Building a green house type coffee dryer

I took a day off of work and started on the greenhouse type of solar coffee dryer.  Rufino found this dryer on the internet and thought it would work in Guatemala.  It is a six foot by 7 and a half foot greenhouse.  I made it seven foot tall sloping down to six foot in the back.  The door way is two foot wide and five foot high.  All I need to do tomorrow is drill the holes for the conduit rafters and attach some extra wood to staple on the visqueen.  I think it will work OK and we can place the soda can solar heater to the front of it.  Then all we need to do is to take the temperature readings and see how well it works and how well it can take the weather.  I will try and get a picture but it will not look to good until it is outside and the visqueen is on it.  But we now have three models to use for test purposes as well as the soda can heat exchanger that I am interesting in.  The information I have on the soda can heat exchanger is that it works quite well, is cheap, easy to build, and it does not look that bad.  It does not look like you put bales of straw around the bottom of your trailer, if you catch my drift. We are getting closer to have some information and data on how to dry coffee.
What I need to do now is to research how to burn vegetable oil in a oil furnace.  I understand that in the resort village they fry a lot of food and the waste vegetable oil is a problem.  If we can burn it to help dry the coffee we can eliminate one type of garbage.  It is still not like using the free heat of the sun and it does pollute the air, although not as bad as fuel oil.  If you can burn free waste vegetable oil in a 50/50 mixture with the fuel oil then you have cut your cost in half and you have more money to invest in better solar devices.  I am going to check the HVAC department and see if we can find a fuel oil furnace to play with.   We could get the vegetable oil from the school cafeteria.  Then we can see how well it will burn and what we need to do.  I started today at 9 am and stopped at 7 pm so I am ready to relax a little.