Some ecological and socio-economic considerations for biomass energy crop production

Pergamon Biomass and Bioettergy Vol. 10. No. 4. pp. 231-242. 1996

Copyright G 1996 Elsevier Science Ltd

0961-9534(95)00072-O Printed in Great Britain. All rights reserved

0961-9534/96 $15.00 + 0.00

SOME ECOLOGICAL AND SOCIO-ECONOMIC CONSIDERATIONS FOR BIOMASS ENERGY

CROP PRODUCTION*

LAURA K. PAINE,? TODD L. PETERSON,~ D. J. UNDERSANDER,? KENNETH C. RINEER,~ GERALD A. BARTELT,~~ STANLEY A. TEMPLE,~ DAVID W. SAMPLE(~ and

RICHARD M. KLEMME** TUniversity of Wisconsin, Agronomy Department, 1575 Linden Drive, Madison, WI 53706, U.S.A.

fwisconsin Department of Natural Resources, Bureau of Wildlife Management, Box 7921, Madison, WI 53707, U.S.A.

SWisconsin Public Service Commission, Electrical Division, Hill Farms State Office Building, Box 7854, Madison, WI 53707, U.S.A.

11 Wisconsin Department of Natural Resources, Bureau of Research, 1350 Femrite Drive, Monona, WI 53716, U.S.A.

TUniversity of Wisconsin, Wildlife Ecology Department, 1630 Linden Drive, Madison, WI 53706, U.S.A.

**University of Wisconsin, Center for Integrated Agricultural Systems, 1535 Observatory Drive, Madison, WI 53706, U.S.A.

(Received 10 April 1995; revised 21 August 1995; accepted 28 August 1995)

Abstract-Power generation using biomass could provide substantial environmental and socio-economic benefits. Production of the feedstocks to fuel biomass power plants can either add to potential environmental gains or contribute to the environmental problems which the agriculture and forestry industries already face. Likewise, the biomass energy infrastructure can help strengthen agricultural economies or speed the decline of rural communities. The purpose of this paper is to suggest a regional approach to ensure that energy crop production will proceed in an ecologically and economically sustainable way.

At this juncture, we have the opportunity to build into the system some ecological and socio-economic values which have not traditionally been considered. If crop species are chosen and sited properly, incorporation of energy crops into our agricultural system could provide extensive wildlife habitat and address soil and water quality concerns, in addition to generating renewable power. We recommend that three types of agricultural land be targeted for perennial biomass energy crops: (I) highly erodible land; (2) wetlands presently converted to agricultural uses; and (3) marginal agricultural land in selected regions. Fitting appropriate species to these lands, biomass crops can be successfully grown on lands not ecologically suited for conventional farming practices, thus providing an environmental benefit in addition to producing an economic return to the land owner. Copyright 0 1996 Elsevier Science Ltd.

KeywordsBiodiversity; environmental effects; herbaceous energy crops (HEC); rural economies; short-rotation woody crops (SRWC); soil erosion; water quality; wildlife habitat.

1. INTRODUCTION

The combustion or gasification of biomass to generate electricity is a promising renewable energy option. Feasibility studies examining potential short-rotation woody crop (SRWC), herbaceous energy crop (HEC) species and the technology required to generate power from them have been ongoing for over a decade,‘-’

*This paper is an effort by an ad hoc group of scientists from a number of agencies and disciplines in Wisconsin. The contents represent the collective view of these scientists and do not represent policy of the respective agencies.

bringing biofuels closer to becoming economically competitive with conventional energy sources.

A 1993 report by the Union of Concerned Scientists4 suggests that biomass has the potential to provide significant amounts of electrical energy in the northcentral U.S. (Wisconsin, Minnesota, and Iowa in particular). In this area, which is highly dependent on fossil fuels imported from other regions, “home- grown” renewable power sources hold much appeal. Legislative and technological develop- ments on both state and federal levels have

232 L. K. PAINE et al.

come together to spur the growth of the biomass industry.

Across the U.S. there are many who believe that protecting the environment and the communities in which energy crops are produced is critical to the long-term sustainability of a biomass-based energy industry. The Audubon Society has begun a dialogue at the national level among environmentalists and power industry interests.5.6 One goal of this paper is to carry this dialogue to the local level with a statewide or regional model for a sustainable biomass energy industry. We do not propose to address technical or policy issues in this paper; rather, our purpose is to suggest an ecologically sound approach to the production of biomass energy crops.

An ecologically sound cropping system is one which is capable of sustaining a complex community of plant and animal life. By all measures, modern cropping practices have dramatically reduced the biodiversity of agricultural landscapes. Crop fields have replaced natural ecosystems such as prairies and forests, with simple monocultures of one or two plant species. Many wildlife species have been unable to adapt to the changes in their habitat, and dramatic reductions in the number of plant and animal species, major shifts in the types of species present, and reordering of the relationships among remaining species have resulted.7,B Use of appropriate plantation siting and native species when possible can enhance biodiversity in several ways: (1) improvement of overall environmental health through reduction of soil erosion and water pollution from farmland; and (2) introduction into the landscape of higher quality, more suitable habitat for many wildlife species.

2. BUILDING A SUSTAINABLE INFRASTRUCTURE

Whether it involves using waste biomass, such as lumber industry waste and crop residues, or dedicated energy crops, production of biomass feedstocks will have an impact on a large land area. Biofuel production, especially from dedicated energy crops, is likely to be regulated either within the context of existing forestry or agricultural laws or as a new land-based industry. If we can address soil erosion, water quality and wildlife habitat issues at the outset, perhaps the many serious problems and costly regulations facing other land-based industries

today can be avoided. Pro-active planning can maximize the potential benefits to the environment and to rural economies which are associated with producing many energy crop species.

2.1. Avoid feedstocks with environmental liabilities

All biomass feedstocks share the advantages of renewability and greenhouse gas emissions reduction (if they replace fossil fuels), as well as some liabilities, such as high levels of particulate emissions. However, biofuels vary in other environmental, economic and practical values. Because of greater environmental liabilities, caution should be used when considering the following:

??

0

??

??

2.2.

Municipal wastes. Questions have been raised concerning heavy metals and other toxins which can occur in municipal wastes and could be released into the atmosphere when the waste is burned.9~‘o Crop residues. A demand for crop residues for biofuel could reverse a current trend toward reducing tillage and leaving over- winter cover on erodible farmland. Re- moval of crop residues from the field encourages soil erosion and robs the soil of organic matter and nutrients contained in the removed residues.” Standing forests. Harvesting biofuel from standing native forests would increase pressure on this resource and the wildlife habitat it provides. Forests in the northcentral U.S. were almost completely logged in the late 19th and early 20th Centuries. Current efforts at developing a regional biodiversity plan for these areas could be jeopardized by increased harvest of regenerating forests.‘*. I3 Annual energy crops. Annual energy crops, such as sorghum, carry with them many of the erosion and water quality liabilities which are inherent in standard row crop production. Their production would provide few, if any, environmental or economic advantages over production of corn or soybeans.

Environmentally friendly biomass crops

Biomass fuel sources having a greater potential for sustainability than those listed above include waste wood and dedicated perennial energy crops. Waste wood from

Some ecological and socio-economic considerations for biomass energy crop production 233

logging, paper and furniture industries is plentiful in several areas of the U.S. and is currently the only biofuel used on a large scale in the north central region4 This source can potentially be exploited more thoroughly than it is now. However, particulate emissions and other air quality considerations should be addressed before further expansion occurs.

Dedicated biofuel crops, if grown sustainably, can provide both environmental and economic benefits for rural communities. While technical considerations dominate the process of biofuel species selection, ecological factors should be considered as well. Short-rotation woody crops, such as hybrid poplar (Populus spp. L.) have been considered by some to be the best candidate for biofuel plantations. However, at least in the first three or four years of production, SWRC plantations present some of the same problems with soil erosion, water quality and wildlife habitat which are associated with row crop agriculture.‘4”5 If these concerns are met through careful siting and sustainable practices, SRWC could provide a sustainable yield.

Herbaceous energy crops can be an excellent option for providing a reliable, environmentally sound biomass energy feedstock. Herbaceous energy crops present economic challenges (e.g. production and transportation costs) as well as some technical problems with combustion.‘6 However, the environmental benefits of over- coming these barriers are many. In an ecological sense, these crops are the most appropriate for the former prairies of the midwestern and northcentral U.S. and could provide substantial habitat for grassland wildlife communities. Other environmental benefits include:

??Carbon storage. Combustion of both woody and herbaceous biofuels recycles atmospheric carbon, rather than converting fossil carbon into greenhouse gases. There is some evidence that switchgrass and other native prairie species (potential HECs) sequester in their extensive root systems more carbon than is released during combustion of harvested above- ground plant matter.”

??Reduction of soil erosion. Once established, a herbaceous, perennial ground cover can reduce both wind- and water-caused erosion of soil.‘5.‘7~ I8 In addition, warm season grasses have soil building qualities and can add organic matter to the soil over time.

Water quality improvement. Both SRWC and perennial herbaceous energy crops can be produced with fewer inputs of fertilizers and pesticides than can annual row crops. In addition, the presence of a year-round ground cover reduces the potential for runoff of the chemicals which are applied.l5,lS, 19 Again, these benefits are greater for perennial grasses, because ground cover is developed and maintained more quickly than with woody crops. Quality wildlife habitat. Perennial grasses grown as biofuels could provide extensive habitat for grassland wildlife similar to grasslands enrolled in the Conservation Reserve Program (CRP).‘7,20. 2’

Large-scale biofuel production has the potential to contribute significantly to the sustainability of both the energy and agriculture industries of Wisconsin and other regions where it is developed. To capitalize on this opportunity, we suggest that guidelines be developed now, so that (1) environmentally sensitive farmland can be targeted for sustainable, perennial biomass crops, and (2) feedstock species can be selected based on their suitability to these sites. Crop species, climate, soil suitability, current land use practices, socio-economic feasibility and regional biodiversity issues should be considered.

3. POTENTIAL LANDS AND CROPS FOR BIOMASS PRODUCTION

The selection of suitable crops provides an opportunity to mitigate some of the agricultural land use problems which we are currently facing. Areas susceptible to erosion and/or water quality problems could be targeted for herbaceous, perennial biomass energy crops, just as they are targeted for federal land conservation programs today. Unlike these government programs, energy crop production on these lands could improve environmental quality and provide wildlife habitat while producing a non-tax-funded economic return to the farmer. We recommend that three types of agricultural land be considered for biomass energy crops:

1. Highly erodible lands. 2. Wetlands which have been drained and

converted to agricultural uses. 3. Marginal agricultural land in selected

areas.


In general, these lands are more difficult to farm. Yields of conventional crops are often low and environmental costs can be very high. Focusing on these lands, biomass crop species can be selected and successfully grown on lands not ecologically suited for conventional farming practices. Establishment and production of energy crops in such areas is likely to be less costly over the long term than producing conventional agricultural crops on these lands.

3.1. Highly erodible lands: tackling soil erosion problems

Today, 8&90% of the land in the midwestern U.S. is used for agricultural production.22,22 Since the 1950s modern agricultural practices have greatly increased the rate at which soil erosion occurs in this area. Erosion losses were estimated in the late 1970s at nearly 7 Mg ha-’ year-’ (3 tons acre-’ year-‘) for Great Lakes states (e.g. Minnesota, Wisconsin, Michigan, Ohio) and 1620 Mg ha-’ year-’ for Corn Belt states (7-9 tons acre-’ year-‘) (e.g. Iowa, Illinois, Indiana).24 Since then, the loss of this resource has been recognized as a serious threat to agricultural productivity. To safeguard the soil resource, government programs such as conservation reserves and soil banks have been implemented.

Under these programs, erosion-prone crop land is identified and designated as highly erodible land (HEL). All agricultural regions have areas of highly erodible land. In Wiscon- sin, for example, almost 1.7 Mha (4.2 million acres) of farmland are classified as HEL (USDA Soil Conservation Service, unpubl. data). Thirty counties in Wisconsin have soil erosion rates greater than “T” (2.3 Mg ha-’ year-’ or 1 ton acre-’ year-‘);25 10 of these continue to have soil loss ratesz5 of nearly 7 Mg ha-’ year-‘. Targeting such land for perennial, herbaceous energy crops could greatly reduce erosion problems.

3.2. Maximizing biodiversity on highly erodible land

If done with sensitivity to landscape scale siting and field size, energy crops could improve the biodiversity of areas now dominated by greatly simplified agricultural systems. Peren- nial grasslands, whether native or managed, are known to support more diverse populations of many native birds, mammals and other animal groups than row crop monocultures.2”29 Highly erodible croplands enrolled in CRP since 1985

have provided valuable habitat for grassland birds.2’.30.3’ Retaining this land in permanent grassy cover and converting other highly erodible cropland to switchgrass or mixtures of native warm season grasses would enhance the ability of agricultural land to support native wildlife communities. Regardless of species, herbaceous perennial biomass crops more closely resemble the native plant communities to which grassland wildlife species are adapted and would thus support a more diverse community of wildlife than do most conventional crops.

3.3. Energy crops for highly erodible land

Energy crops grown on erodible land must be relatively drought tolerant and have minimal fertility requirements. In many cases native species are best adapted to these areas and may produce better yields than introduced alternative crops. Switchgrass (Panicum virgatum L.) and other warm-season grass species, such as big bluestem (Andropogon Gerardi Vitman), little bluestem (Andropogon scoparius), and indiangrass [Sorghastrum nulans (L.) Nash] are native to a broad area of North America and thrive on the often dry and infertile soils of highly erodible lands. Some of these species have been studied extensively for use as biomass feedstocks. With minimal fertilization, switchgrass produces between 4 and 14.3 Mg ha-’ (1.8 and 6.4 tons acree’ year-‘) of dry biomass annually, comparable to hybrid poplar.3.4

In addition, herbaceous energy crops such as switchgrass are similar to forage crops currently being raised by farmers in most regions; thus, the expertise and equipment needed to produce these crops already exists. The cost of initial crop establishment can be high relative to common annual crops and establishment is slow, often requiring up to two seasons.32 Once established, however, maintenance costs for these crops are low because fertilizer and herbicide requirements are minimal. Native, warm-season grasses may provide a good balance between required inputs and acceptable yields. Combinations of native grasses and broadleaf species could also be evaluated for biomass production on HEL. Matching herbaceous biomass crop species as closely as possible to the natural plant community once found at a site could provide a biodiversity benefit as well as producing a biomass crop.

Alfalfa (Medicago sativa L.) is another example of a perennial crop with potential to be used as an energy feedstock on highly erodible


lands. While not a native species, it is a practical alternative which can provide many of the same ecological values. It establishes easily and its deep taproot makes it one of the most drought tolerant of legumes. Alfalfa used for biomass is harvested later in the season than alfalfa for livestock feed, maximizing the amount of stem material produced for combustion. The alfalfa leaves can be stripped from the stems before combustion, removing a potential source of nitrous oxide emissions and producing a high-protein livestock feed supplement as a coproduct.33

By siting biomass fueled power plants in erosion-prone regions such as southwestern Wisconsin, utilities and energy crop growers could work together to target erosive areas to be planted to perennial herbaceous energy crops. Opportunities for valuable coproducts such as the alfalfa leaves should be explored early in utility planning processes. In addition to providing electricity to local communities, energy crop production can provide a stable farm income, reduce soil erosion, and provide wildlife habitat.

3.4. Drained wetlands: improving water quality

Clean water for drinking, recreation and aesthetic enjoyment is an important issue for all of us. Protection of water resources has been made a priority through passage of the Federal Clean Water Act as well as through other state and federal legislation and many point sources of water pollution have been eliminated in recent years in compliance with these laws. Current efforts seek to address nonpoint source pollution problems, such as runoff from residential and agricultural land. Runoff con-

tains soil sediments, pesticides and excess nutrients which cause reduction of water clarity and increased algal growth in streams and lakes.

Water pollution problems have been com- pounded by the large scale draining of wetlands which has occurred in agricultural areas since European settlement. Wetlands function as a filtering system for watersheds, absorbing soil sediments and excess nutrients coming from upstream and halting their movement into larger water bodies downstream. This rich concentration of nutrients and fine soil makes wetlands one of the most productive ecosystems in the world.‘,*

Although not all areas have substantial wetlands, those which do have seen massive reductions in wetland hectarage due to wide- scale draining. Approximately 46% of Wiscon- sin’s 4 million original wetland hectares (9.9 million acres) have been drained,34 primarily for agricultural purposes. As is the case in many regions, the majority of these drained wetland hectares are now planted to row crops. Drainage ditches through crop fields deliver soil sediments, fertilizers and pesticides to streams, rivers and lakes, contributing to turbidity and eutrophication of these water bodies.

Targeting currently farmed wetland hectares for energy crops can reduce non-point source pollution from wetlands and adjacent crop land because appropriate perennial species can be established with minimal tillage and low levels of fertilizer and pesticide inputs. Energy crop production would allow an economic return from land which may be required to be managed under existing or future water pollution control legislation.

Table 1. Breeding bird density” and species richness of row crop, grassland, and aspen habitats in Wisconsin, U.S.A.

Habitat typeb Number of breeding pairs per 40 ha Total number of breeding species

Reed canary grass’ 246 9(N=6) Dense switchgrass 182 10 (N= 8) Monotypic aspen (sapling stage) 180 13 (N= 8) Poor switchgrass 178 9 (N=8) Monotypic aspen (pole stage) 153 22 (N = 10) Mixed warm-season grasses 126 13 (N=7) Corn 32 5 (N= 16) Beans 22 2 (N=9)

“Bird population density values reflect the estimate of the number of territorial pairs on study sites. bHabitat types were categorized as follows: reed canary grass sites were not monotypes-they were fields where reed

canary grass was the most common grass species (cover values ranged from 15% to 97%); dense switchgrass sites had > 40% cover of switchgrass and ~4% cover of other warm season grasses; poor switchgrass sites had ~40% cover of switchgrass and ~9% cover of other warm season grasses; mixed warm season grass sites had r27% cover of native warm season grasses other than switchgrass; aspen monoculture-sapling stage sites were those where trees were 14 m tall; aspen monoculture-pole stage sites were those where trees were >4 m tall (both aspen types were naturally regenerating stands created by logging); bean and corn sites were on commercial bean (soy or snap) or corn fields, respectively.

‘Reed canary grass ranked highest in bird density primarily due to the influence of the large number of red-winged blackbirds (Age/aim phoeniceus L.) which nest in it.


3.5. Safeguarding biodiversity in converted wetlands

Planting converted wetlands which are currently row cropped to perennial vegetative cover will increase the density and diversity of birds and other species which these areas can support (Table 1). However, caution must be exercised

when choosing crop species for these areas. As with HEL, the most desirable crops for drained wetland sites from a biodiversity standpoint would be native species, such as switchgrass, big bluestem, bluejoint grass [Calamagrostis canadensis (Michx.) Beauv.], and cordgrass (Spartina pectinata Link). Some species should not be considered for planting in drained wetlands. For example, reed canary grass (Phalaris arundinacea L.), which is being considered as a biomass crop and thrives under wet soil conditions, is an aggressive species which readily invades natural wetlands, smoth- ers native wetland vegetation, and has little wildlife habitat value.

3.6. Energy crops for drained wetlands

Ideally, landowners should be encouraged to restore drained wetlands to their natural state and to preserve existing, intact wetlands. If crop production on drained wetlands cannot be avoided, we suggest that these areas be considered for production of energy crops. The vagaries of cultivating wetland soils could be avoided through establishment of perennial energy crops adapted to wet conditions. These energy crops would be harvested in mid- to late summer, usually the driest part of the year. Frosts, a problem in low-lying areas in Wisconsin and other northern states, are less likely to affect these crops because we can choose native species adapted to the local climate. A number of grasses and broadleaf species are very productive in this habitat. Potential grass species include bluejoint grass [Calamagrostis canadensis (Michx.) Beauv.], cordgrass (Spartina pectinata Link), big bluestem (Andropogon Gerardi Vitman), and switchgrass.

Some perennial broadleaf species for biomass energy production could have additional benefits. One example is cup-plant (Silphium perfoliatum L.), a large native plant of the sun- flower family which is currently being developed as a forage crop in Wisconsin. Cup-plant withdraws large amounts of phosphorus from the soil and could thus function as a

“phosphorus pump”. Planting cup-plant on drained wetland soils would reduce phosphate and other nutrient runoff as well as filter runoff from adjacent crop fields (K. Albrecht, pers. comm.).

In some wetland areas, SRWC may be the best crop choice. Woody crops, such as hybrid poplar, are highly sensitive to water stress, tolerating only a narrow range of water availability. In dry years, wetland plantations would be buffered from the effects of drought. However, during wet periods, waterlogged soils could cause problems for SRWC3 which would be less likely to occur with native species adapted to wetland habitats. Other, more moisture-tolerant woody species, such as willow (Salix spp.) may work well on such sites, but sites should be chosen based on the ecological suitability for woody vegetation (see below).

3.7. Marginalfarmlandfor woody biomass crops: considerations for plantation siting

Much research has been conducted on SRWC as a source of biomass for energy production. While some have suggested creating SRWC plantations on CRP hectares and other marginal lands, these trees grow best on rich agricultural soils. Productivity decreases at lower soil fertility and, particularly, at lower moisture levels such as exist on many CRP hectares.14’ Is

Plantations of SRWC might be best suited to forest soils currently being farmed, such as areas of the northern portions of the northcentral region. The combined factors of climate and soil type make these areas marginal for conventional agricultural crops, but may be suitable for SRWC. The short growing season in many of these areas, which makes corn and soybean yields uncertain, would have little effect on SRWC. Short-rotation woody crops might provide a more stable income for farmers of the region than row crops do, one guaranteed through contracts with utilities. Establishment of SRWC plantations close to existing wooded areas could provide a buffer zone between forested wildlife areas and open lands, roads and other disturbed areas.

3.8. Biodiversity and the siting of short-rotation woody crops

There are several biodiversity issues sur- rounding the siting of SRWC plantations. Unlike perennial herbaceous biomass crops, SRWC provide a transitional habitat, with a


great deal of change in habitat structure over a relatively short period. These changes are reflected in the wildlife community. The avian community composition of poplar plantations is dynamic over time, changing from grassland/ brush species in the first two years to primarily woodland species later in the seven year rotation.3s Although stands of hybrid poplar are unlikely to be as attractive to birds as stands of native aspen (Populus tremuloides L.) (Table l), they will still support many more birds than row crops. Thus, converting land currently planted to corn and soybeans to SRWC plantations would increase the density and diversity of birds, but could completely change wildlife community dynamics. Creation of woodland habitat in the open landscapes of the Midwest may disrupt the communities of grassland species which are currently occupying these areas. Plantations of woody biomass crops could have the effect of fragmenting grassland or agricultural landscapes to the extent that they are no longer suitable for wildlife species which require large areas of treeless habitat. In addition, fragmenting grassland habitat with woody plantings can create negative “edge effects” by providing habitat for predators and nest parasites.36

In contrast, siting of SRWC plantations in northern forested regions can have a positive effect on biodiversity by reducing some of the problems associated with fragmentation of woodland habitats. Plantations could link existing forested areas or buffer them from adjacent farmland, serving to enhance their value as woodland wildlife habitat.

Ideally, selection of sites and species for dedicated energy crop production should attempt to simulate the original native habitats found in an area. In this way, biomass energy plantations will enhance biodiversity and contribute to a healthy, functioning ecosystem. We believe that, with additional research, it may be possible to meet our biomass feedstock needs with native plant species which can serve a dual purpose, having both crop and ecological value.

4. ECONOMIC AND SOCIAL ISSUES

The biomass energy infrastructure we build must accommodate new relationships among some unlikely partners. It is estimated that energy crop production for a 50 MW plant will require approximately 7% of farmland hectares within an 80 km (50 mile) radius.4 Farmers and

absentee land owners will probably provide most of the land for energy cropping3’ and production and delivery of biomass feedstocks will likely be accomplished through contractual relationships between utilities, land owners and perhaps independent power producers or farmer cooperatives. Several economic and social considerations must be dealt with to ensure the success of such projects in Wisconsin and elsewhere.

4.1. Industry considerations: ensuring a reliable feedstock supply

Currently, more than 70% of electricity used in the Midwest is generated by coal-fired power plants.4 As with coal-fired plants now in operation, biomass-fired power plants will need to have a long-term, reliable and predictable feedstock supply to produce a consistent flow of electricity. At present, fuel prices are probably the primary obstacle to development of biomass fired power plants. If the price of a feedstock cannot be kept low, that feedstock will not be competitive with coal which can cost utilities as little as $18 Mg-’ ($20 ton-‘) or 6&80 e GJ-’ (2-3 e kWh-‘).

Biomass energy crop materials vary consider- ably in heat content, and few energy crops can approach the heat content of fossil fuels. While fossil fuels produce more than 850 GJ kg-’ (3630 Btu lb-‘) of fuel, the heat content of SRWC averages 400 GJ kg-’ (1800 Btu lb-‘) and herbaceous energy crops can be as low as 160 GJ kg-’ (680 Btu lb-‘).37

Superficially, economics do not seem to favor biomass feedstocks. However, several factors may affect the outlook for the future. Many of the nation’s coal-fired power plants are over 20 years old. Replacement of these plants will soon be necessary and both utilities and independent power producers are considering alternatives for providing electricity under very different economic conditions than existed when they were built. In Wisconsin, several government programs are in place to encourage development of biomass and other renewable technologies, making them more competitive with coal and natural gas. These include tax incentives for renewable technology totalling 5.15 $ kWh-I,” a granting program for construction projects and requirements for monetization of externali- ties for fossil fuels at $13.60 Mg-’ ($15 ton-‘) of COz, $136 Mg-’ ($150 ton-‘) of CH4, and $2449 Mg-’ ($2700 ton-‘) of Nz0.4 Using the parameters described above, the total cost


of producing electricity from SRWC in Wisconsin38 for example, is estimated at 1.72 e kJ-’ (6.2 e kWh-‘), not significantly different from coal fired production (1.66 $ kJJ’ or 5.97 e kWh-‘) and much lower than natural gas at 4.58 $ kJ-’ (16.47 e kWh-‘).

4.2. Introducing new crops to the farming community

For farmers, any new crop or farming method should fit into existing cropping systems to be practical. Many factors enter into farmers’ decisions concerning whether energy crops will fit into their production systems. These factors include profit potential, machinery required, availability of markets, farmer expertise, and government programs, as well as many other objective and subjective issues. Adoption of new crops will be slow if these crops require special knowledge, labor, outside resources or equipment.39

4.2.1. Profit potential. The attractiveness of growing energy crops depends in large part on what net profit is possible, in comparison with the next-best crop alternative. What would be needed for an energy crop, such as switchgrass, to allow farmers to break even with other commonly grown crops, such as corn? The net return for growing corn in Wisconsin varies from over $300 ha-’ or $100 acre-’ (for top yields of 130 hl ha-’ or 150 bushels acre-’ on prime land) to close to zero on poor land.40 Switchgrass can produce between 4 and 14.3 Mg dry matter ha-’ (4.4 and 15.8 tons acre-‘). Production cost estimates range from $380 ha-’ to over $600 ($150 to $250 acre-‘).4.4’ On prime land, a farmer would need to gross a minimum of $680 ha-’ ($380 production costs, plus $300 in return) to make as much profit as he/she would growing corn. Assuming a high yield of 14.3 Mg ha-’ on prime land, the required selling price of the switchgrass would have to be at least $48 Mg-‘. To simply recoup production costs, a yield of 8 Mg ha-’ (3.6 tons acre-‘) would be required.

We have recommended growing herbaceous energy crops on marginal land, such as HEL and drained wetlands. Switchgrass yields on HEL are likely to be lower than on prime farmland, while those on drained wetland soils may be higher. In general, corn yields on either of these land types are likely to be lower than on prime farmland, because corn is less tolerant of extremes in fertility and moisture conditions.

The popularity of the Conservation Reserve Program in erosion-prone areas and of wetland preservation programs suggests that farmers are willing to consider taking problematic land out of annual crop production, if some income can still be derived from the land. Farmers may be inclined to plant perennial energy crops rather than corn on their sloping or low-lying land, even if income potential is less than for corn production.

Similar conditions exist in areas where we have recommended growing woody energy crops. One independent power producer suggests that a SRWC-fired power plant could be profitable with a cost of $4~$50 Mg-’ ($45-$55 ton-‘) for wood fuel (R. Chow, pers. comm.). Under current conditions, this price would cover production costs estimated at $45 Mg-’ for SRWC4 but leaves little margin for profit for the producer. Income from corn production is often very low in previously forested farmland in the North Central and North Eastern U.S. Costs for planting, main- taining and harvesting a corn crop are the same regardless of location, but corn yields in northern regions22 average well under 88 hl ha-’ (100 bushels acre-‘). Conversion of crop fields to SRWC plantations may be an attractive alternative for land owners in such areas. Long-term contracts with power producers could provide economic stability for farmers in an area where yields of conventional crops are questionable.

4.2.2. Improving economics with co-products. The development of by-products or co-products in conjunction with biomass production can provide economic incentives for landowners to put land into energy crop production. An example of this is a project involving alfalfa being developed in Minnesota with Northern States Power.j3 Because only the stem material is needed for power generation, the alfalfa leaves can be stripped prior to combustion and sold as a high-protein livestock feed for as much as $145 Mg-’ ($130 ton-‘). Factoring in the income from this valuable co-product brings the overall cost of alfalfa stems as a feedstock to about $1.55 GJ-’ ($1.60 million Btu-‘)33 as opposed to $2.31 GJ-’ ($2.45 million Btu-‘) for switchgrass. The cost of natural gas is about $1.89 GJ-’ ($2.00 million Btu-‘), and for coal about $1.66 GJ-’ ($1.75 million Btu-‘). As mentioned before, renewable-fuel tax incentives and/or environmental externality penalties could affect these figures.


Depending on the biomass feedstock being considered, other co-products may be possible. Growing chemical and pharmaceuticals industries require a number of chemical compounds found in some plant tissues and it may be possible to extract these without reducing the value of the biomass for combustion. The ash left after combustion can be considered a by-product when it is returned to the land as a soil amendment.

4.2.3. Sustainable production. The use of disease- and pest-resistant varieties of grass seed or tree stock will improve both the environmental and economic sustainability of biomass crops. Switchgrass and other native herbaceous species tend to be less prone to disease and pest problems than are many conventional crops. The varieties currently available are genetically quite variable and thus often have built-in resistance to a broad range of pests and diseases.

Short-rotation woody crops, however, present a very different set of problems. Several of the species suggested for biomass production, such as hybrid poplar, are being bred specifi- cally for biomass production. Production of trees for SRWC plantations using cuttings or other cloning methods can result in the creation of large monocultures with little genetic variability which can be very susceptible to disease or insect attacks. Efforts are being made to address these concerns through breeding for disease and pest resistance,3 but even if a mixture of several clones is used in a plantation, genetic diversity will still be much less than in a planting of native woody or herbaceous germplasm, and producing hybrid poplar will present a greater economic risk for a farmer or landowner.

4.2.4. Storage and transportation. Storage and transportation issues for biomass feedstocks differ greatly from those of other fuels because biofuels are perishable. Protection issues, such as mold, rot and fire damage, will need to be dealt with, particularly for HEC, but problems would be similar to those of hay production and are currently dealt with successfully by most livestock farmers.

Woody biomass is less perishable than herbaceous material, but few land owners possess the equipment to harvest and prepare SRWC for combustion. Local tree crop vendors or contractors could be engaged to harvest, transport and store woody biomass material. Landowners would probably sell woody ma-

terial right out of the field, much as timber is sold for the lumber industry.

One major limitation of biomass feedstocks is their bulk and the resulting high cost per joule of transporting the feedstocks to the power plant. Transporting biomass feedstocks for more than 80 km is not considered economically feasible. Transportation costs at this distance would average about $10 Mg-’ ($9 ton-‘).42 Using locally produced ethanol or biodiesel to transport feedstocks could further improve both the sustainability of a biomass-fueled power project.

4.3. Fitting biomass production into rural communities

Industries involving new crops should be compatible with the community into which they are introduced.39 Some important community questions include:

Can the industry’s wastes be used locally? Would new water pollution, odors, or visual nuisances be created which the community would not tolerate? Would the industry provide not only employment, but quality employment? Can local lending support be obtained or would outside capital be required? Would the income from the project be reinvested in the local community or elsewhere?

These questions are important for the community whether the growers of the energy crops are community farmers or contract producers brought in by the utility.

4.3.1. Community relationships. A reliable source of electricity requires long-term guaranteed contracts with fuel suppliers. We encourage existing farmer cooperatives or other local businesses to participate as contract coordina- tors. Coops could, indeed, act as independent power producers, producing the feedstock, burning it locally to produce electricity, and selling the electricity under contract to the utility.

One advantage to a community-based grower system supplying a local biomass energy plant could be the potential to recycle plant wastes or by-products. Combustion of energy crops for electricity would remove organic matter from the field, but some of the mineral fertility could be returned in the form of ash applied back on the producers’ land. Fermentation for ethanol would remove organic matter, but waste


from the fermentation process can be returned to the growers to provide feed for local livestock.

4.3.2. Local employment and the rural economy. A regional energy plant supplied by locally produced biomass crops would provide incomes for individuals in a community and money which would be spent in the community as well. Several studies suggest that communities in which biomass projects are developed will experience employment increases.4.43 Develop- ment of community-based industries often results in strengthening of community support services, providing additional jobs in the local government and service sectors.

4.3.3. Self-suficiency. Some herbaceous biomass crops have alternative uses or co-products associated with them, which would provide the farmer with greater cropping and marketing flexibility. Farmers and other landowners who can be flexible in response to the economic environment have operations which are more sound and less dependent on outside help. Minnesota’s Center for Alternative Plant and Animal Products compared projected farmer income for the Minnesota alfalfa biomass project’s recommended rotation (four years of alfalfa, two years of corn, one of soybeans) to a standard corn-soybean rotation (E. Oelke, pers. comm.). With or without government subsidies, a crop rotation including alfalfa grown as an energy crop would be more profitable than a standard corn-soybean rotation. With no government subsidies, the annual income per hectare for the energy crop rotation would be 160% of that of the corn-soybean rotation.

Strengthening the income of farmers through long-term contracts and reduced dependence on federal subsidies can help stabilize rural economies. The local business cycles and tax support associated with the development of a biomass energy industry would enable rural communities to be more self-sufficient and less dependent on outside assistance. On a broader scale, the use of biomass for generation of electricity could reduce our dependence on fossil fuels and make our energy production systems more efficient and cost-effective.

5. CONCLUSIONS

Hughes and Ranney” state that energy crops offer an environmental and economic compromise between high input, intensively managed

conventional crops (high economic return but negative impacts on local ecology) and natural, unmanaged systems (little, if any, economic reward and little impact on the local ecology). For many hectares of marginal farmland, energy crops could provide a desirable ecological compromise and an economic opportunity.

Development of a biomass energy industry will require creation of a sound infrastructure. There are many technological and economic obstacles to be overcome and a number of social and environmental issues which should be addressed to ensure that a strong infrastructure is built. New relationships among unlikely partners must be formed. These relationships should be encouraged through governmental action on federal, state and local levels. Current subsidy programs for the energy industry and for agriculture should be evaluated and perhaps integrated for this unique sustainable energy opportunity. An obvious possibility would be the Conservation Reserve Program, which pays landowners to maintain environmentally sensitive land out of row crop production and under permanent sod cover. The vegetation produced on these lands could be harvested for biomass with little or no loss in environmental benefits. Some of the funds now used to finance the CRP program could be used to bridge the gap between cost to farmer and the amount utilities are willing to pay.

Biomass energy production has the potential to benefit not only the power industry and agricultural community, but the public and the environment as well. At this juncture, we have an opportunity to plan and develop a new industry which is ecologically and economically sustainable. Biomass energy production has the potential to reduce soil erosion, and to improve water quality and wildlife habitat quality in areas where it is developed. We strongly encourage the use of sound ecological principles in its development, so that this potential can be achieved.

REFERENCES

R. K. Conway, R. Moorer and M. Dungan, Developing biofuels: Federal programs, in New Crops, New Uses, New Markets: Industrial and Commercial Products from U.S. Agriculture. 1992 Yearbook of Agriculture. USDA Office of Publishing and Visual Communication, Washington, DC (1992). W. L. Harris and H. N. Rosen, Conversion of biomass to fuel and energy, in New Crops, New Uses, New Markets: Industrial and Commercial Products from U.S. Agriculfure. 1992 Yearbook of Agriculture. USDA Office of Publishing and Visual Communication, Washington, DC (1992).


3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14

15

16

17

18

19

20.

21.

Wright L.L. Production technology status of woody and herbaceous crops. Biomass and Bioenergy 6, 191-209 (1994). M. C. Brower, M. W. Tennis, E. W. Denzler and M. M. Kaplan. Powering the Midwest: Renewable Electricity for the Economy and the Environment. Union of Concerned Scientists, Washington, DC (1993). J. J. Beyea, J. Cook, D. Hall, R. Socolow and R. Williams. Toward Ecological Guidelines for Large-scale Biomass Energy Development. Executive summary of a Workshop convened by the National Audubon Society and Princeton University, Princeton, NJ (6 May 1991). Beyea J.J. and Keeler K.H. Biotechnological advances in biomass energy and chemical production: impacts on wildlife and habitat. Crit. Rev. Biotechnol. 10, 305-319. (1991) W. B. Clapham Jr, Natural Ecoqstems. Macmillan, New York (1973). M. Begon, J. L. Harper and C. R. Townsend, Ecology: Individuals, Populations and Communities. Blackwell Scientific Publications, Sunderland, MA (1986). Behel Jr D., Giordano P.M. and Stephenson D.R. Attenuation of Cd and Pb solubility in municipal waste incinerator ash. Commun. Soil Sri. Plant Anal. 17, 385-392 (1986). Coalition on Resource Recovery and the Environment, Executive Summary: Characterization of Municipal Waste Combustion Ash, Ash Extracts and Leachates. From a report prepared for the U.S. Environmental Protection Agency, Office of Solid Waste, Washington, DC (1990). Soil Conservation Society of America, Effects of Tillage and Crop Residue Removal on Erosion, Runoff and Plant Nutrients. Soil Conservation Society of America, Ankeny, IA (1979). Probst J.R. and Crow T.R. Integrating biological diversity and resource management. J. Forestry 89, 12-17 (1991). T. R. Crow. A. W. Haney, D. M. Waller, M. B. Hathaway and J. E. Trower, Report of the Scientific Roundtable on Biological Diversity (convened by the Chequamegon and Nicolet National Forests). USDA Forest Service, Washington, DC (1993). E. A. Hansen, D. A. Netzer and D. N. Tolsted, Guidelines for Establishing Poplar Plantations in the North-Central U.S. Research Note NC-363, USDA Forest Service, North Central Experiment Station, St Paul, MN (1993). Ranney J.W. and Mann L.K. Environmental considerations in energy crop production. Biomass and Bioenergy 6, 21 l-228 (1994). K. A. Dripchak, Direct combustion of herbaceous energy crops: market assessment, in D. L. Klass (Ed.), Energy from Biomass and Wasfes, Vol. 10. Institute of Gas Technology, Chicago, IL (1987). Dunn C.P., Stearns F., Guntenspergen G.R. and Sharpe D.M. Ecological benefits of the conservation reserve program. Conserv. Biol. 7, 132-139 (1993). Osborn T. CRP continues to protect natural resources. Farmline 13, l&12 (1992). W. H. Blackburn, J. B. Newman and J. C. Wood, The Conservation Reserve Program: Effects on Soil, Water and Environmental Quality, pp. 27-36. USDA General Technical Report, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO (1991). R. L. Hays and A. H. Farmer, Effects of the CRP on wildlife habitat: emergency haying in the Midwest and pine plantings in the southeast. Trans. North Am. Wild/. Nat. Resour. Conf., Vol. 55, pp. 3@39. Wildlife Management Institute, Washington, DC (1990). M. Patterson and L. B. Best, Avian abundance and

22.

23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

3.5

36

37.

38.

productivity on conservation reserve program lands in central Iowa. Paper given at the 55th Midwest Fish and Wildlife Conference, 11-15 December 1993, St Louis, MO (1993). Wisconsin Agricultural Sfatistics. Wisconsin Depart- ment of Agriculture, Trade and Consumer Protection, Madison (1993). L. L. Adams and G. E. Potts, Proc. Midwest Private Land Wildlife Management Group. Illinois Department of Conservation, Springtield, IL (1991). P. R. Crosson and S. Brubaker, Resource and Environmental Effects of U.S. Agriculture. Johns Hopkins University Press, Baltimore, MD (1982). C. Holden and M. Miller, Joint Program Evaluation Report of the Nonpoint Source Water Pollution Abatement Program and the Soil and Water Resource Management Program. Publication #WR-249-93Rev. Wisconsin Department of Natural Resources, Wiscon- sin Department of Agriculture, Trade and Consumer Protection, Madison, WI (1993). D. W. Sample, Grassland Birds in Southern Wisconsin: Habitat Preference, Population Trends and Response to Land Use Changes. M.Sc. thesis, University of Wisconsin-Madison, Madison, WI (1989). Dennis P. and Fry G.L.A. Field margins: can they enhance natural enemy population densities and general arthropod diversity on farmland?. Agric. Ecosystems Environ. 40, 95115 (1992). Blumberg A.Y. and Crossley D.A., Jr Comparison of soil surface arthropod populations in conventional tillage, no-tillage and old field systems. AgroEcosystems Environ. 40, 95-l 15 (1983). Getz L.L. and Brighty E. Potential effects of small mammals in high-intensity agricultural systems in east-central Illinois, U.S.A. Agric. Ecosystems Environ. 15, 39-50 (1986). T. Z. Riley, Effects of CRP on ring-necked pheasants in Iowa (1985-1991). Paper given at the 55th Midwest Fish and Wildlife Conference, 11-15 December 1993, St Louis, MO (1993). D. W. Sample and L. A. Dlutkowski, Breeding bird communities of agricultural set-asides in southern Wisconsin. Paper given at the 51st Midwest Fish and Wildlife Conference, 3-6 December 1989, Springfield, IL (1989). D. J. Parrish, D. D. Wolf, W. L. Daniels, J. S. Cundiff and D. H. Vaughan, A five-year screening study of herbaceous energy crops, in D. L. Klass (Ed.) Energy from Biomass and Wastes XIV. Institute of Gas Technology, Chicago, IL (1990). D. Morris, Biological Energy: Opportunity and Ob- stacles. Institute for Local Self-Reliance, Washington, DC (1994). T. E. Dahl, Wetlands: Losses in the United States, 1780s to 1980s. U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC (1990). R. L. Verch, Nongame breeding bird activity in an intensively cultured Populus plantation. USDA Forest Service NC Forest Experiment Station Research Note NC-336 (1986). R. G. Johnson and S. A. Temple, Assessing habitat quality for birds nesting in fragmented tallgrass prairies, in J. Verner, M. L. Morrison and C. J. Ralph (Eds), Wildlife 2000: Modeling Habitat Relationships of Terrestrial Vertebrates, pp. 245-249. University of Wisconsin Press, Madison, WI (1986). Wood and Biomass Task Force, Advance Plan 7 Technical Support Document D20. Filed with the Public Service Commission of Wisconsin, Madison, WI (1994). S. Clemmer, The Economic impacts of Renewable Energy Use in Wisconsin. Wisconsin Energy Bureau. Madison, WI (1994).

242 L. K. PAINE et a/.

39. Keeney D.R. New crops and new uses: discovering Renewable Energy Laboratory, U.S. Department of common ground. Leopold Letter 6, 3-10 (1994). Energy, Washington, DC (1993).

40. Gumz R.G., Saupe W.E., Klemme R.M. and 43. E. L. Woolsey and G. Hallberg, Switchgrass to Posner J.L. A four year gross margins comparison of electricity: power generation and jobs creation. Biomass three cash grain rotations. Managing the Farm 27, 1-9 Conference of the Americas, 30 August 1993, NREL, (1994). Golden, CO (1993).

41. Turhollow A. The economics of energy crop production. Biomass and Bioenerg), 6, 229-241 (1994).

42. J. H. Turnbull, Principles and considerations for biomass resource development, in Proceedings of the First Biomass Conference of the Americas. National

44. M. Hughes and J. W. Ranney, Environmental issues related to biomass: an overview, in Proc. of the Firsr Biomass Conference of the Americas. National Renew- able Energy Laboratory, U.S. Department of Energy, Washington, DC (1993).

Documents

Some ecological and socio-economic considerations for biomass energy crop production