Heating values of diesel and biodiesel

The high heating value

• Petroleum diesel: 42.7 MJ/kg.
• Biodiesel derived from seed oils, such as rapeseed or soybean: 37 MJ/kg.
• Biodiesel derived from algae: 41 MJ/kg.

An informative review paper on the physico-chemical properties of feedstocks for biodiesel production

A summarized information was presented in Tables in this paper on the following aspects:

• Yields of vegetable oils and their fatty acid composition.
• Influence of feedstocks on biodiesel process selection and operating conditions.
• Physico-chemical properties of methyl esters from various bio-oils.
• Physico-chemical properties of methyl esters from various bio-oils.

ARPA-E 2011 Keynote: Secretary Steven Chu

News: Secretary for the US Department of Energy, Steven Chu, discusses the big picture of how the United States uses Energy and why innovation in clean technology is the key to Winning the Future.


http://www.youtube.com/watch?v=8QHVOoUDpN4

Universal or “customized” enzyme cocktail for sugar production

Currently available commercial enzyme preparations are limited in number and composition and have generally been optimized for acid-pretreated stover from maize and other grasses.

However, lignocellulosic feedstocks for sugar production include a variety of biomass: woody biomass such as softwood and hardwood, waste paper; non-wood biomass such as grass stovers (e.g., maize, sorghum, switchgrass or Miscanthus); and other biomass materials such as corn cobs, dried distillers’ grains solubles. All these biomass have different chemical composition, which will response differently to different pretreatments (e. acidic, basic, or oxidation), resulting in pretreated biomass with different chemical composition, even sugar composition. Therefore a general enzyme cocktail may work well for one type biomass or one type of pretreated biomass but not efficiently for other biomass. For example, for grass biomass with branchy arabinose and glucuronic acid, it may need GH10 endo-xylanase, a-arabinosidase, and a-glucuronidase. For woody biomass, in addition to the key endo-and exo-glucanases and endo-xylananse, it may need ferulate esterase and beta-mannanase. For acid pretreatment at a temperature >160 C, some of biomass hemicelluloses will be removed but some lignin may condense or re-deposit on fiber surface; while alkaline pretreatment will delignify but may have hemicelluloses re-deposited on the fiber surface. All of these will impact the efficiency of enzymatic hydrolysis and may require specifically modified enzyme cocktails. Therefore, a modified “customized” enzyme cocktail is more appropriate to adapt the spectrum of biomass and pretreatment combination for target hydrolysis.

A good research paper presents a study on this issue.

In planta expression of highly thermostable enzymes

In planta enzyme expression uses plants instead of microbial bioreactors as a “factory” to produce industrial hydrolytic enzymes for biofuel production. The enzymes that are active at typical and ambient plant growth temperatures will hurt plant normal growth/phenotypes and produce shriveled seeds as reported in the research paper.


However, in planta expression of thermophilic enzymes have been suggested as a method to reduce the detrimental effects on plants as these enzymes have higher temperature optima than encountered during plant growth. As a result, the plant stover can be pretreated at a relatively high temperature to induce their activation during processing.


Since a typical enzyme cocktail will require a combination of different class of enzymes to work together to destroy the cell wall for hydrolysis, is it possible to find all the key enzymes with thermophilibility and express them into a single plant without impacting plant growth?