Tuesday, May 25, 2010
Gas Fueled Power Systems
This Spring, many houses in Massachusetts suffered flooding due to failed sump pumps. This motivated me to replace our existing sump pump and install a back system.
When I think about home disaster recovery in general, an electrical power is a single point of failure. When does power fail - during a storm, when you need heat, water pumping, and humidity control.
The likelihood that gas (natural gas/liquid propane) will fail at the same time as electrical is very remote, so natural gas powered electrical generators seem like a reasonable choice for creating home electrical redundancy.
Home Depot sells the kind of unit that is needed.
Yes, it must be professionally installed, but if you live in an area with frequent storms and power outages, natural gas fueled standby and backup power systems make sense.
Speaking of "natural" gas, the New York Times recently published an article about using methane from cow manure to power data centers. Since many new data centers are being built near inexpensive hydroelectric power in rural areas where manure is prevalent, this may be a reasonable alternative energy source.
Here's the opinion of our power experts on using manure to power infrastructure:
*Similar in some ways to a co-generation plant but using farm waste instead of natural gas.
*Natural gas in the streets only has a small amount of methane, because methane is a low pressure gas.
*High pressure gases need to be used to generate significant amounts of power via gas turbines & steam.
*Methane being a low pressure gas does not burn as hot and cannot handle sudden increases in loads.
*Typically farmers burn the cow patties directly to produce heating for their homes.
*The NY Times article did not describe the step needed to store methane in a high pressure form that can support power generation.
* Bird manure has a higher energy content and has been used more successfully.
A few thoughts specific to data centers:
*Natural gas back-up generators typically do not have on-site storage since stored natural gas can be highly explosive
*Storage of liquified gas is allowed on ground level floors, but it is stored at 0-degrees Kelvin and a large containment area needs to be established because if a leak were to occur, everything it comes in contact with would be frozen instantly and become brittle.
*The diesel generators at datacenters typically have 48-72hrs. of fuel available on site to run stand alone.
*Natural gas turbines are twice as expensive as diesel engines.
*Reliability and redundancy are always important, therefore the methane power plant would need a utility back-up line to supplement the methane plant during sudden increases of electrical load and back-up the plant in the event of failure or maintenance downtime. The utility line would have to be sized to feed the entire datacenter.
*When a gas leak is detected in the street the utility provider will shutdown the entire line affecting all users until the leak is found and repaired. Therefore, redundant pipes from different sources would be needed to maintain uptime of the gas feed.
Thus, manure is not an easy solution to the problem of growing data center power needs. However, as energy costs rise and carbon footprint becomes more important, it's worth keeping in mind.
The best quote from the article - “Information technology and manure have a symbiotic relationship.”
Posted by John Halamka at 3:00 AM