Optimization of Electrical and Heat Storage in University Buildings

This paper discusses the optimization of electrical and heat storage in university buildings, exploring various methods such as Phase Change Material tanks, building thermal mass, hot water tanks, and thermochemical materials. The article also covers the drivers of energy storage and the benefits of thermal energy storage.

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Introduction

The storage of electrical and heat energy is an important aspect in various institutions such as
universities. Depending on numerous knowhow, it permits the keeping of excess energy
awaiting usage in the coming hours, days or months. This paper simply articulates the
optimization of electrical and heat storage in university building and there are several ways that
can be used by various universities to store the energy and this includes;
 Phase Change Material tanks(PCM)
 Building thermal mass (Kerry, 2010, p. 103)
 Hot water tank (HW) (Dincer, 2011, p. 98)
 Thermochemical material (TCM) (Hall, 2010, p. 34)
State- of- the- art
Thermal and electrical energy mainly develop as a result of a combination of heat and power
plant. This involves the residential micro-CHP plants which have an advanced energy proficiency
than conventional thermal power system thus resulting to a reduction in ecological effect,
mitigated greenhouse release of gases, reduce consumption of fuel and increase in economic
profitability. The accumulation of thermal energy is done when the price of electricity in the
market is low and discharged when the price is high as mentioned by Katulic et al 2004. The
research was also conducted showing the yearly power demand and also cold climate with a
high penetration of electric space heating as shown below;

Fig 1: Showing the demand of power yearly (Hadorn, 2013, p. 218)
An efficient operation of the production unit at more efficient loads comes as a result of the
heat storage system (Fleischer, 2015, p. 56). And the accumulation of heat can be done using
three mechanisms which include;
a) Upsurging the working fluid temperature or heat carrier (Hall, 2010, p. 34).
b) Transforming the working fluid phase (Hadorn, 2013, p. 89).
c) Thermochemical amassing of heat (Kosny, 2015, p. 67).
The idea of associating or incorporating a system of thermal energy storage to a prevailing
combined heat and power which assist in upgrading the productivity of energy decades started
a long time ago (Paksoy, 2008, p. 129). The preceding writers did not pay much attention to the
notion of having a very powerful and squeezed system of storage (Paksoy, 2008, p. 54). The
storing of energy has been acknowledged as a significant answer for decentralized energy
system. The energy consumption in building conducted in a few selected countries is shown by
the bar graph below;

Fig 2: Showing the energy consumption in buildings (Kerry, 2010, p. 345)
Literature Review
According to Victor et al 2013, the storing of the heat in a large amount can be done in
reversible scorpion process and chemical processes. The storage of heat in scorpion process is
done by dismantling the force existing amid the sorbate and sorbent in terms of the strength of
a chemical. Other authors who also conducted research involving storing of energy in which
entails reaction of chemical included Sakha and Don 2012, Chan et al in 2012 and Mette et al.
2012.
The identification of thermochemical as composition of storing chemical ignoring
electrochemical and electromagnetic was done by Souk Poe et al. 2009 and later amended by
Yu et al. 2013 who came up with idea that sorption thermal storage to be disseminated into
four groups which includes liquid absorption, solid adsorption, chemical reaction and composite
materials (Paksoy, 2008, p. 63).

Thermal mass
When designing a building, the technique mentioned above belongs to the mass of a building
that allows the storage of heat and setting up of inertia against variations in temperature. And
this is the reason why it is useful in areas where there are temperature fluctuations on a daily
basis (Kerry, 2010, p. 120). The thermal mass is capable of absorbing the thermal energy when
there is a high temperature in the surrounding compared to the mass and then reverting the
energy when the surrounding is not hot. The materials that should be used for thermal mass
should have high density as well as high specific heat capacity and the thermal mass is ideal
placed inside the structure and positioned where it can still be unprotected to low-angle winter
sunlight since it is warmed positively by the sun or furthermore by internal heating systems
during the day (Fleischer, 2015, p. 129).
Hot water storage tank
This is a water tank used in hot water storage for space heating (Rumbarger, 2009, p. 56).
Water has a high specific heat capacity thus making it be a suitable heat storage medium and
more heat can be stored per unit of weight. These type of tanks are enclosed with heat
insulation to assist in the reduction of energy being consumed, speeding the process of heating
and maintaining the desired operating temperature (Hadorn, 2013, p. 123).
It is important to note that the addition of insulation to an already insulated tank during
extremely humid locations may cause condensation leading to mold or rust. In the case of the
solar hot water storage tank, heat is stored from the solar thermal collectors (Kosny, 2015, p.

31). Closed water circuit is also used in hot water storage tanks and this is achieved by
tremendously applying coils or external heat exchangers that assist in powering other external
heat exchangers. The use of a closed water circuit is beneficial since it avoids drawing off
domestic hot water directly and also reduction in the level of oxygen thus allowing relaxation of
materials used in hot water tank. The mineral precipitate may be caused in the tank when the
water supplied locally entails greater composition of liquefied minerals, for example, limestone
and this leads to leakage in the tank as a result of corrosion (Dincer, 2011, p. 98).
Phase Change Material
This is an efficient and economical strategy of storing a large number of heats and material
phase transformation performs a beneficial task in the conservation of energy because it has
high storage density with small change in temperature making it the latent heat storage
material (Paksoy, 2008, p. 76). A rise in the source temperature causes breakage in the
chemical bonds within the PCM making the phase of material to convert from solid to liquid.
Attaining the phase change temperature makes the material to start melting and the process of
melting thus referred to as the Latent Heat. The storage of heat is done all through the process
of melting or the phase change process. The achieving of storage of latent heat can be done
through a solid-liquid, solid-solid, liquid-gas and solid-gas phase change in case paraffin is used
as the changing phase of the material.

The absorption of heat continues in the PCM deprived of a noteworthy the temperature
increase until the material transformation takes place to the liquid part (Fleischer, 2015, p. 67).
The diagram below shows a working model of PCM.
Fig 3: Showing a model of Phase Change Material (Paksoy, 2008, p. 98)
Drivers of energy storage
The drivers of energy storage include;
 Frequency regulation in select market (Fleischer, 2015, p. 78)
 The state level incentives (Kerry, 2010, p. 34)
 Demand charge reduction for commercial and industrial customers
 Synergy between solar PV and energy storage (Rumbarger, 2009, p. 54)

Bibliography
Dincer, I., 2011. Thermal Energy Storage. s.l. Sanoma.
Fleischer, A., 2015. Thermal Energy Storage Using Phase Change Materials. s.l. Adventure Works Press.
Hadorn, J., 2013. Energy and Climate in the Urban Built Environment. s.l.: McGraw-Hill Education.
Hall, M., 2010. Materials for Energy Efficiency and Thermal Comfort in Buildings. s.l. Media Participation.
Kerry, I., 2010. Solar Thermal Energy Storage. s.l.: Wiley.
Kosny, J., 2015. PCM-Enhanced Building Components. s.l. OLMA Media Group.
Paksoy, H., 2008. Thermal Energy Storage for Sustainable Energy Consumption. s.l. Scholastic.
Rumbarger, J., 2009. Architectural Graphic Standards for Residential Constructions. s.l.:Informa.