Chicker Feathers to Biogas: A PhD thesis

Chicken is something that almost everybody love and eat, regardless of the culture and religion. We eat the meet, but, there are a lot of wastes over, in which, feather is a major one!

In the last 30 years, the production of chicken feather was increased from 1,5 to 5 million tons per year. So the question is what to do with this feather! Our PhD candidate Gergely Forgacs took this question seriously as part of his PhD thesis and he is defending a few days. His focus was on biogas. The feather from slautherhouses can produce about 180 m3 biogas (methane) per ton of the material (volatile solid), and he could improve it to 400 m3 methane gas. Let's hope he can produce well both the biogas and also a PhD title for him from the feather :)

The thesis:
Biogas Production from Citrus Wastes and Chicken Feather: Pretreatment and Co-digestion

His publications:
1) Pourbafrani, Mohammad; Forgács, Gergely; Sárvári Horváth, Ilona; Niklasson, Claes and Taherzadeh, Mohammad J.: Production of biofuels, limonene and pectin from citrus wastes. Bioresource technology, 2010 101, 4246-4250.

2) Forgács, Gergely; Pourbafrani, Mohammad; Niklasson, Claes; Taherzadeh, Mohammad J. and Sárvári Horváth, Ilona.: Methane production from citrus wastes: process development and cost estimation. Journal of Chemical Technology and Biotechnology, 2012 87,250-255.

3) Forgács, Gergely; Alinezhad, Saeid; Mirabdollah, Amir; Feuk-Lagerstedt, Elisabeth and Sárvári Horváth, Ilona.: Biological treatment of chicken feather waste for improved biogas production. Journal of Environmental Sciences, 2011 23,1747-1753.

4) Forgács, Gergely; Lundin, Magnus; Taherzadeh, Mohammad J. and Sárvári Horváth, Ilona.: Pretreatment of chicken feather waste for improved biogas production. Submitted.

5) Forgács, Gergely; Niklasson, Claes; Sárvári Horváth, Ilona and Taherzadeh, Mohammad J. Methane production from feather waste pretreated with Ca(OH)2: process development and economical analysis. Submitted.


(The cover page of the thesis)

(The global production of chicken feather, extracted from the thesis)

Biogas in fuel market in Sweden 2009-2012

Biogas (biomethane) has the same chemical material as natural gas (methane). Sweden has a pipeline of natural gas in the south and west coast of the country, that bring the gas from north sea into Sweden via Denmark. There is also a smaller gas grid around Stockholm area. These networks were previously used to bring the gas for heat and energy applications, while it is now used for delivering fuel to cars and trucks which run on gas (methane).

The biogas and landfill gas produced in Sweden was previously used mainly for heating applications. However, the biogas (not landfill gas), wherever possible, is upgraded (means purified to have more than 97% methane) and injected to the gas grids and delivered as car fuels. In 2011, a total of 75 million m3 biogas and 45 million m3 natural gas were delivered to the pumps, which was 30% more than in 2010. The biogas delivery per months was increased from about 3 to 6,5 million m3 from 2009 to 2012. The consumption of natural gas was also increased from 1.9 to 4.7 in the same period. It means the share of biogas in Swedish fuel market is increasing. It is now about 2% of the gasoline equivalent. Still low, but the trend is good!


(Monthly consumption of Biogas and natural gas in Sweden as car fuel, Data from SCB)

Fuel consumption in Sweden 1946-2011

The total consumption of gasoline in Sweden was almost constant at 5,5 million m3 for 20 years during 1986-2006. However, this trend was broken in the last 5 years, by reducing a bit every year. In 2011, we the gasoline consumption was reduced by 7% to 4,2 million m3 according to SPBI. There are different reasons for this reduction:
- More renewables in the market (ethanol and biogas) in pure form (such as E85) or mixed with gasoline (such as E5),
- More fuel-efficient cars,
- More diesel cars.

The Ethanol share in total (E85 and E5) is about 10% of the gasoline market in total, while biogas has still very low contribution. However, it should be noticed that the total amont of gasoline and diesel are increasing from less than 9 million m3 in 1990s to 9.5 million m3 in 2011. It means that in general, Swedes are getting more interested to diesel than gasoline.

Looking at the other fuels, show aviation fuels as almost constant at about 1.1 million m3 per year, while heating oil has been significantly decreased in the last decades.

It means that Sweden has been successfull in replacing heating oils with other alternatives, while gasoline and diesel comsumption is still a challenge for the country's environmental authorities!


(Oil consumption in Sweden, according to SPBI)

Are you pressed by environmental actions?

The politions usually forget about the "sustainability" and general acceptance of people in environmental actions and laws. It is a big damage to the "environment". Here are some examples:

Stockholm Airport (Arlanda) declares that it is the best environmental airport in the world. It is great. But, when I talked to a taxi driver in Stockholm, he hated the airport. He invested into a new environmental (ethanol) taxi, but they changed regulation too fast, and it was not possible for him to adapt himself, so he was very upset.

We pay a lot of tax in Sweden and almost the entire European countries on gasoline and diesel. The tax is getting more and more every year, while the oil price is also increasing. So, we have to pay more, while many people have no option than continue taking the cars. How can we ask them to reduce their fuel consumption?

In another example, we all remember that ethanol was considered a great biofuel in Sweden a few years ago, and the government gave a lot of subsidiary to people who bought ethanol cars. It was a great investment, considering Sweden as net exporter of grains. But, they go too fast and too far, so they want to remove most the subsidiary on fuel ethanol. It is a great damage to people who buy ethanol cars, and all the investments that companies have made!

When we asked King of Sweden a few months ago, if he is interested to biogas for his next car, he said charmly no, and mentioned Electrical car as an environmental option. But, we shouldn't forget where the batteries for these cars should come from, and where we should get the energy from. These are two major challenges for the new electrical cars to introduce into the market.

In EU, we have a goal to use 20% renewables in 2020. However, we hear from different sides that this goal might not be possible to reach, and many people are not happy with these actions.

There are many other examples to mention. But, one important aspect that is usually forgotten in these environmental actions is the sustainabilty of the actions in short and long terms.


(The tax and production costs of gasoline in Sweden)

Waste sorting: Technology vs social solutions!

Waste is generally a mixture of valuable materials. However, people do not use it, since it is a mixed materials and most of us have no economically-feasible technology to use this material. However, if we succeed to separate it, then, we can have access to these valuable materials.

The global view on waste sorting into different fractions is an "impossible mission" or we, as engineers, usually look for an engineered technology to turn this impossible task to a possible one, and forget about the role of people in sorting and separation. Let's have a look on what we do:
1- In most of the countries in the world including industrial and developing countries: We have no solution, so lets dump it!
2- In some countries such as some European countries and Japan: Let's burn it altogether in an incinerator! They sometimes extract energy or sometimes not!
3- Let's separate the waste! But, we have a major question: Who should do it? Technology at waste stations? Scavengers? People at home?

In low wage developing countries, it is usually the scavengers who try to pick up valuable things among the wastes and then sell it. But, in more developed countries such as Sweden, there is no access to such people. In addition, it is just the recycling parts that the scavengers separate, and the rest remains.

Let's compare 3 methods to separate the wastes:

1- In Borås (Sweden): it is now many years that people separate wastes into black (biological wastes) and white bags (combustible wastes). It is easy to do and they close the bags and throw them together. They have one transporting system and then, machines separate the bags based on its color. They have done a huge investment on teaching people (social aspects) and the system works well. The black bags become biogas and the white bags become electricity and district heat via combustion.

2- In Göteborg (Sweden): The have recently started to separate the wastes into food wastes (paper bags) and other wastes (plastics bags). Then, there are two different transport system. The food wastes become biogas and the other wastes are combusted as in Borås, but different technology.

3- In Copenhagen (Denmark), they still burn the waste as mixed. But, they have different view of development. They forget about the social aspects, and put efforts in technology development to separate the "mixed wastes". They are testing in a pilot plants now (REnescience), in which the wastes are heated to less than 100 C, and then by enzymes, part of the wastes are dissolved into a slurry phase.

I belive, separation of wastes after the mixing is too costly and has low efficiency. If the politions and municipalities in the world invest more in developing social aspects in parity of technological aspects, we will have more economical solutions for converting "Wastes to Wealth"!


(An Indonesian Scavenger in Sulawesi)


(The technology used in Borås to separate black and white bags after collected together)



(Waste sorting in Göteborg, in which, the food wastes and other wastes are collected separately)


(The technology developing in Copenhagen for separating of mixed waste, still in pilot phase)