The method using floatable block for aquaculture substrate will save labor as follows.

At start of aquaculture, seeded floatable blocks are mechanically scattered, and at harvesting, the floatable blocks to which grown seaweed is attached can be mechanically collected by ship equipped with device such as colander.

Separation of seaweed from floatable block could be mechanized with device such as potato peeler.

When seaweed is cultivated on a floatable block, it is thought that it is unevenly distributed due to wind and tidal current, and the growing rate would decrease.

In nature, it is known that the Crown-Shyness- Phenomenon, in which leaves do not overlap, and seaweeds grew almost uniformly at the Olympic venues in China.

It can be expected that the seaweeds on the floatable blocks will also interfere with each other during growing progress, are maintaining a certain interval and obtaining practical glowing rate.

Seaweed collects nutrients such as nitrogen and phosphorus by culturing in eutrophic waters.

Since the collected nutrients are contained in the wastewater during ethanol production, nutrients can be recycled by returning them to the farmland.

The floatable block is porous body and can be impregnated with aqueous nutrient solution. By coating the surface of the floatable block with biodegradable plastic film, the impregnated nutrient can be released slowly.

Though almost of Japanese Exclusive Economic Zone (EEZ) is oligotrophic water area, seaweed can be cultivated by floatable block that release nutrients.

In near future, there is concern that the supply of phosphorus will be insufficient.

In which case, deep sea water containing high-density nutrients will be pumped up to cultivate seaweed.

In natural, there is the case that nitrogen is supplied by the symbiosis of seaweed and microalgae.

The traditional ethanol condensation methods consume large energy for vaporization.

The ultrasonic-mist-separation-method has been developed to reduce ethanol condensation energy by needlessness of vaporization.

Though waste glass is used as the material for the floatable block, coal ash or incinerated ash that is separated rare earths and metals by high-temperature reducing and melting furnace will be able to be used in future.

As separated rare earths and metals are concentrated, they can be recycled.

Ethanol made from seaweed can be used as fuel for automobiles.

The activity of exhaust gas treatment catalyst decreases in low temperature period.

As a method of improving the low temperature activity of the catalyst, there is a method of raising the electron temperature by non-equilibrium plasma. For this purpose, a switching device MAGT (MOS-assisted gate triggered thyristor) that realizes high speed and large capacity might be required. MAGT was developed for excimer lasers.