During the summer of 2003, most of the North American transmission grid shut down at around 4:15 p.m. Eastern Standard Time. During the winter of 1998 the American Northeast and parts of Eastern Canada were battered by a severe ice storm that incapacitated much of the transmission grid in that region for up to two weeks. Power outages still occur during severe storms that inflict damage on local distribution networks and to sections of the transmission system.
Since the late 19th century when large generation facilities first appeared, the economy of scale has favored large-scale power generation at centralized installations. By the early 20th century it became cheaper to generate electric power at Niagara Falls and transmit electric power to New York City along transmission lines than to build multiple small thermal power stations in the city. By the mid-20th century many small hydroelectric power dams ceased operation as economics favored the mega hydroelectric dams at remote locations from major population centers. At the dawning of the 21st century there is still a powerful economic case for generating power at remote locations and transmitting it over extended distances using ultra-high voltage transmission lines.
Historically, hydroelectric was the only cost-competitive form of renewable power generation. The cost per kilowatt of many other renewable technologies is gradually declining and over the long term they are projected to become cost-competitive with fossil-fuelled power generation. The promising technologies include airborne wind turbines that can access powerful air currents that flow at higher elevations and free flow kinetic turbines that can be placed in ocean currents, ocean tidal currents and in fast flowing rivers. There have been recent research breakthroughs in solar thermal power conversion technology and into concentrating solar power onto advanced PV cell technology.
There have also been ongoing and recent research breakthroughs into various forms of on-site and small-site power generation. Micro gas turbine engines of around 30-kW output evolved from automotive turbocharger technology and can burn a variety of fuels in very remote locations where no transmission lines exist. Micro turbine engines that burn natural gas and/or biogas from gasified biomass can generate up to 150-kW output in the basements of several large office towers in large cities like New York. Such technology can provide essential back-up power, base line power and/or additional power during peak demand periods.
A project recently got underway in France where ultra-deep geothermal wells are being drilled to access high-grade heat that is in excess of the boiling point of water. Such temperature can be found at the bottom of salt domes that have been flushed of salt and that the natural gas industry uses to store compressed natural gas. It is theoretically possible to build an office tower located next to a river or ocean coast and generate electric power from geothermal heat. A closed-cycle engine that circulates a refrigerant such as ammonia or R-134a can operate from the difference in temperature found between the lower depths of the geothermal well and water in the nearby river or ocean coast.
The cost per kilowatt is expected to decline for both thin-film solar PV technology that can be installed as siding on buildings and for solar PV windows. Both technologies would likely be included in the construction and refurbishing of high-rise commercial buildings located in regions that receive generous solar energy throughout the year. Over time and as the cost per kilowatt decreases over time for decentralized power generation, the percentage of such power generation may be expected to increase over time. Some building owners may choose to go off-grid altogether and transfer on-site renewable power generation for solar and wind sources into on-site storage technology such as flow batteries.
Other owners of buildings with on-site power generation may maintain the grid connection and sell excess renewable power to the grid during weekends, during the AM period that precedes the onset of the business day and during the PM period after the close of the business day. In this way decentralized power generation that is connected to the grid could benefit a larger population. There are several micro nuclear technologies that could be used where mass decentralized power generation feeds into the grid.
Toshiba has developed a micro nuclear reactor that uses lithium-6 for fuel and can produce several hundred kilowatts of power for several years. Another competing group proposes to develop atomic batteries use the isotopes from spent nuclear fuel rods. Each atomic battery is estimated to be able to continually generate electric power without using nuclear reactors for up to 28 years. The spent atomic batteries would contain a radiation-free form of strontium. Hyperion Technologies has developed a sealed nuclear battery that uses uranium hydride fuel. Each generating unit can be buried underground from where it may generate up to 25MW for up to five years when the unit would be returned to Hyperion and recharged.
Buildings with off-grid decentralized power generation and energy storage capability may be independent of any outside power line while serving the needs of building owners and their tenants. Decentralized power generation that is connected either to privately owned power lines that connect to other buildings or to the power transmission grid can serve the needs of a larger community. There is future role for both types of decentralized power generation where they may co-exist with various forms of renewable and non-renewable forms of centralized mega-power generation installations.