Biofuels are important substitute for fossil fuel with the advantages such as susatainablility, environmental friendly and good adaptability. In the last 10 years, biofuels development has been ...driven by the government policies. Many countries and areas have authorized laws and regulations to ensure the sustainable development of biofuels. By the support of the government, some biofuel projects have been commercialized. This paper reviews the national biofuel policies and strategy plans of the world׳s leading states, the government has provided sustained and cost-sharing privileges decreasing subsidies for the whole process from feedstock, from experimentation to industrialization of bioenergy industry in order to reduce investment risk. As a result of these supports, bioethanol and biodiesel have commercialized in several states, aviation biofuels are developing rapidly in the support of world׳s major airlines and US military. While there is political debate over the impact of biofuels on climate change and food security, it would be a challenge for the policy makers to continue trends of biofuels production while complying with sustainable production requirements.
Biofuel and bioenergy systems are integral to most climate stabilization scenarios for displacement of transport sector fossil fuel use and for producing negative emissions via carbon capture and ...storage (CCS). However, the net greenhouse gas mitigation benefit of such pathways is controversial due to concerns around ecosystem carbon losses from land use change and foregone sequestration benefits from alternative land uses. Here, we couple bottom-up ecosystem simulation with models of cellulosic biofuel production and CCS in order to track ecosystem and supply chain carbon flows for current and future biofuel systems, with comparison to competing land-based biological mitigation schemes. Analyzing three contrasting US case study sites, we show that on land transitioning out of crops or pasture, switchgrass cultivation for cellulosic ethanol production has per-hectare mitigation potential comparable to reforestation and severalfold greater than grassland restoration. In contrast, harvesting and converting existing secondary forest at those sites incurs large initial carbon debt requiring long payback periods. We also highlight how plausible future improvements in energy crop yields and biorefining technology together with CCS would achieve mitigation potential 4 and 15 times greater than forest and grassland restoration, respectively. Finally, we show that recent estimates of induced land use change are small relative to the opportunities for improving system performance that we quantify here. While climate and other ecosystem service benefits cannot be taken for granted from cellulosic biofuel deployment, our scenarios illustrate how conventional and carbon-negative biofuel systems could make a nearterm, robust, and distinctive contribution to the climate challenge.
Environmental impact of biogas: A short review of current knowledge Paolini, Valerio; Petracchini, Francesco; Segreto, Marco ...
Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering,
08/2018, Volume:
53, Issue:
10
Journal Article
Peer reviewed
Open access
The social acceptance of biogas is often hampered by environmental and health concerns. In this study, the current knowledge about the impact of biogas technology is presented and discussed. The ...survey reports the emission rate estimates of the main greenhouse gases (GHG), namely CO
2
, CH
4
and N
2
O, according to several case studies conducted over the world. Direct emissions of gaseous pollutants are then discussed, with a focus on nitrogen oxides (NO
x
); evidences of the importance of suitable biomass and digestate storages are also reported. The current knowledge on the environmental impact induced by final use of digestate is critically discussed, considering both soil fertility and nitrogen release into atmosphere and groundwater; several case studies are reported, showing the importance of NH
3
emissions with regards to secondary aerosol formation. The biogas upgrading to biomethane is also included in the study: with this regard, the methane slip in the off-gas can significantly reduce the environmental benefits.
Research highlights ► Biobutanol is an important renewable chemical building block and a superior next generation biofuel. ► Production of 1-butanol using solventogenic clostridia is a proven ...industrial fermentation that has been re-commercialised in China. ► Significant reductions in production cost can be achieved using low cost cellulosic feedstocks. Choice of microbial strain is critical to the success of the fermentation. ► Future work should focus on robust strains that can tolerate high solvent concentrations and feedstock inhibitors.
Algae are among the most potentially significant sources of sustainable biofuels in the future of renewable energy. A feedstock with virtually unlimited applicability, algae can metabolize various ...waste streams (e.g., municipal wastewater, carbon dioxide from industrial flue gas) and produce products with a wide variety of compositions and uses. These products include lipids, which can be processed into biodiesel; carbohydrates, which can be processed into ethanol; and proteins, which can be used for human and animal consumption. Algae are commonly genetically engineered to allow for advantageous process modification or optimization. However, issues remain regarding human exposure to algae-derived toxins, allergens, and carcinogens from both existing and genetically modified organisms (GMOs), as well as the overall environmental impact of GMOs. A literature review was performed to highlight issues related to the growth and use of algal products for generating biofuels. Human exposure and environmental impact issues are identified and discussed, as well as current research and development activities of academic, commercial, and governmental groups. It is hoped that the ideas contained in this paper will increase environmental awareness of issues surrounding the production of algae and will help the algae industry develop to its full potential.
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•Pyrolysis of TFW was conducted at 500, 600, 700 °C and at 10, 15, 20 °C/min as HR.•The highest bio-oil yield (60 wt%) was reached at 600 °C and 15 °C/min.•The bio-oil HHV is 39.36 ...MJ/kg and the syngas energetic content is 10 MJ/Nm3.•Biochar properties suggest its use as biofertilizer or bioadsorbent.
Nannochloropsis oculata
CCMP 525,
Dunaliella salina
FACHB 435, and
Chlorella sorokiniana
CCTCC M209220 were compared in mixotrophic and photoautotrophic cultures in terms of growth rate, protein, and ...lipid content. Growth improved in glucose, and the biomass productivities of
N. oculata
,
D. salina
, and
C. sorokiniana
were found to be 1.4-, 2.2- and 4.2-fold that observed photoautotrophically. However, biomass and lipid production decreased at the highest glucose concentrations. Meanwhile, the content of protein and lipid were significantly augmented for mixotrophic conditions at least for some species.
C. sorokiniana
was found to be well suited for lipid production based on its high biomass production rate and lipid content reaching 51% during mixotrophy. Expression levels of
acc
D (heteromeric acetyl-CoA carboxylase beta subunit),
acc
1 (homomeric acetyl-CoA carboxylase),
rbc
L (ribulose 1, 5-bisphosphate carboxylase/oxygenase large subunit) genes in
C. sorokiniana
were studied by real-time PCR. Increased expression levels of
acc
D reflect the increased lipid content in stationary phase of mixotrophic growth, but expression of the
acc
1 gene remains low, suggesting that this gene may not be critical to lipid accumulation. Additionally, reduction of expression of the
rbc
L gene during mixotrophy indicated that utilization of glucose was found to reduce the role of this gene and photosynthesis.
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