The single junction solar cell was described in Chapter 3, before Figure 3.17. The limiting efficiency of a single junction cell is 31% at one sun illumination, but as high as 40.8% with concentrated sunlight. The Si single-crystal solar cell shown in Figure 3.17 is the most common first-generation solar cell. Elaborations on this cell […]

9.1 Intermittency of Renewable Energy Hydrogen is available, but tightly bound, in water and many other compounds. To produce hydrogen from water requires an energy input. Hydrogen is not a source of energy, but rather a means of storing energy. A hydrogen infrastructure for storing and transporting energy is a possible alternative to batteries to […]

Another potentially inexpensive form of solar cell is the dye-sensitized solar cell. This approach is based on an absorber that is partly titanium oxide, TiO2 in its anatase tetragonal form, and partly dye molecules. Anatase can be prepared in a nanoporous form (sometimes, described as mesoporous, although microscopy shows particles of 10-80 nm diameter) by […]

One scenario for future distribution of energy is in the form of hydrogen, which might be compressed or liquefied. The “hydrogen economy” scenario has been promoted along with the idea that automobiles may switch to electric motors for which the electricity comes from fuel cells run on hydrogen gas stored in the car’s fuel tank. […]

Here (Fig. 7.14) solar cells are mounted vertically on the edges of the light collecting plates, which have dissolved dyes. The upper plate collects blue photons, the dye reemits (fluoresces) and that light is sent to the cells on the edge. The fluorescence quantum efficiency of isolated dye molecules approaches unity. (Total internal reflection helps […]

One of the questions on many aspects of solar and renewable energy is the optimum scale of the device or system. We have seen in Figures 5.4 and 5.5 concentrating solar thermal installations on the scale of 11 MW and 25 kW, respectively, with a good indication that the present efficiency of the smaller installation […]

Inert electrodes such as stainless steel or platinum, immersed in water (containing a small addition of ions to promote conductivity), will evolve hydrogen gas at the cathode and oxygen gas at the anode if ~1.9 volts is applied. The chemical potential energy associated with a molecule ofhydrogen is 1.23 eV, so the efficiency ofthe electrolyzer […]

The operation of this device follows the steps indicated in Figure 6.17: step 1 is absorption of a photon by a dye molecule. Typically, the dye is a metal-organic ruthenium complex with response in the wavelength range 700-900 nm, light that is not absorbed by the titania. This is the idea of dye sensitization, to […]