1 de abril del 2001
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A Hot Shower Can Be Eco-Friendly

By Mario Osava

In Brazil, a new invention based on solar energy feeds dreams of the pleasure of a hot shower with low economical and environmental costs.

RIO DE JANEIRO - The 27 million homes in Brazil that use electrically heated showerheads could soon have a low-cost solar water heater (aquecedor solar de baixo custo - ASBC), a simple system that provides hot water for bathing with minimal energy consumption.

The country would save 20.5 million kilowatt hours per year, or six to seven percent of total national consumption of electricity, if this heater were utilized by 25 million families, according to the calculations of Augustín Woelz, inventor of the system.

Along with the energy savings, it would prevent the emission of 10 million tons of carbon dioxide a year, the gas that contributes most to global warming.

The relative savings are even greater. The electrical showerheads are a burden to Brazil's energy production and distribution systems because their use is concentrated at the time of day when the country's energy demands are highest.

It is at nightfall that most household appliances are used, streets and buildings are illuminated and industry and other businesses continue in action. By reducing consumption for heating water for bathing, the overall pressure on the system would be reduced. The electric water heaters absorb 10 percent of the potential generated during this energy ''rush hour.''

Brazil plans to use natural gas imported from Bolivia for its thermoelectric plants, given the difficulties of hydroelectric dams to keep up with the country's growing energy demands. But saving energy through other means would imply the reduced emission of gases that contribute to the greenhouse effect.

The electrical showerheads that ''democratized the hot shower'' are a solution that is typical of Brazil, observed Woelz. In the rest of the world, it is more common that water heaters function with natural gas.

The ASBC, initially designed for more modest homes, can heat 150 to 200 liters of water per day, converting solar light into heat through black honeycombed panels, plastic tubing and other readily available construction materials.

The process can be installed taking advantage of the water tanks that are generally used in Brazilian home construction, adding insulation.

Water from the lower part of the tank passes through the apparatus and panels and is returned, a naturally occurring flow because warm water is lighter than cold water, so it remains in the upper layer of the volume of water until the full tank reaches a homogenous temperature.

The water temperature can reach 55 degrees centigrade, more than warm enough for a hot shower, and on cloudy or rainy days it may fall to 40 degrees.

Due to these fluctuations, users might opt to keep their electrical showerhead on hand, though adding a temperature gauge so that goes turns on automatically when the solar heat proves insufficient.

Anyone can install this system for a total cost of around 100 'reais' (50 dollars), according to Woelz, an electrical engineer who says he pondered this invention over 10 years and developed it over the last two years.

He designed the apparatus with the poor sectors of the population in mind, families that live in marginalized neighborhoods. The inventor worked with the support of the National Council for Scientific and Technological Development and the Sao Paulo Research Foundation, two governmental agencies.

The firm created to disseminate the use of the water heater, Sunpower Engenharia (www.sunpower.com.br), does not intend to seek patent rights, but rather to mobilize volunteers and train technicians, builders, teachers and social workers to promote their installation on a massive basis.

The widespread use of the solar water heater would lead to the expansion of the industries that manufacture its components. In the future, other companies could sell complete kits, as well as develop systems for larger buildings.

The objective is social benefit, affirms Woelz, pointing out that each family would save nearly 150 'reais' (75 dollars) a year in energy costs, and the impact on the environment would be greatly reduced.

* Mario Osava is an IPS correspondent

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