Transport is assumed to be for a large part responsible for the climate change. On the other side, it is common practice to transport cellular glass, produced with ultimate ecologic care, several 1000 km to a job site with environment unfriendly trucks. And we all know that cellular glass is 5% solid material and 95% gas.

A European truck with lorry has an internal load volume of 157 m³ and loaded with 120 kg/m³ cellular glass, we get a load of maximum 18000 kg. A typical truck + lorry has a weight of 15000 kg. As a consequence the tool to transport has about the same weight as the load. On top of that, the load is a watertight and water resistant product that floats on water.

Not using transport with boats is in fact Kafka because transport over water of a floating product should have almost a negligible energy consumption.

M8 ships are equivalent with 32 “trucks + lorry” and can be fully loaded with cellular glass (about 600 Ton while 2050 Ton is possible). Compared with trucks, the energy consumption is about 20% and personnel cost is negligible (about 5%).  With good logistics, there is also no time issue. On top of that, bigger ships (M12), equivalent with 58 trucks are in the picture today.

On these M8 ships, we could install photo voltaic panels for a peak power of 125 KW, while these ships, if loaded with cellular glass (low load) can do their job with a 600 kW motor.  I guess (but it is a wild guess) that an important part (50%) of the transport could be CO2 neutral.

Maybe, it is possible to put the cellular glass (like log driving in the past) directly on the water, avoiding the investment in a boat, only a “pusher boat” is needed.

Today, the economic logic favors 100% truck transport because there will be always a truck transport between water and job site. This handling is today not well organized. But the economy becomes greener every day which means that the ecologic and economic logic are becoming the same. Ships, specially designed for the transport of cellular glass to the job site and transport of recycled glass / raw materials to the plant have to be considered and designed. One day, humanity has to live with only sunshine as energy source.

Not so long ago, a thermal conductivity of 0.025 W/mK was considered as very good. But today, it is possible to buy 0.005 W/mK and it seems that the market is interested.
This super insulation, called VIP, is very fragile because it is in fact a moderate vacuum bag, filled with a nano porous material. A little damaging and the thermal conductivity increases to 0.025 W/mK. Changing dimensions is not possible due to the vacuum and also the life time is limited due to the thin bag, which allows always a certain diffusion.

I was teached that the market is always right but marketing is a strong weapon which is able to put the market on the wrong leg. Is the market stupid? Windows makes a lot of money with the WINDOWS operating system and OFFICE suite while LINUX and LIBRE OFFICE are free of charge. Free of charge Android was able to pass IOS but GOOGLE has a strong marketing machine. It seems that only strong marketing is able to let happen what is logic.

In the building industry, Ytong (Xella) was the first building material which was insulating and load bearing. With a thermal conductivity of 0.090 W/mK and U= 0.15 W/(m²K), we get walls of minimum 60 cm thickness for passive housing. The price is typically 96€/m³ or 58€/m². The same job can be done with cellular glass GLAPOR PG900.2 (0.055 W/mK) boards up to 3×1.5m at 73€/m². The last one has as bonus water- and vapor tightness. For comparison, VIP-insulation has a cost of 224€/m² for the same U-value, while VIP-insulation is totally not load bearing.

For a 1 stock house of 200 m² in 10 x 10 m, we arrive at 500m² or 40000€ for the construction materials (GLAPOR) in case we use an intelligent shape. Better insulating materials without load bearing capacity need extra construction materials. A the end, the construction is much more expensive if the market joins the race of the best thermal insulators. Efficient marketing needs to promote the use of load bearing thermal insulation for the building industry. With large GLAPOR boards, passive house construction can be done at very sharp prices.

For the building industry, I believe that the race for the best thermal conductivity is like an F1-race. At the end of the race, you are back at start, there is not any evolution. The race for the best thermal conductivity is a useless race for the building industry.

We know that natural gas and crude oil will be gone within maximum 100 years. I am sure that I will not “enjoy” this situation but I guess everybody wants to be the Elon Musk in its own field. And yes, the world should be happy with this kind of guys, because the others (we) were able to consume in 150 years what earth could save in about 4000 million years.
The energy, radiated by the sun can be converted in electricity by absorbing wind energy, due to temperature gradients on earth and by solar – electricity converters using photovoltaïc or ORC on a liquid, heated with sunshine and parabolic mirrors.

For the production of glass, the technique of electric melting with electrodes, injecting energy in the liquid glass is well known. For the glass foaming, electric heating seems logic but some recipes need a reducing atmosphere, generated with gas burners, feeded with an excess of natural gas. That will be a problem which can be solved by the techniques, used in the tin bath of a float glass plant. Other recipes, like the GLAPOR – method, are foaming in a neutral atmophere and electric heaters can simply replace the burners.

But the energy density of gas burners is a lot larger than the one of electrical heaters. Working with a longer furnace (and longer foaming time at lower temperature) is of course possible but we can also consider the old fashion wood gas (syngas).Wood gas was used during World War II, where natural gas and crude oil were not available and is proven technology. The gas can be liquified to have a certain buffer. Today, technology with more performance is available, even as a hobby.

This mixture (syngas) of H2 and CO is obtained by gasifying wood. A rather limited wood (700 ha for 100 000m³ / year cellular glass ) is able to produce enough energy to drive a cellular glass plant in a constant way. If cellular glass plant and wood production are combined, losses due to energy transport are eliminated while the foaming of the glass is in that case CO2 neutral. On top of that, foaming recipes with a reducing atmosphere can also be foamed.

However, converting wood in wood gas to foam the glass is in fact an avoidable step. I am dreaming now about a layer of fine ground wood (pellets), a layer glass powder / foaming agent and a top layer of fine ground wood. This sandwich is transported on a belt, turning around  in a furnace, electrical or wood gas heated, just to compensate the heat loss through the furnace walls. The burning of the wood induces the foaming of the glass in the most efficient way possible. This last idea can easily be tested in a small furnace.

The durable thermal insulation cellular glass, saving tons of CO2 during use can be produced in a CO2 neutral way from just sunshine and waste glass. This cellular glass can be used to build the shell and floor insulation of durable passive houses with a wooden & plaster board inside structure, eliminating the use of cement. Solar cells (photo-voltaic and water boiler) on the cellular glass shell and Elon Musk’s Power Wall batteries inside the house are generating the energy needed for a comfortable living in a CO2 free way. The whole climate catastrophe is in fact pure bad will of human kind because the above is certainly not rocket science. Nevertheless, the bunch of climate negationists, supported today by a certain Donald Trump,  have also the legal right to have their opinion. Elon Musk for president, I call him tomorrow.

In previous blogs about self supporting structures and the possible height of these structures, it became clear that typical family homes can be built entirely in cellular glass without bricks, wood or concrete for the outside structure. Only for the foundation, some concrete would be necessary. This cellular glass structure should pass the standard for passive housing.
The best structure should have the curve of a reverted chain, hanging between two points to eliminate tensile or bending forces and to make optimum use of the large compressive strength of cellular glass. Such a curve is called a catenary, described by a hyperbolic cosinus. To be honest, the word “catenary” did not belong to my vocabulary untill now.
However, googling with “catenary house” learned that others were already attracked by this shape because it is indeed a very strong structure, which resists better storm and hurricanes. Built with cellular glass, the structure is strong, thermally insulated and water tight. It can be even installed (partially) under the soil to minimize even further the ecologic foot print and to be perfectly protected against more and more frequent hurricanes.
In the following, some pictures and websites are given.

We selected two small and a larger home. In both cases, the catenary dome can be entirely manufactured with cellular glass, being wall and thermal insulation at the same time.

Once we speak about self supporting structures of cellular glass, which are implicit thermally insulated, the next question raises: what should be the maximum height of such a structure under earth’s gravity?

I estimated this for a cellular glass with 2000 and 1000 kPa compressive strength by calculating the stress under the weight of a cellular glass tower and compared this with other materials. We use the short time compressive strength (or creep stress for wood and steel) and as a consequence, such a high tower is not stable on the long term. However, in the case of pg900 and pg2000, a safety factor = 3 is on the safe side to remain under sub critical crack growth.

The PG900 is commercial available material from GLAPOR, as is the Ytong C2/350. The other materials are standards available at many suppliers. We see that other materials than cellular glass are not necessarily much more self supporting due to their higher density. Wood, developed by nature is very stable in the strongest direction.

Self supporting structures in cellular glass of about 400m height are stable. If we reduce the height to typical home heights, a lot of strength is available to hang the inside structure if a shape is used where only compressive stress is present by using an intelligent curve like a catenary.

Cellular glass is a vapour tight, non-combustible thermal insulation with a high compressive strength. In the builing industry, cellular glass boards are mainly used in flat roofs, less as floor insulation and almost negligible as facade insulation. The rather large compressive strength is in fact only used as thermal interruption at the foundations, although this property could also be very usefull in self supporting structures. A very good introduction is given in a paper about arches and bridges. It is demonstrated that the entire arch ban be under a compressive stress when a certain curve is respected.

If we would replace the bricks by cellular glass plates, we obtain a stable structure which is vapour and water tight, non – combustible and thermally insulating. The structure can be prefabricated with cellular glass boards of 3m x 1.5m as delivered by GLAPOR. In case of 3 layers of 15cm, the passive housing norm is easily achieved. Rendering outside and inside with natural hydraulic lime is one way of finishing. The complete structure can be combined with cellular glass gravel floor insulation between cellular glass plates. I guess that we arrive at a low cost passive housing system in case of prefabrication, transport with containers and fast building at the job site.

Installation of windows should be easy because the window has almost exact the same thermal expansion coeffcient as the cellular glass. In principle, a window frame is not needed, the window pane can be directly installed in the cellular glass wall. I guess that a high air tightness, typical for passive housing is easily reached. A  building could look as follows but the inside ceiling needs extra support (or can be hanged) in the case of a cellular glass construction.

This is only one suggestion to work with cellular glass as the complete supporting outside structure, which is implicit thermally insulated. I am convinced that we have to work in this philosophy and to avoid to work with structures, which needs separate thermal insulation. In fact, this last method is patchwork on the building tradition since cement was used. Before cement, lime was used for walls about 1m thick, which was thermally equivalent with 5cm mineral wool. The introduction of cement in the home building industry was in fact an ecologic step backwards

The standard thinking is to select raw materials in function of the requested cellular glass. The glass is made by the melting of sand, soda and lime. At a certain point, it became clear that the use of recycled glass was an interesting economic alternative which could be sold as an ecologic improvement. The same approach is used with towels in hotels (please drop your towel only when needed for the sake of the environment) and we all know that reducing cost is the real reason. However, the economy becomes greener which means that an ecologic and economic reasoning gives the same result.
In my opinion, we have to start from the available waste and convert this waste to a product with added value with a minimum ecologic footprint. This is a clear consequence of the future lack of fresh raw materials and energy and also of the climate change. Also transport is becoming an issue.
The best recycling of bottles is still cleaning and refill. But there will be always an important amount of broken bottles, windows and wind screens. And this waste glass is today a better investment than money on the bank thanks to the green economy. But what can we do with this glass waste?

• The most suited glass (colour specification) goes to the bottle and window industry.
• What is left can be converted in cellular glass but is not clear whether it has to be used for thermal insulation with the lowest thermal conductivity possible.
• One possibility is foaming cellular glass gravel. This product is rather easy to produce and can be used as floor thermal insulation but also as landfill for streets or large gardens. Recycled glass powder is mixed with a foaming agent and foamed at 800°C. The foaming is done on a belt and free cooling after foaming generates the gravel.
• Annealing the ribbon allows to produce cellular glass boards. These boards can have a thermal conductivity of 0.048 W/mK and sizes up to 3m.
• Alternatively, foaming can be done in a mold of any shape. However, this method is less interesting and in fact not logic when rectangular boards with larger dimensions are requested.
• The obtained thermal conductivity depends on the glass composition and when a value of 0.040 W/mK is needed, a special composition has to be melted. This involves extra raw materials and an extra heating up to 1400°C together with a large investment. In most cases, this is also not logic because a larger thermal conductivity can be compensated with a larger thickness.
• As foaming agent, we know carbon, which needs a reducing atmospfere. SiC and glycerin, a side product of biodiesel can be used in an efficient neutral atmosphere. Glycerin is clearly the natural choice
• Transport has to be eliminated as much as possible. The logic location of a cellular glass plant is the extension of a glass recycling company. I guess that glass recyclers will extent their companies with a cellular glass production line once the world realizes that cellular glass is not necessarly expensive.
• Mineral wool and glass wool are also produced from recycled glass but both need a melting step at 1400°C. This is also not a logic choice if we compare with cellular glass foamed at 800°C. However the world still buys much more of these wools at comparable prices with cellular glass.

Walter Frank, founder of GLAPOR WERK, in the past a fair competitor and today a friend has chosen the right approach:

• Direct foaming at 800°C of recycled glass WITHOUT remelting at 1400°C.
• Continuous foaming in a neutral atmosphere to large dimensions and later down sizing to pallet dimensions.
• Depending on the quality of the glass powder, thermal conductivities between 0.065 and 0.048 W/mK can be produced.

But between ready to deliver and convincing the world is a big step, called marketing. Windows still owns the PC market while LINUX is a very good free of charge alternative. The same was true for iOS of Apple but ANDROID is growing like shown hereunder.

I expect that the classic cellular glass (0.040 W/mK) will evolute like iOS and the GLAPOR method like ANDROID if enough money is available to take market share from the others (mineral and glass wool). It is the logic evolution but marketing is needed to let faster happen what is logic.

The University of Rennes in France is also performing research about cellular glass. Probably they were the first to use AlN as a foaming agent but moreover, they introduce now the use as cellular glass as a support of a catalyst. The use of AlN as a foaming agent was already mentioned in a previous post.

In this paper, Glass foams for environmental applications, they investigate a possible catalyst for toluene. The foaming is done with waste glass and AlN. Other additions like TiO2 and steel waste dust are studied. The foams have all a large open porosity and are probably not interesting for thermal insulation. The following table from the paper give an idea about the experiments.

From this paper, we remember the use of cellular glass as a catalyst support and the a foaming recipe for open cellular glass.

The generally accepted methods, described in standard EN12667 to measure the thermal conductivity are:

• The guarded hot plate method is an absolute method which does not need samples for calibration.
• The fluxmeter method on the other side needs a calibration with samples, measured on a guarded hot plate system.

The hot wire method is not accepted as a method to measure thermal insulation, while it is in fact a two dimensional method, measuring the thermal conductivity in a cylinder around the wire. The EN12667 methods are measuring in one direction because they give the thermal conductivity through a board. On top of that, the hot wire method is a transient method, which measures the heat diffusivity and thermal conductivity.

Although less accurate, the method is fast and needs only a small sample. A cylinder of 20 cm with a certain radius is already large enough to do comparative measurement. This is very interesting when testing new formulations for a foam in a laboratory environment. The above was extensively calculated in a paper about the hot wire method for low density cellular materials. It can be concluded from the paper that the method is reliable for cellular glass, because cellular glass is opaque.

In case a unidirectional thermal conductivity is needed, we can replace the hot wire probe by a surface probe, like for example used in the ISOMET of Applied Precison Ltd. This method can be applied by for example fast non-destructive QC in the ware house by internal and external inspectors. Today, standard QC measurements according EN12667 take easily a few hours up to 24 hours  after sample preparation while the surface probe transient method is ready in less than 30 minutes without sample preparation. In a comparative mode of working, the method is reliable.

I would never trust transient methods if not tested on samples, measured with the EN12667 methods. But after testing and checking, they can be very helpful on a comparative basis.

A nice groups work about the insulation of a thermos with only recycled materials was done at Rutgers School of Engineering by Kahyee Fong, Damin Hashash – Gabe Kooreman, Crystal Mckenzieand Elaine Wang . I give the abstract hereunder:

The goal of this project was to take advantage of the capabilities of nanotechnology by using the room temperature sol-gel process to form a
silica nanofoam composite with a common household foam, in an effort to synthesize a cheap, lightweight insulator for use in a thermos. Through testing of hybrid insulators, it was determined that a silica nanofoam and packing peanut composite combines the natural insulating properties of the packing peanuts and
of the silica nanofoam to make an insulator for a thermos.

With a smart comparative and low cost thermal conductivity measurement, they were able to get the following list.

This is not direct a cellular glass subject but I simply liked the work and I was surprised by the results.