Ah, ongoing methane production. I haven’t looked into this, but I have never seen it suggested as a major renewable energy source. I have seen some minor production facilities at old landfill sites. I have speculated about harnessing clathrate deposits. If you know of any workable schemes, please post links.
I’m speculating here, but I expect there are major problems with this.
* Concentration. Wetlands, animal farming, etc. produce a lot of methane, but it’s spread over a huge land area, and as soon as it is released it mixes with air. We can’t just cap over thousands of square miles of wetlands or pasture to collect the methane because they’d stop being wetlands or pasture, and even if we could we’d still need to separate the methane from the air.
* Emissions. Burning methane still releases carbon dioxide, so to use it as a fuel without increasing global warming, all of it that we burn would have to be derived from atmospheric carbon dioxide or oceanic carbon, with none from fossil sources.
* Rate of production. The reason we use fossil methane ie. natural gas is because highly concentrated deposits of it accumulated over vast, geological periods of time. But we’re burning it thousands of times faster than nature deposited it. This is the essential problem with fossil fuels; when we burn coal, we’re releasing the carbon accumulated from millions of years of tree growth in just a few centuries. When we burn oil and gas, we’re releasing the carbon accumulated by oceanic life over millions of years in just two centuries. This is how we’re disturbing the balance.
* Sea bed destruction. I don’t know how long the clathrates have been accumulating but it has to be a lot longer than the rate we’d burn them, so in this sense clathrates would anyway be just another fossil fuel. But getting them off the seabed would also disrupt the ecosystem that already exists there. This is one reason we’re in a climate and ecological emergency; we have many methods of capturing energy, but all apart from nuclear and geothermal require vast areas, of land or of ocean. But that land or ocean is already used by Earth’s ecosystem, which is our life support system, providing oxygen, fresh water, atmospheric nitrogen, the iodine cycle, the compounds that seed cloud formation, detoxification, recycling of organic matter etc. etc. etc. We’re degrading that ecosystem rapidly; the current rate of extinction of species appears to be orders of magnitude above the geological background rate; human activity is initiating Earth’s sixth mass extinction. How many threads can we remove from the web of life before there’s a major collapse? It’s better not to find out.