Kombikraftwerk - energy reliability through diversity
Sunday, January 6, 2008 at 04:20PM
Toby Considine in Enterprise Interaction, Microgrids and Distributed Systems, Smart Grid, System Architecture

At the University of Kassel in Germany, researchers are assembling a reliable power grid from a number of unreliable components. Kombikraftwerk (Combined Power Plant) is a grid assembled from 36 biogas, wind, solar and hydropower plants in a distributed network. The project was designed as a demonstration project to prove that it is possible for the German power grid to be reliable even if based entirely on non-traditional power sources.

This is a demonstration (again) of the old principle that you can gain additional reliability and availability from multiple technologies then you can from any single technology. While it is certainly possible that with additional research, development, any one (or two) of the technologies could be made ever so much more reliable, such efforts soon run into the age-old 90% problem. (This is usually expressed as “After you've done 90% of the project, you have the other 90% to do.”) Achieving each additional increment of reliability from an existing technology usually requires large amounts of additional effort.

A problem in scaling Kombikraftwerk will be the fallacy of large scale control. As the size of community to be orchestrated increases, the complexity of orchestration increases. Sooner or later, the Kombikraftwerk will fail due to the deep integration and direct control  of power production that appear to be embedded in its model.

The other apparent problem in Kombikraftwerk is the fine tuning of energy production to meet actual rather than anticipated needs. This requires additional spin reserve (Plants that are operating but not supplying the grid) to handle surprises. Some spin will always be required, but it is easy to imagine scenarios requiring much less than we require today.

These issues are just the sort that the abstract interoperability and intelligent end nodes envisioned by the GridWise Architectural Council (GWAC) will solve easily. GWAC is working toward abstract e-commerce style interfaces between each component of the grid, including generation, transmission, distribution, and end customer face. Both sides of each interface are assumed to be intelligent peers, able to defend their internal missions.

The GWAC smart grid is the simultaneous optimization of the diversity problem (which combines a number of unreliable technologies to produce a reliable cloud) and the complexity problem (it is difficult to control a mix of systems with different operating characteristics into a single large-scale control system) and the money problem (how do we fund this in such a way that each innovation can be rewarded).

Generating systems can signal their operating postures and capabilities using abstract messages. These interfaces hide the underlying diversity to prevent the overall grid management from becoming too complex. New technologies for storage and generation can come to market faster, and make money faster, because they need only interface to the simpler abstract interface rather than undergo deep integration.

The GWAC customer face addresses coordination of the demand side. Local agents representing smart buildings become participants in the smart grid. Initiatives like the Zero Energy Building foresee hybrid nodes, usually consumers of energy, but occasionally selling back site-stored or site-generated energy.

Kombikraftwerk and GWAC are compatible approaches that can easily build off one another. Because the defined interfaces of the GWAC are abstract and standard, new generating technologies can join the mix without extensive review. Easy recombination enables innovation by shortening time to market. More innovation enhances reliability by adding additional sources of diversity.

Money is the best, and most universally accepted, abstract interface for communicating scarcity and value. When we add money to each interface request, the natural target for the building-side of the interface is the enterprise and the tenant, not the systems. It may be that the best demand/response decision, when incentivised with pricing, is to shut down the office building, declare a telecommuting day, and run the building generators (whatever they may be) flat out. Such decisions would only further enhance Kombikraftwerk.

Looks like Kombikraftwerk and the GridWise Architectural Council could work well together…

References:

Article originally appeared on New Daedalus (http://www.newdaedalus.com/).
See website for complete article licensing information.