Abstract: At an absorber station, CO2 is absorbed from a gas stream into a suitable solvent whereby to convert the solvent into a CO2-enriched medium, which is conveyed to a desorber station, typically nearer to a solar energy field than to the absorber station. Working fluid, heated in the solar energy field by insolation, is employed to effect desorption of CO2 from the CO2-enriched medium, whereby to produce separate CO2 and regenerated solvent streams. The regenerated solvent stream is recycled to the absorber station. The CO2-enriched medium and/or the regenerated solvent stream may be selectively accumulated so as to respectively optimise the timing and rate of absorption and desorption of CO2 and/or to provide a storage of solar energy.

Abstract: A macromonomer of the formula I is described:Q--B(L--B).sub.n T (I)wherein n is zero or at least 1.0;Q is a polymerizable group;B may be the same or different and is a difunctional block of molecular weight in the range of from 100 to 8000 and wherein at least one B is a residue from a difunctional polymer or copolymer wherein B has a molecular weight of 248 to 8000 comprising silicone repeat units of formula II ##STR1## where R.sub.1 and R.sub.2 may be the same or different and are selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aryl, haloalkyl, haloalkenyl, haloalkynyl, haloaryl, heterocyclyl and haloheterocyclyl;L is a difunctional linking group; andT is a terminal group.The macromonomer may be used preferably in the production of contact lenses.