Experiment adopted

[JAN 19] [TIMOR] Briquette Recipe Iteration (Solution)

Lean Phase:




Briquette recipes can be iterated to perform better than firewood and competitor briquettes.


Time Box:

January Project Month


Success Metrics:

Green Light (Proceed): Move forward with looking into future manufacturing of the chosen briquette recipe.

Success Point: 75% of tests are favourable towards homemade briquettes when compared to current alternatives

Orange Light (Optimise): Search for different ingredients within Dili, continue ideating with these different recipe ingredients. Potentially look for a commercial partnership to create higher quality briquettes with the same ingredients

Failure Point: 25% of key tests are favourable towards the chosen briquette when compared to current alternatives

Red Light (Failure Protocol): Continue assessment of other solutions (stove and briquette press)


Experiment build:

The following experiment aims to test the capability of coconut and coffee husk briquettes against the current market options of bamboo briquettes and wood to contribute conclusive data to ascertain which briquette we should move forward with.

The Timor-Leste Sustainable Fuel December team identified that coffee husks are a viable material candidate and the Cambodia Sustainable Fuel team verified that briquettes can be made from coconut husks. With the availability of both materials locally, tests should be performed in order to determine which option is most suitable.

To test the physicality of the different fuel sources, six aspects will be compared; ease of ignition, burn duration, burn rate per mass, physical integrity, water resistance, and the fuel’s ability to boil water. The results will be compared and analysis of this data will assist in the determining post experiment options.

Tests designed are:

A water boiling test which measures the time needed for the water to reach boiling temperatures.

  • 600 ml of water is placed in a pot on a stove. The initial temperature is recorded and the stove is lit. Record the time to reach 70 degrees Celsius. From this determine the energy transfer rate (energy/time) and total energy transferred (energy = mass*Heat Capacity of Water *Change in time).

A water resistance test in which a briquette is submerged and the material lost is weighed. This test also measures the amount of water absorbed by the briquette materials.

  • The briquette is weighed initially then completely submerged in water for 120 seconds. It is then removed and excess water is allowed to drip off. The briquette is then weighed again.

  • The water resistance capacity is calculated as WRC% = 100-((mass_1-mass_2)/(mass_1))

  • Further, notes are made how much of the briquette remained intact or if it broke apart in the water

A physical handling test in which briquettes are dropped and the effects are noted and measured

  • Briquettes are weighed initially and then dropped from a height of 1.5m onto a catch tray.

  • Collect any pieces that could be viably burned after the fall and weigh them collectively. Also note the number of pieces.

  • Calculate the loss using the following formula: %Loss= 100 – (mass_1/mass_2)

An ignition time test where briquette is placed on a metal rack and a small flame (e.g. candle) is placed underneath it. The time taken for the briquette to ignite is recorded.

A complete combustion test where the briquette is allowed to completely burn and the time taken to do so is recorded.

A burn rate test where the final products of the briquette after combustion are weighed. The initial mass minus final mass over time is equal to the burn rate.

edited on 15th January 2019, 07:01 by Harry Telford

Thomas de Heus 2 months ago

Going to split this over two comments, as I have a fair bit to add to this.

Firstly, the experiment itself - based on my experience in Cambodia, here's something to think about with each of the tests.

Water test: We tried this one and didn't have much success, as there are a lot of variables to keep constant. How many briquettes do you plan to place in the stove for the test? Or if you're planning to compare multiple recipes, how what weight of briquettes?

Water resistance test: I like this one and it's a good selling point in rainy Timor. Especially if people have identified a pain point of struggling to have dry wood in the wet season. A good briquette should perform well here, they are extremely dense - you may want to consider longer than 120 seconds as I don't think it will be long enough to take on enough water to even be measured on a scale, but I may be wrong so see how the first one goes. I'd be interested in the results over 10+ minutes and up to 2 hours, and then also determining how easy they are to dry out and use once saturated.

Dropping test: A simple test, will give a good indication of whether your recipe needs more/less starch/binder. The ones we made were dropped a lot (accidentally) during production and were compressed and binded enough that they barely chipped. Whether this is a good thing or not I'm not entirely sure, as slightly more brittle may be better.

Ignition test: This one will struggle, as these are *charcoal* briquettes and shouldn't 'ignite' with flames like wood. The coconut ones we made burned super hot, but this wasn't evident until you blew on them and they glowed a brilliant red. Lighting a candle underneath it is a good idea though, you just need a reliable way of determining when it's hot enough to be considered a complete test (do you have any way of measuring temperature?).

Complete combustion: Same as above and very dependent on a lot of variables. Charcoal briquettes just burn really hot and slowly break down into ashy powder, same as hot coals on a fire. I think the best way to do this test is to heat a single briquette to a certain point (perhaps determined from the above test) and then place it on a heat resistant plate on its own and see how long it takes to cool to a certain temperature. This will give a more controlled measure of how long a briquette can provide sustained heat once hot, without any additional heat being added.

Burn rate: We tried this one too in a stove and couldn't measure the change in weight reliably (wasn't planned well enough on our behalf). I think if you combine this with what I suggested for the above test, then remove what's left of the solid briquette (that could still be viably burned again) from the plate (if any) and measure the weight of that, it would provide a good indication (i.e. leaving the ash on the plate). We tried to do it with multiple briquettes in a stove, which was uncontrollable.

Also remember, there's not much point comparing to firewood for most of these tests. Yes the recipe can be iterated on to improve, but even the first run of a recipe (if proportions are roughly correct) should always perform better than wood in terms of burning time, heat produced, and smoke output as they are tightly compressed and the carbonisation process stops smoke production.

Reply 1

Thomas de Heus 2 months ago

Second half: Looking at the benefit of this to the project.

Running these experiments can be a lot of fun, but remember there's no point putting all your time into the perfect briquette recipe until you know the customer actually wants it - you're better off initially getting a working one (minimum viable product) and knowing its selling points, and then validating it against the lean canvas. It's all about getting as much validated learning as you can from the customer with the least amount of effort, and a functional but not perfect briquette should allow you to do that. I say this from my own mistakes in Cambodia and pushing too far ahead with a solution before we had properly validated whether anyone wanted it - which is the idea behind lean and the FOCUS framework.

This experiment is great, but be aware of where it fits into the timeline of the project. You definitely want to make briquettes to test with customers, as this was super helpful to us, but running extensive and time consuming tests on them won't offer much benefit to the project currently, especially with stoves/briquette press still as solutions to be tested. Just some food for thought.

Reply 2

David Gailey 2 months ago

Hi Thomas,

Thanks for your comments and insights. The advice you have given will no doubt help the direction of the project. In particular, your experiences in making briquettes in Cambodia, and your experience with testing them, will certainly help us in our own endeavors.

You make an interesting point about the water resistance test and we may well increase the time the briquette is submerged. The reasoning behind this test is to make sure that if the briquette is exposed to rain, that it holds up well and can still be used as a fuel. Depending on how heavy the rain is and how long the briquette is exposed to said rain, we felt 120 seconds submerged was a reasonable figure to work with. That being said, given your experiences we may need to lengthen this time. Certainly, it would be interesting to see how the briquette responded to a lengthy period of time submerged in water.

Additionally, your recommendations on the combustion and ignition tests will be very helpful. We do have a reliable method to measure temperature as we have an infrared thermometer that has performed accurately and reliably in the testing done so far. We have also devised some makeshift improvements to it in order to improve its usefulness in some situations where it had previously faced limitations.

With regards to firewood, we used it to provide a base performance. While we believe that briquettes should perform better than firewood, to ensure that our product has a positive social impact, even in its most minimal form, we want to measure the performance of the briquettes against the status quo. If our briquettes have a similar performance, hopefully better, then we can be satisfied that we are being honest to our customers.

With regards to the time spent on testing and refining the briquettes, we too agree with your concern on being distracted by the developing a solution when there is some doubt over whether there is sufficient demand. However, having reviewed the data collected by the December team and the experiments they ran (in particular their currency tests), we feel there is sufficient demand to proceed.

At this stage, our attention is focused more on developing the supply chain and working out the cost of each solution. Then we can price test all the solutions. Further, we are still making progress with the rocket stove, which we are investigating manufacturing costs for, and the press, which while it has a less clearly defined path, still offers potential as a solution.

Once again thank you for your advice. Hopefully when you pick up the project in February it will be in a strong position for you to smash it out with your experience.

David Gailey

Reply 3

Thomas de Heus 2 months ago

Good stuff! Sounds like you've thought it through well.

Working out the cost of each solution is definitely a priority, so it's good you're working on that. While December showed significant demand for briquettes, you still need to determine how much customers will be willing to pay, as well as how much you can actually make them for. Having briquettes on hand will help with this, but it's a difficult experiment. But I left a comment about that on that post.

My (limited) experience with briquettes is that they seem very positive at the start but long term there's a lot to think about in the long run in terms of scalability. Distribution in Timor is difficult - how is firewood currently deliviered and sold to villages, for those who purchase it?

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Harry Telford 2 months ago

Status label added: Experiment adopted

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