Most places I hang around have only 5 to 10 minutes batter. We, NAC, usually plan on 10 minutes at full load, sometimes a little more. If your genset doesn't start and sync in 30 seconds, it's unlikely, that even with really good planning, that you'd get a rollup there, hooked up, etc., in time. Murphy wouldn't hear of it. On Wed, 2 Apr 2003, Richard Welty wrote:

On Wed, 2 Apr 2003 15:37:28 -0800 Dan Lockwood <dlockwood@coe.shastalink.k12.ca.us> wrote:

...

Our current plan is to purchase the UPS with a minimal amount of battery, approximately 15min worth; just enough to get the generator running. Is this the better way to go? Or should we consider more battery?

just how certain are you that your generator is always going to start within 15 minutes?

richard -- Richard Welty rwelty@averillpark.net Averill Park Networking 518-573-7592 Unix, Linux, IP Network Engineering, Security

-- Alex Rubenstein, AR97, K2AHR, alex@nac.net, latency, Al Reuben -- -- Net Access Corporation, 800-NET-ME-36, http://www.nac.net --

...

He also is strongly opposed to us purchasing a natural gas generator which seemed like a shoe-in for us.

We currently have a 133 kwatt nat gas genset. It has performed flawlessly -- they work well. The point of the marshall shutting of gas is a valid one, but I've not run across that. Also, if you are in a situation that the fire marshall need sto shut of nat gas, it may be a moot issue. -- Alex Rubenstein, AR97, K2AHR, alex@nac.net, latency, Al Reuben -- -- Net Access Corporation, 800-NET-ME-36, http://www.nac.net --

Speaking on Deep Background, the Press Secretary whispered:

...

He also is strongly opposed to us purchasing a natural gas generator which seemed like a shoe-in for us.

I know of several cases where the San Jose fire marshall turned off natural gas as a precaution. You may wish to discuss with your local fire marshall under what conditions they will turn off the gas.

Some places require auto-shutoff valves for NG as an earthquake precaution.

Natural gas is a big plus in many ways; one undervalued by both customers and generator sales folks.. But all that ONLY in non-tilting/shaking enviroments. If 'earthquake' does not mean "something that happens out in THEIR state.." to you; then don't consider it. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433

I'm in Santa Cruz County. Since I've been here, natural gas has been off for multiple days in a row twice. Once because of an earthquake, the second time because a winter storm put a lot of water in a hillside and the slide severed the (only) high pressure gas feed for the county. In both cases, electricity wasn't stable either. So for the last datacenter I built, I went with diesel. I've also been told, though I don't know how true it is, that diesel generators can go longer between service intervals, though for a datacenter I wouldn't skimp on routine maintenance anyway. Matthew Kaufman matthew@eeph.com <-home mkaufman@dsl.net <-work

-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Bill Woodcock ... Why? In what case is it still not preferable to diesel? The _only_ reason I've ever heard an informed person state for going with diesel is that the fire marshal wouldn't allow them to store anything else.

-Bill

The goal of the generator is to keep the datacenter running when the power fails. Power around here fails because of storms and earthquakes, both of which have a demonstrated history of also taking out natural gas at times. This means that at least one of your generators (around here) should run on something you store on-site. And thus, if you can only afford one, that one must be in that category. By your logic, the fact that electricity is _usually_ available on tap eliminates the need for a generator altogether. Matthew

-----Original Message----- From: Bill Woodcock [mailto:woody@pch.net] Sent: Friday, April 04, 2003 4:04 PM To: Matthew Kaufman Cc: 'David Lesher'; 'nanog list' Subject: RE: Looking for advice on datacenter electrical/generator

On Fri, 4 Apr 2003, Matthew Kaufman wrote: > natural gas has been off for multiple days in a row twice. > So for the last datacenter I built, I went with diesel.

I'm not following your logic... How does the fact that natural gas is _usually_ available on-tap, and diesel _never_ is make diesel preferable?

-Bill

In a message written on Fri, Apr 04, 2003 at 04:13:46PM -0800, Bill Woodcock wrote:

Right. So if you have a choice of storing gas or diesel, and gas usually doesn't have to be replentished by truck, since it's _usually on-tap_, but diesel _always has to be replentished by truck_, since it's _never on-tap_, why would one ever choose diesel unless, as per previous caveat, clueless fire marshalls thought it was really preferable?

I'm not an expert but: 1) Storing natural gas is significantly harder (both in the containers and permiting) than Diesel. It also has less energy density, so it takes more space. 2) Having natural gas trucked in, rather than delivered via pipeline is also extremely difficult, and possibly impossible in some areas. The infrastructure simply doesn't exist. On the other hand I could pick up the phone and have a semi-truck full of Diesel in any major metropolitan area in an hour or so for cheap. Indeed, it's very easy to get "guaranteed responce time" diesel contracts for emergency generators, I'd love to know if anyone has even attempted that with Natural Gas delivery by truck. 3) Getting a natural gas feed for a large data center (read a couple of megawatts) is probably impossible in most areas. The distribution network for natural gas just isn't set up for it. Much less of a concern for the people who need a few hundred kilowatts. 4) In larger sizes, Diesel gensets are _cheap_. Remember, the thing sitting outside the data center is essentially the same as every diesel-electric railroad locomotive, every portable power source, and a whole number of other things. Natural gas isn't generally a good idea for your train locomotive, so the gensets are less tested, harder to find, and more expensive. So, IMHO, natural gas is good for smaller applications (probably under 250Kw), in areas where the gas is stable so you don't have to do on site storage. Otherwise Diesel is probably cheaper (both in genset cost and fuel cost), and easier to obtain. -- Leo Bicknell - bicknell@ufp.org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/ Read TMBG List - tmbg-list-request@tmbg.org, www.tmbg.org

At 05:01 PM 4/4/2003 -0800, Bill Woodcock <woody@pch.net> wrote:

...

4) In larger sizes, Diesel gensets are _cheap_.

The only difference between the diesel and gas genset is the carburetor, which is just different, not more expensive.

Not entirely accurate. Since has low volumetric energy density compared to diesel, NG/Propane gensets are basically de-rated diesel gensets. A 150KW diesel would be approximately 100KW as a NG and slightly less than that when running on propane. There is an interesting research/marketing paper from Onan/Cummings on current and emerging power generation methods including diesel, ng, propane, hydrogen, turbines, reciprocating engines, microturbines, and fuel cells. http://electrochem.cwru.edu/yeager/ohiofuelcell/Norrick-Cummins.pdf When I was evaluating gensets for our datacenter, I found a really interesting unit which uses propane and/or natural gas mixed with the air to extend the runtime by adding significant BTUs from the gas. However, it can run directly on diesel alone should the gas supply be interrupted for some reason. Very neat technology and obvious after the fact, but much more expensive. We opted for a standard diesel genset since it is reliable and proven. The last thing I wanted was unknowns in a energy source I need to depend on when everything else goes to hell. -Robert Tellurian Networks - The Ultimate Internet Connection http://www.tellurian.com | 888-TELLURIAN | 973-300-9211 "Good will, like a good name, is got by many actions, and lost by one." - Francis Jeffrey

At 06:25 PM 4/4/2003 -0800, you wrote:

> http://electrochem.cwru.edu/yeager/ohiofuelcell/Norrick-Cummins.pdf

You're right, that's really good reading.

It is interesting to see where they think backup power generation is going and the current ratios of operating costs vs. purchase costs vs. fuel availability vs. power outputs and duty cycles.

> interesting unit which uses propane and/or natural gas mixed with the air > to extend the runtime by adding significant BTUs from the gas. However, it > can run directly on diesel alone should the gas supply be interrupted for > some reason. Very neat technology and obvious after the fact, but much more > expensive.

URL?

http://www.gastechnologies.net/bifuel.htm This is one manufacturer of the control systems. We currently have enough diesel fuel to run for about 10 days without refueling so I couldn't justify the 2-3 times higher expense of a bi-fuel genset. Apparently, pretty much any genset can be modified for bi-fuel operation without any internal modification. The other advantage to bi-fuel systems is that the slew rate problems of lp/ng gensets are completely avoided. For those who haven't seen or heard of problems with natural gas or propane powered gensets, this is another argument against them. We heard from multiple genset vendors of slew problems and several actually refused to sell us gas gensets when they learned about our application - powering high inductive loads (A/C compressors) as well as UPSes with computer equipment. Apparently as the load changes based on cooling equipment cycling on and off, gas generators (even with electronic governors) have trouble keeping the RPMs constant. Cummings specifically stated that diesel gensets don't have this problem due to the higher slew rate and more accurate RPM control due to the higher energy density of diesel fuel - just another data point. He also noted that the bi-fuel (diesel/gas) systems did not exhibit this problem either. -Robert Tellurian Networks - The Ultimate Internet Connection http://www.tellurian.com | 888-TELLURIAN | 973-300-9211 "Good will, like a good name, is got by many actions, and lost by one." - Francis Jeffrey

On Fri, 4 Apr 2003 19:48:17 -0500 Leo Bicknell <bicknell@ufp.org> wrote:

So, IMHO, natural gas is good for smaller applications (probably under 250Kw), in areas where the gas is stable so you don't have to do on site storage. Otherwise Diesel is probably cheaper (both in genset cost and fuel cost), and easier to obtain.

this is the gist of what i learned a couple of years back. when i asked the PE at the vendor (a Cat reseller) about gas vs. diesel, he showed me that for the size generator we were looking at, diesel was a much better bet on the economics alone. richard -- Richard Welty rwelty@averillpark.net Averill Park Networking 518-573-7592 Unix, Linux, IP Network Engineering, Security

At 07:42 PM 4/4/2003, Stephen Sprunk wrote:

Thus spake "Bill Woodcock" <woody@pch.net>

...

On Fri, 4 Apr 2003, Matthew Kaufman wrote: > natural gas has been off for multiple days in a row twice. > So for the last datacenter I built, I went with diesel.

I'm not following your logic... How does the fact that natural gas is _usually_ available on-tap, and diesel _never_ is make diesel preferable?

As noted by other posters, natural gas often goes out at the same times as electricity in some areas (e.g. California). In fact, many power companies use natural gas to generate electricity.

Relying on one public utility to supplant another is not logical unless either you have historical data to satisfy you that outages in one are rarely linked to the other, or you can store natural gas onsite to run "long enough" and only need the utility to refill later.

It's quite as simple to store propane as it is diesel. Propane stored on-site is stable, needs no cleaning, and the genset is the same as you'd use for natural gas. Given the choice between storing a large quantity of diesel and storing a large quantity of propane, I'd take propane. Other folks would argue the other way. Scared about fire reaching your propane tank? Use in-ground tanks. Unlike fuel oil or gasoline, buried propane tanks are allowed, at least in some places. Think about it... leaking propane tanks don't pollute the soil, they pollute the air. Though I'm in an area where interruption of gas service isn't really a problem, the availability of gas is. Some towns just don't have gas service. So, we store propane. Not a big deal. I suspect, though I've never seen it done, that it'd be possible to set up a gas genset with both a pressurized tank of fuel and a connection to the mains, with valves to switch between.

A) Piped natural gas is highly reliable here in the East. I've not had such in 10+ years. An even-momentary outage is cause for great alarm (and media coverage) since they can't restart the line without visiting every residence, closing the shutoff, only then re-starting the line, and visiting every residence to re-light pilots, & run a nose-check. (Dirty little secret of old black steel lines is they rust from the inside; but then don't leak much since the line pressure holds the flakes in place. But drop line pressure, they deflake and it's swiss cheese when restarted.) I infer the req'd earthquake valves in Califunny also close on line pressure failure; so you can restore the line without a shutdown visit first? B) I know of no good way to store natural gas on-site. The utility typically uses an underground cavern that was a salt dome and hollowed out with lotsa H2O. Compressing gas locally is even less likely; it takes real KW to run the compressor station, as well as a safety zone surrounding. C) Yes, you CAN store propane, a different product. But if you need a lot of fuel, errr. A big propane tank is 300 gallons. I suspect the Fire Marshall will take intense interest in storage near a building of any size, much less in. Propane is heavier than air. Some codes ban its use in a basement without positive ventilation, gas detectors etc. D) Diesel engines, err Diesel-fueled piston engines, be they 2 or 4-cycle, need frequent oil changes. I have every reason to think natural gas/propane fuel would require same less often; the washdown of such will evaporate out unlike #2 diesel. But I've been wrong before. E) There are "dual fuel" diesel engines; maybe several kinds. I've read of the ones at sewage plants that suck ...methane vapor... from the digester tanks; not only is it "free" but the stink burns with it. There are also natgas/propane/gasoline generators in the ~10KW size, but that's spark ignition. By the ways: 1) "We don't mind dumb questions; they're easier to handle than dumb mistakes.." is the sign on a friend's machine shop. I applaud the OP for being willing to ask. 2) At least pre-Ashcroft, the cops need a warrant, or probable cause, to haul you off. At least in most states, the Fire Marshall does not. He can show up unannounced, throw you out, pull the main breakers and shut all the fuel valves. He leaves a red tag on the door and you are out of business. Especially post 7 WTC and West Warwick; I'd not expect lots of latitude from your local/state fire inspector. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433

On Fri, 4 Apr 2003, David Lesher wrote: :> A) Piped natural gas is highly reliable here in the East. I've :> not had ^ in 10+ years. : an outage Agreed; same here, though in the northeast, we do lie on what's considered a fairly significant fault line. Of course, should such come into play, geographical diversity of critical services would likely be of more importance. I'd suspect a quake in the northeast would have similar operational impact to a blizzard in SJ :) cheers, brian

On Sat, 5 Apr 2003 17:47:33 +0000 (GMT) "E.B. Dreger" <eddy+public+spam@noc.everquick.net> wrote:

DL> Date: Fri, 4 Apr 2003 21:26:25 -0500 (EST) DL> From: David Lesher

DL> D) Diesel engines, err Diesel-fueled piston engines, be they DL> 2 or 4-cycle, need frequent oil changes.

I thought it was the exact opposite. Diesel fuel has much better lubricity than LPG/CNG/gasoline.

diesels need frequent oil filter changes because they load the oil up with soot. the oil itself can last a long time. richard -- Richard Welty rwelty@averillpark.net Averill Park Networking 518-573-7592 Unix, Linux, IP Network Engineering, Security

On Fri, 4 Apr 2003, Timo Janhunen wrote: > Natural gas is volatile, hence not a good option in earthquake prone > areas - earthquake + natural gas line = big smelly leak - big smelly leak + > spark = big fire They're already there. Whether or not you use it doesn't affect the likelihood that it'll break in an earthquake. And FWIW, I've been throught a lot of earthquakes, and I've been through a lot of gas-line cuts, but the two have never coincided. Backhoes always so far. > - The gas gets cut off immediately in any fire situation, usually > affecting a few city blocks at a time When was the last time you saw a fire that affected a few city blocks? I'm sure gas would be cut off in the event of a fire of that magnitude, but are you arguing that diesel delivery would continue? Trucks rolling through the maelstrom? I'm not sure what your point is here. > Diesel generators come in both turbocharged and naturally aspirated > models, which can easily be serviced Hey, and engine is an engine, regardless of what you dump in the top. Doesn't make any difference to the mechanic, or the parts guy, or whatever... It's all the same parts. -Bill

At 05:51 PM 04/04/2003 -0800, Bill Woodcock wrote:

On Fri, 4 Apr 2003, Timo Janhunen wrote: > Natural gas is volatile, hence not a good option in earthquake prone > areas - earthquake + natural gas line = big smelly leak - big smelly leak + > spark = big fire

They're already there. Whether or not you use it doesn't affect the likelihood that it'll break in an earthquake. And FWIW, I've been throught a lot of earthquakes, and I've been through a lot of gas-line cuts, but the two have never coincided. Backhoes always so far.

Backhoe, earthquake, bottom line is that there's a break.

> - The gas gets cut off immediately in any fire situation, usually > affecting a few city blocks at a time

When was the last time you saw a fire that affected a few city blocks? I'm sure gas would be cut off in the event of a fire of that magnitude, but are you arguing that diesel delivery would continue? Trucks rolling through the maelstrom? I'm not sure what your point is here.

Gas being turned off usually affects a few city blocks.

> Diesel generators come in both turbocharged and naturally aspirated > models, which can easily be serviced

Hey, and engine is an engine, regardless of what you dump in the top. Doesn't make any difference to the mechanic, or the parts guy, or whatever... It's all the same parts.

Ask a mechanic that question. You'll likely get a somewhat different opinion. Timo

Bill Woodcock wrote:

Backhoes always so far.

> - The gas gets cut off immediately in any fire situation, usually > affecting a few city blocks at a time

When was the last time you saw a fire that affected a few city blocks? I'm sure gas would be cut off in the event of a fire of that magnitude, but are you arguing that diesel delivery would continue? Trucks rolling through the maelstrom? I'm not sure what your point is here.

If they backhoe a NG pipeline in front of your colo, it will ultimately hose both your gas *and* your mains power: <http://groups.google.com/groups?selm=314AF8E7.3D59%40InterNex.Net&oe=UTF-8&output=gplain> Determining whether the fire marshall would allow you to operate a locally fueled Diesel genset is left as an exercise for the reader. Does anyone have any info regarding if NG pipeline delivery was affected (did gas pipeline pumps or valves stop working when the power went out?) when the Pacific Intertie went down in June 1996? jc