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California has been heralded as a national and international leader for its aggressive policies on renewable energy, climate change, and low-carbon fuels. A critical lInchpin in reaching its green power, greenhouse-gas-reduction, and petroleum-reduction goals is maximizing use of the state’s abundant biomass resources from the forestry, agricultural, and urban sectors.

Governor Arnold Schwarzenegger, in announcing his executive order to expand biofuels production, stated: “Turning waste products into energy is good for the state’s economy, local job creation, and our environment. By implementing biomass programs in California, we will help fight critical waste-disposal and environmental problems, including the risk of wildfires, air pollution from open field burning, and greenhouse gas emissions from landfills.”

California’s single largest source of biomass is found in the MSW stream. According to a recent state-sponsored biomass-resource assessment, 38 million tons of MSW biomass are generated each year, or 1 dry ton per person. Annually, about 6-8 million tons of these organic materials are utilized to produce compost and mulch, and an additional 1.5 million tons are used to produce power by traditional biomass burn facilities. The remainder, about 70%–75% of the more than 40 million tons disposed annually, represents a tremendous untapped resource for in-state biopower and biofuel production.

Technologies that can safely and efficiently produce alternative energy from biomass-waste feedstocks are now commercially available. Given the state’s vanguard energy initiatives, the runaway cost of petroleum, increased global-warming concerns, and a willing set of new industry partners, one would expect to find a wealth of state incentives for biorefinery development. Unfortunately, this is not the case. Current laws and regulations are, in fact, skewed to prevent this.

The root problem is a chronic disconnect between California’s energy and waste-management policies. New state bioenergy initiatives call for the creation of a favorable legal, regulatory, and economic environment to stimulate industry investments in technologies that utilize biomass for green power and green fuel production. Waste-management policy, in contrast, is mired in a decades-old hierarchical framework that artificially limits bioindustry access to these same resources. It does so by favoring certain landfill-diversion technologies and products over others through the maintenance of statutory barriers and the granting or withholding of incentives.

Specifically, “low-temperature” processes for the conversion and beneficial use of MSW biomass, such as composting and anaerobic digestion, are encouraged through the granting of landfill-diversion credit, state funding, and clear permitting pathways, whereas “high-temperature” technologies, such as gasification and pyrolysis, are specifically discouraged through onerous permitting standards and state-funding ineligibility.

Favored Technologies
The persistent bias toward low-temperature biomass-conversion technologies in California, and the de facto disqualification of biorefineries with thermal-process elements, presents a significant limiting factor in the achievement of reduction goals for greenhouse gas (GHG) and the fostering of a viable bioenergy platform. Low-temperature processes that are currently being promoted by state laws and regulations, to the virtual exclusion of others, include composting, anaerobic digestion, and acid and enzymatic hydrolysis.

Composting
In June of this year, the California Air Resources Board (CARB) released its Climate Change Draft Scoping Document, a so-called “market-based roadmap” to guide the state in achieving the ambitious GHG-reduction goals set forth in the California Global Warming Solutions Act (AB 32). The report focuses on landfill methane emissions as the principal challenge for the waste-management sector, and it promotes the composting of landfill-bound organics as the operational strategy for GHG reductions.

Renewed emphasis has also been placed by the California Integrated Waste Management Board (CIWMB) on programs to increase the diversion of “compostable organics,” along with the siting of new composting facilities. The state legislature has followed suit this session with bills that promote expansion of the compost industry. While never clearly defined, “compostable organics” generally include such separated materials as food wastes and green wastes, which comprise about 30% of disposed waste (as opposed to over 70% for biomass generally).

The favored-technology status of composting is grounded in the California Integrated Waste Management Act and the allegedly superior life cycle benefits of both recycling and composting over all other potential diversion technologies. When this hierarchy of management practices was drafted more than 20 years ago, it was based largely upon presumption and folklore rather than hard science. This notion of inherent superiority, however, has been extremely resistant to change or scientific scrutiny, despite the availability of several scholarly peer-reviewed studies that reach alternative conclusions.

While composting has a definite role to play in the diversion of waste from disposal, its utility as an effective GHG-reduction strategy is limited by the following:

Fugitive emissions—Composting facilities have their own set of air quality challenges, including VOCs and gases that can contribute to GHG formation. A recent study contracted by the Los Angeles County Sanitation Districts challenges the notion that the composting of greenwaste is more effective in reducing GHG emissions than is alternative utilization of these materials in a landfill as alternative daily cover (ADC).

Feedstock/processing limitations—Due to product-quality requirements, composting technologies can effectively deal with only a minor portion (30%) of the total biomass disposed of in landfills, i.e., organics that are source-separated, preprocessed, and relatively homogeneous.

Marginal economics—While compost products remain valuable as soil amendments, markets for these products are generally weak. Except in situations of in situ processing and usage, such as in agricultural operations, the composting industry has suffered under the dual burden of narrow profit margins and stringent regulatory requirements.

Siting obstacles—Public perception of composting facilities, fueled by their urban land-use interface and historic issues of odor, emissions, and water quality, has made the siting of new facilities extremely challenging.

No bioenergy element—Composting produces no energy, and it diverts biomass feedstock from other technologies that can produce biopower/biofuels and that are arguably more effective in net GHG reduction.

Anaerobic Digestion
Current California statute is silent on anaerobic digestion (AD) technology, but it does place “biological processes other than composting” under the “transformation” umbrella (a category that also includes incineration). The CIWMB has chosen to address this silence by drafting regulations that define AD as, in essence, in-vessel composting. Favored-technology status has thus been conferred on AD, including clear permitting pathways and landfill-diversion credit. Legislative amendments have recently been proposed to codify this interpretation in statute.

AD technologies have significant advantages over traditional composting, including the efficient capture of organic decomposition gases and their beneficial conversion to electricity, pipeline gas and, potentially, hydrogen. AD bioenergy applications seem particularly well-suited to agricultural operations, but they share similar constraints with traditional composting in the following critical areas:

Feedstock/processing limitations—In order to optimize the performance of acetogenic and methanogenic bacterial cultures, the feedstock for AD processes must be uniform and limited to specific types of separated, preprocessed biomass. It is particularly compatible with high-moisture streams, such as manures and foodwastes, but it cannot effectively handle the heterogeneous fractions that make up the bulk of California’s biomass supply. An Israeli company has developed an AD-technology facility that recovers various biomass feedstocks from mixed waste via a front-end water-separation system. The end result is a wet-biomass sludge feedstock, rather than a separated dry-biomass feed to which water is added.

Marginal economics—A major economic challenge for AD operations is finding a home for the large quantities of digestate byproduct resulting from the in-vessel gas-production process. The marketability of digestate is potentially affected by the nature and quality of the feedstock (separated “clean green” versus mixed biomass derived from the MSW residual stream). In the absence of a geographically proximate end use for these tonnages, their removal and/or further processing can be cost-prohibitive and contribute to secondary GHG effects.

Acid and Enzymatic Hydrolysis
Literally hundreds of millions of federal dollars have been dedicated to the research and development of hydrolysis/fermentation processes that can successfully solve the riddle of cellulose recalcitrance, its conversion to fermentable sugars, and the commercial production of biofuels and biochemicals. This R&D funding, supported more recently by major oil companies, continues in California with the establishment of the Energy Biosciences Institute (UC Berkeley & Lawrence Berkeley National Lab), which focuses almost exclusively on the sugar-fermentation platform in combination with local energy-crop production.

Legislative proposals have been advanced to confer favored-technology status on low-temperature acid and enzymatic hydrolysis (“lignocellulosic ethanol processing”) by defining these conversion processes separately from “transformation” and “disposal” and making them eligible for full landfill-diversion credit. If passed and codified, such statutory changes would create an uneven playing field for new bioindustries, favoring biochemical over thermochemical pathways for ethanol production from organic/biomass residues.

The capability of both acid and enzymatic processes to produce ethanol has been demonstrated, at least at the pilot scale, with various types of biomass feedstocks, such as switchgrass, sugarcane bagasse, wood and woodwastes, and separated urban-waste fractions. Commercial-scale projects are proposed and pending. But certain limitations inherent in these bioconversion technologies are notable:

Feedstock limitations—As with AD, relatively homogeneous, preprocessed feedstocks are required by bioconversion technologies for optimal efficiencies. Enzymes are often specifically tailored to particular types or classes of biomass, and they require a consistent feed and carefully controlled environments. Similarly, acid technologies nearing commercialization, while more robust, perform most efficiently with homogeneous streams.

Process efficiencies/yields—The sugar-fermentation platform relies upon the breakdown of biomass into cellulose, hemicellulose, and lignin, only a portion of which is successfully converted into ethanol or other chemicals. Much of the current R&D efforts are focused on increasing the conversion efficiencies for C5 and C6 sugars, and in finding beneficial uses for the lignin by-product.

Economic challenges—The most burdensome challenge for cellulosic-ethanol production via enzymatic hydrolysis has been the cost of enzymes themselves. While significant progress has been made in this regard over the past decade, production costs remain high. Similarly, the cost of sulfuric or nitric acid has been an important driver in the financial balance sheet of acid plants. Finally, the capital costs of both enzymatic and acid plants are extremely high. This creates a challenging investment portfolio when debt service is combined with feedstock and processing costs, moderate product yields, and an uncertain fuel-additive market.

Sustainability concerns—Because bioconversion technologies rely heavily on homogeneous feedstocks, they are often paired with dedicated energy crops that provide predictable conversion ratios and product yields. While there is future potential for the development of new crops that may be grown on marginal lands or in aquatic environments, major concerns are currently being raised about the impact of energy-crop production on land use, water, and other environmental issues.

Thermal Alternatives
California is unique in equating “high-temperature” biomass-conversion technologies, such as pyrolysis, with incineration or landfill disposal. Gasification technologies, while defined separately in the state’s waste-management statutes, have been assigned onerous performance standards, such as zero emissions, that are applied to no other industrial sector. This inequitable treatment has created burdensome permitting requirements and rendered many potential biorefinery projects ineligible for state diversion credit or grant funding. More importantly, it has created an atmosphere of investor uncertainty that continues to hinder bioenergy development.

Thermal/fermentation technologies utilize a gasifier or a plasma arc to heat and decompose biomass into its gaseous elements (carbon monoxide, water, and carbon dioxide). This synthesis gas is then scrubbed, cooled, and introduced to a bacterial culture. The bacteria ingest the gas and convert it to ethanol and water, which is then distilled away to produce fuel-grade ethanol. Steam created during the gas-cooling phase may also be utilized for the production of electricity in the absence of combustion.

Biorefineries with thermal-process elements are a critical component of an integrated bioenergy platform for the following reasons:

Feedstock versatility—Thermal/fermentation technologies can receive and process any carbonaceous material in any combination (municipal solid waste, biosolids and animal wastes, greenwaste, agricultural residues, used tires and plastics, timber and woodwastes, coal, natural gas and other hydrocarbons, and refinery tars and waste oils). This greatly expands the volume of feedstocks available for energy production.

Process efficiencies/yields—Unlike hydrolysis bioconversion processes, the thermal and biocatalytic steps combine to convert 100% of the biomass components (cellulose, hemicellulose, and lignin) into energy products. Fuel-grade ethanol yields can range from 85 gallons per dry ton of biomass to 150 gallons per ton of high-Btu materials, such as plastics and tires.

Superior economics—Because these technologies have the ability to process diversified, heterogeneous wastestreams, their feedstock costs can be zero, or even a positive source of revenue through tipping fees. Thermal plants also have a significant production-cost advantage over other ethanol technologies due to their rapid throughput and high yields—the entire process, from the time the feedstock material enters the thermal unit to the creation of ethanol, takes only a few minutes, as opposed to hours or days for low-temperature bioconversion processes. Establishment of such commercial-scale plants can make low-cost ethanol and E85 a reality in California.

Environmental excellence—Thermal/fermentation technologies employ a fully enclosed non-combustion process that has minimal air emissions and creates no environmental or health hazards and no groundwater or surface-water contamination. When biomass is used to co-produce ethanol and electricity, significant reductions in GHG emissions can be achieved. Several scholarly peer-reviewed studies conducted by the CIWMB (life cycle–analysis studies), University of California (thermal conversion–emission studies), County of Los Angeles (dioxin- and furan-emission studies), and others, as well as operating data from similar plants throughout the world, support this exceptional environmental performance.

Sustainability—Since thermal/fermentation technologies can utilize any and all carbonaceous wastestreams in the state’s biomass inventory, they provide the dual benefit of renewable energy production and environmental mitigation. It’s estimated that these conversion technologies could produce as many as 2.7 billion gallons of ethanol and 2,500 MW of power just from the over 40 million tons of post-recycled municipal wastes California will place in landfills this year. It is more sustainable to beneficially use the waste biomass feedstocks the state already has in such abundant supply rather than consume valuable land and water resources for energy-crop production.

Clearing the remaining hurdles for commercialization of thermal/fermentation technologies, however, has been fiercely opposed by a small but effective group of individuals—both inside and outside the state legislature. Attempts to more closely align California’s renewable-energy and waste-management policies have been consistently blocked by key “gatekeepers,” who cloak their political arguments in an environmental mantle.

Zero Thermal and Zero Waste
Environmental opposition to thermal MSW processing harks back to the early days of mass-burn facilities, when dioxins, furans, and other pollutants posed tangible air-quality hazards to surrounding communities. Although modern incinerators have dramatically reduced their emissions and now operate in compliance with strict federal guidelines, the stigma of past pollution remains. So enduring is this legacy in California that only three waste-to-energy facilities are operating currently, all of which were permitted prior to 1995.

Thermal opponents have recently launched a national campaign to extend the pollution tar-brush to new non-combustion biomass-conversion technologies as well, characterizing them as “incinerators in disguise.” Despite ample scientific evidence to the contrary, this type of fear mongering continues to color the perceptions of legislators and the general public alike.

For ardent supporters of the “zero-waste” platform, the crusade against thermals goes well beyond pollution claims. It raises the more fundamental question of whether MSW should be utilized for energy production at all. Critics argue that the entire wastestream can be feasibly abated through a strategic combination of producer responsibility, consumer abstinence, and more aggressive recycling and composting. Since the ultimate goal is to reduce wastestream materials to zero, MSW residuals are viewed as neither renewable nor sustainable.

In this mindset, the fear is not that new biomass-conversion technologies won’t work. It’s that they will actually perform as advertised. The theory is that if advanced clean technologies are commercialized to economically produce green power and fuels from residual urban biomass, then runaway consumption and waste-generation patterns will proceed unchecked.

Herein lies the heart of the waste-versus-energy disconnect. Continued hoarding of California’s largest biomass-resource supply for the exclusive use of the recycling and composting industries is increasingly untenable. The CIWMB faces an escalating challenge to demonstrate how its current zero-waste policies can both complement and facilitate the achievement of state renewable-energy and climate-change imperatives.

While recycling is often touted as an energy-saver and an effective strategy for GHGs reduction, the new CARB climate-change roadmap notes that in-state benefits attributable to recycling and composting have not been quantified. Indeed, the life cycle assessments on which these conclusions are based seldom calculate the energy and pollution costs of shipping the bulk of California recyclables to Asian markets. Nor do they consider the global air-quality impacts of shifting the burden of remanufacture and reuse to developing nations where environmental controls are minimal or nonexistent. California’s ability to realize GHG reductions in the future may depend, in part, on its role in increasing or decreasing the state’s exposure to industrial pollutants originating in the Pacific Rim.

Similarly, strategies for reducing GHG emissions from landfills will require the application of several diversified technologies for the productive upstream diversion of biomass materials. Despite its claim to a 54% recycling rate, California will bury the same amount of waste this year as it did in 1990. Population and economic growth have kept pace with source reduction and recycling efforts, and this trend is expected to continue. Since composting can effectively deal with only 30% of targeted biomass materials, the systematic exclusion of other conversion technologies from the state’s bioenergy toolkit virtually guarantees that the bulk of these resources will continue to be disposed of rather than put to beneficial use.

This represents a lost opportunity to not only achieve emissions reductions from landfills, but also to redeem the climate-change and petroleum-displacement benefits that may be derived from alternative biopower and biofuels production. Experts agree that the most sustainable method of producing renewable transportation fuels is through the conversion of biomass wastes. The GHG benefits of commercializing both low- and high-temperature biorefineries are geometric in effect—reduction of landfill disposal and associated emissions, utilization of a sustainable feedstock supply, and net emissions reductions from both the refining and burning of resultant fuels when compared to their petroleum equivalents.

Closing the Gap
Each of the biomass technologies discussed here has a critical niche and a role to play in the achievement of renewable-energy and GHG-reduction goals. But if we are to be successful in meeting both state and national objectives, the disconnect between bioenergy initiatives and policies governing the largest perpetual source of domestic biomass must be bridged. Similar to recent amendments to European Union waste law, the middle “recovery” rung of the waste management hierarchy must be expanded—beyond recycling and composting—to recognize the beneficial use value of conversion technologies that produce green power, fuels, and chemicals from recovered biomass.

Access to and productive use of biomass materials must be democratized, and market success based ultimately upon process efficiency, cost, and environmental performance. In the spirit of California’s Low Carbon Fuel Standard, a truly integrated bioenergy and climate-change policy restrains government from picking winners and losers and instead creates a level and competitive playing field to spur industry innovation.