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Rapid And Effective Oxidative Pretreatment Of Woody Biomass At Mild Reaction Conditions And Low Oxidant Loadings
One route for producing cellulosic biofuels is by the fermentation of lignocellulose-derived sugars generated from a pretreatment that can be effectively coupled with an enzymatic hydrolysis of the plant cell wall. While woody biomass exhibits a number of positive agronomic and logistical attributes, these feedstocks are significantly more recalcitrant to chemical pretreatments than herbaceous feedstocks, requiring higher chemical and energy inputs to achieve high sugar yields from enzymatic hydrolysis. We previously discovered that alkaline hydrogen peroxide (AHP) pretreatment catalyzed by copper(II) 2,2 -bipyridine complexes significantly improves subsequent enzymatic glucose and xylose release from hybrid poplar heartwood and sapwood relative to uncatalyzed AHP pretreatment at modest reaction conditions (room temperature and atmospheric pressure). In the present work, the reaction conditions for this catalyzed AHP pretreatment were investigated in more detail with the aim of better characterizing the relationship between pretreatment conditions and subsequent enzymatic sugar release. Results: We found that for a wide range of pretreatment conditions, the catalyzed pretreatment resulted in significantly higher glucose and xylose enzymatic hydrolysis yields (as high as 80% for both glucose and xylose) relative to uncatalyzed pretreatment (up to 40% for glucose and 50% for xylose). We identified that the extent of improvement in glucan and xylan yield using this catalyzed pretreatment approach was a function of pretreatment conditions that included H2O2 loading on biomass, catalyst concentration, solids concentration, and pretreatment duration. Based on these results, several important improvements inpretreatment and hydrolysis conditions were identified that may have a positive economic impact for a process employing a catalyzed oxidative pretreatment. These improvements include identifying that: (1) substantially lower H2O2 loadings can be used that may result in up to a 50-65% decrease in H2O2 application (from 100 mg H2O2/g biomass to 35–50 mg/g) with only minor losses in glucose and xylose yield, (2) a 60% decrease in the catalyst concentration from 5.0 mM to 2.0 mM (corresponding to a catalyst loading of 25 mumol/g biomass to 10 mumol/g biomass) can be achieved without a subsequent loss in glucose yield, (3) an order of magnitude improvement in the time required for pretreatment (minutes versus hours or days) can be realized using the catalyzed pretreatment approach, and (4) enzyme dosage can be reduced to less than 30 mg protein / g glucan and potentially further with only minor losses in glucose and xylose yields. In addition, we established that the reaction rate is improved in both catalyzed and uncatalyzed AHP pretreatment by increased solids concentrations. Conclusions: This work explored the relationship between reaction conditions impacting a catalyzed oxidative pretreatment of woody biomass and identified that significant decreases in the H2O2, catalyst, and enzyme loading on the biomass as well as decreases in the pretreatment time could be realized with only minor losses in the subsequent sugar released enzymatically. Together these changes would have positive implications for the economics of a process based on this pretreatment approach. Author: Zhenglun LiCharles H ChenEric L HeggDavid B Hodge Credits/Source: Biotechnology for Biofuels 2013, 6:119 Continue reading
New Sustainability Hoops To Jump Through For UK Biomass
Posted on 23 August 2013 by Vicky Ellis http://www.energyliv…h=250&zc=1&q=90 Biomass firms will face new hoops to jump through under government plans to make sure the fuel is sustainable. From April 2015, biomass-fuelled generators which don’t hit targets – such as how much carbon can be emitted and whether enough trees have been planted to replace those used as fuel – could lose financial support. The UK industry is worth more than £1billion in new investment and supports over 3,000 jobs, according to the Department of Energy and Climate Change. Another new requirement will mean generators with 1MW worth of capacity and more must provide an independent sustainability audit with their annual sustainability report. The UK biomass sector has fielded criticism from some for being too opaque with questions asked about the source of wood chips and pellets and where wood will have to come from if the industry grows. Environmentalists fear deforestation in endangered forest areas around the world could be the disastrous result of a badly managed biomass supply chain. The Government is clearly hoping to silence such criticism for good. It says the “tough new criteria” for sustainable forest management will mean it won’t have to change the rules until April 2027. Ministers believe this will encourage the industry to continue to take root in UK. Announcing the change yesterday, Energy and Climate Change Minister Greg Barker said: “The new criteria will provide the necessary investor certainty and, crucially, ensure that the biomass is delivered in a transparent and sustainable way.” Large and small energy generators are split into two categories in the new biomass regime. For larger generators of 1MW and above, which covers around 98% of biomass power in the UK, by 2020 for every megawatt hour (MWh) of electricity they produce they must only emit 200 kilos of carbon dioxide equivalent (CO2eq) a year. Government says this is a 72% saving compared to the EU fossil fuel electricity average. This drops further to a 180 kilos of CO2eq for each MWh from 2025. As for the other 2% of generators – those with a capacity between 50kW and 1MW – they will have to report against the criteria but not to comply with it. The smallest biomass generators – those under 50kW, known as microgeneration -are not included in the scope. Continue reading
The Sustainable Approach – Powering Africa Through Biomass Energy
Countries within the great African continent are blessed with enough resources to see them benefiting from biomass energy. Biomass is an important source of energy and the most important fuel worldwide after coal, oil, and natural gas. Bio-energy, which is derived from biomass, is expected to be a pivotal resource, which will contribute to global sustainable development. Dr Segun Adaju, the Project Manager of the Bank of Industry/United Nations Development Project (UNDP), Access to Renewable Energy (AtRE) Project, notes thus: “Biomass is a clean renewable energy resource derived from the waste of various human and natural activities. It excludes organic material, which has been transformed by geological processes into substances such as coal or petroleum.” The energy of biomass is extracted from three distinct sources, the largest energy source of biomass being wood (contributors include the timber industry, agricultural crops and raw materials from the forest); the second largest source is waste energy (main contributors are municipal solid waste and manufacturing waste); and the third largest source is alcohol fuels ‑ derived mainly from corn. Accordingly, in the developed world, biomass should become more important for dual applications such as heat and power generation. This is so since most countries within and across the African continent have a lot of resources for biomass energy; the continent is blessed with an environment and geography that supports the growth of anything. Importantly, biomass energy is especially relevant for Sub-Saharan Africa where over 80 percent of the population relies upon wood, crop and animal residues for meeting their household needs (mainly cooking). Notwithstanding extensive plans for electrification and provision of fossil fuels, a vast majority of households in Sub-Saharan Africa will still depend on biomass resources for their energy needs for at least the next two decades. It is also critical to note that African countries have adequate biomass resources for biomass energy because there is waste like sawdust and/or wood chips, which should not waste away. These countries can convert them into energy by simply putting the waste into small devices called bio-digesters, so that they can digest those waste through bacteria and the rest, scientists know more about that. Since African countries have so many resources (biomass energy resources), developing biomass industries in the continent will have more impact and it will ease some problems affecting the development of the continent. For instance, developing biomass industries in African countries will create more jobs; it will create adequate energy and it will solve the problem of how do we deal with waste. To effectively use resources for biomass energy, policy makers in African governments need to know the technologies that are available and how to apply them. There are also many technologies that can be imported and used to develop local (African) technologies. More so, to tap into these resources, the first thing is for African governments to create awareness so that people know that the waste they are even generating in their houses is actually money and it is a material to generate energy. Crafting of policies is a crucial step if the continent is to effectively utilise its resources for biomass energy. Adaju concurs: “We need government’s support in terms of policy so that we can be able to use our resources to generate our needs. It is not all the time we have to import what we want to consume or use so we need government’s policy to encourage production, and to support entrepreneurs.” The World Bank’s Director for Sustainable Development in the Africa Region, Jamal Saghir, said partners now need to foster mainstreaming of biomass into national economic policies. “The development of biomass energy is closely linked with forestry, agriculture, indoor air pollution and health, environment and climate change, rural electrification, and gender development,” he said. “And all these linkages have to be explicitly recognised and harmonised to have a unified sustainable approach.” This means Africa must embrace biomass energy and utilise it as a developmental tool. One of the major reasons why unemployment is high in the continent and why manufacturing companies are shutting down is because of energy is insufficient. If African countries have adequate energy, there will obviously be more employed people. Without doubt, biomass is an important source of energy and the most important fuel worldwide after coal, oil, and natural gas. Continue reading
