Renewable energy


Tuesday, February 22, 2005

Effluent odours

I have not yet produced any slurry from my BioDigesters (largest is 10 m3 and operating for about 2 months now). Influent is 20 litres of manure per day soaked in an equal amount of water for 4 hours prior to feeding into the Digester.

In response to a recent discussion with Paul and Simon, Influent was increased 4 days ago to 40 litres of manure per day soaked in 60 liters of water for 4 hours prior to feeding. This to double Biogas production rate and give the BioDigester sufficient incoming liquid volume to push out effluent or slurry.

I expect the slurry to smell BAD -- like sewer water. If this is to be used as a fertilizer, shouldn't something be done to keep it from stinking the area where it is used?

If allowed to settle for awhile, the effluent should separate into a muddy sediment and free-flowing liquid. Do you have any suggestions on handling the free flowing liquid? I want to pass it through a simple waste water treatment process (again to remove its foul odour) before using it to irrigate plants in the farm.

Thursday, February 17, 2005


Hi Gerry,
I was not suggesting codigestion as being essential to the well-being of your biodigester. It is just common for the larger biodigesters to take in the scraps from the local markets or whatever else is available.

After all, you have a permanent source of feedstock, but anything else is just extra. You are getting rid of the rubbish for them and doing something useful with it. All the big ones in Switzerland are codigesters.


large-scale biodigester

Hello again,

my little presentation went very well except for the fact that my audience thought my radical ideas were backed by a lot of in-experience compared to PhilBIO’s track record for building HUGE digesters. Patience and practical examples, however, gave my audience something to think about. I can only hope at this stage that they keep my ideas to themselves, give me some credit and allow me to build their digester.

The “model” confirms that my proposal is on the right track. PhilBIO is proposing a HUGE 20,000 m3 digester because they have to process 9,000 liters of manure + 80,000 liters of wastewater everyday. I propose a 5,000 m3 BioDigester because I want to settle, collect and only allow wet manure of approximately 19,000 liters into the digester. PLH proposes a VERY small 1,451 m3 digester and there seems to be a typo on the dilution rate. I believe should be 0.30 (not 3.0). If PhilBIO’s 20,000 m3 digester costs 4 million pesos, my 5,000 m3 BioDigester will cost less than HALF that (or less than 2 million pesos). The PLH digester at 1,451 m3 will cost less than 1 million pesos. The savings ARE SUBSTANTIAL if the digester is sized correctly.

My audience eventually appreciated the ingenuity of NOT HAVING TO DIGEST ALL the wastewater.

Again based on the “model”, if:PhilBIO’s 20,000 m3 digester will produce 668 m3 of biogas/day,My 5,000 m3 BioDigester will produce 669 m3 biogas/day; and,PLH’s 1,451 m3 digester will produce 562 m3 biogas/day, my BioDigester is PREFERABLE to PhilBIO because it is CHEAPER!

Simon, I anxiously await your two cents. Btw, does codigestion mean feeding the digester with something other than pig manure? If so, its safe to say this system will use 100% pig manure on a regular basis. However, I might advise them to occasionally add chopped grass or the like to feed the system some carbon.

Salamat at mabuhay kayong dalawa!


Sunday, February 13, 2005

Biogas and codigestion

To produce 1 m3 of BIOGAS, to cook 3 meals daily for a small family of 4 to 6, you need at least 5 litres of pig manure/day. 8 sows will produce 5+ litres/day easily and your 36 heads total will probably give you at least 15 litres. A 2 m3 digester wil produce 1 m3 of BIOGAS/day -- good for experimental purposes. I suggest your first digester be at least 5 m3. This will produce more BIOGAS when needed and accommodate your farm's growth.

The China Fixed Dome, India Floating Cover and DOST-PSTC designs are the most popular here in the Philippines. Download drawings from the internet but I suggest you get professional help as the building process is not easy.

Here are people who can help:

Roberto Bajenting Trained at Asia-Pacific Biogas Research and Training Center, Chengdu City, Sichuan, China.
Provincial Agrarian Reform Officer, Cebu CityCell No: +63920-923-6930

Engr Orlando Anselmo. Has installed 35+ DOST-PSTC digesters in Aurora Province
DOST Officer, Baler, Aurora ProvinceCell No: +63915-569-9631

The BioDigester I designed is made of 1.5 mm HDPE or High Density Polyethylene. It’s the same material used for landfills worldwide. Working with HDPE requires special equipment and trained technicians. Building just one or two is not cheap and economical.

I have 5 m3 BioDigesters available as ready-to-install kits because I had them pre-fabricated and mass-produced, resulting in lower costs. You can have a complete 5 m3 BioDigester system for about P20,000.00 (a 10 m3 unit for about P30,000.00) plus P5,000 max for delivery and installation. To compute SAVINGS just remember: 1 m3 BIOGAS/day replaces one 11 kg tank of LPG worth P400.00 per month. Using 2 m3 BIOGAS/day will save P800.00 per month.

The CFD, IFC and DOST-PSTC digesters all cost over P25,000.00. For this reason, I have asked Bobby Bajenting and Engr Anselmo to help me promote the BioDigester. I avoided bagasse despite its energy potential for two reasons. It is not readily available and its near-solid nature will probably fill-up and clog my digester. As you said, there are lots of other wastes available. I have used grass cuttings from the local golf course, spoiled vegetables from the "palengke" and all our kitchen scraps.I am currently installing a 10 m3 BioDigester at my brother’s restaurant. I am also talking with local officials about a 10 m3 BioDigester for the "palengke" to digest vegetable scraps and provide some kitchenettes with cheap cooking gas.

When I started my BIOGAS experiments, I checked temperatures and pH. First with an expensive kit from BioResearch and eventually with plain litmus papers. I measured quantities of manure used, volumes of BIOGAS produced, etc. It was a lot fun – but largely unnecessary -- I think. Conditions for digestion in the Philippines are ideal. Its so EASY to produce BIOGAS here! Just follow some tried and tested procedures.

Biomass and codigestion

You can gasify material. You will find information on it if you check around under pyrolysis as it is generally called. The big disadvantage of pyrolysis is that you have to put a lot of energy into it to get a result, and the gas you get is mainly a mixture of carbon monoxide and hydrogen. It is very combustible but equally toxic. Pyrolysis has the advantage that it works on wood, which is indigestible for anaerobic bacteria. Lignin, the wood fibre material, just will not decompose without oxygen. Probably there was not much wood around when these bacteria evolved, many millions of years ago! If bagasse will decompose, and I have no idea, never having seen the stuff, then you will get more energy more safely this way.

I have been reading up on the codigestion projects in Switzerland, and they have all been chopping the vegetable matter and pasteurising it before use. Perhaps there are residual conservation chemicals (antibacterials?) that have to be removed before it will work properly.

The question of H2S is one that comes up more when you are storing the gas or feeding it into the mains gas supply. It is corrosive and there are strains of bacteria that thrive in it. We are permitted to keep it at work in concentrations less than 50 ppm. This is not considered dangerous, but you can definitely smell it!The traditional method of removing it is either washing or passing it over iron, usually both are used. The problem only really occurs with manure, vegetable matter has little sulphur in it, and it is very diluted. That is another advantage of codigestion, the manure is diluted, so the production of H2S and NH3 is also diluted. For small scale use I would simply ignore it.

Tuesday, February 08, 2005


Biodiesel is a clean burning alternative fuel, produced from domestically grown, renewable resources. Biodiesel contains no petroleum products, but can be blended at any concentration with diesel from traditional sources to create a biodiesel blend. It can be used in compression-ignition engines with little or no modification. Biodiesel is simple to use, biodegradable, non-toxic, and intrinsically free of sulphur compounds and aromatics.

Biodiesel is made in a chemical process called transesterification, where glycerine is separated from the vegetable oil. The process results in two products -- methyl esters (the chemical name for biodiesel) and glycerine (a by-product used in soap manufacture).

Looking at the disadvantages, biodiesel does not supply the same energy yield per unit area that simple green plants used in a biodigester would. The biogas produced there would give about twice the energy that the same area devoted to oil plants for biodiesel production.
Biodiesel is so attractive because it can be used in existing engines with very little needed in the way of adaptation. At very low temperatures it will probably prove impossible to use pure biodiesel (B100), but mixtures up to 20 % biodiesel (B20) should cope with most climates. This advantage means that the technology can be applied generally without any preparation stage. Converting fleets of vehicles to gas propulsion is a very costly and time-consuming business, to say nothing of the down-time caused.

Thursday, February 03, 2005

Combustion efficiency

Combustion efficiency is one of those terms which are bandied about and sound as if everybody should know what is meant. The problem is that combustion efficiency is only one small part of the total efficiency of a heating system. Particularly with old systems, the radiation losses from the boiler and the poor lagging on the pipe-work can lead to losses far in excess of any stack loss or loss by incomplete combustion.

Combustion efficiency is, as the name suggests, purely a measure of the amount of energy that is lost up the stack and, perhaps, lost by unsatisfactory conversion of fuel and air to carbon dioxide and water. As such, it is a good measure of what can be gained by tuning a boiler, or better still, what has been gained by tuning a boiler, but it does not and cannot take the other factors into consideration.

It is a value readily measured by a combustion analyzer, and this makes it very useful for boiler maintenance technicians, who cannot be expected to take radiation losses into account. These losses can only be altered by changing to a newer boiler anyway.

Wednesday, February 02, 2005

More news from the Philippine biodigester

I have managed to test a few carbon based feedstocks as we last discussed.
They are:
1. lawn-mower grass cuttings from the greens of a nearby golf course
2. shredded sweet potatoes (yams) - from waste bin in vegetable market
3. shredded potatoes - from waste bin in vegetable market
4. sliced tomatoes - from waste bin in vegetable market
5. pressed coconut meat - from a native cake bakeshop

The sliced tomatoes and pressed coconut meat did not appear to produce biogas.d(When fed to a working biodigester, biogas output continued to decline as if no feedstock was added.)

Worse, the pressed coconut meat floats and may be floating inside the digester impeding digestion.

With the grass cuttings, gas production did not drop. In fact, there was a small noticeable increase for a few days.

The yams and potatoes, however, gave a surge in biogas production for a few days. Yams and potatoes (apparently, vegetables that cause one to fart) are good for biogas production.

In all instances, approximately 5 % feedstock by volume was added once and production was observed for two weeks.

I plan to repeat the tests and validate the results.
I have also been keeping track of the listserv forum. The composting of biomass wastes before using it as feedstock is a good idea specially for wastes that tend to float.

Returning from a vacation, we passed a little remote-community that had signs saying they were using biogas. We stopped, interviewed two users and examined their set-ups. Though they invested heavily when their digesters were built in 2001, they are very happy to have them now that LPG prices have almost tripled.

I was able to track down one of the technicians who happily reported that he has built 41 digesters ranging from 5 to 10 m3 since 2000 -- with funding assistance from UNDP.

It was great to find that community with home-type or family-type biodigesters. The find affirms that biogas WORKS!

My biodigester which only costs about 80 % today for what they paid for in 2001 continues to appear to be a great idea for the Philippines. The DOST tech I mentioned above agrees and plans to try my units in his next projects.

The 10 m3 HDPE units installed in our farm are now full of biogas. We are going to test burning the biogas when I go there tomorrow.

I also have a couple of relatives interested in 10 m3 units for their farms. This is getting interesting.


Biomass is another of those topics that is becoming more and more interesting these days. Basically, there are two ways in which biomass may be used directly: Direct combustion to produce heat or power and gasification to produce a gas that can be used to power vehicles etc. The version chosen will depend on the needs of the local industry. Biomass can also be used to feed a methane digester, but we are talking about the direct uses here. Biomass can be defined as any waste vegetable matter, such as straw, wood branches or other leftovers, very similar to what our ancestors were burning 10000 years ago. So what has changed? Modern combustion technology can use this biomass to produce electricity on a small scale without leaving a trail of smoke across the landscape, supplying a single village or smaller group of houses with their own power. The combination of a combustion plant with a gasification unit is equally possible, allowing a number of vehicles to be run without the need for imported gasoline. Biomass is the up and coming technology in many outlying areas in Europe, where the supply of piped fuel is not available and liquid fuel must come a long way across difficult terrain.

Renewable energy is a recognised goal for the future, and one of the most successful routes is via the use of fuels that can be grown or collected from nature, where they will be replaced in a reasonable period of time. Perhaps the best description is “second-hand solar energy”.

Sunday, January 30, 2005

The biodigester

It has been some time since I added a post, and I have more news of the biodigester in the Philippines. The experimental use of other material to charge the biodigester is underway, but has not proved as successful as expected. The whole information will be added tomorrow, but he gist of the matter is that only the potatoes and yams really boosted gas production.

This is surprising, since codigestion is a recognised practice with almost all vegetable rests. Possibly the pieces were slightly large, but that should really just slow the process. It is, however, common practice to pasteurise such material before adding it to a digester, and maybe the vegetables had been treated with an antibacterial agent before being offered for sale. They were simply waste from a large market, so that is a possibility that will have to be investigated. The potatoes and yams did boost production though, but there is no information available for bagasse (the remains after sugar cane has been processed).

Being a waste product, this is a very hopeful avenue for research. Clearly, it will leave a large quantity of fibrous matter which will not be digested, but there should be a quantity of gas to be gained from the material. The fibrous matter left can either be burnt (which is the usual use for bagasse) or composted afterwards. Aerobic bacteria are quite capable of dealing with wood or fibrous matter.

Friday, January 14, 2005

Back to biogas!

sorry for the departure form the usual topic. Time was pressing this week. One of the main sources of information in Europe, the Swiss Biogas Forum, no longer seems to be very active. Although there have been more English speakers posting there, the pages have not been updated in a long time and they do not answer emails. A shame, they supplied some really very good information on the topic of anaerobic digestion and had a lot of active members in the industry.

Perhaps a few people can visit there and try to get it going again. Austria is doing some good research into anaerobic digestion of grass. Solid material is notoriously more difficult to convert into biogas, but the work is going well, and a pilot plant is just starting up now.

There has been no new information from the biodigester in the Philippines. I will drop Gerry a line at the weekend and see what is happening. He should be getting results from the codigester by now.

Monday, January 10, 2005


Washington, January 10, 2005 - The President of the World Bank Group, James D.Wolfensohn, yesterday visited tsunami-hit areas in the Meemu Atol of theMaldives, where he visited affected communities and saw at first-hand the extentof damage to their lives and the local infrastructure. During his day-long visit, Mr Wolfensohn met with President Maumoon AbdulGayoom, Foreign Minister Fathulla Jameel, Finance Minister Mohamed Jaleel as well as other ministers and senior officials."Communities are demonstrating their resilience by organizing local support networks and coordinating relief operations," Mr Wolfensohn said. "It is truly impressive to see the way the Maldives has provided basic necessities to affected people, and started to lay the foundations to reconstruct the country in order to make it again one of the most successful examples of development in South Asia."Maldives is proportionately among the countries worst affected by the disaster and will likely face the highest per capita reconstruction cost. Damage to the infrastructure of what was for a long time the most prosperous South Asian country is immense. Over a third of the total population of almost 300,000 was greatly affected, and over 122,000 people were made homeless. These figures reflect the fact that, out of a total of 199 inhabited islands, 20 were totally devastated and 53 suffered severe damage.

Sunday, January 09, 2005

Nuclear energy

I am also a supporter of nuclear energy. What other options are there? As I have posted in the renewable energy forum, there is a great deal we can do to reduce our dependence on fossil fuels, but not everythig that is being done is helpful. The wind energy here is so expensive to produce, and the amount of material and energy required to erect a reasonably sized wind turbine, that I have heard there is no positive energy balance there. They are certainly unsightly and not possible everywhere.

Hydroelectric cannot be used everywhere, and wave power is only possible in coastal areas. You are used to the tidal effects in the Atlantic, North Sea etc. For us, the nearest piece of sea is the Med. Tides there are only a metre or so. All the water has to go in or out through the Straits of Gibraltar, so there are basically no tides to speak of. One of the main problems are the environmentalists, I am afraid! You want to install a large hydroelectric scheme? Then you have to flood a valley, build a dam etc. You will have thousands of people saying it can't be done where you want to have it. Nuclear power is clean. There are indeed risks involved, most of which are exaggerated wildly.

But can you show me the alternative? Like it or not, we need the power produced, so it has to come from somewhere. Reducing our dependence on fossil fuels has to be the first priority. For a start, they are limited in supply, and we are agreed that they are damaging in effect. So where should it come from? When all the landfills are producing gas, unused farmland is producing biomass for heating and power production, or at least material to fuel biogas plants. A reasonable amount of district heating has been installed to make use of heat from cogeneration units, then we can take a look at the energy equation and see what can be done.

Saturday, January 08, 2005


Colombo, 8 January, 2005 - The President of the World Bank Group, James D. Wolfensohn, today visited tsunami-hit areas in the Hambantota district of Sri Lanka, where he met with affected communities and saw first-hand the extent of damage to their lives, livelihoods and public infrastructure. He also flew over devastated areas of Galle, Ampara and Batticaloa. The United Nations Secretary General, Mr Kofi Annan, and Mr Wolfensohn combined their visits to these sites in order to minimize pressure on local governments coping with relief and rehabilitation work. During his day-long visit, Mr Wolfensohn also met with Sri Lankan President Chandrika Kumaratunga, Prime Minister Mahinda Rajapakase and Minister of Finance Sarath Amunugama as well as representatives of other political parties. He assured them that the World Bank, in collaboration with other donors, would provide Sri Lanka the financial and technical support it needed to recover from the tragedy.

Build your own computer to save resources and money

Building Cheap Computers can be fun!
Like most PC enthusiasts, you will want to experience that true pride and satisfaction that you get from building your own computer from scratch at a cheap price. This approach not only saves you from unnecessary expenditure, in also reduces the environmental impact by eliminating the parts and steps that are not really essential. The packaging etc. on a modern computer will only be thrown away and end on the nearest landfill, so why do you need it? So why not? Start building your own computer!


India has to import nearly 70% of its annual crude petroleum requirement, which is around 110 million tons. The prices are in the range of US$ 33-50 per barrel, and the expenditure on crude purchase is thus in the range of Rs.800 billion per year, which is a major factor for the country's foreign exchange reserves. (Oil Prices touched a record high of $55 per barrel.)

The petroleum industry in India now appears fully committed to the use of ethanol as a fuel, since it will benefit sugarcane farmers as well as the oil industry in the long run.

Russia adds third large combined cycle plant

23 December 2004 - Russia's electricity utility RAO UES on Monday inaugurated the Sochinskaya cogeneration plant, only the third one in Russia to use combined cycle technology.

Cogeneration plants add a considerable increase in efficiency to traditional thermal power plants. Such moves are a real sign of improvement in the Russian power supply network and herald a new generation of thinking in the country. Full story here.

Siemens wind division secures first major order

29 December 2004 - Siemens Power Generation (PG) is to supply npower renewables, a subsidiary of RWE npower plc., with 40 wind turbines, in the first major order for its new wind power division. The full story is to be found here.

Friday, January 07, 2005

Renewable Energy Conference Las Vegas

Here is information about the upcoming conference in Las Vegas about bioenergy. This should start things moving worldwide.

POWER-GEN Renewable Energy is the renewable energy industry's premier event, with all the major players in the renewable energy (wind, solar, hydro power, geothermal energy, ocean/tidal, and biomass), renewable fuels (biofuels, ethanol, methanol, and biodiesel), and emerging energy technology (hydrogen systems, fuel cells, microturbines and energy storage) sectors of the energy industry on hand discussing key technical, regulatory, structural, economic and market issues impacting the commercial future of the important industry. The event will be featuring session tracks on technology and business issues, as well as an exhibit floor to showcase cutting edge products, systems and services.

We would like to bring this event to your attention with hopes that you will be inspired to lend your own expertise to the event and participate as an exhibitor. It is imperative that you join others in the digester industry to have a strong presence at a renewable energy fair of this magnitude. This is a great opportunity to display your products and services to a qualified audience of leading decision-makers, an audience with the power to purchase. This event is America's first all-renewables conference and exhibition, and will be the industry's leading hotspot for connecting renewable energy suppliers and customers in one place to do business. Bringing together over 1,000 power professionals, you'll join other leading renewable energy companies in three days of fast-track networking and new business negotiation.

Indeed, the expanding market demand for manure and organic waste digesters reflects the state of the entire renewable energy market. It is becoming common industry knowledge that digester technology is capable of much more than just simply electric generation, and so it is important for our industry to have a strong presence at this pivotal conference. It will be advantageous to all concerned to have the growing, thriving digester market well-represented at this event. Since the role of the digester has morphed from mere power generation to self-financing waste management techniques, it is imperative to extend this information to consumers and other energy market professionals alike.

The principal target audience will be present at this event, the broad potential array of customers for renewable energy systems and solutions. Parties to be involved in the successful widespread adoption of renewable energy include electric utility companies, independent power producers and project developers, industrial companies, high technology companies, commercial building developers, owners, architects, and engineers, residential developers, architects and builders and government agencies that buy and/or apply renewable energy solutions. Don't miss out!

Please feel free to contact me or Donna Welsch at _donnaw@pennwell.com_ ( (please copy me if you do so) for more information, or visit _ ( .

Richard MattocksENVIRONOMICS
2517 Rte. 44, 11-221Salt Point,
NY 12578845 635 4206845 635 4169 (Fax)

There have been new developments on the biodigester in the Philippines. Gerry Baron is now adding vegetable waste to operate a codigester instead of simply using pig manure. We will see what sort of gas production results from this.

I felt like Dr. Emmet Brown of "Back to the Future" fame feeding test digester #1 with sliced tomatoes, #2 with shredded potatoes, yams, breads & other fruit scraps and #3 with golf-green grass shavings.

Each digester which a 200 liter drum got about 5 liters of the stuff representing 1/2 of chicken manure bi-monthly feed. I will begin measuring biogas output and testing flamability on Jan 9. It's probably safe to say my pets ate very well today. They deserve it.

We will soon see what results this has. One of the main secrets of operating a codigester is to chop the material small enough. In general, it must be reduced to around 1 - 2 mm in size to digest in a normal period of time.

Thursday, January 06, 2005

First post

Hi, my name is Simon Fowler, and this blog will be about all forms of renewable energy and efficient use of energy. My background is mechanical engineering, but I have worked mostly in the field of electronics since finishing university. This blog will mostly be in English, but I will add sections in German as well, just to keep you interested!

Bioenergy in my use of the word has nothing to do with medicine or any of the parapsychological sciences. i am simply referring to all forms of energy from biological sources, such as biogas, biomass: landfill gas just qualifies!