I'm confused.
You don't want fake smoke but you don't want to use wood?
Are you asking for a synthetic substance you can burn that will not be worse for the environment than burning wood?
First of all- burning wood is not bad for the environment- that carbon has not been sequestered and so it would be released into the atmosphere anyway when the wood decayed.
Secondly-
mesquite is a cancerous weed here in Texas
and I encourage everyone to smoke with it to restore the damaged ecosystem.
Thirdly-
You can't fake the taste of smoking with wood.
That's the point.
Even liquid smoke is actually made by distilling real smoke.
(I originally posted a comment and decided to modify it into an answer.)
cooking.stackexchange.com/users/2001/Sobachatina
i made a smoked salmon recently that used tea leaves (from tea bags, specifically chai and a black tea with citrus), and it was very subtle and awesome.
highly recommended.
i used, i believe, 3 tea bags total, plus 2T of brown sugar and 2T of white rice in a lightly folded foil packet.
cooking.stackexchange.com/users/1415/franko
I believe that cooking on a plank of wet wood will give you some of the flavor of smoking without actually burning the wood.
But I don't think the flavor will be nearly as strong.
cooking.stackexchange.com/users/1887/Martha F.
it is possible to smoke foods with products other than traditional wood chips.
however i have achieved best results by mixing with wood.
i like ginger (sliced the same size as a wood chip), star anise, cinnamon stick (broken to roughly the same size as a wood chip), garlic, thyme (soaked in water), tea
(i enjoy using jasmine tea), rosemary, peppercorns (soaked in water), citrus peel, chips from wine casks or bourbon cask.
any type of woody plant stalk will do as well.
cooking.stackexchange.com/users/24599/aaron
There are many different woods used for smoking throughout the world, each giving a characteristic flavor, intensity, and color to the foods that are smoked with it.
You are not going to get the "hickory smoked" taste by using anything but hickory.
Here is the list of common smoking woods given by Nathan Myhrvold in Modernist Cuisine Vol 2 : grapevine straw ash, elm, hornbeam, chestnut tea leaves alder apple cherry, peach corncob heather (dried) mahogany thyme, marjoram, or sage (dried) walnut linden birch, poplar,
willow hickory pecan laurel rosemary, dried beech juniper camphor laurel oak mesquite Additionally, in some areas where vegetation is less available locals use dried manure or peat to smoke meat.
Other sources: http://www.deejayssmokepit.net/Woods.htm
cooking.stackexchange.com/users/10685/Didgeridrew
The best alternative to wood chips is a new product called Smokin-os and they are sold on Amazon.
They give great smoke and are very simple to use.
All you do is preheat your grill and put one on the grill surface where you put your food.
They are made of fruitwood trimmings that are normally piled and burned.
The trimmings are ground up and then extruded under high heat and pressure putting the wood back together denser (up to 2 times more dense) than it was in its natural state.
Therefore it takes less of it to produce a lot of rich smoke.
Its the only product that I'm aware of in the market.
This process is done using heat and extreme pressure to bind the wood back together using the woods natural resins.
cooking.stackexchange.com/users/33982/Ryan Conner
I am looking for alternatives to using wood chips for smoking meats.  I would like the process to actually smoke the meat.  Liquid smoke/marinades are not what I'm looking for.    Has anyone heard of any projects or items that could be used?  I'm thinking of a more environmentally friendly way to smoke meats without relying on wood such as apple, cherry, hickory or mesquite.  The cost of obtaining these woods in some parts of the world make it cost-prohibitive.
Artificial Wood Chips/Smoke for smoking meat
cooking.stackexchange.com
<barbecue><pork><ribs><smoking><smoke-flavor>
cooking.stackexchange.com/questions/5978
cooking.stackexchange.com/users/2174/It Grunt
Nathan Myhrvold lists the following common smoking woods in Modernist Cuisine Vol 2:   grapevine  straw ash, elm, hornbeam, chestnut  tea leaves  alder  apple  cherry, peach  corncob  heather (dried)  mahogany  thyme, marjoram, or sage (dried)   walnut  linden  birch and poplar. Smoked salmon with tea bags can taste good, and  any woody plant stalk can be used for smoking. Teabags or any woody plant can be burned for smoking. You can also you a plank of wet wood.
You can smoke using any woody plant stalk like thyme or marjoram. You can also use teabags. Try placing your meat on a plank of wet wood over the heat source.