SteamyTea

I think that is about the first thing I have heard of that makes it worthwhile getting a 3D printer. Used to spend months making drilling jigs when I was an apprentice, then looked at the CNC machining centre and wished I could work that.

And ours sadly.

There are a lot of if free articles, and you can subscribe to the news letters. It is a good comic as you get an up to date snapshot of what is going on. Don't think the online only version is that expensive.

https://www.newscientist.com/article/mg26034621-600-how-countries-can-go-fossil-fuel-free-with-wind-and-solar-superpowers/

Yes. I blame the IT industry, everything has to be reduced to a 0 or 1, with 0 being wrong and 1 being right. The main thing is to reduce usage, there was a bit about food waste in the USA, apparently a third is wasted (and they start with a lot more). The emissions from this waste was equivalent to 55 million tonnes of CO2. About the same as running 12 million gasoline cars (and they are not the most economic cars in the USA).

This was in my comic. I knew the hydrogen had to be 'clean' to run though a fuel cell, never thought about the water that makes it. Can we get limitless green hydrogen by splitting seawater? Electrolysers that split water to produce hydrogen have trouble working with seawater, but overcoming this would offer new ways to produce the clean-burning fuel using offshore renewable energy By James Dinneen 25 October 2023 Seawater could be a limitless source of hydrogen, but we need electrolysers that can handle the high salt concentration Shutterstock/andrejs polivanovs The following is an extract from our climate newsletter Fix the Planet. Sign up to receive it for free in your inbox every month. 97 per cent of the water on Earth is in the ocean. If even a small amount of that could be harnessed to make hydrogen using clean energy, it would provide a practically limitless source of clean-burning fuel that would accelerate the transition away from fossil fuels. But there’s a catch. The devices currently used to split water molecules to make hydrogen — called electrolysers — require ultra-pure water to function. And seawater is full of dissolved salt, other minerals, metals and microorganisms that degrade components and gum up the works. Recently, researchers have made headway on solving these problems. Some are pushing ahead with plans to make hydrogen from desalinated seawater, while others have developed new electrolyser designs that could be attached to offshore wind turbines to make hydrogen directly from the ocean. Success here would not only reduce the demand for freshwater to make the fuel, but also expand the range of places where it makes sense to produce hydrogen. Something in the water Hydrogen will play an increasingly important role in decarbonising our energy systems on the way to net-zero by mid-century. The clean-burning gas can be used to store and transport energy, and it can power things that are difficult to power directly with electricity. The latest projections from the International Energy Agency see global production of low-emission hydrogen increasing rapidly, with planned projects amounting to 38 million tonnes per year by 2030. Sign up to our Fix the Planet newsletter Get a dose of climate optimism delivered straight to your inbox every month. Sign up to newsletter There are a variety of sources of low-emission hydrogen, but most of it is set to be made by splitting water molecules using renewable electricity, making what’s known as “green hydrogen”. The main limitation now on green hydrogen production is access to cheap renewable electricity. But as hydrogen production increases, access to water could also become an issue. “We need to avoid creating a situation where there is competition between water that we need for drinking and water that we need for fuel production,” says Pau Farras at the University of Galway in Ireland. Estimates vary for how much water might be needed for hydrogen production – and some argue the problem is overstated – but Farras says producing hydrogen could eventually account for as much as 20 per cent of water use in some places, especially where there is scarce freshwater. Using abundant seawater would avoid this problem. Splitting seawater could also enable new ways of combining offshore renewable energy with hydrogen production, expanding the geographical range of both. This possibility in particular has driven new interest in splitting seawater. For instance, in March the Netherlands announced a plan to build a large offshore electrolyser in combination with an offshore wind farm in the North Sea. The hydrogen produced there would then be sent back to shore via an existing natural gas pipeline, avoiding the need to lay expensive new undersea transmission lines. At least 10 other major projects combining offshore wind and hydrogen are in the works elsewhere, including several off the coast of the UK. For wind farms built more than 50 kilometres offshore, it could actually be cheaper to transport the energy they produce back to shore as hydrogen via ships or pipelines rather than as electricity via copper wires. Researchers at the technology firm Siemens, which is investing large sums in wind-t0-hydrogen technology, even envision automated “production islands” that use seawater and offshore wind energy to continuously make hydrogen and other chemicals like ammonia to refuel ships sailing by. Stripping salt A big problem for these futuristic visions, however, is that seawater is poorly suited to the finicky chemistry of electrolysis. Even normal potable water requires extra purification steps before it can be used in a conventional electrolyser, says Alexander Cowan at the University of Liverpool in the UK. “Seawater is the extreme.” In an electrolyser, water — H2O — is run past two electrodes. Hydrogen atoms move to the negatively-charged cathode, while the oxygen atoms stay near the positively-charged anode and are released into the atmosphere. Normally, ultra-pure deionised water is used in this process. Using seawater, with all its impurities, causes problems. The dissolved salts and minerals degrade many of the catalysts and other components used in the devices, so they wear out very quickly. Running electricity thought the water can also oxidise chloride to produce corrosive chlorine products. Biofouling from microbes growing in the water is another issue. “If you have a biofilm on top of the electrodes your reaction is dead,” says Farras. A hydrogen refuelling station in Tenerife, Spain Lucia Villalba One way around these problems is to desalinate the seawater before sending it to the electrolyser. On Tenerife, one of Spain’s Canary Islands, Farras and his colleagues have installed a self-contained system that uses desalinated seawater and solar energy to make hydrogen using a conventional polymer electrolyte membrane (PEM) electrolyser. Farras says officials were interested in the project to reduce the island’s reliance on imported fossil fuels. The system, which is the size of a 12-metre shipping container, can now produce up to 65 kilograms of hydrogen each day, which Farras says would be enough to supply two to three hydrogen fuel-cell powered buses and several cars. His team is now in conversations with Tenerife’s transport administration to fuel public buses with hydrogen next year in an effort to “kickstart” demand for hydrogen on the island. Using desalinated seawater for hydrogen production makes sense, especially where substantial desalination capacity already exists, says Farras. The hyper-futuristic Saudi Arabian city of Neom, for instance, is supposed to include a facility that could produce 600 tonnes of green hydrogen a day using desalinated water from a plant that will also supply the city with drinking water. Going direct However, desalination isn’t an ideal solution. It adds to the energy requirements of making hydrogen, and may be poorly suited for smaller, more distributed systems, says Zongping Shao at Curtin University in Australia. Another approach is to design electrolysers that can work directly with seawater, thus avoiding the need for a separate desalination step. There has been a flurry of research on how these seawater-hardy devices could work, with a variety of designs. According to Cowan, they fall into two broad categories: some involve using membranes to purify seawater before it flows through the electrolyser, and others use different components or designs that are more robust to seawater. In one design, Shao and his colleagues sandwiched an electrolyser between special Teflon membranes and then ran seawater around the outside. The membranes enabled water vapour to diffuse into the electrolyser while leaving impure components outside. In a study published last year, this system continuously produced hydrogen using seawater in tests for at least 3200 hours without any noticeable changes in function. “That could change the calculation,” says Cowan. “If you could run something for years without much maintenance that’s interesting.” Read more Waste plastic can be recycled into hydrogen fuel and graphene Another approach, taken by Daniel Nocera at Harvard University and his colleagues, similarly purifies water before it reaches the electrolyser by passing it across a membrane. As the water molecules are split on one side of the membrane, this maintains a concentration gradient that draws more water through by osmosis. Daniel Esposito at Columbia University in New York and his colleagues have done away with membranes entirely in an effort to make cheaper, more robust electrolysers. A company he co-founded called sHYp is aiming to commercialise these membraneless electrolysers by pairing them with a proprietary saltwater processing step that produces other valuable byproducts, such as magnesium hydroxides that could be used to make carbon-negative cement. According to the company’s CEO Carl Fischer, the processing unit works by increasing the alkalinity of the seawater before it reaches the electrolyser, which he says avoids biofouling and unwanted reactions with chlorine. He says the company has pilot projects planned for next year in the US, the UK and Europe, including plans to install the electrolysers on offshore wind turbines and at ports. Horses for courses Cowan says that while many of these methods of direct seawater electrolysis are promising, at scale they are likely to suffer from some of the same problems as conventional electrolysers trying to manage the complexities of seawater, such as biofouling from the ubiquitous microbes that live in the ocean. Farras also has doubts about this approach. “You can work around these problems in the chemistry. But I don’t think you can work around the biology,” he says. “Direct seawater electrolysis is a fantasy.” Even if the direct approach could be made to work at scale, Farras says it may be unnecessary in contexts where large-scale desalination is already available. Desalination adds to energy requirements, but only a small amount when compared to the energy demand of electrolysis itself. However, Cowan thinks direct electrolysis could have its uses, especially for remote places where large-scale desalination might be impractical. It could also be key for the many projects aiming to integrate electrolysis with offshore energy production, opening valuable space on offshore platforms that would be taken up by a bulky desalination operation. Further, he says research on directly using seawater could lead to more robust electrolysers in general. These could use wastewater, or simply better withstand the inevitable impurities in any water on its way to becoming fuel.

How countries can go fossil fuel free with wind and solar superpowers South Australia is a renewable energy champion and now plans a truly fossil fuel-free grid. How did it make such a remarkable turnaround, and can the rest of the world follow suit? By Alice Klein 24 October 2023 Clever use of solar and wind energy is providing three quarters of South Australia’s power Paul Souders/Getty Images A DECADE ago, the main landmark in Port Augusta, a town in South Australia, was a 200-metre-tall chimney puffing fumes from a coal-fired power station. “You could see it from 40-odd kilometres out,” says Gary Rowbottom, who worked at the plant for 17 years. Today, however, there are no hints of this history. The chimney is gone and the sky is a pristine blue. The chief landmark now is a tall tower topped by a dazzling light, where sunlight reflected from 23,000 mirrors on the ground is focused to power four giant greenhouses in which tomatoes are grown. Next door is the newly built renewable energy park, home to 50 wind turbines and 250,000 solar panels. Port Augusta is representative of a remarkable shift that has swept South Australia. In 2007, just 1 per cent of the state’s electricity came from solar and wind. Now it is 73 per cent (see below graphic) – the highest proportion of any major grid in the world. On days that are particularly sunny and windy, it powers itself with 100 per cent renewables. That happened on 180 days in 2021 and for a 10-day consecutive stretch in December 2022. The state is now racing to ramp this up to renewable-only power year-round. Coming from neighbouring New South Wales, where just 31 per cent of electricity is from renewables, I find this clean energy rush highly enviable. It is also highly instructive to the wider world, which needs to rapidly wean itself off fossil fuels to avert a climate disaster. To find out how such progress is possible, I have crossed the border to meet those leading the charge. source: opennem.org.au South Australia covers almost 1 million square kilometres – more than seven times the area of England – but has a population of just 1.8 million. Almost 90 per cent of the state is desert, so most people live along the wetter, cooler south coast, largely in the capital Adelaide. The state’s renewable energy push began in 2002, when the South Australian Labor Party was elected to government. Its initial interest in renewables was in fact economic, says Tom Koutsantonis, the state’s current energy minister under its latest Labor government. At the time, South Australia’s electricity was very expensive, partly because its large, spread-out grid is paid for by a relatively small population, and partly because the previous Liberal government had privatised the state’s electricity assets “on terms that wouldn’t benefit consumers”, he says. Weaning off fossil fuels The Labor government wanted to “smash up the monopoly” of the newly privatised coal and gas-fired power stations to drive electricity prices down and “the obvious answer was renewables”, Koutsantonis tells me at his office in Adelaide. The government realised the desert could actually be a “massive opportunity” because it provided the vast amounts of space, sun and wind needed for competitive renewable energy generation, he says. In 2002, the government approved the state’s first wind farm on the Fleurieu peninsula. This opened the floodgates to more renewable energy projects, with 24 onshore wind farms and five large-scale solar farms now operating. In 2008, it also began incentivising households to put solar panels on their roofs by offering generous payments to them for any excess solar energy that was fed back into the grid. “We had this at our house and suddenly I was getting credits on my electricity bill because I was selling more than I was using,” says Jenny Paradiso, a former librarian in Adelaide who co-founded a solar panel installation business called Suntrix in 2009. As word spread, people rushed to get panels and cash in, she says. Now, more than 40 per cent of South Australian homes have them – one of the highest rates of uptake in the world. One afternoon last month, a major new milestone was reached when the state’s entire electricity demand was met by rooftop panels alone. The drive for solar power Certainly, as I drive around, the enthusiasm for solar is evident. There are panels carpeting the roofs of homes, shops, pubs and public toilets. I meet Adam Langham, a chemical engineer in the Adelaide suburb of Netley, who has 58 panels on his house and car port. They produce 12 times more power than he, his wife and two children consume. The government discontinued its subsidy in 2011, but smaller payments are still offered by private electricity companies, meaning the family makes more than enough money to pay off the upfront cost of the installation. “I’ve had quite a few friends call me up over the years and say, ‘OK mate, solar panels, what’s the go?’ and I tell them, ‘they’re a no-brainer – go for it’,” says Langham. Wind energy has also been received more warmly in South Australia than in New South Wales, where a planned wind farm near the town of Berrigan was recently scrapped due to a community backlash. One Berrigan resident told the local newspaper the project would “pose physical and mental health threats to our children”. Here in South Australia, however, there are framed paintings of wind turbines in my motel room in the town of Burra. Read more Renewable energy boom may help us limit warming this century to 1.5 ̊C What explains this difference in attitude? Fran Baum, a public health social scientist at the University of Adelaide, says one reason may be that South Australia has a long history of being progressive. It was one of the first places in the world to allow women to vote and stand for parliament, for example, and the first Australian state to decriminalise male homosexuality. Port Augusta’s coal-fired power station is gone. Today a solar farm dominates the skyline Gary Rowbottom Wind farm developers are also getting better at working with communities, says Tom Jenkins, who heads the South Australian branch of Neoen, a company that is building the state’s biggest wind farm, Goyder South. For example, it funds community projects near its wind farm sites, including local clubs and sporting teams; encourages its contractors to employ local businesses; and hires First Nations people to supervise construction in case of the discovery of artefacts or remains. For the Goyder South project, the company will also offer annual payments of AUD$1000 to $5000 to every household within 6 kilometres of a wind turbine as a goodwill gesture. I do, however, meet some people for whom the switch to renewables has been challenging. Rowbottom and around 400 colleagues, for example, lost their jobs in May 2016 when Port Augusta’s coal station, the last one in the state, closed. Few were able to find jobs in the town’s new renewable energy sector, which required fewer staff and different skills. Rowbottom initially had to move to Queensland to work at another coal power plant, but has since found employment back in Port Augusta. There have been other hurdles to overcome. In September 2016, South Australia suddenly faced its biggest test yet when almost the entire state experienced a blackout that lasted for days in some areas. “It was the first state-wide blackout like that in Australia in about 50-odd years,” says Christiaan Zuur at the Sydney arm of the Clean Energy Council, which represents Australian renewable energy businesses. The 2000-watt energy saving challenge may be hard, but it’s worthwhile A Swiss vision of a low-energy society set a goal that is irresistibly simple: consume energy at a rate of just 2000 watts. It’s a great way to push us to use less power - good for the purse and the planet The blackout was triggered by a violent storm that knocked over more than 20 electricity pylons and cut three of the four major transmission lines in the state. Coal enthusiasts in the federal government seized on the event to argue that renewables were unreliable. For example, Scott Morrison, Australia’s treasurer at the time, who became its prime minister from 2018 to 2022, accused the South Australian government of “switching off jobs, switching off lights and switching off air conditioners and forcing Australian families to boil in the dark as a result of their Dark Ages policies”. Koutsantonis believes the state’s supply would have gone down regardless of its energy mix, due to the severe damage to transmission lines. But the mocking that South Australia received made the government there determined to prove the naysayers wrong, he says. “We hated the ridicule we got from the rest of the country.” “After the blackout, a whole bunch of very positive things were put into place that have led to South Australia now being where it is – a world leader in terms of its renewables uptake,” says Zuur. In 2017, for example, the state government created a AUD$150 million technology fund to provide grants or loans to businesses that could offer new technologies that would make the grid more resilient. Backup batteries One project to get funding was a giant battery – the first of its kind in the world – to provide back-up in the event of major grid disturbances. It was built by Tesla following a famous bet on Twitter between Mike Cannon-Brookes, Australia’s best-known tech billionaire, and Tesla boss Elon Musk. Musk told Cannon-Brookes that Tesla would get the battery installed and working in less than 100 days, otherwise it would be free. Luckily for Tesla, it achieved this in 63 days. The battery is near Jamestown and looks like hundreds of refrigerators lined up in rows in a field. Each is filled with lithium-ion cells that are all connected to form one big battery with a capacity of 194 megawatt-hours. The facility monitors the frequency of the local electricity grid and if it suddenly rises or falls, the battery rapidly charges or discharges to stabilise the grid. This has since proved its worth on multiple occasions, including in August 2018, when lightning strikes caused widespread grid problems across the eastern half of Australia. Major blackouts occurred across New South Wales and Victoria, but the lights stayed on in South Australia, as the battery was able to rapidly reverse the sudden drop in grid frequency. Inspired by its effectiveness, Victoria and New South Wales have since built their own big batteries. A giant battery provides backup to the grid in South Australia Bradley Cooper / Alamy Stock Photo The same is true in several US states that are also ramping up their wind and/or solar generation. California, Texas and Florida have recently built or are building big batteries to help maintain the stability of their grids as they change their energy mix. Another innovative project that emerged after the blackout was a “virtual power plant“, also built by Tesla with some initial government funding. It comprises a network of solar panels and batteries that Tesla installed for free on more than 4000 government-owned social housing properties across South Australia. Tesla uses sophisticated software to coordinate the individual systems so they function like a single power plant. This allows it to trade surplus solar energy stored across the battery network on the electricity market. This appears to be a win-win for everyone because it makes money for Tesla, reduces electricity costs for the social housing residents and helps to stabilise the grid so that blackouts are less likely for the wider community. I meet Craig Renton, who lives in a social housing property in the outer Adelaide suburb of Elizabeth. He joined the virtual power plant in August last year and says it is “really good”. “My wife and I are pensioners and it saves us money – about AUD$60 a quarter – which makes a difference,” he says. Renton uses a machine to help him breathe at night and if there was a blackout in the past, “I had to get up to get the generator going, but since we got the battery, now the power comes back on within 5 seconds”, he says. Equitable access to renewable energy Renton says there is “no way” he would have been able to afford solar panels or a battery without the scheme. In this way, the virtual power plant is helping to address a key criticism levelled at these technologies, which is that they are typically only accessible to the wealthy. “One of the principles that we have in this energy transition is that we want to make sure we don’t leave anyone behind,” says Scott Oster at the South Australian government’s energy department, who has helped manage the project. Despite all this progress, however, average electricity prices are still higher in South Australia than in most other parts of the country. This has meant there has been “a bit of fatigue creeping in” among the community, with people questioning the benefits, says Koutsantonis. Electricity prices have remained stubbornly high because South Australia still relies on gas-generated electricity to fill the gaps on days when there isn’t enough sun and wind, and gas has become increasingly expensive in recent years, he says. Should we be worried about AI's growing energy use? The expanding use of large AI models demands huge numbers of powerful servers, which could end up consuming as much energy as whole countries As a result, the most pressing matter now is to find ways to store the excess solar and wind energy produced at particular times of day or on certain days, so it can be used when there is a deficit, instead of falling back on gas, he says. One solution may be to use excess solar and wind energy to power electrolysers that split water to make hydrogen. This hydrogen could then be stored and converted back into electricity when needed, either by burning it or feeding it through hydrogen fuel cells. To test this idea, the state government will commit AUD$600 million to building a hydrogen power plant near the town of Whyalla, which is due for completion in 2025. If it works, the state will be able to meet its target of running solely on renewables by 2030 and will probably have the world’s first large fossil fuel-free grid based on solar and wind energy. “If we can decouple ourselves from coal and gas prices, we decouple ourselves from international price shocks, and then all of a sudden the cost of power is just what it’s costing us to generate it,” says Koutsantonis. A massive solar farm powers a tomato farm in South Australia Gary Rowbottom According to Zuur, there is no reason why other parts of the world couldn’t replicate South Australia’s rapid adoption of renewables. The state has certain advantages, including large amounts of space, sun and wind, but other places can tap into their own advantages, he says. For example, nations with less land, like the UK and Japan, have built wind farms offshore, while Iceland, which gets little sun, uses alternative renewable resources like hydropower and geothermal energy to generate almost 100 per cent of its electricity. Personally, seeing what South Australia has achieved in a relatively short space of time has filled me with optimism that the world will be able to wean itself off fossil fuels sooner than we think. Although its energy transition hasn’t been perfect, it has shown that the key ingredients for success are strong political leadership, winning community trust, willingness to try new technologies, equitability and, most important, never giving up. Alice Klein is a New Scientist reporter in Sydney, Australia

The biggest problem is going to be the warmer months. Changing the air 0.5 times an hour, or 10 times an hour, via MVHR or not, is not going to help if the OAT is close, or above your ideal temperature. You may have to factor in some cooling. Personally, having grown up in the tropics, I like a warm bedroom. It can take a few weeks to get used to it, but then I sleep as well as I ever do. And getting up to a warm house is lovely.

When out with someone called Maureen.

Too right.

Do those panels lift up when you close a door, or on a windy day.

Welcome. What sort of engineer are you? With any project, make the big decisions first, then stick to them. You don't want it to end up like HS2. Design in the PV and the ASHP right at the start. That will make it a much cheaper place to build. Don't add complications.

I heard Dido singing earlier.

Can you use a bit of cord screwed between the cabinet and door? There seems to be a lot online. https://www.ironmongerydirect.co.uk/product/door-restrictor-matt-nickel-440624 https://www.ironmongerydirect.co.uk/product/friction-stay-210mm-length-nickel-plated-&-white-252830 https://www.ironmongerydirect.co.uk/product/heritage-brass-by-m-marcus-locking-quadrant-stays-155mm-length-114mm-throw-antique-brass-699719 Just noticed they are all from ironmonger direct.

In reality that is what already happens. Your excess power goes to the nearest load. What is really the issue is the billing. We would all like to be paid for selling excess energy, but non of us what to enter into a contract what would, by necessity, penalise us is we did not supply when we had to. The easy way around this is to have a lot more distributed generation and accept that the import unit price will either fluctuate wildly or we pay a higher fixed unit price all the time. By higher price I do not necessarily mean higher than we currently pay, just higher than the cheapest production price.

In the lab yes, that is how they know it works at very high temperatures. From a quick read though of the article, it seems they are pretending that excess solar energy has zero value and thermal energy has a very high value. I would think that with a bit of digging you will find they are looking to raise funding, not actually sell a product that is useful. Do you remember the man that made a battery from aluminium cans a while back, I bet he has retired on the development money. Then there were all those micro wind and water turbines that would save us. Oh, don't forget the perovskite, that was all the rage 5 years ago. Meanwhile, back in the real world the big boys have raised PV efficiency a few percent and reduced the cost another 5 fold.

Solid Oxide Fuel Cells have been around a while in the labs.

I posted up a request here: https://oceanofpdf.com They say a couple of days, so lets see if it appears.

Gets a bit slippery down the natural log

Start by getting accurate measurements of what you currently use and when you use it. Most off grid people have a generator tucked away.

Shall have a look here when I have time. https://math.libretexts.org/Courses/Rio_Hondo/Math_175%3A_Plane_Trigonometry/02%3A_Graphing_Trigonometric_Functions/2.04%3A_Transformations_Sine_and_Cosine_Functions Surely your Joking!

Have you done a comparison with a standard rate?

Isn't it simple harmonic motion. Punch in the material parameters i.e. mass, density, flex modulus, and the answer should come out, I actually missed the lecture about sound waves when at university (had to see the eye surgeon about my cataracts), so when I read the notes I seem to remember that because the ends are attached to a non moving part, they are modelled like a piano string i.e. only full or half waves allowed.

On another tread, I typed up a bit about Portland Cement. Now I am not a chemist at all, in fact I am rather dismissive of them. Having said that, 5 Chemists that I have chatted to informally have been very good at explaining what happens without relying on using memory test in Latin. One Chemist, a recent PhD graduate was working in sales and explained long chain polymers to me, they are really quite simple, repeating 'units' that attach to each other. Another one, again a PhD in chemicals, explained the electron orbits and how they are NOT 2D as drawn on paper, this is what governs, to a certain extent, the shape of molecules. Another, PhD again, sat me down in a lecture theatre and explained the polarity of molecules and why that causes CO2 to vibrate at certain frequencies and causes a disproportional amount of movement. This principle of polarity is why a small amount of some molecules can cause a large amount of heating. Then there was my old line manager, who also had a PhD in Chemistry who once said "when you design, or change a chemical formula to get the properties you want, you get what you are after, and something else". It is that something else that is important. Then there was our own @Jeremy Harris, who initially studied Chemistry then moved onto Physics. He was brilliant as he was a practical man and understood the limitation of the 'something else'. Now the above is just a way of asking if we have a decent chemist on here who can help out with a lot of the products used in the building trade, there must be at least one. So getting back to the title, I had a look at Portland Cement and then Lime because of a question that @saveasteading asked about releasing and absorbing CO2. After a bit of googling I found a long, but easy to read article explaining how Portland Cement is made and then used. http://matse1.matse.illinois.edu/concrete/prin.html Basically, from what I understand, is that during the roasting, free water is evaporated and then elevated temperature drives out CO2 that is attached to the calcium. When water is mixed back in, a reaction takes place that causes a rise in temperature, and the hydrogen and oxygen are split up and combine with the Di and Tri Calcium silicates and aluminate, with some Tetracalcium aluminoferrite and Gypsum thrown in. Di, Tri and Tetra I understand, the Ates and the Ites I don't, they need to be memorised. I was going to show the changes in formula when Limestone, Clay and Ferric Oxides are roasted, but I can't find a decent explanation (why we need a Chemist). The reverse hydration i.e. when water is added, is shown. Tricalcium silicate + Water--->Calcium silicate hydrate+Calcium hydroxide + heat 2 Ca3SiO5 + 7 H2O ---> 3 CaO.2SiO2.4H2O + 3 Ca(OH)2 + 173.6kJ And Dicalcium silicate + Water--->Calcium silicate hydrate + Calcium hydroxide +heat 2 Ca2SiO4 + 5 H2O---> 3 CaO.2SiO2.4H2O + Ca(OH)2 + 58.6 kJ If I understand the chemistry correctly, because the CaO is already attached to something the SiO2.4H2O chain and the Ca(OH2) there is nothing for the carbon in CO2 to attach to. So then I had a look at Lime, wanted to know what happened as way too many people seem to think that it is the bee's knees and will cure all ills in a building. I have been very dubious of those claims and can never find decent evidence to support it. So Lime is made in a similar way to Portland Cement. Get the right rocks, crush and heat them to change them: CaCO3 to CaO + CO2. Then the difference from Portland Cement happens, water is added, in the right proportion. CaO + H2O to Ca(OH2). Calcium Hydroxide. This forms a dry powder called Slaking. Also known as Hydrated Lime, add a bit more water and you get Lime Putty. Now, and this is where it is really different from Portland Cement, it absorbs both H2O and CO2 from the atmosphere as it wants to convert back to limestone CaCO3 (calcium carbonate). So come on Chemists, put me right and explain it better, maybe with a bit of basic theory as a grounding.