Tuesday, December 22, 2009

Biofuels, Not Food for Fuel (Part 2)

Puerto Rico has a severe used tire problem. At some point Puerto Rico became the point where the excess tires of other states ended being stored. This was given our lack of vision of establishing a tire recycling program. Currently the practice of recycling in Puerto Rico is reduced to storing recyclable materials until a fire or environmental incident burns the material down. This bad press has killed any attempt to reuse tires as an energy source.

A couple of days ago I wrote the first part of this series on Biofuels. For those that have not read the original article it is included here:


On that article I summarized that Puerto Rico has a large amount of raw materials that can be used to generate biofuels or used as an energy source in PREPA power plants or other large kilns and furnaces available on the Island. Cemex tried this approach in Ponce and failed, given the opposition of 'environmentalists' that prefer the threat of a large scale fire, or a mosquito outbreak that is the typical fate of the tires in Puerto Rico. I stated several sources that could be used. Today I have decided to focus in used tires.

Why tires? Because I am reminded of the problem every day whenever I pass Comerio Avenue and see buildings filled with recapped or damaged tires waiting to be transported to a storage area where they are eventually burned 'accidentally'. Plus a whole recycling program was supposedly established to manage this issue and all it has left us is with more charges when we buy tires or oil for our cars. Tires fill our landfills.

So two things are needed to deviate tires from landfills. One is taking them out of the regular trash, as required by the recycling laws already written and the other implies shredding or reducing the size of the tire to be managed more effectively. Both require machinery.
The following excerpt is from american recycler:
Of the 290 million scrap tires generated in the United States annually, more than 80 percent are reused or recycled for sale into various markets. That’s up from just 17 percent in 1990. The biggest markets for scrap tires generally require shredding as part of the process and that’s turned into a good business for tire shredder manufacturers.also:
Overall, the future remains bright for shredder manufacturers and the customers they serve. As SSI’s Fleming says, “Scrap tires will continue to be a disposal problem, populations will continue to grow and consume more raw and recycled materials, and used tires will increasingly be needed in order to make longer-lasting new products as well as synthetic fuels and other valuable materials.”
So before even entering into using tires as a fuel or biofuel source they have a useful purpose by simply shredding them. Now that is interesting. It is something we should have been considering a long time in Puerto Rico but we still do not believe. For instance, I got interested on rubber mulch a few months ago when I saw these bags of rubber mulch in Sams Club at Bayamon. Bought 10 sacks because the product convinced me. It did not make the ground I wanted to cover impervious to water, as would have happened with concrete, but it would not rot and float away as that cheap imported pine mulch chips do.

Their product got me interested and I have included a picture and a link to their website. It is a nice idea that should be checked more often by municipal landscape designers as seen on the picture below.


If not as a mulch, smaller machines can be used to cut the tires to make bumpers, mats or other items...This one is a good idea for our economically challenged times.

However the operation of managing used tires is not as simple as it seems initially. It requires a huge capital investment and should be left to a properly planned and well designed central facility. For instance here are recommendations from one potential supplier of machinery of those seen during the research of tire recycling equipment:

Now, this only solves part of the problem. Fortunately there are other uses are available for the material shredded. It could be used to control excessive erosion of our public landfills or to control the nasty leachates produced from landfill runoff. This still does not require burning or converting the tires in fuel.

Preliminar studies indicate the leachate from tires is not toxic since below toxicity levels

Example of uses to control landfill leachate...

However, care must be taken on the disposal method of the used tires. The leachate removed chemicals are entrapped with the rubber in the tires, the metal in the tires remains. If burned or used as fuel these concentrations need to be studied further to not cause a larger environmental problem. This should not be an issue on residential or institutional use.

Summarizing this already technically complex article: Tires should be managed more efficiently than our current practice. Municipalities can benefit from mulching tires for landscaping.

On the end, if all these efforts fail the shredded tires can be used to generate fuel by direct burning on a kiln or power plant boiler. It can also be used to generate syngas and other biofuels. Some links on this below:

Burning increases the metal levels on the total ash but air emissions can be managed by pollution control equipment. It just requires more monitoring on the ash quality disposed of.

Or it can even be used to produced activated carbon for many industrial applications, including the removal of trihalomethanes on potable water.

http://www.p2pays.org/ref/11/10504/html/biblio/htmls/pyh1.htmInfo from [http://pubs.acs.org/doi/abs/10.1021/ie00048a023]

Tags en blogalaxia

No comments:

Related Posts Plugin for WordPress, Blogger...