EMERGENCY SPACE HEATING DURING GRID POWER OUTAGES
SOLAROOFTM has a unique application during Grid power outages such as has occurred under SANDY and other weather catastrophes. It can provide emergency space and hot water heating during power outages since it can circulate stored solar hot water through baseboard heaters with only a 5 watt d.c. pump driven by a small, 12 volt solar panel and/or one or two 12 volt batteries.
Its installed cost is less than the cost of an automatic fuel-fired backup generator, which has no cost payback advantages. The SOLAROOFTM emergency backup continues to provide hot water and heat throughout the year when normal grid power is available and pays its cost back in a little as 5 years.
Reacting to the current series of wide scale grid power outages, many homeowners have purchased automatic gas or propane motor driven power generators, costing approximately $30,000 for the complete installation. The following describes a solar system that provides emergency heating and some electricity during these grid power outages at less than one half the cost of a motor-generator installation. Moreover, when the grid power is on, it continues to provide domestic hot water and some space heating throughout the year, thus paying off the initial investment, and helping to reduce climate change.
Figure 1 shows a block diagram of this emergency heating system. It is based upon the high temperature solar thermal system developed and produced by Optical Energy Technologies Inc.. The heating system that provides the lowest consumption of electrical power is a baseboard hydronic convection system, already installed in many residences, or which can be economically installed in key rooms for emergency heating. The advantage of this heating system is that its heat can be distributed by a very low power dc pump which uses less than 30 watts of electrical power. A baseboard hydronic heating system requires relatively high water temperature to provide efficient convection to heat the space. This high temperature is achieved with the SOLAROOFTM integrated heat pipe, solar thermal system as described above.
As is shown in Figure 1, when the grid power is available, solar thermal energy is stored in a 1,000 gallon non-pressure tank and an 80 or 120 gallon pressure tank, which provides high temperature water for baseboard space heating, and lower temperature pressure water for hot water. The 5 watt pump, which is driven by the house thermostat, and a 20 watt solar panel, can also be driven by a larger version of a battery backup UPS system similar to that currently used for backup power to computers. Using two, 100 ampere-hour 12 volt marine batteries, initially fully charged by grid power, this system can provide emergency heating from the solar thermal heat storage tank for up to one week, under the worst case assumption that there is no solar energy input for this time period. Any solar input, either thermal, or photovoltaic, will extend this time period. The UPS will also provide a small amount of electricity for lights during the power outage period, and will recharge the battery bank to extend this period. It is important to emphasize that the thermal storage of heat energy in the water tank has a much lower cost that a large bank of batteries that would be necessary for an all electric emergency backup system.
The net installed cost of this emergency power and heating system after the Federal and State tax rebates are incorporated, is expected to be less than $15,000 or less than that of a motor generator, which would have zero payback capability, in comparison with a less than 5 year payback capability of this proposed system, which operates throughout the year, saving fossil fuels.