The Global Energy Future – Part 5

Today, there are only some 50,000 solar homes in the U.S., but their number is increasing at a rate of ten-fold per decade. As experience is gained and production volume rises, the cost of collectors is dropping by about 5% per year. In the U.S., some 90% of the existing solar collector installations generate only hot water, while about 10% also generate electricity.

The renewable home energy installations can also use household wind turbines, which are usually small (2kWh/day 10 kWh/day at 10 mph wind speed). A 10 kWh/day unit costs about $8,000 if used to charge batteries, while one tied to the grid costs about $12,000, including inverter.

There are also a few solar and geothermal combination homes, such as the Strizki home in New Jersey. The United States Merchant Marine Academy has one of the first solar-hydrogen generating installations.

Another likely feature of the private homes of the future will be continuous optimization and wireless remote access. Energy optimization will be provided by computer software packages that continuously watch the cost-effectiveness of operation. For example, if a home has both an old oil furnace and a solar-powered hot water, electricity and geothermal heat pump, the optimizing software will continuously maximize the use of the least expensive form of energy.

For example, in the winter, the storage of solar hot water will be exhausted before starting the geothermal heat pump, and the furnace will only be used as needed to supplement these sources. Similarly, in the summer, this control software will cool the home by operating the geothermal heat pump in reverse and by using solar electricity to drive it. During all seasons, the system will watch the cost of grid electricity continuously and make the decision on selling or buying energy from the grid on that basis, taking advantage of peak energy costs.

This optimizing software can also be integrated with miniature cameras, smoke and security alarms that will automatically contact the owner in case of an emergency. In addition, it can also allow the owner to view or change the conditions in the home using a wireless mobile phone to adjust thermostat settings and stop and start equipment.

Go to www.controlglobal.com/lessonslearned.html for more resources.

Béla Lipták, PE, process control consultant, is editor of the Instrument Engineers' Handbook and a gormer chief instrument engineer at C & R (formerly John Brown) and former adjunct professor at Yale University.  He can be reached at liptakbela@aol.com.