Are algae ready to take off? GHG emission savings of algae-to-kerosene production

Aviation alternative fuels are perceived as an effective short-term mean to decarbonise our flights. Sustainable aviation fuels from algae have been recently approved for commercial flights, and here we present an assessment of their greenhouse gas (GHG) savings. Three case studies have been investigated with different plant designs and cultivation strategies. The Carbon Offsetting and Reduction Scheme for International Aviation's Life Cycle Assessment methodology is used as a guideline to assess the GHG saving potential of aviation fuels from algae. The approach here presented allows having a sound comparison with other alternative fuel production pathways. We show that the cultivation strategy based on oil maximisation does not necessarily provide significant advantages in terms of GHG savings. The assessed GHG savings fall in a wide range, being dependent on the inputs and cultivation strategy considered. In the best-case scenario, up to 68% of GHG savings can be achieved, therefore offering a substantial advantage over traditional fuels. When compared with the GHG saving of kerosene from other traditional bio-based feedstocks, like rapeseed, the results confirm algae as an interesting alternative, provided that certain conditions for their cultivation, such as high process optimisation, nutrient recycling and use of renewable energy to meet input demand, are met. The study also assessed the area potentially needed for an algae production plant able to supply large volumes of raw material to an existing commercial biorefinery. The findings confirm the potential of this feedstock to mitigate land abandonment on the coasts of the Mediterranean basin

Vanillyl alcohol oxidase from Diplodia corticola:Residues Ala420 and Glu466 allow for efficient catalysis of syringyl derivatives

Vanillyl alcohol oxidases belong to the 4-phenol oxidases family and are found predominantly in lignin-degrading ascomycetes. Systematical investigation of the enzyme family at the sequence level resulted in discovery and characterization of the second recombinantly produced VAO member, DcVAO, from Diplodia corticola. Remarkably high activities for 2,6-substituted substrates like 4-allyl-2,6-dimethoxy-phenol (3.5 ± 0.02 U mg -1) or 4-(hydroxymethyl)-2,6-dimethoxyphenol (6.3 ± 0.5 U mg -1) were observed which could be attributed to a Phe to Ala exchange in the catalytic center. In order to rationalize this rare substrate preference among VAOs, we resurrected and characterized three ancestral enzymes and performed mutagenesis analyses. The results indicate that a Cys/Glu exchange was required to retain activity for ɣ-hydroxylations and shifted the acceptance towards benzyl ethers (up to 4.0 ± 0.1 U mg -1). Our findings contribute to the understanding of the functionality of VAO enzyme group, and with DcVAO, we add a new enzyme to the repertoire of ether cleaving biocatalysts. </p

Quantifying methane emissions from rice fields in the Taihu Lake region, China by coupling a detailed soil database with biogeochemical model

As China has approximately 22% of the world&apos;s rice paddies, the regional quantification of CH&lt;sub&gt;4&lt;/sub&gt; emissions from these paddies is important in determining their contribution to the global greenhouse gas effect. This paper reports the use of a biogeochemical model (DeNitrification and DeComposition or DNDC) for quantifying CH&lt;sub&gt;4&lt;/sub&gt; emissions from rice fields in the Taihu Lake region of China. For this application, the DNDC model was linked to a 1:50 000 soil database derived from 1107 paddy soil profiles compiled during the Second National Soil Survey of China in the 1980s–1990s. The simulated results showed that the 2.3 Mha of paddy rice fields in the Taihu Lake region emitted the equivalent of 5.7 Tg C from 1982–2000, with the average CH&lt;sub&gt;4&lt;/sub&gt; flux ranging from 114 to 138 kg C ha&lt;sup&gt;&amp;minus;1&lt;/sup&gt; y&lt;sup&gt;&amp;minus;1&lt;/sup&gt;. As for soil subgroups, the highest emission rate (660 kg C ha&lt;sup&gt;&amp;minus;1&lt;/sup&gt; y&lt;sup&gt;&amp;minus;1&lt;/sup&gt;) was linked to gleyed paddy soils accounting for about 4.4% of the total area of paddy soils. The lowest emission rate (91 kg C ha&lt;sup&gt;&amp;minus;1&lt;/sup&gt; y&lt;sup&gt;&amp;minus;1&lt;/sup&gt;) was associated with degleyed paddy soils accounting for about 18% of the total area of paddy soils. The most common soil in the area was hydromorphic paddy soils, which accounted for about 53% of the total area of paddy soils with a CH&lt;sub&gt;4&lt;/sub&gt; flux of 106 kg C ha&lt;sup&gt;&amp;minus;1&lt;/sup&gt; y&lt;sup&gt;&amp;minus;1&lt;/sup&gt;. On a regional basis, the annual averaged CH&lt;sub&gt;4&lt;/sub&gt; flux in the Taihu Lake plain soil region and alluvial plain soil region were higher than that in the low mountainous and hilly soil region and the polder soil region. The model simulation was conducted with two databases using polygons or counties as the basic units. The county-based database contained soil information coarser than the polygon system built based on the 1:50 000 soil database. The modeled results with the two databases found similar spatial patterns of CH&lt;sub&gt;4&lt;/sub&gt; emissions in the Taihu Lake region. However, discrepancies exist between the results from the two methods. The total CH&lt;sub&gt;4&lt;/sub&gt; emissions generated from the polygon-based database is 2.6 times the minimum CH&lt;sub&gt;4&lt;/sub&gt; emissions generated from the county-based database, and is 0.98 times the maximum CH&lt;sub&gt;4&lt;/sub&gt; emissions generated from the county-based database. The average value of the relative deviation ranged from &amp;minus;20% to 98% for most counties, which indicates that a more precise soil database is necessary to better simulate CH&lt;sub&gt;4&lt;/sub&gt; emissions from rice fields in the Taihu Lake region using the DNDC model