So now we’re going to think about heat. And we’re going to think about all the lit­tle devices that we use. Microprocessors in our phones. About industrial-scale process­es. Steel pro­cess­ing, oil refin­ing. About trans­port, so planes, trains, and auto­mo­biles. And the heat that’s gen­er­at­ed in those process­es. You’ve all had a hot phone, I’m sure.

Machines gen­er­ate waste heat when they do work for us. And this year, sev­en bil­lion of us will use twenty-five tril­lion kilo­watt hours of elec­tric­i­ty. An awful lot of that will end up as waste heat. So, we treat waste heat as a prob­lem. We see it as a chal­lenge to design how we can man­age it. We don’t think of it as a resource. If we thought of it as a resource, that would be results we are just throw­ing away.

But it’s worse than that. We’re not just wast­ing heat, we’re using even extra ener­gy try­ing to man­age that heat. So extra sys­tems on air­craft, for exam­ple, to keep the sys­tem cool. At the oth­er end of our ther­mal spec­trum, refrig­er­a­tion and air con­di­tion­ing is now using some­thing like 15% of our glob­al elec­tric­i­ty production.

So here we are in the 21st cen­tu­ry. Wouldn’t it be great if we could do some­thing bet­ter? If we could use that heat to extract elec­tric­i­ty. Or if we could use elec­tric­i­ty more effi­cient­ly. Cool sys­tems, sys­tems we could just embed­ded into every­day objects, that would allow us to have elec­tric­i­ty back to pow­er systems.

So, why aren’t we doing that? Well, there are a few prob­lems. But real­ly they’re both two sides of the same coin. How can we use heat to extract elec­tric­i­ty? How can we use elec­tric­i­ty to extract cool­ing? They’re about mate­r­i­al sys­tems that have tran­si­tions in them. And we could start to address some of those prob­lems if we think a bit more clev­er­ly about how we do mate­ri­als engineering.

So one of the key chal­lenges is one of chem­istry. How do we get the atom­ic struc­ture of the mate­ri­als we’re using right so that they do effec­tive­ly and effi­cient­ly cou­ple between ther­mal and elec­tri­cal ener­gy? The sec­ond prob­lem is one of struc­ture. How do you get mate­ri­als that can pump effec­tive­ly elec­tric­i­ty or heat in and out of those sys­tems? We’re going to need new mate­ri­als com­bined at the nanoscale to be able to do this.

So when we talk about chem­istry and nanos­truc­ture, we only have to look around us to see lots of exam­ples. Nature does this nat­u­ral­ly. Beautiful, inter­con­nect­ed sys­tems. And we can start to look to biol­o­gy to think about ways to both design and to start to grow new nanoscale nanocom­pos­ite systems.

You might have mul­ti­ple lay­ers of mate­ri­als, just atom­ic lay­ers thick, that behave dif­fer­ent­ly to their com­po­nent struc­tures. Or you might direct­ly mim­ic some­thing bio­log­i­cal like a leaf or a bone. Or in my lab we work on opals to have inter­con­nect­ed, active sys­tems. And once you’ve got that cou­pling of nanos­truc­ture and chem­istry into a new mate­r­i­al, you can start to think about dif­fer­ent applications.

At a sim­ple lev­el, you can think about low pow­er devices. So hav­ing self-powered health mon­i­tor­ing, just from the ambi­ent tem­per­a­ture of your body. Monitoring in remote haz­ardous envi­ron­ments where you don’t want to send peo­ple in. New sys­tems that will allow us bet­ter con­nec­tiv­i­ty and bet­ter infor­ma­tion gathering. 

Our trans­port sys­tems will use less fuel, and that means less emis­sions. And We can start to think about con­nect­ing our sys­tems so that the heat from the engine is then recap­tured and used to pow­er say, the air con­di­tion­ing units in urban trans­port networks.

In refrigeration—this is a huge topic—you could just swap out con­ven­tion­al devices that have not real­ly changed for about a hun­dred years with magnetically-powered tech­nol­o­gy. They’ll be 50% more effi­cient. Straight away, 50% effi­cien­cy improve­ment. That, on a grid-scale elec­tric­i­ty amount is 3% sup­ply, just from your domes­tic hous­ing. Twelve mega­tons of car­bon diox­ide would be saved with that technology.

But just because we’re think­ing about nanoscale mate­ri­als does­n’t mean we should­n’t think even big­ger. Why don’t we join up all these sys­tems, have ther­mal recap­ture with local renew­ables, local ener­gy stor­age, to have a com­plete­ly off-grid fac­to­ry or data cen­ter. We would reduce resource con­sump­tion, reduce pro­duc­tion costs, reduce envi­ron­men­tal impact.

So we’re already sev­en bil­lion and grow­ing. The demo­graph­ic’s shift­ing. More and more of us are mov­ing to cities. And those urban envi­ron­ments are lit­er­al­ly hotspots. What if we could think a lit­tle bit more clev­er­ly about heat cap­ture. What if we could start to har­ness some of this ener­gy that’s just being wasted?

So, we’re fac­ing a triple chal­lenge in ener­gy: secu­ri­ty, sus­tain­abil­i­ty, and equi­ty. Heat is a huge part of our ener­gy ecosys­tem. If we even start to make small changes, we will have mas­sive impacts on our ener­gy econ­o­my. In the future, these smart nanocom­pos­ites will be embed­ded into every­day devices. They will change the way we think about indus­tri­al and urban design.

But right now, it’s still a wast­ed resource. The tin can you just saw, none of you will be throw­ing that away. You see that as a resource. What can we do to make peo­ple see heat and heat cap­ture as a resource, and make heat cap­ture the new recycling? 

Further Reference

Faculty page at Imperial College London

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