Shaharin,

I suggest you look up literature on embodied energy and cost analysis for biogas systems. A lot has been written on this, and quite a bit of it is available on the internet.

-Sanjay

Dear Dr. Shaharin,

The article mentioned below gives a review on the biomass gasification and various methods and criterion for comparison, which would help you to asses the energy content.

https://www.researchgate.net/publication/222429674_A_review_on_gasification_of_biomass

Article A review on gasification of biomass

I recommend that you do elemental analysis on the biomass being considered for gasification. The elemental analysis will provide quantitative data on the contents of this biomass like carbon, hydrogen, nitrogen, sulfur, etc. Such quantitative data can used to estimate how much carbon dioxide (CO2), carbon oxide (CO), hydrogen sulfide (H2S), nitrogen oxides (NOx), and moisture would be expected during the biomass gasification process.

The result of biomass gasification is a gaseous mixture of syngas (CO + H2), H2S, H2O, ammonia (NH3), etc. plus particulate matter (PM). The sour gases like H2S are considered impurities and must be removed from the syngas as they can poison the catalyst used in the downstream water-gas shift (WGS) reaction. Ammonia gas (NH3) can also poison the catalyst used in the WGS reaction. Moreover from the elemental analysis of the biomass being considered for gasification, you can calculate the hydrogen-to-carbon ratio which is a critical factor to be considered in the needed WGS reaction.

Other than what I recommend regarding the biomass elemental analysis, you will need to know: 1) the growth rate of the biomass and whether this feedstock can support the gasifiers being designed and 2) how far is the source of the biomass from the gasification plant as the transportation cost of the biomass will also impact the economics of the gasification plant.

Hope this helps answer your question!

Thank you everyone for the answers and suggestions. All the best.

Shaharin.

Dr. Shaharin,

While the above answers are good, perhaps the first question is "what is the plant-based biomass?". 

For gasification, with a biomass with high water content, you have several issues:

- high transport cost if the water is still contained in the biomass vs methods to reduce water content prior to shipping

- long term storage methods to preserve the biomass

- drying cost to an acceptable moisture content prior to gasification

In the pulp & paper industry, many types of plant-based biomass have been and are used, and this issue has been addressed in various fashions using various techniques depending on the feed stock.

I expect that some of the methods used for plant-based biomass in the pulp & paper industry likely could be used for your application but need more information on the specific biomass to be able to make some suggestions.

Dr Hurter,

You are right on those. The material is oil palm frond (minus the leaflets).

Among other issue to add is the low fuel cost in the country. So far we've published some papers on gasification of this material.

Thank you.

Shaharin

Shaharin,

Thanks for your reply.

Oil palm fronds typically have a moisture content of about 70-75% in the stem and about 55-60% in the leaves, so I can see your issues.

In the plant-based pulp & paper industry (commonly referred to in the industry as nonwood fibers), for long term storage we look for the biomass to be less than 20% moisture (cereal straws, grasses, industrial hemp, bamboo, kenaf, jute etc. are all harvested and delivered at less than 20% moisture) or more than 80% moisture used for wet bulk storage of sugarcane bagasse (Ritter process).  These conditions are best to preserve the biomass in long term storage.

While the oil palm fronds could be stored in wet bulk storage, this would not be the solution for a gasification feed stock as you would have high transport costs for the wet bulky fronds and then the drying cost ahead of gasification.

So, the route to tale is to look at methods of drying the fronds to less than 20% moisture before shipping to the gasification plant.

The one method that I know of for reducing the moisture in biomass is the Bagatex-20 process developed in Brazil in the 1980's for sugarcane bagasse. 

Bagasse is the fibrous residue left over after the cane has been crushed and the sugar juices extracted.  It is discharged from the sugar mill at about 50% moisture.  Most bagasse-based pulp & paper mills are next door to the sugar mill and store their bagasse in wet bulks storage using the Ritter process.

A Brazilian pulp & paper mill looked at getting bagasse from sugar mills farther away and led to the development of the Bagatex-20 process.  The bagasse is treated with a simple cocktail of yeast and other components (sprayed on) and then baled in large bales which were piled with air channels.  Over a few weeks, the moisture content dropped below 20%.  While this did preserve the bagasse for future use in pulp & paper, the process did not get wide acceptance in the pulp & paper industry as the baled and dried bagasse now had more value as fuel.

If you do a Google search for "Bagatex-20" you will get links to several technical papers on the process.  One very good one is from Australia "MOISTURE LOSS FROM BALED BAGASSE DURING STORAGE", M.W. Dawson, T.F. Dixon and P.A. Inkerman, Sugar Research Institute, Proceedings of Australian Society of Sugarcane Technologists, 1990. 

For this process to work, it will have to be mechanized but I expect that the equipment can all be mobile.  You will need a shredder/tub grinder to reduce the fronds to something like bagasse (mobile tub grinders and shredders are readily available), a conveyor system with showers to add the reagents and tankage (likely could be mounted on a flat bed trailer or a modified mobile grain conveyor), a baler to make the large balers (many mobile balers exist), and bale handling equipment.

Hope this helps.  Let us all know if you have a look at this approach.

Bob

Dear Bob,

Many thanks for the detailed information. I will surely explore into those.

Usually our fronds can dry good enough under the sun for three consecutive days. We've yet to deal with pile of the fronds because so far we've been handling only small amount enough for small-scale gasification experiments. 

Shaharin