Rocket Mass Driveway

As I spent my morning last week shoveling the driveway at work out from under half a foot of snow, I reflected on the state of things. I've not yet hit 40, but already my back reminds me that I'm not in my youth any longer. What will another 20 years mean for this sort of back-bent manual labor? Thinking back on years before struck on a memory. When I was in college, the entire campus had heated sidewalks. I shudder to think about the energy bill, but briefly thought of how nice it would be to set up a battery bank just for that purpose.



Then it struck me, why does it have to use power at all? Wouldn't it be simple enough to set up a few rocket mass heaters in a garage or in small sheds along the way? It seems to me that it would be possible, as long as there wasn't too much driveway to heater ratio. It certainly seems like it would be possible. I for one would be happy to feed a batchbox on a few heaters right before or at the start of a storm. Even if it wasn't perfect, it would have to beat shoveling the entire driveway.

So I find myself wondering if anyone has tried this yet?

I hear you about the back and body aches and pain issues as we progress in age.

I have seen in more affluent homes that the boiler system can have a circuit routed to the driveway and sidewalk to bring the surface to above freezing then turned off to allow for energy conservation.

My driveway will never see such luxury. It is in excess of 1300 feet long. I could not afford such a luxury for the entire length. But, I do plan to have a large supply of hot water stored in tanks. I'll have up to 15,000 gallons of solar and rocket-fired boiler hot water at my disposal for home heating, greenhouse heating, water heating and for some localized snow and ice clearing from around our home. Perhaps when I get more settled and my time is a little freer, I won't mind waiting for the woodgas tractor to fire up so that I may clear my driveway beyond my garage with a renewable energy source. Until then, I have plenty of gas and diesel equipment for snow clearing and removal for the rest of the driveway.

If you do try heating your driveway, just make sure that melted snow doesn't get under the driveway and re-freeze. That happened on our campus sidewalks.

If you want to make snow shoveling an upper-body workout instead of a back-killing workout, these are awesome:
Snow Wovel

Brian Stretch wrote:If you do try heating your driveway, just make sure that melted snow doesn't get under the driveway and re-freeze.

Yes, thank you! I just returned inside from the ice covered lawn I currently have. Water needs to be directed away from where it could stand or seep where it would refreeze only to cause more trouble than just allowing it to behave as it would undisturbed. I think I could direct the runoff to my 6" drains straight to my pond.

Seems like it's more appropriate to cover the driveway with a roof, which could double as solar panels.  Or glass, greenhouse.

A driveway is a funny thing.  You can't use it for growing much, unless it's always short and will always fit between the wheels of a car.  Maybe greens?  

When I was a kid the neighbors had a starter mansion at the bottom of a long steep hill (glacial moraine).  They ran electrical heat to melt the snow under the steep part (probably 200' long).  All was well until a house-sitter accidentally flipped the wrong switch and left it running for a week.

building codes prevent covered driveways in some places, I hear.  So after the sanity revolution, that won't be a problem.  but hten again neither will we need cars, because we'll love where we are.  but the idea of having a covered area for elderly or disabled people to be able to walk when it's snowing will be useful long after that time.  

I have wondered about a grid of pipes just under the driveway surface to carry water from a submerged tank pushed by a small sump pump. The tank would need to be below frost and the pipes would have to be self draining. Ground temps are 45 to 50 F so circulating that temp under the driveway would thaw snow...eventually. What I don't know is how big the tank would need to be to absorb that much cold without freezing and have enough surface area to shed it before the next use. Or maybe like a ground source heat pump there would need to be deep buried pipes to spread the cold out.

I looked into this briefly, and found it was one of those ideas that sounds great until you start doing the math. I don't want to go through all that math again, but the critical bit is that if you have a 2 liter bottle of water, and you want to raise it 1 degree (I'm using metric here, just because the math is easier) it takes as much energy as the average full grown man burns in a day. However if that 2 liter bottle is already ice (which snow is) you have to use 80 times that much energy to melt it, before you can heat it up at all..  And that's before you even start to take into account how much heat you lose heating an uninsulated driveway, where all the heat can escape to the atmosphere or into the surrounding ground, which is likely either saturated with water or frozen itself.

Brian Stretch wrote:If you do try heating your driveway, just make sure that melted snow doesn't get under the driveway and re-freeze. That happened on our campus sidewalks.  

I'd like to have a driveway with a slight slope to it, maybe 4 degrees to either side of the center, and which had drainage to either side that fed to some other location or into a swale. I'd not like to have it just soaking in on or under the driveway itself given the problems that would cause.

Joshua Myrvaagnes wrote:Seems like it's more appropriate to cover the driveway with a roof, which could double as solar panels.  Or glass, greenhouse.

A driveway is a funny thing.  You can't use it for growing much, unless it's always short and will always fit between the wheels of a car.  Maybe greens?  

My experiences with covered driveways have involved two problems. First is that if there is bad weather, it tends to come in anyway. So if there is heavy snow, the driveway is mostly covered and a spot five feet to one side is mostly clear. The second problem is more difficult to work around. That's that when there are a series of poles to either side of a narrow drive (and being honest, I don't want a large driveway that spans a car and a half on either side) people invariably find a way to ram some of the poles. At best, it is less stable and at worst it might come down on top of everything. Glass seems like it would melt things well, but also dry things or even start fires when things weren't so damp.

I'd probably not use a driveway to grow anything I plan to eat, but have seen some where they consist of two narrow strips for the tires to rest on and open ground between.

The way I picture it, the key would just be having two strips that stay clear when you fire it up and to fire it up /before/ the snow has fallen to prevent it from even being a problem to start with. Melt the snow and drain it away and there won't be anything to form sheets of ice in the first place.

Anthony Friot wrote:I hear you about the back and body aches and pain issues as we progress in age.

I have seen in more affluent homes that the boiler system can have a circuit routed to the driveway and sidewalk to bring the surface to above freezing then turned off to allow for energy conservation.

My driveway will never see such luxury. It is in excess of 1300 feet long. I could not afford such a luxury for the entire length. But, I do plan to have a large supply of hot water stored in tanks. I'll have up to 15,000 gallons of solar and rocket-fired boiler hot water at my disposal for home heating, greenhouse heating, water heating and for some localized snow and ice clearing from around our home. Perhaps when I get more settled and my time is a little freer, I won't mind waiting for the woodgas tractor to fire up so that I may clear my driveway beyond my garage with a renewable energy source. Until then, I have plenty of gas and diesel equipment for snow clearing and removal for the rest of the driveway.

15,000 gallons of heated water.  I am intrigued about your storage site for this much hot water.  I like the idea of a large thermal battery for my house just curious how you have or will construct it.

The system y'all are referring to is called a "snow melt" system and it's traditionally hydronic or steam driven so it's usually work covered by the "wet" side of the HVACR community, that is, steam/pipe fitters and or plumbers. After visiting Wheaton Labs this past October for the RMH Jamboree it came to me that a dry snowmelt system would be an awesome thing to test. I live in a small town that calls itself a city so the city government can have more control over how the community looks; they would insist upon permits and fees for a permanent roof of any kind over the driveway. They would not, however, even notice if I dug up my driveway, installed piping and covered it back up. While grade would have to be a consideration for melt run off, I think a driveway with a pronounced grade would be a better fit for a RMH snow melt system than a flat or slightly graded driveway. Tossing off the idea, I'd build the firebox at the bottom of the drive, break off a 10" round feed to a true manifold that fed a number of square duct runs up the drive, opened up into a bell and exhausted from there. I'd make sure the ducting had the same or slightly higher combined cross sectional area as the system itself.

As a fifty year old with plenty of aches and pains, and having watched my parents and in laws decline over the years, let me assure you on the subject of physical labor:
The less you do, the less you'll be able to do
Keeping a rigorous physical regimen deep into old age will be far more rewarding than spending the money to avoid said regimen.
Rest homes across the country are filled with "young" old people, (60's and 70's) that started taking it easy in their forties and fifties.
The loss of muscle mass in just six months on retirees that quit a job of hard physical labor is shocking.

To install a reliable snow melt system would be a big job.  Usually a snow melt system involves a boiler, controller, heat exchanger, circulators, pressurized piping in the concrete slab, glycol and water fluid mixture which would be circulated through the piping.  Replace the boiler with a RMH and you would need to introduce a large insulated water storage tank, another circulator for the water side and more complicated controls.  The system would need to distribute fluid in all likely hood of between 1,000,000 and 2,000,000 BTU per hour.  Doable but I would not think this would be a very reliable set up.

Along these lines, applying permaculture principles to the self (body-mind) makes a huge difference.  Back pain is, in my professional opinion, usually a result of how you move, not how much you move.  If you can unlearn interfering patterns of coordination you can have exercise strengthen you instead of hurting.  Observe, observe, observe, with an open mind.  Have a friend put their hands on your head and spine as you move to give a reference point or "kinesthetic mirror."  Question your assumptions about your experience of movement.  Old people in the countries where back pain is the least still move gracefully, with poise, and can work hard to very advanced ages.

Red Smith wrote:As a fifty year old with plenty of aches and pains, and having watched my parents and in laws decline over the years, let me assure you on the subject of physical labor:
The less you do, the less you'll be able to do
Keeping a rigorous physical regimen deep into old age will be far more rewarding than spending the money to avoid said regimen.
Rest homes across the country are filled with "young" old people, (60's and 70's) that started taking it easy in their forties and fifties.
The loss of muscle mass in just six months on retirees that quit a job of hard physical labor is shocking.

Jonathan Zettlemoyer wrote:15,000 gallons of heated water.  I am intrigued about your storage site for this much hot water.  I like the idea of a large thermal battery for my house just curious how you have or will construct it.

We knew we would be building a new house for a while and we wanted to build with no mortgage. I looked around the internet for sources of materials for our house. In my browsing travels, I have found 40 12" I-beams 13-20' long, 14 17' steel trusses, 10 14' steel trusses, a number of sliding glass doors for a greenhouse, a parking lot sweeper powered by a 25 hp industrial ford engine that drives hydraulic pumps for powering my future firewood processor, 60 3/4" 4x8 sheets of CDX plywood for my living roof, 62 2" x 6" x 20' for building my roof trusses, a street signal light pole I'm using to support the center of my house and to use as my chimney, 250 amp gasoline lincoln welder, various hydraulic pumps, lifts, tanks, valves and cylinders, EPDM rubber for my roof, Craigslist for cellulose insulation, 900 ft2 2" 2' x 8' foam insulation, 900 ft2 2" x 4' x 8' foam insulation, large cement mixer, but I found some 5,000 gallon poly tanks at a great discount. They were single-wall tanks used by state DOT to store liquid salts. They were being replaced by double-walled containers.

I read about somebody in Alaska using water to store heat from solar and wood fire boiler. Their storage was so grand (9,000 gallons if I remember correctly) that they could leave their house for weeks to come back to a house that hadn't dropped below a temperature that was still somewhat unbelievable. I do not remember the temperature right now, but it was high enough that it made an impression on me since we, at the time, were thinking of being snow birds and going back to Florida in the winter for a few weeks to visit and get away from the cold. Coming back to a warm house was a nice thought that stuck! Solar water heat can save money warming water and wood has been used for heating things for a long time. After that, I knew I wanted to heat the house with radiant heat in the floor. I knew some people had on-demand systems, but I wanted simple and versatile system that was safe to operate. The plastic tanks are good for up to 140F/60C. That's as hot as I would ever want to go. In the summer, I could use the solar water heater to preheat the water to a nice temperature for cooler days and still use the heat storage to heat our hot/warm water for the house. I built a small plastic system over last summer to test the temperatures possible in a non-commercial system. It took a couple tries, but I was getting 110F/43C water for our outdoor showers for a reasonable cost. A couple hundred feet of 1/2" irrigation pipe, tees, elbows, 55 gallon plastic barrel and a 24 volt $5 circulatory pump I bought on ebay (we already had a 24 volt 1800 watt photo-voltaic panel system for our power and a couple pallet jack batteries for electrical storage). A couple sheets of insulation, a couple of sliding glass doors for the glazing and some 2" x 4"s for a frame. I had my reservations as to the amount of heat I was going to get, but it soon became apparent that warm water was going to be a welcome visitor to our camp. Last year was too wet to build our house to we built a small, 288 ft2 camp to get us through the winter. We are building this spring, rain or shine! Anyhow, back to the water and the tanks. During this time, I saw an article about a development in Canada that was using solar water heaters to heat water too. But they were also storing the heat in the ground! Maybe I should do that too! use the summer sun to heat the ground deeper than it can penetrate by itself. Bury the tanks that I bought under the ground being sure to fill them with water first because the earth would just cave them in if they were empty and I would lose my water storing capabilities. If I used my insulation around the tanks and heated the earth around the tanks to help heat my home I would have one hell of a heat battery! Honestly, I am afraid I don't have the math skills to determine if it's economically viable. So, I'm just going to lay down insulation on the ground, upright my tanks, build a foundation around them, frame it up using the I-beams and steel trusses and build a straw building around them with my solar equipment in with them to keep it warm and away from the house thereby reducing the chance of fire in my home.

I have yet to determine the BTU requirements of my home, but expect it to be under 6,000,000 BTU/yr. It is a 800 ft2 straw bale home with 4 inches foam insulation under it and 20 inches cellulose above it.  Say I heat 5,000 gallons to 140F/60C and I take that water down to 110F/43C. Please forgive me and correct me if I am wrong. Using simple math and neglecting heat loses, 5000 gallons is 40,000 lb and if I lower that temperature by 30F/17C I will in effect take 1,200,000 BTU from that tank. That would need replenishing 5 times during the year to take care of my needs. If I fire a rocket boiler at least 50% efficient I burn sugar maple @

By pound:
3740 BTU/lb.) 1,200,000 BTU / (3740 BTU/lb * 50% = 1870 BTU/lb) = 642 lb * 5 = 3210 lb/yr

By cord
23,200,000 BTU/Cord)  1,200,000 BTU / (23,200,000 BTU/Cord * 50% = 11,600,000 BTU/Cord) = 0.10 Cord * 5 = 0.50 Cord/yr

That is with one 5,000 gallon tank neglecting heat loses. I still need to determine heat loses for the site. I currently have three tanks and I plan to heat a greenhouse as well as our house.

I should start a thread on this topic to get input as to how to best determine my requirements and it's use.

Wesley Crusher wrote:To install a reliable snow melt system would be a big job.  Usually a snow melt system involves a boiler, controller, heat exchanger, circulators, pressurized piping in the concrete slab, glycol and water fluid mixture which would be circulated through the piping.  Replace the boiler with a RMH and you would need to introduce a large insulated water storage tank, another circulator for the water side and more complicated controls.  The system would need to distribute fluid in all likely hood of between 1,000,000 and 2,000,000 BTU per hour.  Doable but I would not think this would be a very reliable set up.

I'm confused about what size of driveway, what rate of snowfall, and at what ambient temperature you are basing your 1,000,000 to 2,000,000 BTU/Hr figures on?

Brian Stretch wrote:

If you want to make snow shoveling an upper-body workout instead of a back-killing workout, these are awesome:
Snow Wovel

If I didn't have a hubby who loved his snowblower, I would totally be rocking a snow wolf contraption.  I agree that we need to keep moving, this seems a far safer and less back breaking way to do so.

I would suggest researching geothermal.  
Basically drilling two well holes and adding a pump.  Pull water (usually low 50 degrees) up, through a loop system buried under the driveway and returning it to the second hole.