Barley Wine

It is always fun to push a beer to extremes. Barley wine is a category that can be pushed as far as the yeast, wallet, and equipment can allow. I have made beers over 30 Plato and 100 IBU's. One beer, called Superbeer, exceeded the 32 plato mark on the refractometer. A couple of points before making a barley wine.
First, this is a beer that can be made with extract added after the mash process is complete to boost the OG without detriment.
Second, this is one of those beers where the malt will eat the hops. I have used 100 IBU's in every barleywine I make, and that is basically the maximum that can be added as hop utilization becomes negligible after that. It is important to figure out roughly what the specific gravity in the kettle will average during the boil so that enough hops are added. Use the hop utilization and iBU calculations here on the site, or Papazian book or available in various hop calculators. Hop bitterness will fade quite a bit so it is important to be a maximum bitterness rating.
Thirdly, the brewer must determine what he or she can get out of their system as far as an OG goes. I use a double mash, boiling first runnings while the second mash is being done. This adds some caramelization to the wort and raises the gravity a bit. Doing one full mash for a 5 gallon yield on a 10 gallon or more system will also work. The recipe below follows the double mash method.
Grain Bill:    24 lbs Thomas Fawcett Maris Otter (floor malted) or other high quality Pale Malt.
                     1/4 lb rice hulls for second mash
Hops:          100 IBU's worth of a hop of the brewer's choice for bittering
                     1/2oz pelletized hops (brewer's choice) first runnings boil
                     4oz pelletized hops (brewer's choics) 10 minutes left in boil (flavor)
                     4oz pelletized hops (brewer's choice) @ Flame Off (aroma)
Irish Moss or other clarifier : 15 minutes left in boil
White Labs English Ale Yeast or other Favorite UK strain, and a starter culture, for initial fermentation. It may be advisable to pitch yeast off of an actual freshly fermented batch transfered to secondary just prior to pitching into the barleywine.
White Labs Super High Gravity Ale, with starter, pitched into secondary after primary fermentation complete.

Mash in 13 lbs of grain at 120F and hold for 10-15 minutes (dough-in, use just enough water to wet the grains)
Raise temperature slowly up to 155 F using remaining water and hold until conversion is complete. I usually do this in steps, where there is a rest in between where I take a temperature measurement, and hold for 5-10 minutes before adding more water to get the temperature up to 155. Once at this temperature get the sparge water ready. Time the final temperature increase with the sparge water becoming ready, with mash out being around 170F. Sparge and collect around 1.5 gallons of first runnings in the brew kettle, the rest into a second pot. Place brew kettle on a burner, add 1/2 oz hops. and boil until second mash is complete.

When sparging of the first mash is complete, bring wort up to mash in temperature and mash 11 lbs of grain with the rice hulls as above. Keep in mind slightly less sparge water is required as there is already some volume in the pot. Collect about 6 gallons total of wort in the brew kettle.

Boil for 15 minutes, then add bittering hops. Boil for 75 minutes and add irish moss or clarifying pellet. Boil another 5 minutes and add the cooling coil to the pot for sanitization, along with the flavor hops 9Boil 10 more minutes). When the boil is done, turn off the flame and add aroma hops. Cool and transfer to carboy. Aerate (we use a stone). Pitch the starter.

Fermentation usually takes about a couple weeks. It is helpful to use a carboy for fermentation so as to be able to observe fermentation activity. After 2 weeks, even if there is still activity, transfer to secondary to get beer off of the dead yeast, and pitch the Super High Gravity yeast. I recommend a transfer every 2 weeks to another carboy, to get the beer off the dead yeast. Keep an eye on the activity and bottle when still. This can take a few weeks so be patient. Bottle when ready.

OG usually ends up in the 24-27 Plato range. I don't measure the final gravity, as I find it to be a waste of beer, but ABV will be in the 10% range.

Notes:
1) Cramming in extra hops for this beer for me has been futile. Have even dry hopped with limited success. The malt tends to dominate. The hops generally are there the first few months, then fade, so drink early if you are a hop head!
2) Another method to flavor and aroma hopping this beer would be to add all or the late edition hops to the mash, and eliminate the late hops altogether. Not sure yet about which mash to add the hops to, and it may take a couple of years to figure all this out. Springtime will bring about a fresh batch with which to experiment.
3) I am using water in the 70-100 ppm solids range.
4) Try the Thomas Fawcett. It is a great malt! 
5) I have found that this beer, when fermented in the 68-73 F range, will be excellent to drink as soon as it carbonates, and only needs to age if I want to see what it is like in a year or two. Having done the aging thing, I find that these barleywines tend to all taste the same after aging. Fuel for thought.