Distributed power is finally going mainstream! A 1.1 megawatt (MW) combined heat and power (CHP) system is being planned for the 48-story Transamerica Pyramid building in the financial district of San Francisco, California. Long story made short: a CHP has very high total fuel efficiency in part because it uses waste heat from electricity generation to run HVAC systems. The greatest gain for the dollar invested comes from using CHP in densely developed urban core areas; but, suburban office buildings and even homeowners can benefit. "Northern Power's CHP system will consist of two 560 kW natural gas-fired reciprocating engine generators, which will operate in parallel with the utility's downtown network grid. The two generators are designed to provide approximately 70% of the electrical requirements of the 530,000 square foot commercial office building. Recovered waste heat from the engines will be used to heat the building, displacing 100% of the steam currently purchased for heating purposes. Additionally, waste heat will drive a 320-ton absorption chiller that will be installed to create chilled water for the building".
"The project marks Northern Power's third CHP system that will be interconnected with Pacific Gas & Electric Company's downtown network grid". The publicity sheet for one of the earlier Northern Power projects states that "Northern's power system is also considered a "green" system. In recovering waste heat, the system's overall fuel efficiency rises to approximately 80% (lower heating value), compared to typical efficiencies of 40% (lower heating value) from utility-produced power.The dramatically increased fuel efficiency can reduce greenhouse gas emissions by up to 40%".
There is no "line loss" efficiency issue with the CHP provided power because there is no transmission. So, add those "nega-watts" to the combined fuel efficiency boost from the CHP on-site, and the total represents the cumulative societal gain in efficiency.
When the grid goes down, or if there a "brownout," business interruption is unlikely. This provides a strong incentive for 24/7 businesses to become tenants. Good fit for a financial district.
There is a theoretical drawback to widespread use of CHP in an urban area. Air emissions everything from particles, to NOX, SOX, and C0 are released where electricity is consumed instead of at a remote utility. But since metropolitan air sheds with degradation problems are immense in size, they likely already encompass all "receptors" and significant "emitters." In other words, it's a theoretical drawback that has little meaning in practice.
Ever wonder why there aren't more of these around? Every megawatt from a distributed CHP system is a megawatt not purchased from a central utility. Up until now there has been subtle, bureaucratic, if not direct political resistance from "the powers that be" (literally). Plus the capital cost is much higher than just getting power off the grid. Given California's recent experience with power blackouts and distribution monkey business, it's no wonder they're at ground zero for a bold step forward. Congrats to everyone involved in this scheme. It's the kind we need more of if we're going to take Climate Change seriously.
Conclusion: every city ought to give tax and other incentives to encourage CHP for major commercial buildings. Once the infrastructure for distributed power is set up, the market for other non-combustion forms of CHP, like stationary fuel cells, will blossom.