I agree with the biochar suggestion, but I'd also suggest to bury both biochar and syn-oil deep in the ground -- at least, in the first decades or so. That's because I don't believe the usual sales pitch for biochar actually works.
Biochar as a soil amendment is not a reliable means to increase yields. Depending on the produce and the soil, it decreases yields. Sometimes, it seem to have no effect, at all. So far, the most reliable results have been observed in tropical areas. People there don't have the money to invest in farm land, yet.
Refining syn-oil is hard, because its quality is low -- comparable to bunker oil. Tar is one of the few products that can be made out of it, successfully.
Therefore, burying both seem to be the best option. After all, there should be quite a few depleted oil fields and coal mines in the world, so space is not a problem.
Biochar as a soil amendment is not a reliable means to increase yields. Depending on the produce and the soil, it decreases yields. Sometimes, it seem to have no effect, at all. So far, the most reliable results have been observed in tropical areas. People there don't have the money to invest in farm land, yet.
Refining syn-oil is hard, because its quality is low -- comparable to bunker oil. Tar is one of the few products that can be made out of it, successfully.
Therefore, burying both seem to be the best option. After all, there should be quite a few depleted oil fields and coal mines in the world, so space is not a problem.