Biomass Feedstocks презентация

Biomass Feedstocks

Biodiesel (B100) ASTM PS 121 Biodiesel Fuel Standard similar to ASTM D 975 Used pure or blended with #2 or #1 diesel, JP8, Kerosene, or Jet A. Use pure or blends in existing diesel engines on road, marine, off road, stationary, turbines, air craft B100 has 10% less energy than #2 diesel Power loss and fuel economy loss 1% for every 10% biodiesel in fuel Reduces CO, PM, toxicity of PM, and HC emissions

Handles Just Like Diesel No engine modifications required for B20, if using B100 then: rubber seals may deteriorate metals (Zn, Cu, W, bronze, brass) lead to oxidation Storage stability up to 6 months More sensitive to cold weather (Cloud pt = 0oC) Cetane number = 47 to 70 No sulfur, no aromatics, 11% oxygen by wt Stays blended even in presence of water Use biocides if needed

Constituents of Biomass Lignin: 15%–25% Complex aromatic structure Very high energy content Resists biochemical conversion Hemicellulose: 23%–32% Xylose is the second most abundant sugar in the biosphere Polymer of 5- and 6-carbon sugars, marginal biochemical feed Cellulose: 38%–50% Most abundant form of carbon in biosphere Polymer of glucose, good biochemical feedstock

Plant Cell Wall Models

Plant Cell Wall Models

Hemicellulose Structure Complicated branching and bond structure Affect solubility and enzyme accessibility Different bonds affected by different pretreatments i.e. Esters cleaved at alkaline pH, elevated To Highly variable across species Xylans, mannans Glucomannans Xyloglucans Etc.

Biofuels from Biomass Other organisms produce butanol or isobutanol

Diesel Biofuels from Biomass Green diesel is virtually identical to petroleum-derived diesel, can make a true jet fuel as well

Thermochemical Pathways Gasification is high temperature with air or steam Pyrolysis is moderate temperature

Comparison of feeds and processes Biochemical is low temperature but long times Thermochemical is high-throughput but high temperature and sometimes high pressure Not enough sugar except perhaps sugar cane in Brazil Oil-seed yields too low for high impact Ligno-cellulosic feeds high yields but more difficult to process Algae has high yields but many processing difficulties

Sustainability of Cellulosic Ethanol

Is there enough land? If biomass competes with food crops for farm land, then food prices will rise causing the poor to suffer

The 1.3 Billion Ton Biomass Scenario

When will the fuels come? Corn ethanol and biodiesel are here now to some extent Cellulosic ethanol, mixed alcohols, and green diesel are rather near, 15% ethanol will be allowed in near future Hydrocarbons from biomass are further away Algal fuels are a long way off

Life Cycle Assessment: Definition LCA Is a systematic analytical method Used to quantify environmental benefits and drawbacks of a system Performed on all operations, cradle-to-grave, resource extraction to final disposal Ideal for comparing new technologies to the status quo Helps to pinpoint areas that deserve special attention Reveals unexpected environmental consequences (no showstopping surprises)

Summary Energy is the driver of everything we do in today’s society Energy has an enormous impact on the environment Looking at the emissions of the production plant is not enough LCA allows us to evaluate the broader environmental impacts Renewable energy Not zero impact, but lower and more sustainable Different impacts; be careful of shifts (e.g., CO2 to land-use) Often more distributed impact Solutions do exist to reduce our energy / environmental problems