I've got a stack of wood that I don't think we will ever burn. I might try this this spring. I don't think I'll go for 7' tall though.
...try it. Write back. Lemme know how it goes. Something to keep in mind about Hugelkultur is it's championed by Sepp Holzer, who is not a member of the science-based community. His largest claim to fame is turning a 100-acre conventional farm into a 100-acre permaculture farm, thereby slashing its yields by about 80%. Something else to keep in mind is that Paul Wheaton is... a flake. He has a youtube video in which he threshes grain in a Home Depot bucket with a cordless drill and some zinc-plated Chinese Home Depot chain... and a podcast in which he castigates some poor cottage-industry canning company husband-and-wife team because the plastic lids of their jars might (might) contain "chemicals" since they're only "food grade" and the couple didn't investigate further than that. He also champions rocket-mass heaters as the way to provide cheap warmth but when he needed to heat his apartment he set a 100W bulb over his head and bought a heated mousepad. I'd say do one raised bed, then do another raised bed with a log under it and lemme know how it works. This stuff is dear to my heart and quite important but there's an awful lot of woo and not a lot of science to some of it.
That said I made a miniature hugelkultur bed last spring, which I just dug up yesterday. The plants in it (watermelons, zucchini) did terribly, due to a) crappy drought and less than adequate irrigation; b) a month following the drought in which we got somewhere in the region 24" of rain; c) fairly low quality lowes soil which compacted easily. Imagine my surprise yesterday then when I scooped off the most beautiful, worm filled black soil that I've ever seen, and further that the wood underneath had decayed into soft, spongy water retention _machines_. It makes me think that had I left the bed in place that it might have worked quite a bit better in year two.
One of my main objections to Paul Wheaton is he's reactionary and not particularly evidence-based. Sepp Holzer is kind of like a homeopathic gardener - he does stuff because he feels like it and when it works, he calls it "science." Hugulkultur seems like a worthwhile tool to have in the box, but it isn't a be-all end-all. Thanks for sharing your experiences. I'm soaking this stuff up every chance I get.
Speaking of (sort of) self promotion, have you checked out r/seedswap? I've spammed r/gardening a couple times with it. Hoping it'll gain some more traction, but there are already some good trades in there. Paul seems to have a lot of zeal. I feel kind of bad for him receiving the smack down recently, as he seemingly means well (although definitely comes off as a dick periodically). Rocket mass stoves are neat too (as well as hugelkultur) but the way he tells it they are without problems and are the essential answer to any heating need. (That said I may experiment with one when I get around to building a wood fired hot tub...which is pretty far down the list.) Cheers (& thanks for the link to this site).
Paul has six pictures of himself in the header at permies.com. Six pictures. Six. Not only that, but when he wanted to tell the world about how to save money on heating costs, he didn't build a rocketmass heater, despite espousing their virtues on three podcasts and two videos. No, he launched a jihad against the compact flourescent lamp and bought a heated mousepad. I think I really lost patience with him when he posted a video about how to thresh grain at home, using lengths of chinese zinc-plated chain and a Home Depot plastic bucket, and then gave some poor canning company shit for using plastic lids on their jars because even though it's food-grade plastic, "you just don't know about these things." He's just not a "practice what you preach" kinda guy, and he's more interested in self-promotion than problem-solving. The smackdown was due any day - I had a long discussion with him when he tried to use permies.com to upvote his heated mousepad video and I told him that he was totally violating Reddit's TOS and could get his account banned. It wandered to "who do you know in Bellingham that I could take to lunch to talk about permaculture" at which point he gave me a name and then said "but you shouldn't take him to lunch, you should arrange a meeting and invite a bunch of people because I get really angry when people try to monopolize my time with the paltry price of a meal." When I said "....uh, why did you give me his name if you thought me asking would make him mad?" he just sorta spun off on some direction about how ungrateful most people are. I had a long discussion about rocketmass heaters with my dad - we're both mechanical engineers, he's got more background in thermo than I do. He pointed out that you could make it work with a computer-controlled thermostat, but that with the simple setup demonstrated, you wouldn't be able to run the contraption in the "sweet spot" for much of its burn and that you'd likely end up with a pretty smoky house most of the time. It's observations like that that I'm more interested in - "how to domesticate a rocketmass heater so that your mother in law doesn't think you're crazy" and less of the "people who think CFLs are a good idea are ENEMIES OF THE STATE" vitriol.