The Mosul Dam in Iraq is considered among the most dangerous dams in the
world today. Completed in the mid-1980s, it is Iraq’s largest hydroelectric
dam, producing power for thousands of homes. The dam is built on soft
gypsum rock, which is constantly eroding. Underground repairs to mitigate
the damage and keep its foundations intact are going on almost constantly.
Should the dam collapse, the city of Mosul and surrounding areas could
be inundated by as much as 70 feet (21 m) of water within hours of the
breach, with the lives of at least 1.5 million people at risk.Solar
Solar energy consists of collecting and harnessing radiant energy from the sun to
provide heat and/or electricity. Electrical power and/or heat can be generated at
home and at industrial sites through photovoltaic cells, solar collectors, or at a
central solar-thermal plant.
A passive solar heating design does not include any type of mechanical
heating device, and it functions by incorporating building features that absorb
heat and then release it slowly to maintain the temperature throughout the
building. These building features, often referred to as thermal mass, may include
large windows, stone flooring, and brick walls. The energy collected moves
through the building according to the second law of thermodynamics, which
states that heat moves from warm to cool areas and is transferred through
convection.
Additional steps that homeowners of passive solar designs can use
(depending on the local solar and weather conditions) include:
■ In areas of high solar input, planting deciduous trees to block sunlight
(leaves fall in the winter to allow sunlight in); in areas of little solar input,
decreasing light-blocking vegetation around windows
■ Using reflective coatings on roofs and exterior walls
■ Using double- or triple-paned windows with heat-reflective coatings
■ Increasing insulation in attics, walls, and crawl spaces or basements
■ When designing a home, positioning the home to maximize or minimize
(depending on the location) solar input
■ Using skylights to allow free sunlight in
■ Installing awnings and thermal blinds on all windowsActive solar heating is a much more involved process and generates more