The cow burp effect is a myth. With five minutes thinking about it, is easy to see why is a no solution. I have explained here before why will not work.
Most of the seaweeds are water. And the dry matter is salty.
Coastal areas are extremely busy. You can't remove Honk Kong city to culture seaweeds. You can't block maritime traffic routes to culture seaweeds, or stop all commercial fishing near the shore, or ban tourism. In most areas is a no-way.
And there are other problems and obstacles that could be spotted easily by biologists, for example that water temperature is rising.
If you think that you can obtain a permit to put such eyesore as a seaweed farm in front of Copacabana, well... good luck with it.
But we could of course build it in the middle of nowhere, and then spend lots of fuel to move the product to the far-far-away markets, and even feel good about our ecological trace for a couple seconds.
This is not about being clean or not, is about being previously occupied by another activity that is economically much stronger so you just can't compete or displace them. All the good places near the coast are heavily occupied yet so, where do they want to culture all this volume?. The other companies have enough money to buy you off of the road and build an hotel, or are the only remaining place suitable for the local authorities to place the new airport
And not all places are suitable to grow brown algae. (Not they aren't. Algae are not so easy to grow as National Geographic seem to suggest. They have predators also). Chinese grow a lot of Palmaria since thousands years and the trend is to replace it for its relatively low value by Hectare, either transform it into crab farms to increase the benefits, or turn it into a developed urban area.
Dry areas are required for logistics and as a safety vault. You need space for storage. Space for wintering. Space for each machine that you need to process the production. And drying algae smell. And if you have a big storm alert, you will need to rush to move a huge volume of stuff, cords and algae safely ASAP to the coast and keep there for several hours. You can't just put this in the closest hotel terrace.
There is a lot of things that a sea farm needs to survive. And there is a huge load of legal issues, because the sea is not a "free for all" space. Is a high skill / high luck and deep pockets activity.
Why could be a big company be interested in this? Well, If you have the money you could culture much higher value products in the same space, right?. I would speculate that is a combination of being able to obtain government aids + real state grab. I can be totally wrong about it, of course.
If you don't care about harvesting it you might want to bioengineer something that will grow on the coast of Namibia and seed it there. This coast pretty much can't be used for anything.
>We model a nationwide transition [in the US] from grain- to grass-finishing systems using demographics of present-day beef cattle. In order to produce the same quantity of beef as the present-day system, we find that a nationwide shift to exclusively grass-fed beef would require increasing the national cattle herd from 77 to 100 million cattle, an increase of 30%. We also find that the current pastureland grass resource can support only 27% of the current beef supply (27 million cattle), an amount 30% smaller than prior estimates
[…]
>If beef consumption is not reduced and is instead satisfied by greater imports of grass-fed beef, a switch to purely grass-fed systems would likely result in higher environmental costs, including higher overall
methane emissions. Thus, only reductions in beef consumption can guarantee reductions in the environmental impact of US food systems.
The cow burp effect is a myth. With five minutes thinking about it, is easy to see why is a no solution. I have explained here before why will not work.
Most of the seaweeds are water. And the dry matter is salty.
Coastal areas are extremely busy. You can't remove Honk Kong city to culture seaweeds. You can't block maritime traffic routes to culture seaweeds, or stop all commercial fishing near the shore, or ban tourism. In most areas is a no-way.
And there are other problems and obstacles that could be spotted easily by biologists, for example that water temperature is rising.