Thursday, 24 July 2014

Renewable Energy Resources for HVAC

HVAC is an absolute necessity in almost every building in San Jose. Whether it is for heating, cooling, or ventilating, energy is required for the systems to do the job effectively, efficiently, and comfortably. But, there's not one system that will do the job for every facility.

Traditionally, electricity is generated from fossil fuels - coal, natural gas, and petroleum. As the demand for energy increases, the supply for it is decreasing and depleting rapidly all over the world. Plus, this energy is also responsible for the green house gases that have adverse effect on the environment and are the cause for the global warming that is melting glaciers and causing tsunamis.

All this has led to increased environmental awareness and the need to source energy for electricity from alternate sources and renewable sources such as wind, sun, biomass fossils. According to the reports, renewable energy is one of the most vital recently discovered resources. A report from the National Renewable Energy Laboratory (NREL), quotes, "Renewable energy resources—such as wind and solar energy are constantly replenished and will never run out."

Renewable Energy for HVAC

For HVAC/R (heating, ventilation, air conditioning and refrigeration), solar and geo-thermal energy is most suited for heating and cooling in the residential scenarios. While a majority of energy in the United States comes from fossil fuels, there is also tremendous growth in alternative and renewable energy technologies.

Solar Energy

A solar energy system produces electricity from the sun’s rays. This electricity is then used to power a building’s HVAC system. This system is made up of photovoltaic (PV) cells. The solar modules in the system harvest the energy from the sun and convert it into electricity. This is how you can use solar energy to run your HVAC units, lights, other electrical devices.

Basically, there are two types of solar power systems. These are stand-alone and grid-connected systems. The stand-alone systems are designed in such as way that they operate independently and do not need an electric utility grid and supply certain DC or AC loads. In many such solar power systems, energy storage needs to be done through batteries.

The other type, the grid-connected power systems need an electric utility grid. These systems are designed in such a way that they are interconnected with the grid and operate parallel to the grid. These systems also use photovoltaic cells to generate energy from the sun’s rays and this energy is stored in a grid as AC power. The electricity from this grid is supplied into the building or the household.

Geothermal HVAC

Geothermal HVAC is said to bring a household or building in harmony with the earth beneath. It takes advantage of subterranean temperatures to generate heat in winter and cool air in summer.

The temperature at the bottom of the earth's crust is constant, typically over 1000°F. In some locations, the temperatures are so high and so close to the earth’s surface that they result in hot springs, geysers, and volcanic activity. Such places have high potential opportunity for geothermal electricity generation. Through geothermal plants, the steam is tapped and used to operate turbines which generate electricity.

A geothermal system typically consists of an indoor handling unit and a system of pipes that is buried in the earth. These pipes are called an earth loop and connected to a pump to reinjection well from where the steam is tapped. The constant temperatures provide the “free” energy.

In winter, the fluid that circulates through the system’s earth loop or well absorbs the heat stored and carries it indoors. The indoor unit then compresses this heat to a higher temperature and t releases it into the building, working as a heater. In summer, the geothermal system pulls out the heat from the building and transports it through the earth loop/pump to reinjection well. Here it deposits this heat into the cooler earth/aquifer. Geothermal systems do not need periodic maintenance. Once installed properly, the buried loop lasts for generations. However, filter changes and annual coil cleaning are required.

The United States Environmental Protection Agency (EPA) is expecting that some states in the US will switch to natural gas for electricity generation, according to senior agency officials on a media briefing. There are attractive discounts also available for new constructions and upgradation projects.

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