Dry or wet / flooded refers to whether or not the electrolyte is liquid. A dry cell means that the electrolyte is a solid powder electrolyte; a wet cell means that the electrolyte is liquid and is allowed to flow freely in within the cell casing. Dry cell batteries are used in flashlights, toys, radios, laptops and mobile phones.
The ability of biomass and biofuels to contribute to a reduction in CO2 emissions is limited because both biomass and biofuels emit large amounts of air pollution when burned and in some cases compete with food supply. Furthermore, biomass and biofuels consume large amounts of water. Other renewable sources such as wind power, photovoltaics, and hydroelectricity have the advantage of being able to conserve water, lower pollution and reduce CO2 emissions.
In general, renewable energy is more expensive to produce and to use than fossil fuel energy. Favorable renewable resources are often located in remote areas, and it can be expensive to build power lines from the renewable energy sources to the cities that need the electricity. In addition, renewable sources are not always available:
The panels, which will be installed on hundreds of rooftops across the city, are capable of producing up to 60 megawatts of solar power, the companies said. Work has started on the project, and it will be up and running by the end of the year.
In the case of crystalline silicon modules, the solder material, that joins together the copper strings of the cells, contains about 36 percent of lead (Pb). Moreover, the paste used for screen printing front and back contacts contains traces of Pb and sometimes Cd as well. It is estimated that about 1,000 metric tonnes of Pb have been used for 100 gigawatts of c-Si solar modules. However, there is no fundamental need for lead in the solder alloy.
Biomass energy, or bioenergy, is energy from plants or other organic matter. Bioenergy can be used to provide heat, generate electricity, or power cars. Wood is our largest source of biomass energy. Waste energy is another form of bioenergy that can come from gases produced by landfills. Biofuels are fuels that are made from plants and can be used to power cars or other vehicles.
There are 9 solar power plants, in different locations in California’s deserts. These plants comprise the Solar Energy Generating Systems (SEGS). SEGS plants are concentrating solar thermal plants. They are the largest solar power generating plants in the world, generating up to 354 MW.
Directive 2004/8/EC of the European Parliament and of the Council of 11 February 2004 on the promotion of cogeneration based on a useful heat demand in the internal energy market includes the article 5 (Guarantee of origin of electricity from high-efficiency cogeneration).
Solar water disinfection (SODIS) involves exposing water-filled plastic polyethylene terephthalate (PET) bottles to sunlight for several hours. Exposure times vary depending on weather and climate from a minimum of six hours to two days during fully overcast conditions. It is recommended by the World Health Organization as a viable method for household water treatment and safe storage. Over two million people in developing countries use this method for their daily drinking water.
The third general approach is to use renewable energy. Of the various renewable energy sources, by far the largest resource is provided by the sun. More energy from sunlight strikes the earth in 1 hr (4.3 × 1020 J) than all of the energy currently consumed on the planet in 1 yr (4.1 × 1020 J in 2001) (5). Yet, in 2001, only <0.1% of electricity and <1.5% of fuels (mostly from biomass) were provided by a solar source (1). Against the backdrop of the daunting carbon-neutral energy needs of our global future, the large gap between our present use of solar energy and its enormous undeveloped potential defines a compelling imperative for science and technology in the 21st century. Solar energy is a free, inexhaustible resource, yet harnessing it is a relatively new idea. The ability to use solar power for heat was the first discovery. A Swiss scientist, Horace de Saussure, built the first thermal solar collector in 1767, which was later used to heat water and cook food. The first commercial patent solar panels a solar water heater went to Clarence Kemp of the US in 1891. This system was bought by two California executives and installed in one-third of the homes in Pasadena by 1897.
This uncertainty about the most practical financial model reflects the fact that in sub-Saharan Africa there is a great deal of economic diversity, both between countries and within them. One morning, I found myself walking down a line of houses in the Arushan suburb of Morombo. At the first house, a two-room cinder-block structure with a broken piece of mirror on one wall, a woman talked with me as we sat on the floor. The home represented a big step up for her, she said—she and her husband had rented a place for years, until they were able to buy this plot of land and build this house. She had a solar lantern the size of a hockey puck in her courtyard, soaking up rays. (Aid groups have distributed more than a million of these little lamps across the continent.) She assured me that she planned to get a larger solar system soon, but, for many of Africa’s poorest people, buying a lantern is the only possible step toward electrification.
The use of renewable fuels dates to Neolithic times, when cave dwellers made fire from wood and other biomass for cooking and heating. For thousands of years thereafter, renewable energy was all humans used. The small amounts of energy accessible to humans through traditional dispersed renewable energy sources meant that for millennia, human lives remained unchanged. Today, many are seeking to use technology made possible by modern, concentrated energy forms to capture and harness dispersed renewable energy potential into concentrated forms. Renewable energy relies upon the natural forces at work upon the earth, including the internal heat represented by geothermal, the pull of lunar gravity as it affects the potential for tidal power, and solar radiation such as that stored through photosynthesis in biomass.
Undeterred, AES Southland pressed forward with its proposal. In 2013, Firooz updated her analysis at the request of the city of Redondo Beach, which was skeptical that a new plant was needed. Her findings remained the same.