Image: Fraunhofer IZM / Volker Mai

More ener­gy effi­cien­cy for the Inter­net of Things

Today, more and more devices are con­nect­ed to each oth­er via radio with the help of intel­li­gent sen­sors. But this grow­ing “Inter­net of Things” is con­sum­ing more and more pow­er. In the Fraun­hofer lead project ZEPOWEL, hard­ware was there­fore devel­oped that makes the sen­sors not only ener­gy-effi­cient, but down­right ener­gy savers.

Whether it’s pro­tect­ing your home from bur­glars or keep­ing an eye on the machines in a fac­to­ry, sen­sors for mon­i­tor­ing and con­trol are on the rise: Sen­sors that report when a win­dow is sud­den­ly opened, or those that reg­is­ter that a machine is idling and wast­ing ener­gy. With the help of a micro-con­troller, the tiny devices ana­lyze the sit­u­a­tion and then sig­nal and receive instruc­tions via a radio unit. In view of the grow­ing num­ber of these devices, the so-called sen­sor nodes, experts have been talk­ing for some years now about the Inter­net of Things (IoT) — about many mil­lions of devices in the future in the home or in indus­try that are con­nect­ed to each oth­er via the Internet.

An ener­gy demand like the whole of Germany

How­ev­er, these many sen­sor nodes still con­sume large amounts of ener­gy them­selves. In 2013, the ener­gy con­sump­tion of all net­worked devices world­wide was already equiv­a­lent to the total elec­tri­cal ener­gy require­ments of the whole of Ger­many, accord­ing to a study by the Inter­na­tion­al Ener­gy Agency in Paris. For this rea­son, eight Fraun­hofer Insti­tutes joined forces some time ago in the Fraun­hofer lead project ZEPOWEL (see box) to devel­op par­tic­u­lar­ly ener­gy-effi­cient sen­sor nodes. In the course of this year, two solu­tions will be pre­sent­ed that approach the chal­lenge from two dif­fer­ent angles: The first is a self-suf­fi­cient sen­sor node that sup­plies itself with ener­gy and col­lects envi­ron­men­tal data — on air qual­i­ty, for exam­ple. And sec­ond­ly, a sen­sor node that detects the oper­at­ing sta­tus of machines, motors or pumps in order to dras­ti­cal­ly reduce their ener­gy requirements.

“The sen­sor node hard­ware we devel­oped in the project is char­ac­ter­ized by the fact that it can be built up mod­u­lar­ly from dif­fer­ent com­po­nents and can thus be adapt­ed to dif­fer­ent pur­pos­es,” says Erik Jung, project staff mem­ber at the Fraun­hofer Insti­tute for Reli­a­bil­i­ty and Microin­te­gra­tion IZM, which com­bined the indi­vid­ual devel­op­ments from the par­tic­i­pat­ing insti­tutes into a func­tion­al whole. “Some part­ners con­tributed their knowl­edge about build­ing effi­cient chips and con­trol elec­tron­ics, oth­ers about build­ing small and effi­cient bat­ter­ies and ener­gy con­vert­ers. Oth­ers have con­tributed with their exper­tise in secure wire­less protocols.”

Autonomous sen­sor for the smart city

The ener­gy-autonomous sen­sor node, the “smart city node”, is char­ac­ter­ized by the fact that it falls into a very ener­gy-sav­ing deep sleep mode when it is not need­ed. In this state, it con­sumes only a few nanowatts. Only when it is acti­vat­ed via radio does it start up — for exam­ple to mea­sure fine dust and send the mea­sured val­ues via radio. The smart city node will be installed on cars and bus­es in the com­ing months. It uses an ener­gy con­vert­er to gen­er­ate elec­tric­i­ty from vibra­tions while dri­ving. “The nodes are tiny, main­te­nance-free and inex­pen­sive and can be used in many places — giv­ing you a very fine-meshed mea­sure­ment net­work,” says Erik Jung. In the future, such sen­sors could also be used in agri­cul­ture to mea­sure soil mois­ture and nutri­ent con­tent very pre­cise­ly at spe­cif­ic points, so that farm­ers can irri­gate and fer­til­ize in a more tar­get­ed man­ner. This sen­sor-based “pre­ci­sion farm­ing” is on the rise, says Jung.

Teach­ing machines to save energy

The sec­ond type of sen­sor node will be used in machines with rotat­ing motors, ini­tial­ly in machine tools pro­vid­ed by an indus­tri­al part­ner. Even today, there are many machines that are start­ed and stopped by hand. Once a job is com­plet­ed, they con­tin­ue to spin at idle until you press the but­ton. In addi­tion to the mea­sure­ment tech­nol­o­gy, the new sen­sor node now con­tains inno­v­a­tive pow­er elec­tron­ics for con­trol­ling 15 kW at switch­ing volt­ages of up to 850 V. It is cou­pled to the machine and can now ramp the machine up and down as required or con­trol it to the respec­tive required speed. “There are still many machines in indus­try today that are not speed-con­trolled,” says Erik Jung. Replac­ing them with new machines would be enor­mous­ly expen­sive. It there­fore makes sense to equip them with the intel­li­gent sen­sor node instead. “Rough­ly esti­mat­ed, we would save around 20 per­cent of car­bon diox­ide emis­sions nation­wide if intel­li­gent sen­sors with inte­grat­ed con­trol were used across the board in indus­try,” says Erik Jung. The lead project ZEPOWEL has now deliv­ered a cor­re­spond­ing standard.