Photobioreactor

1. A photohioreactor that uses sunlight as a light source, comprising:

a container holding a photoactive biological material; and

an optical waveguide at least partially located within the container;

wherein the optical waveguide is formed at least in part from highly scattering optically transmitting polymer, and

wherein the optical waveguide is formed with a light collecting part contacting a light distributing part, the light collecting part having a surface configured to collect the sunlight, wherein the light distributing part is formed as a sheet, wherein the light collecting part and the light distributing part have a fixed size ratio, and wherein the light collection part has a first surface configured to collect sunlight and second surface directly directing the collected sunlight into a side of the sheet that the light collection part contact.

2. The photohioreactor of claim 1 wherein the light distributing part is formed entirely from the highly scattering optically transmitting particles.

3. The photohioreactor of claim 1 wherein the light distributing part is located wholly within the container.

4. The photohioreactor of claim 1 wherein the light collecting part is located wholly outside the container.

5. The photobioreactor of claim 1 wherein the light collecting part and the light distributing part have a size ratio selected to provide a light dilution factor of about 2 to 10 times.

6. The photobioreactor of claim 1 wherein the waveguide includes at least a portion that is a flexible part.

7. The photobioreactor of claim 1 wherein the waveguide is doped with wavelength shifting dopant.

8. The photobioreactor of claim 1 wherein the container is a cell having at least one wall that is gas permeable and liquid impermeable.

9. The photobioreactor of claim 1 , wherein the light distributing part is a sheet and the light collection part injects the collected sunlight along a side of the sheet.

10. The photobioreactor of claim 1 further comprising supplemental light sources that direct light into the waveguide.

11. The photobioreactor of claim 10 wherein the supplemental light sources are light emitting diodes positioned to inject light into the light distributing part along a side that is different from a side along which the light collecting part contacts the light distributing part.

12. A photobioreactor that uses sunlight, comprising:

a container holding a photoactive biological material, and

an optical waveguide at least partially located within the container, wherein the optical waveguide is formed as a sheet that has a light collecting part and a light distributing part,

wherein the light distributing part is formed in part of a highly scattering optically transmitting polymer,

wherein the light collection part has a surface configured to collect sunlight and to direct the collected sunlight into a side of the sheet that the light collection part contacts, and

wherein the optical wave guide has only one light collecting part and one light distributing part, wherein the light collecting part and the light distributing part have a size ratio selected to provide a light dilution factor of about 2 to 6 times.

13. The photobioreactor of claim 12 , wherein all of the light collected by the light collecting part is directed into the one light distributing part.