I could give several examples such as wet waste, sorted municipal solid waste, forest residues, dedicated energy crops, agricultural residues and algae which you can chose from based on a number of factors such as availability, capacity to produce and potential of the specific feedstock.

I believe that the answer to this question depends a lot on the region or country where you are analyzing the use of renewable fuels. The availability of the types of raw materials that can be used efficiently depend largely on their availability in each region or country. That is the main criterion to answer the question: Which are the most promising kinds of feedstock for renewable fuels?

Availability and the response for experimental operation may matter your choice. Meanwhile, agricultural wastes are still recommended.

I think the answers provided by others seem more than adequate. Anything non-lignacious should be appropriate.

Feedstock that is available to you at all times and in large quantity

1. Algae

2. De-oiled seeds of plants

3. Garden grass and weeds (Everything depending on the biochemical properties of the feedstock)

organic waste such as food waste, agriculture waste and manure.

Ideal feedstock will be those which have no enduse, like weeds like Parthenium, water hyacinth etc. Moreover lesser the content of lignin, better is the feedstock for syngas generation. The feedstock should not have secondary usage like, animal feed etc.

Food waste, Agricultural waste, Animal waste.

according to the available biomass in a particular place

Valerio Paolini

Food waste is quite a promising option

You may want to refer our paper on this

Article Social Cost Benefit Analysis of Operating Compressed Biometh...

Hello Valerio Paolini, in my latest research, I could see that in developing countries with a predominance of tropical climate, the best type of waste to develop new technologies is food waste, these being analyzed throughout their production chain, producer, transport, markets and consumers. Also believe that the biggest challenge is not just the waste or biomass used in the biodigestion process, but the process itself, even though it is a well-discussed subject, many difficulties still remain in its operation.

Lignocellulosic biomass is the most abundant renewable feedstock and is considerably cheaper than crude oil. Also, microalgae are amongst the most promising renewable feedstocks for biofuel production.

Food waste is best feedstock for bigas production, and for gasification process we can uses lignocellulsic feedstock or any solid waste of biomass

It depends on your desired product mean which type of renewable fuels you want. The best one is available easily and will not increase the carbon footprints. Utilising waste for energy production, food waste, forests wastes, agri wastes, etc.

The best way we must depend on energy plants

Hamid Salih, I believe that the challenge for the use of lignocellulosic as a raw material is the decomposition of lignin, so that the biodigestion process uses the content of the vegetals cells. And there is the problem of the pretreatment of those vegetables to break the lignin.

For fermentation, the lower the lignin content the better. You may want to keep algae out of it unless you ensure suitable enzymes are present, and you must be ready for some stinking residue and mercaptans in the gas.. Microalgae will give you very ammoniacal solutions at the end.

For gasification, you want your feedstock reasonably dry but it can be just about anything. If you externally heat it, a very high per centage of your energy goes to maintain the temperature. If you use the organic matter to provide the heat, air blown leads to producer gas which is really of fairly low quality. Oxygen blown gives the best quality gas, but you still have to make the oxygen, and there is also the issue of materials to hold the molten alkaline slag.

I rather favour hydrothermal liquefaction because you make liquid fuels, which are more valuable, but you still have to heat the mix. The reaction is exothermic, so if well-judged, this may be minimal, and you can use the gas you make.

There is no single "stand-out" solution. My view is to make that which is easiest to sell at the best value, which may depend on location.

I wonder why this question that has a textbook related answer require so many contributing to saying the same thing in different words. I stay surprised!

Article Fuel properties and emission characteristics of biodiesel pr...

Article Production of biodiesel from unused algal biomass in Punjab, India

Microalgae compete with nothing so the direction is towards it

1. Cotton seed oil and cotton seed oil fatty acids

They come with cotton production so they do not compete with plant oils

2. Castor oil. which does obviously not compete with food either

Both could be easily with little technology and cost into biodiesel using our

MBT-Technology. Methane sulfonier acid catalyzed transesterification

The state of the art alkaline transesterification does not work sufficiently with these oils

From a more generalized viewpoint, the promising kinds of feedstock for renewable fuels should:

• Exploit energy plants of high heating value (HHV) and low moisture content.
• Follow low carbon footprints.
• Be cost-effective, in terms of feedstock transportation from the source to bio-refineries.
• Satisfy energy demand to local and remote residential areas, having no stable connection to the mainland grid.

There are several kinds of feedstock for renewable fuels. From my point of view, algal biomass is better than cellulosic biomass. But it depends on your aim and goal (bio-oil product, bio-char product or gaseous product) and it depends on the process utilized.

Sunflower oil. Sunflower grow on dry area

and Castor grows everywhere and there is definitely no food competition