from livestock diets releasing an additional 0.18 ha of land growing wheat, together with 0.42 ha of soya land displaced in South America giving a net land area requirement of 0.40 ha per ha of bioethanol feedstock crops. Taking into account the typical GHG savings from wheat and sugar beet bioethanol (JRC, 2008; EU, 2009) and adding to these the coproduct credit estimated in Table 9, conversion of the feedstock from 1 ha of land in the EU would be associated with GHG savings of around 115 g CO2e MJ−1 bioethanol produced.
Table 10. Estimation of net land area requirement and ethanol output from 1 ha of land in Europe, growing variable proportions of wheat and sugar beet
If the higher yields representative of NW Europe are used (SBP 6.47 t ha−1 and wheat 7.75 t ha−1), the land area equivalent displaced by soya increases to 0.62 ha, and the net land area is reduced to 0.22 ha. With a higher proportion of sugar beet in the rotation, the net land area decreases as the equivalent land area of wheat diminishes (and at the same time the amount of ethanol produced increases). The intermediate scenario in Table 10 (relative areas; 0.90, 0.10) represents the rotational situation in Germany based on FAO Statistics. For a high sugar beet frequency scenario, the inclusion of 0.25 ha sugar beet in the rotation potentially enables a higher ethanol yield per hectare (3141 L ha−1) than growing 1 ha of wheat alone (2118 L ha−1) and results in a reduction in the net area of wheat to 0.40 ha and the net effective area of total land to 0.32 ha (Table 10). It is unlikely that sugar beet would be grown at levels higher than 0.25 in the rotation for agronomic reasons.
This analysis illustrates that when taking into account the substitution of other feed ingredients by biofuel coproducts, bioethanol produced from wheat and sugar beet in the EU27 has the ability to make more efficient use of existing arable land within Europe, while at the same time reducing the pressure on high carbon stock land outside Europe and delivering significant GHG savings from substitution of fossil fuels.
The authors would like to thank Mick Hazzledine of Premier Nutrition for running the least cost ration formulations, and Santiago Véron and José Volante of INTA for information on soya bean rotations in Argentina.