Emerging Scanning Technologies:
PATH Roadmap Applicability:
As you look out the window during a recent storm, the neighborhood looks particularly dark. The power grid has gone down again. Fortunately, on this exceptionally cold night, your heating system continues to operate from the electricity generated by a recently-installed microturbine. In fact, all of the townhomes on your block are powered and heated using this form of decentralized energy generation for much less than the cost of energy purchased from the electric company.
Decentralized energy distribution is increasing as an alternative method of power generation. Microturbines generate electricity by burning natural gas or another fuel to produce pressure that turns a shaft. The shaft is connected to a turbine wheel on one end and a magnetic generator on the other. The electricity that is produced is typically passed through an inverter to provide AC power.
Several companies have introduced commercially-available microturbines, sometimes called mini-turbines. Currently, the smallest systems are about 30 kW in size, about three to six times as much capacity as is needed for a typical home. But the time may arrive when separate units will be available for an individual home.
Benefits of microturbines include societal benefits such as potentially reducing or eliminating the need for new power plants. Microturbines can also produce each kilowatt of electricity with fewer smog-producing emissions than all but the very latest natural gas-fired utility plants. Much higher efficiencies are also possible with distributed energy production.
Benefits at the site or the home level include minimized need for connection to the grid, or elimination of this infrastructure altogether, typically a large cost in rural or isolated regions. The cost to produce electricity with a microurbine can be half that of electricity purchased from the grid in many areas of the United States.
Application to PATH Roadmaps
The use of microturbines is applicable toward meeting the goals of the energy efficiency and affordable goals of PATH. The Year One progress report of the PATH Energy Efficiency in Existing Homes Roadmap identifies the need for distributed or decentralized energy production as one of the primary strategies of the roadmap. Microturbines also can be used for new homes, and thus have implications on the Whole House and Building Process Redesign Roadmap. Microturbines bring us closer to the realization of a net-zero energy home--a home that produces as much or more energy than it uses.
Current Status of Technology
About 3,000 microturbines have been shipped world-wide since their introduction in 1998. The smallest units are in the range of 28 to 30 kW. Although this size is more applicable to multi-family homes, townhomes or possibly a group of detached homes, than to the typical individual home, smaller turbines will likely be part of the future.
The current initial cost of microturbines is a factor, especially compared to other alternatives such as connecting to the grid or other distributed technologies. Cooperative research efforts with the major manufacturers of microturbines and the U.S. Department of Energy have set a goal to improve the efficiency and reduce the cost of microturbines. Their target is to reduce today's cost of $800 to $1,000 per kW to about $500 per kW, which is comparable to today's engine-driven generators.
There are many advancements taking place to improve the efficiency of microturbines. One approach is focused on recuperators. A recuperator is similar to a heat exchanger that is designed to capture exhaust heat and return it to reduce the amount of incoming heat required to turn the turbine shaft. Information on existing microturbines and related research efforts is available from the contacts listed below.
Content updated on 5/6/2003