NOVELTY - For the production of at least one biofuel selected from an alcohol and biodiesel, a tunicate or an extract obtained from a tunicate, is used.    USE - For production of biofuel(s) selected from alcohol and biodiesel, including 1-4C alcohol (preferably ethanol) and fatty acid alkyl ester; for farming ascidians; and as tunicate colonization apparatus (claimed).    ADVANTAGE - The method involves use of tunicate as new source of biomass for production of biofuels including alcohol and biodiesel, where the method involves producing first biofuel from tunicate and additionally producing a second biofuel from tunicate, where the first and second biofuels are different and are selected from alcohol and biodiesel. Tunicates are opportunistic and have very high growth potential and can potentially provide large quantities of biomass; and their farming has secondary positive effects such as improvement of water quality, particularly in areas subject to undesirable levels of eutrophication due to terrestrial run-off. Thus tunicate as new source of biomass meets the requirements for renewable energy source. With the method for production of biofuels, ethanol and biodiesel yield can be much greater than the estimated yield. The present studies have shown that C. intestinalis can grow to 31 g (1.37 g dry weight) after 6 months of growth. Further, using elongated members which support several colonization surfaces in form of plates, densities of 9690 individuals per m2 can be attained. Using 3-dimensional farming model, annual ethanol yield per hectare will be about 180000 L or 188000 L annually including contribution from 5C sugars. Using 3-dimensional farming model, annual biodiesel yield per hectare will be about 102000 L. The method is suitable for industrial scale-up. For method of producing alcohol existing reactors used in pulp or paper industry can be used, and for producing biodiesel, existing reactors for producing biodiesel from vegetable oil can be used. The method further provides 3-dimensional farming of ascidians in sea. The method of farming enables production of large quantities of ascidians, and favors natural recruitment and settlement of ascidians and does not involve step so that ascidian population has to be seeded or supplied from nursery stock. The method of farming results in growth of monoculture of ascidians with minimal biofouling caused by colonization of organisms other than ascidians. Nutrients are bound to phytoplankton, the ascidians eat phytoplankton for growing, and the ascidians are removed and used for biofuel. Thus the nutrients are removed from the waters and consequently they will reduce the effect of eutrophication of an ecosystem. Therefore, ascidian farms can advantageously be used for remediation purposes in areas having large nutrient inputs from human activities. Thus method of farming of ascidians is also method of reducing effect of eutrophication of sea, and involves placing sub-sea structure in sea region subject to eutrophication or high nutrient load. There are many advantages in using ascidians as a source of biomass for the production of biofuels, such as they have very high growth rates which results in large annual biomass production; they are relatively easy to culture and harvest; they do not require arable land for growth and therefore they do not compete with terrestrial food crops; they contain significant quantities of C6 sugars (for ethanol) and fatty acids (for biodiesel); the extraction of sugar and oils are easier from biomass derived from ascidians than from wood; the ascidians will have a remediation effect in eutrophic waters as they are filter feeders and are capable of removing large quantities of algae; they can be harvested in situ in the ocean, which is a major advantage compared to genetically modified algae which have to be cultured in bioreactors, which are subject to strict regulations regarding handling and waster management; ascidians' culture installations will provide excellent reef possibilities for local fish recruitment; and they are environmentally friendly as they have a low impact on the environment.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) method (M') for farming ascidians involving: (a1) colonizing surfaces of a sub-sea structure with ascidians; and (b1) harvesting the ascidians from the structure, where the structure comprises several elongate members having colonization surfaces and the structure defines a three-dimensional sub-sea region arranged to support tunicate colonization; and    (2) a tunicate colonization apparatus comprising: at least one elongate support member (3) and several colonization members (8, 8a to 8e), where each colonization member is coupled to the support member and comprises at least one smooth and uninterrupted colonization surface.    DESCRIPTION OF DRAWING(S) - The figure shows arrangements of the colonization apparatus.    Elongate members (3)    Sea level buoy (4)    Sea bed (5)    Buoy (6)    Weight (7)    Planar colonization members (8, 8a to 8e)