Solar-hydrogen plants

The fuel used to make solar-hydrogen is free (sunshine) and unlimited, the raw material for H2 is water, and the emission when burning the H2 in fuel cells, internal combustion engines, or in power plants is distilled water. The cost of building the solar-hydrogen plants will be known once the demonstration power plant described in this book is built. It might turn out that this cost is already competitive but whatever it is, we know that it will drop by an order of magnitude when the mass production of ultrathin-film solar collectors and reversible fuel cells is started. 

Experimental solar-hydrogen plants (Bockris, 1975) using the electrochemical approach to the splitting of water began to be built in France in 1988. Some half dozen plants in various countries are current. However, only two plants supply more than... 

Fig. 15.11. Block diagram of the 350-kW solar-hydrogen plant at Riyadh (Saudi Arabia). (Reprinted from Yu. I. Khar-kats, Electrochemical Storage of Solar Energy, in Environmental Oriented Electrochemistry, C. A. C. Sequeira, ed., Fig. 3, p. 473, copyright 1994. Reproduced with kind permission of Elsevier Science-NL, Sara Burgerhartstraat 25, 1055 KV Amsterdam, The Netherlands.)...

Further work in process evaluation has been done to evaluate the potential performance of the process when energized by a solar heat source. These studies, which were of a preliminary nature, were based on the solar hydrogen plant being integrated into a chemical process to produce a currently marketable commodity. 

The first test runs of an experimental liquid-hydrogen refueling device for cars and buses began at Solar-Wasserstoff-Bayern s prototype solar hydrogen plant in Bavaria. The goal was to refuel a car in a few minutes. 

Solar-Hydrogen Plant Principles of Design and State-of-the-Art... 

Fig. 2. Comparison of computed (solid lines) and measured (dashed lines) characteristics of the solar-hydrogen plant throughout the day [22], 1 - hydrogen production rate 2 -sun-to-hydrogen efficiency 3 - incident radiation power density.

Fig. 3. Block-diagram of the 350 kW solar-hydrogen plant at Riyadh (Saudi Arabia).

Solar-hydrogen plant Principles of design and state-of-the -art... 

Solar-hydrogen plant Simulation Solar-hydrogen plant Optimization Optimization of the plant "solar array + electrolyzer + secondary battery"... 

A Princeton study of the Los Angeles area focused on the potential for solar photovoltaic plants in the desert areas east of the city. The study concluded that enough hydrogen could be produced with solar power in an area of 21 square miles to fuel one million fuel cell cars. 

The thermochemical cycles (S-I > 850°C) or hybrid cycles (S-electrolysis > 850°C) still feature many uncertainties in terms of feasibility and performances. Uncertainties still exist in parts of the flow sheet and technologies needed to provide high temperature heat whether from solar or nuclear nature. Potential assets of thermochemical cycles lie in a theoretical potential for a global efficiency above 35% and a scaling law of the hydrogen plant after the volume of reactants instead of the total surface of electrolytic cells. In return, their practical feasibility and economic viability have to be entirely demonstrated. Especially, a global efficiency above 30% is to be demonstrated to compete with alkaline electrolysis. Moreover, the safety of co-located nuclear and chemical plants has to be demonstrated. 

The time for holding conferences and writing articles is over. The Secretary General of the United Nations, on September 24, 2007, put it this way "The time for doubt has passed." It is time to build those demonstration plants that will clearly establish the feasibility and costs of the various alternative energy systems. It is time to start to replace fossil fuels with clean and renewable energy sources such as solar-hydrogen. 

Another carbon-capturing invention is to convert the captured C02 into methanol. If this process matures by the time the solar-hydrogen demonstration power plant described in this book is built, and if there is a C02 source near the plant, I will incorporate it as a subsection of the plant that is described in Chapter 4 of this book. 

In a solar-hydrogen power plant, when excess solar energy is available, the RFC is switched into the electrolyzer mode to split water into hydrogen and... 

If the March insolation in Figure 1.28 also represents the yearly average, then each square meter of collector area receives 2,628 kWh/yr. If these numbers are correct, and if the collector efficiency is 20% (solar collector efficiencies can range from 5 to over 30%), then each square meter of collector area will produce 526 kWh/yr. Based on such calculations, one can calculate the area requirements of solar-hydrogen power plants in any location (see Section 4.2). 

Therefore, even if an installed solar-hydrogen power plant costs 1 billion more than a regular solar plant, this is still under the costs of state-of-the-art nuclear or fossil power plants of the same size range. If the solar collector cost is estimated at 3,000/kW, the life expectancy of the equipment at 25 years, and the interest on investment at 5%, the unit cost of electricity generated will be about 12tf/kWh. This cost is already competitive with fossil-generated peak electricity costs and even with nonpeak electricity prices in some areas. (In June 2007, in Connecticut in my household, we paid 18.9 /kWh for our electricity.)... 

After the solar-hydrogen demonstration plants have operated for a few years, methods will be found to increase their efficiencies, reduce their operating costs, and take advantage of mass production and free market competition to optimize their first costs. If the best scientific talent is mobilized, it... 

The four main equipment blocks of the solar-hydrogen power plant. (Four percent of the Sahara can supply the total energy needs of the planet or 15% of the Mojave Desert can supply the total electricity needs of the United States.)... 

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