Dear Editor,

Once again permit me to offer a response to Mr Tony Vieira’s letter in the Stabroek News ‘Briquettes are irrelevant, GuySuCo estates not producing sufficient bagasse’ (January 8). In this response, I am choosing to ignore the intemperate language and unnecessary resort to ad hominem commentary.

Editor, permit me also to acknowledge the balanced, respectful and carefully reasoned letter written on this subject by Mr Ken Norman in the Kaieteur News, titled ‘Let’s avoid another GuySuCo white elephant’ (January 8). As with some of Mr Vieira’s points, I agree fully with all points raised by Mr Norman. I hope that in perusing my response below he will appreciate that the installation of the briquetting technology has the potential of reducing the corporation’s dependence on and costs for firewood in the short term (until sugar supply to the industry is hopefully addressed) and the potential of revenue generation through co-generation of electricity for supply to the national grid in the long term.

In Mr Vieira’s original letter to which I responded he made the claim that energy briquettes from bagasse are an unworkable technology and additionally sought information on whether this technology had been tried at GuySuCo. Since energy briquettes are used in many places around the world to generate energy and since the IAST had indeed conducted two tests at GuySuCo, I sought in my previous letter (SN, January 6) to address both concerns expressed by Mr Vieira. My letter dealt with facts, not conjecture, and I carefully avoided other issues raised by Mr Vieira. I also very carefully indicated that I was restricting my response to only these two issues, as I retain no ability to respond on diverse issues affecting GuySuCo itself. I therefore am quite stunned to have my letter described as misleading. Every single thing I recorded in my letter is completely factual and verifiable.

Had my invitation to review our reports and the video footage of the tests been accepted, then Mr Vieira would have been able to ascertain for himself all the details of what was recommended. It would also have avoided him having to make some of the arguments he puts forward in his latest letter, for they have been taken into account. I would like to earnestly suggest that science and technology solutions cannot be debated in short letters in the dailies without commentators investing time to understand what is being suggested, Editor. If individuals wish to offer criticism, they must invest the time to understand the entirety of what has been done.

Had Mr Vieira taken the time to peruse our proposed solution he would have appreciated, and probably agreed with what is being proposed, as it takes so much of what he has written into consideration:

1. GuySuCo currently utilizes a significant amount of firewood for frequent start-ups of its furnaces to power its boilers. One of the main factors causing this is the intermittent supply of canes to the factories.

This is acknowledged as an issue in the work we did. GuySuCo as an industry obviously needs to address this urgently, but this is the situation currently. Questions on what is being done to address cane supply are best directed at GuySuCo.

1. The cost for firewood accrues measurably towards the cost of converting cane to sugar currently at GuySuCo.
2. Firewood is used for the start-up of the furnaces so that the furnace can be heated up to the temperatures required for loose bagasse introduced into the furnace from the top to combust in the upper third of the furnace.
3. If loose bagasse is used instead of firewood to achieve the required temperature range in this start-up phase, a large amount of bagasse must be used as the combustion is inefficient. Therefore, firewood is used. This, of course, is exacerbated if the factory is not processing a sufficient volume of cane to produce either excess or sufficient bagasse.
4. Since it is a fact that some sugar estates such as the one at Albion generally have excess bagasse (Editor, your staff can verify this by sending a reporter to take a photograph of the giant pile of excess bagasse stored at Albion, or by reviewing our video of the process), conversion of this excess into briquettes allows for complete eradication of the use of firewood.

Our tests have demonstrated that it is simpler to load the briquettes into the furnaces for the start-up phase (particularly if some simple conveyors are installed), and that the time for the required temperature ranges to be achieved is significantly reduced. There is also less potential damage to the furnace walls when briquettes are used as opposed to firewood. Furthermore, the briquettes have between 2-4 % moisture content, whilst the firewood typically has between 45 to 50 % moisture, so that a significant amount of the energy generated by using firewood is spent in the latent heat of vaporization for the moisture in the wood, creating steam that is simply exhausted and therefore wasted.

1. The cost of producing briquettes, at for example Albion, and transporting them to Uitvlugt is a fraction of the cost of purchasing firewood, not to mention the environmental degradation caused by deforestation.
2. Our recommendation is not to supplant the ongoing feeding of the furnaces by loose bagasse once the required temperature ranges for combustion have been achieved, but to start up the furnaces using this cheaper source of fuel (briquettes).

1. It is a fact that if the sugar factories at GuySuCo are fed uninterruptedly with canes to their fullest capacity (obviously a very desirable situation which GuySuCo must work diligently at or face the inevitable), feeding loose bagasse into the system will still not consume all of the bagasse created.

The energy conversion ratios and the required energy of the plant is simple enough to calculate to demonstrate this is factual, and this is exactly what obtains at many other locations in the world. Some of the industry’s best practices for use of this excess bagasse relate to:

1. Utilization in digestors to produce organic fertilizers
2. Processing into briquettes for generation of energy (co-generation), or, if the factory is large enough to support an on-site electricity facility selling into the grid, gasification of the bagasse without briquetting.
3. Use of excess bagasse in particle board and plastic composites (this latter is also a project which has been used at IAST to produce roofing shingles).
4. A variety of other uses which it is not efficient to enumerate in a letter to the editor.
5. Investing the relatively small sums in briquetting technology given the current issues faced by GuySuCo will without question allow it to generate significant savings by replacing costly firewood. If GuySuCo is willing to share its business plan for this technology, the public can be informed about the economic feasibility of the process.
6. What happens to this investment (which is much less than US$100, 000) when (hopefully) the corporation has begun to address its cane supply issue? The excess bagasse generated by the corporation will be even larger when this state of affairs has been achieved (as is the case in every sugar factory with similar systems and an at-capacity supply of cane around the world), and it can begin to generate income by co-generating electricity for the national grid.

I should also inform your readers that the efficient burning of renewable fuels such as bagasse is considered to be climate-neutral, as successive crop cycles sequester the carbon released from the combustion of crop residues. In fact, in some countries, the combustion of crop residues attracts carbon rebates.

Editor, I wish to assure Mr Vieira that my letters mean no disrespect to him; I am a science and technology professional whose responsibility it is to represent the work done in this arena by IAST on behalf of the taxpayers of Guyana. And I hold no brief to defend GuySuCo. I am simply doing my job.

Yours faithfully,

Professor Suresh S Narine

Director

IAST