Bubbles from underwater seeps can be captured using sheeting/ducts. Relief wells can be drilled, preventing this methane reaching the water.
Significant bubble streams from enduring point sources can be directed into ducting, then to the surface for flaring or use. Subject to seabed conditions, seeps may be plugged; sealed & ducted; or actively pumped. Relief wells may be drilled to intercept and depressurise source reservoirs. Engineering techniques can be adapted from the oil and gas industry. Salter proposed the use of pipe-laying ships to deploy impermeable sea floor sheeting, with ducting for gas recovery. This technique can be used for area sources, and grouped point sources.
Category of the action
What actions do you propose?
Who will take these actions?
Where will these actions be taken?
What are other key benefits?
There exists a potential for energy recovery as gas, gas-to-liquids, or electricity, if high-volume, high-concentration fluxes are identified.
What are the proposal’s costs?
Costs for this proposal will vary dramatically, based on the scale, type and recovery options used. At its simplest, dumping gravel or similar onto subsea seeps will be adequate to disrupt concentrated bubble streams. Somewhat more complex would be manufactured equipment, such as colander-type apparatus, or ducting to the surface. In each case, costs of manufacture and deployment would likely range from a few hundred to a few thousand dollars, principally depending on depth and wave/current conditions.
The addition of any recovery or processing technology, over and above flaring, would add significantly to the costs. However, the use of the recovered energy for electricity generation or for small-scale gas-to-liquids has the potential to offset costs. In ideal circumstances, it may be possible to fully commercialise the technology.
At the opposite extreme, Salters' proposal for large scale coverage of the Arctic sea bed with contiguous plastic/rubber sheeting would cost millions or tens of millions to deploy, even at small scale, due to the high capital costs of manufacturing plant required and the costs of operating heavy, specialised ships in open water.