Your Home in 2050

The earth's magnetic field is essential to life on our planet. It shields us from the harsh conditions of space. The field is produced, we think, by the constant circulation of the earth's metallic liquid iron core. But how long the iron core has been flowing, and therefore the age of the planet's magnetic field, have been open questions that have led to a paradox, which, speaking with Connie Orbach, Stewart McWilliams thinks he can now solve...

Stewart - The paradox - well it was proposed a couple of years ago. Really, it was clarified a couple of years ago and that is that when you have a very high thermal conductivity in the Earth's core of iron at these conditions, it's very hard to sustain the Earth's magnetic field. The heat is removed out of the core relatively quickly and there's not enough energy left to support the vigorous kind of motion that produces the Earth's magnetic field.

Connie - So this paradox lays out a problem. We have a highly conducting molten core of iron but, if it's highly conducting, then either:

1) the Earth's magnetic field couldn't have been around for that long, it would have burnt itself out.  And we have rocks that date back almost to the beginning of the Earth showing its presence.

Or -

 2) early Earth must have had a super hot molten core in order to retain the heat for as long as it has.

But that doesn't really work either as we know the Earth has remained largely the same. So what's going on? Well it all hinges on this question: what are the properties of iron in a super hot pressured environment like the centre of the Earth?

Stewart - We take two diamonds similar to those in a diamond ring but, if you take it out of the ring, you'll notice that there's a really pointy part at one side, and we essentially take those two points of two of those diamonds and press them together. In this case, on  a piece of iron and we squeeze down as hard as we can on this iron and we can create the same kind of force that's on iron in the centre of the Earth. Of course, the centre of the Earth is also very hot so, of course, the iron in the centre of the Earth is partially liquid because it's so hot and melted. And so to get to those conditions, we have to heat it up and this is where the diamond is also very helpful, so it's very strong that helps us squeeze on it. It's also transparent so we can see through it or, in this case, we can shoot a laser through it and that heats up this little piece of iron to many thousands of degree.  So we create, by squeezing on the sample, and heating it up with lasers, we create those conditions in the centre of the Earth.

Connie - And from that, what are you trying to find out?

Stewart - We've been able to get to these conditions with this technique for a long time but what we're trying to find out is something very specific and something that's really hard to measure, that is how well the iron will conduct heat at those conditions. This is really important for establishing properties of the Earth's magnetic field. How long it's lived and so on. So to measure how the heat is transported at these conditions, we have a little tiny piece of iron between these two diamonds that, if we heat it on one side with a laser pulse, then the heat will slowly transport itself across this hair's width sample and we can measure it coming out the other side. I say slowly, it happens on the scale of nanoseconds so we have to make the measurements very quickly but, if we can measure how fast this heat goes, we can determine how the heat also flows inside the centre of the Earth.

Connie - So this is where you came into trying to recreate the centre of the Earth to see how well this conduction happens, and what did you find?

Stewart - So for these very high thermal conductivities that we expected for iron, the Earth's magnetic field might only be young, it may not have been around very long, and it might also have a very short lifespan into the future. We find that, surprisingly, the thermal conductivity is very low, unusually low for metals and what this means is that the Earth's magnetic field can, in fact, be very long-lived. In fact, it might have been around since the very formation of the Earth, even before the first life on Earth which has really important implications for the spread and evolution of life.

A few years ago, the news wires were buzzing when researchers showed that flowers attract bumblebees using electrical signals, and that the bees can tell one bloom from another just on the basis of "flower power". But how do the bees do it? Emma Sackville caught up with the buzz from researcher Gregory Sutton...

Gregory - Bumble bees are magnificently fuzzy and this fuzz gives bumble bees a sensory ability to tell things about the world around them. It's not just for keeping them warm, and it's not just for measuring wind currents, it's also for measuring the electric fields of various plants and animals around them.

Emma - And how did you go about testing these hairs on the bees?

Gregory - There are two experiments we ran. The first is we put a hair in an electric field and used a device called a laser vibrometer to measures the hair's motion in the electric field. And we found that when you change an electric field, the hair moves back and forth and you can actually oscillate a hair using an electric field.

And then the second experiment is - you put a hair in an electric field and we were able to get very, very fine wires placed at the base of a hair. And those fine wires would tell us what the cells and other structures at the bottom of the hair were doing and you record the electrical activity in the nervous system to see if the motion of the hair causes an electrical signal to be sent back to the nervous system.

Emma - You mentioned that bees can detect these small electrical fields. What are the implications of this, if they can detect flowers, can they detect other electric fields?

Gregory - We don't see any reason why not. We found that they can tell the difference between different flowers, and we're currently working towards defining exactly the kind of electric field they can detect, and what electric fields affect them, and what electric fields don't.

Emma - So could electric fields that we produce cause any effect to them?

Gregory - That is a very careful question and I'm not comfortable answering that. Any answer I give to that question will make somebody angry. So I'm not comfortable answering that question until I have data that says specifically one way or the other.

Emma - Sure, OK. Bees can detect these fields because they're fuzzy -  are a lot of other insects similarly fuzzy?

Gregory - There are many, many insects and spiders that are fuzzy. There are fuzzy moths, fuzzy butterflies, there's a couple of fuzzy crickets. The abdomen of a lot of spiders are fuzzy, which makes us suspect that there are many, many insects measuring electric fields in this way.

Emma - And what would other insects use the electric fields for?

Gregory - Well, the easiest thing is that we've found is that insects are actually electrically charged and they create their own electric fields. And if you had something that sensed electric fields, you would be able to detect the presence of another insect nearby. This would be no further than say 10 or 20cms but it would be a close way to tell if there were other insects nearby and because many insects eat other insects, this would be a great, great utility to all sorts of insects if they could do it.

Emma - Why is it important for us to know how bees detect flowers?

Gregory - In the pure scientific sense, everything that's known between bees and flowers is important for just agriculture and fruit. There are many, many fruits pollinated by bees. If we know how flowers and bees interact, we can actually create farms that are more friendly to bees and increase pollination levels. From a larger sense, this is branching into a field of electrostatic biology which, if we find this in many, many other insects, might be a whole realm of interactions that we might need to know in order to control or otherwise affect insects.

This was not the first paper over the last couple of years to show that the insects we deal with everyday are doing amazing things, and this will by no means be the last. And we know so little about what's going on in the insect world, and the guys we just encounter in the park, and just in the garden, and just on your windowsill. And that whole area of science, I think, is fascinating and it tells us about the world we live in and it's the things we see every day.

Making concrete accounts for 5% of GLOBAL carbon emissions, so is there a better alternative? Chris Smith laid the foundations with Darshil Shah from Cambridge University...

Darshil - Well, there is a founded industry around steel already and also steel has high strength and stiffness, therefore load bearing capacity and you can form it into complex shapes and that enables load transfer efficiently. I think one of the advantages of concrete is that the material is available abundantly in many places and that you can form it into different shapes of all sizes.

Chris - So it is a good material but it's not as good as a natural material, potentially?

Darshil - Yes, in different ways though. The three mainstream construction materials are concrete, steel and timber. So, for example, up to 25% of new homes in the U.K. are based on light frame timber and the advantage of timber, in this respect, is that it is a carbon sink...

Chris - Because it's soaking up carbon dioxide from the atmosphere to turn it into wood in the tree?

Darshil - Yep. The production process itself can be carbon neutral if you employ a closed loop cycle where the fuel is generated through the offcuts of the wood that is produced...

Chris - That's why I asked you about natural materials because on the one hand, if we were to build buildings with wood, that sounds good because they're going to soak up CO₂ from the atmosphere. They will be a strong material that we know from thousands of years of construction appears to work. But how quickly do we need to renew buildings made of wood because there's obviously going to be an energy cost in building the building, building it with wood sounds good but then if I have to do it every 20 years - not so good? So how does the maths and the equation balance?

Darshil - So the design life that we tend to work is between 50 to 100 years and that matches quite well with the harvest cycle or the rotation cycle of timber. So once you have a new harvest, once you have a new set of wood, you can create new homes and replace the existing ones.

Chris - Now one of the projects you're working on is to look at or explore the possibility of using GM wood or bamboo in order to better serve the requirements of architects and engineers - tell us about that?

Darshil - I think we first need to understand wood as a material. We are looking at the cellular level through plants like arabidopsis thaliana, which are the mice of the plant world whose genetic sequence is well known. And our host biochemist, Professor Paul Dupree's group, is able to modify these plants and change the polysaccharide constituents of the cell wall and the microstructure confirmation of the stem. The interesting thing is that the wood formation is these tiny little stems (1mm in diameter, or even smaller) is similar to that in hardwoods, in poplar for example. Therefore, by studying these genetically modified stems and looking at how maybe a small change in the xylan content, or the cellulose content, and even small functional group changes and how the interaction between the polysaccharide changes affects the properties of the material. And therefore, we can then work our way towards genetically modified poplar and better understanding of how the properties of wood come about and what we can do, perhaps, to improve the properties of wood.

Chris - Right, so we have this project here where you're actually going from the cell right up to the mature plant, organism, tree, whatever. So you can actually, potentially, generate a tree that will generate the wood that will have the properties that you need for a certain building project - I mean is that what you're doing?

Darshil - In a way, yes. I think that's an important point because trees weren't made to be used in a dry state. In nature, trees are quite wet and it's not really a building material and we are using it as a building material so, if we want to use it as such, we may have to engineer it for those properties.

Chris - Right, so because we dry the wood out to turn it into a plank, it then loses some of the naturally evolved properties it had as wet wood?

Darshil - Yes.

Chris - Are you there, have you solved the problem, are you getting close?

Darshil - It's not only a multiscale project from the cellular level to the building level and even to the city level but also this work is at a fundamental level. So we are still trying to understand, at the cell wall scale, how the properties are derived and at the other extreme, we are trying to develop concepts and products that can actually be implemented for the designs of actual buildings. You have to keep in mind that there's a life cycle in growing a tree and it's only after 50 years or so you'll be able to harvest that tree. So you have to do a lot of long term planning with these sort of projects and we are, I think, a long way away from it but it's a strong start in the right direction.

Chris - In other words you can make sure that what you plant to be the sustainable wood source of the future because, at the end of the day, we want to reassure people here that you're not talking about going to the nearest forest, chopping down a whole load of trees, getting wood and turning those into houses? You're talking about let's have sustainable wood supplies but let's plant something now with 50 years hence in mind, which is actually going to be fit for purpose?

Darshil - Yes, absolutely. Deforestation is still a problem, although deforestation rates have been reducing. Importantly for us, substantial amounts of wood can be harvested sustainably without depleting or degrading forests. And since the 1990s, on average, Asia and the developed countries, so North America and Oceania, Europe have extracted about 3.8 billion metres cubed of wood annually and yet forest cover has increased annually by 1 million hectares. So you can extract wood resources efficiently and sustainably.

Chris - Now given that the Mckinsey report we referred to earlier said that there is this very pressing need, just by 2025, of 440 million households in really quite poor conditions or needing better quality housing. Are you going to get there with this work fast enough, taking into account it's going to take 50 years to grow this sustainable timber source?

Darshil - By 2050 we will have an additional 30% of wood resources, just new growth resources to use. It is possible it will be hard but if we think carefully about it and think about how we are actually designing homes, because using timber we will have to think about redesigning them using these new materials rather than basing designs on steel construction or concrete construction. So the efficient use of resources is the key and like in the energy industry, you want a diverse mix of energy, you would want to use a diverse mix of materials efficiently.

Chris - And I suppose if it does need a bit of DIY then you can always grow the raw material in the garden - couldn't you?

What's being done NOW to build environmentally sympathetic homes? In a number of countries, proposals that, from 2016, new buildings should be sustainable have been watered down or scrapped. But one development in Cambridge is sticking to the principle anyway. Emma Sackville went - on site - to speak to construction director Gavin Heaphy... 

Gavin - We are recycling water. We are generating our own electricity and heat through our energy centre which centralises the production of electricity and hot water across the whole of the development for all 3,000 homes. We are generating electricity through photovoltaic cells, but what we're also doing to achieve that is ensuring we reduce our carbon footprint both in the construction of the homes but also in the materials and also in the performance of the homes when they're in full use.

Emma - And we've got this energy centre behind us - is that right? So it's a sort of tall, grey building - how's it going to function?

Gavin - So, within that building there are different ways of both generating electricity and heat. In the initial phases where the whole project is very much heat lead, so we've got more demand on heat rather than the electricity, we use boilers. So the centralised boilers pump hot water around the development and then, as the development requires more in the way of electricity, we'll start generating electricity with engines.

Emma - This system is known as combined heat and power, or CHP, and by centralising the boilers, not only do they make it more efficient over the whole site, they can also use the waste heat from the engines to power the boilers. And Gavin reckons it can add up to an overall energy saving of up to 40%.

Building on this kind of level is quite a big ask. What have been your main challenges and stumbling blocks when you've been trying to achieve it?

Gavin - The main stumbling blocks have been to do with finding the best people to deliver these projects. Not everybody has done anything on this scale before, so finding the right resources both in terms of the management team, but also the contractors and their sub-contractors as well and, also, making sure we keep a close eye on how that performance is working on site.

Emma - And, obviously, there's higher costs associated with building something sustainably. How are you balancing off the cost with the trade off of making sustainable housing?

Gavin - Well, ultimately, if it's sustainable it also means it's also going to be more cost effective to run during it's operational phase, so we're actually making an early investment in sustainable development to ensure that what we have to manage for the next 50 to 100 years on this development is, actually, more cost effective in the long run, so lower energy bill, less maintenance if you like, and so on. It will reap the benefits in the long term.

Emma - Oh, I've lost my hat! Once I'd retrieved my hat, I wanted to find out a little bit more about their water recycling plans. Water management and recycling are the major consideration when planning sustainable housing because, at the moment, we use completely clean, drinkable water and, essentially, flush it down the toilet. There's an option to recycle so called grey water, which is any used water that hasn't been down the loo with all the associated extras. We could use this for things like flushing the toilet, or watering plants, basically, anywhere that we don't need to drink it. We headed over to the water management part of the development for Gavin to tell me a little bit more about what they were doing on this site...

So, at the moment, we're here by this very lovely, surprisingly lovely, lake actually. What's the lake doing here - what's it part of on this site?

Gavin - The lake's part of our water recycling system but also has other uses as well. If you like, the whole water attenuation and recycling system we have across the site has many purposes. The lake actually retains water on the site so, as you can imagine, a site of 150 hectares has an awful lot of water falling on it when it rains and we need to deal with all that water. So, what we've done by attenuating the water on the site we are alleviating flood risk, that water gets recycling and there are two water networks across the whole of our site. A normal potable water network you get from your supplier, say Cambridge Water from this area, and there is a second network that is used for irrigation, for toilet flushing, and also now for washing machines as well.

Emma - So you've got two different kinds of water going on?

Gavin - Yes. I think water recycling has been around for many years, hundreds of years, but what we're doing here is doing it collectively if you like. The whole system is feeding the whole site so you're not reliant on individuals collecting the water themselves. This is being done centrally and it's the first time it's been done at this sort of scale. The lake also provides amenities both for the public people and, as you've just said, you quite like the look of the lake, it's a very nice place to be. Hopefully when the sun's out a bit later in the year it'll be even nicer but, on top of that, it also creates habitat for wildlife too.

Emma - And speaking of wildlife, one of the things I found really surprising on this site was the commitment to ensuring the impact on the local environment was newt-ral.

Gavin - So, throughout the delivery of the project we've had to look after Great-crested newts. In the area immediately in front of us here there's a large pond just beyond those bushes there. The small green fences you see are how we control the movement of the newts to ensure they don't get out into the wider site and get squashed - putting it bluntly - and we're standing at the moment right on top of our newt tunnel. This tunnel is of a reasonable size and will allow the little gems to migrate between the ponds and make sure they don't get hurt in that process.