Chapter 2

Which effects can a high moisture content have on storage and handling, and which in combustion processes?

Why would a high porosity of the fuel lead to more fines when combusting a solid biofuel?

Discuss the effects of particle shape and size on storage and handling of biomass.

What are the main biopolymers on Earth?

What is the difference between homopolysaccharides and heteropolysaccharides? Give a few examples of both.

What is the nitrogen content of pepper plant residue on a mg per MJ basis (HHV, as received fuel)?

What are similarities and differences between starch and cellulose?

For the following fuels, calculate the emission of \(\mathrm{CO}_{2}\) in \(\mathrm{g} \cdot \mathrm{MJ}^{-1}\) (HHV basis) for complete stoichiometric combustion: \- Wood pellets \- Peat \- Brown coal \- Bituminous coal Which fuel gives the highest value?

Why would lignin have a higher heating value than carbohydrate constituents of biomass? In which ways does the lignin content influence biomass combustion behavior?

A woody fuel has an HHV of \(19 \mathrm{MJ} \cdot \mathrm{kg}^{-1}(\mathrm{db})\), what is the LHV (ar) when the moisture content (ar) is \(15 \mathrm{wt} \%\) and the ash content is \(0.8 \mathrm{wt} \%(\mathrm{db})\) ?

What distinguishes fats from oils?

Sugar extracted from sugar beets can be fermented to produce ethanol. Why is this an example of a first-generation biofuel production process?

Why is Jatropha curcas-derived biodiesel sometimes called a "1.5-generation" biofuel?

An ash analysis of all the ashes discharged from a waste wood-fired thermal conversion plant revealed that this plant produces ash with a lead \((\mathrm{Pb})\) content of \(100 \mathrm{mg} \cdot \mathrm{kg}^{-1}\). What is the \(\mathrm{Pb}\) content of the original fuel on a dry basis ( \(\mathrm{db}\) ) assuming that the fuel has been completely converted and given that the fuel contained 1 wt \(\%\) ash (db)? Which assumption(s) did you have to make for this calculation and is this entirely realistic?

Which elements in biomass do you expect to be most troublesome in thermal conversion processes and in which respect?

Why is the procedure for the determination of the volatile matter content in the proximate analysis different for biomass and coals?

In TGA analysis, hardwoods (e.g., birch, beech, and acacia) show the presence of a "shouldered peak," whereas this is less visible for softwoods (e.g., spruce). What can be the reason for this difference?

In TGA analysis, nitrogen can be used as sweeping gas, but also helium might be used. What is the main difference between these gases and why is helium attractive to use?

Explain in your own words the difference between the HHV and LHV of a fuel.

Discuss the different ash fusion methods; do they represent well the phenomena occurring in a fuel combustion reactor?

In which respects could biomass fuel blending be advantageous? Does it also have disadvantages? Explain.

Certain plant species but also (modified) chitosan can take up some elements very selectively and concentrate them. What are possible risks and opportunities of this specific uptake behavior? See Dodson et al. (2012).