cooling applications such as desalination , refrigeration and even the production of electricity . The paper concludes , however , that the best economic value is achieved when recovered heat at a temperature of about 70 ° C is used for space heating purposes .
This directly exposes one of the major issues around data centre heat reuse at the moment . Servers generally remove their heat using air . Currently , in the best case this heat is rejected at a temperature of about 35- 40 ° C . Generally , it is lower . Depending on the heat collection effectiveness , this temperature quickly drops to 28 ° C before the heat is captured in a system that can transport it to the user . Water cooled servers will eliminate this problem . But these are still at least five years away from becoming mainstream and have been so for the past 15 years . This article therefore only considers air cooled servers .
Nevertheless , more recently , several operational systems have been realised in The Netherlands . In particular , campus settings with a large share of the building population being new builds are interesting . These often utilise low temperature heating technologies , where data centres in combination with underground aquifer cold and warmth storage can be a real asset to the campus . Similarly , at a different campus a data centre has been connected to a dis-balanced warmth and cold ring . With the connected buildings asking for more heat than is available , and producing more cold than is required , these data centres were a welcome connection onto this ring . The common theme in these success stories is the cooperation with a campus .
This being said , the theme of energy reuse is also ‘ out of the box ’ thinking . For smaller data centres there are opportunities : offices can be both heated and cooled by making smart use of the data centre heat removal system .
What if you do not yet have a heat reuse customer , but want to prepare for one ? Your best bet may be on installing a chilled water system , which for only a little extra investment can be equipped with a heat exchanger for realising heat harvest and reuse .
To summarise the above : the challenge for heat reuse is either to find nearby users that can make good use of the available heat , or to transfer the low grade thermal energy ( warm air and warm water ) into high grade thermal energy that has a larger audience of possible consumers . The latter may require additional investments , for instance for additional heat pumps , and the business case therefore could require guaranteed customers with dedicated contracts .
What could happen next ? And now new and exciting possible collaborations are visible on the horizon . The Dutch glass house agriculture industry , a large consumer of heat and power , is uniting to investigate the feasibility of putting excess data centre heat to good use . This is an industry which is accustomed to large scale cooperation in energy projects and park development .
However , while 80 per cent of the operational expenditures of glass house greeneries is energy related , it is not necessarily a given that external heat supply is required . It depends on the crops grown . These generally fall into two categories , lit or unlit . Lit crops demand large quantities of electricity , which is currently most efficiently produced using cogeneration facilities that at the same time provide the required heat . But the non-lit crops still require heat , and green house farmers too are working on reducing the use of fossil fuels . Therefore , within a park development with several growers there will always be a substantial base load that can be supported by data centre facilities . Upgrading the available data centre heat by means of heat pumps will be required , as the ideal temperature of the heating medium in green houses is 63 ° C . When working towards realising the necessary facilities , a data centre / green house collaboration can draw on the extensive cooperating experience of the green house industry .
So maybe , in a few years ’ time the tasty salad you serve for dinner might have been grown from the heat produced by your Facebook and WhatsApp activities .
18
cooling
applications such as desalination,
refrigeration and even the production
of electricity. The paper concludes,
however, that the best economic
value is achieved when recovered
heat at a temperature of about 70°C
is used for space heating purposes.
This directly exposes one of the
major issues around data centre
heat reuse at the moment. Servers
generally remove their heat using air.
Currently, in the best case this heat is
rejected at a temperature of about 3540°C. Generally, it is lower. Depending
on the heat collection effectiveness,
this temperature quickly drops to 28°C
before the heat is captured in a system
that can transport it to the user.
Water cooled servers will eliminate
this problem. But these are still at
least five years away from becoming
mainstream and have been so for the
past 15 years. This article therefore
only considers air cooled servers.
Nevertheless, more recently,
several operational systems have
been realised in The Netherlands. In
particular, campus settings with a large
share of the building population being
new builds are interesting. These
often utilise low temperature heating
technologies, where data centres in
combination with underground aquifer
cold and warmth storage can be a
real asset to the campus. Similarly, at
18
a different campus a data centre has
been connected to a dis-balanced
warmth and cold ring. With the
connected buildings asking for more
heat than is available, and producing
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