Review of biomass energy utilization technology and policy

1.5 Other Technologies

Other technologies mainly include pretreatment technology of biomass energy raw materials and manufacturing technology of biomass energy equipment. Among them, the pretreatment technology mainly includes steam explosion method, ozone decomposition method, solvent method, oxidation delignification method, alkali treatment, dilute acid treatment, etc. The consensus is the best pretreatment method is dilute acid method (Li Shizhong, 2006). In the utilization of straw biomass, pretreatment method is one of the technologies to promote the efficient utilization of biomass straw. At present, there are mainly physical method, chemical method, physico-chemical combination method and microbial biological method. Among them, the physical method mainly refers to mechanical grinding, high-energy radiation treatment and microwave treatment technology; Chemical method refers to acid, alkali, ionic liquid, organic solvent, ozone and wet oxidation treatment; Physicochemical combination mainly includes sulfur dioxide, ammonia, carbon dioxide combined with steam explosion and high temperature pyrolysis; The biological principle of microorganisms is to use microorganisms such as brown rot bacteria, white rot bacteria and soft rot bacteria to improve the enzymatic hydrolysis and saccharification rate of cellulose and hemicellulose (Wang Keqin et al., 2015). European and American countries in the biomass energy equipment manufacturing has achieved marketization, biomass molding equipment and biomass boiler technology has developed mature, many equipment are exported to other countries, such as Sweden's biomass boiler. In general, Europe is ahead of other countries in the pretreatment technology and equipment manufacturing technology of biomass raw materials, and China is still short in these aspects, and technical breakthroughs are still needed.

2 Evolution of policies to promote biomass energy development in major countries

In recent years, the relationship between economic growth and environmental pollution has become a hot issue. Energy production and consumption are at the heart of the problem. In order to reduce environmental pollution, reduce carbon emissions, and achieve sustainable and green development, countries have accelerated energy transformation and promoted economic transformation and development. It is in this context that the relevant policies for the development of biomass energy are constantly introduced. In general, policies related to biomass energy are mostly proposed in the framework of new and renewable energy development. Due to the different levels and stages of development in each country, the needs and positioning of biomass energy development are also different. Generally speaking, the biomass energy policy of developed countries is to achieve sustainable, green and low-carbon development. The biomass energy policy of less developed countries is proposed either to promote energy transformation, or to ensure the security of energy supply, or because of the lack of fossil energy.

2.1 European Union

The "Renewable Energy Directive" adopted by the European Union in 2008 put forward the strategic goal of "20-20-20" renewable energy, that is, to reduce greenhouse gas emissions by 20% compared with 1990 by 2020; Increase the share of renewable energy in total energy consumption to 20%; Increase energy efficiency by 20%. At the same time, through the Strategic Energy Technology Plan, it is proposed to develop biotechnology and promote the development of low-carbon economy. In 2010, the EU 2020 Energy Strategy was launched. In 2011, the EU Energy Roadmap 2050 was published. These documents propose that the proportion of biofuels in transport fuels must reach 10% by 2020. Overall, the policy environment for the development of biomass energy in the European Union has changed, and biomass energy has been given the opportunity to develop under the new energy and renewable energy development plan. Because biomass energy has the advantages of carbon neutrality, easy storage and strong stability, it is of great significance for the EU to achieve sustainable and low-carbon development. Therefore, under the policy framework of the European Union, in order to achieve the enforceable goals (such as "20-20-20" and FIT), member states combined with national resource endowments, have successively introduced a variety of policies and regulations to promote the development of the biomass energy industry, providing support in terms of material sources, investment production, technology, equipment and products. With the development of the biomass energy industry, biomass energy products have partially replaced traditional fossil energy products, and the development of the biomass energy industry has a certain market competitiveness, and countries have begun to stop policy subsidies in some areas.

2.2 United States

In 2003, the United States introduced the "Biomass Technology Roadmap", which plans to increase biomass energy and biomass-based products by 20 times compared with 2000 in 2020, reaching 25% of the total energy consumption (reaching 50% in 2050), and reducing carbon emissions by 100 million tons per year. Since then, The United States has successively proposed the Advanced Energy Program (2006), the Cellulosic Ethanol Research Roadmap (2006), the U.S. Bioenergy and Bio-based Products Roadmap (2007), the Biomass Development Plan 2007-2017 (2007), the National Biofuel Action Plan (2008), and the Biomass The Multi-Year Project Plan (2009), etc., further clarified the strategic trend and development goals for the development and utilization of biomass resources (Wang Hongyan et al., 2016). The United States is a big energy producer, and in the case of shale gas resources that have been discovered and exploited, the policy on biomass energy utilization depends entirely on the intentions of the ruling government.