Solar Domestic Refrigeration Equipment

A. Chikouche, B. Abbad, S. Elmetenani, M. Chikh, S. Bouadjab
Unit for development of solar equipments, Bou-Ismail, Wilaya de Tipaza

In the last decade, the demand for perishable products has increased drastically, resulting in an increasing demand for domestic refrigerators and freezers. The use of solar energy for environmental control is receiving much attention as a result of the projected world energy shortage.


Risks Inherent in the Use of Counterfeit Refrigerants

Intergovernmental Organization for the Development of Refrigeration

International Institute of Refrigeration
177 Bd Malesherbes – 75017 PARIS, France

23rd Informatory Note on Refrigeration Technologies

Several cases of explosions occurring in marine refrigerated containers (reefers) have been reported in various parts of the world in recent months. Besides causing major material damage, these accidents have resulted in the deaths of several operators. The assessments performed following these accidents have established that these explosions were due to the use, for maintenance of refrigeration equipment, of counterfeit refrigerants containing R40 mixed with R134a, the refrigerant initially used in these units. A report published by the Container Owners Association1 describes the global situation concerning contamination of R134a by a refrigerant mixture composed primarily of R22, R30, R40 and R142b. There are no external signs indicating that counterfeit refrigerants have been used during maintenance operations.


Research on A New District Heating Method Combined with Hot Water Driven Ground Source Absorption Heat Pump

Zhang Qunli[1], Di Hongfa[2], Hu Wangyang[3]
(1 Beijing University of Civil Engineering and Architecture, Beijing, 100044)
(2 Department of Building Science, Tsinghua University, Beijing, 100084)
(3 Chinese Association of Refrigeration, Beijing, 100142)

Abstract:  A new district heating method combined with hot water driven ground source absorption heat pump to extract shallow geothermal was put forward, and the district heating system provides hot water for the driven heat source of the absorption heat pump. By the first energy efficiency and economical analysis method, research results show that compared with the conventional district heating system, the heating capacity of the new district heating system with absorption heat pump can be greatly improved and the heating costs can be largely reduced without expanding thecapacity ofdistrict heating system and increasing other energy consumption. Also, compared with electric-driven ground source heat pump heating system, the new district heating system utilized high temperature water as the driven heating resource to replace the high grade electricity, which can improve significantly the energy utilization efficiency and decrease sharply the power consumption. Compared with electric-driven ground source heat pump heating system on the same heat quantity condition, the new district heating system has the advantage of lower first energy consumption and smaller size of underground heat exchanger and the smaller heat extraction during winter period which was conducive to achieve winter and summerheat balance.  

Keywords: District heating system; shallow Geothermal; Absorption Heat Pump

1 Introduction

The electric-driven ground source heat pump was widely researched and applied to extract shallow geothermal resource for building cooling or heating [1-5]. It relied on electricity for driven resource of heat pump to extract heat from soil for heating in winter and releasing the chiller condenser heat for cooling in summer.

If the electric-driven ground source heat pump fails to maintain seasonal heat balance between winter and summer period, its coefficient of performance will gradually decrease withthe increase of its running time. So the seasonal heat balance of the ground source heat pump is the key point. In addition, electric-driven ground source heat pump in the heating condition consumes much electricity, and the heating cost will depend on the electricity price. So the higher electricity price will be the disadvantage of the electric-driven ground source heat pump system for heating.

A new district heating system combined with ground resource absorption heat pump to extract shallow geothermal resource was presented. The ground resource absorption heat pump is placed in the heat substation to extract heat from the soil or ground water, the district heating system provides hot water with primary heating network for the driven heat resource of the ground resource absorption heat pump. Also, such absorption heat pump can be converted to be absorption chiller for building cooling in summer driven by hot water with district heating system.

Heat exchange facility is applied in heat exchange station in conventional district heating system. Heat exchange equipment only transfers the quantity of heat of the high temperature water of the primary heating network to the secondary heating network, and heat exchange equipment only make use of the thermal of the high temperature water and fails to fully develop the work ability of the high temperature water. Compared with conventional heat exchange equipment in heating substation of district heating system, the absorption heat pump not only makes use of the thermal of the high temperature water but also develops the work ability of the high temperature water, because the absorption heat pump uses the hot water supplied with primary heating network as its driven heating resource to extract the shallow ground resource.

The primary energy efficiency and economic analysis mode of the new district heating method combined with ground source absorption heat pump was set to analyze the difference of the energy efficiency and economy feasibility with conventional system and electric heat pump system. Comparative analysis of district heating system combined with ground source absorption heat pump with electric-drive means for ground source heat pump shows that compared with conventional district heatingsystem, the heating capacity of the new district heating system can be greatly increased and the heating costs can be largely reduced without expanding thecapacity of the heat resource and other power consumption ofdistrict heating system.

Unlike electric-driven ground source heat pump makes use of high-quality electrical to drive, the ground source absorption heat pump system takes advantage of the high temperature water as the driven source, thus the power consumption of the absorption heat pump system will be significantly reduced and then the incremental investment of the new district heating system combined with ground source absorption system can be recovered in four years. Also the ground absorption heat pump system not only combines shallow geothermal with conventional district heating system, but also optimizes the configuration and energy efficiency of districtheat system. Consequently, compared with conventional district heating system or electric-driven ground source heat pump, the new district heating system combined with ground source absorption heat pump system makes significant energy efficient, economic benefits.

2 District heating system combined with ground source absorption heat pump

2.1 System Description

The new district heating mode mainly makes use of ground sourceorwater source absorption heat pump to replace heat exchanger of heat substation in conventional district heating system, and uses high temperature hot water provided by primary heating network as driven heating source for absorption heat pump to  extract heat from low-grade heat sources such as the shallow soil or water, and then both the heat of driving heat source and low-grade heat of ground source are supplied for heating building users by the secondaryheating network.

The new district heating system is mainlyconstitutedwith district heat source (usually a combined heat and power plant, coal or gas heating boiler, etc.), primary heating network, secondaryheating network, distributed ground source absorption heat pump, underground pipes(water taken wells and recharge wells), heating users and their connection accessories.

1.district heat source  2.primary heating supplying water network  3.primary heating returning water pipe 4.ground source absorption heat pump  5.secondary heatingsupplying water network  6.secondary heating returning water network 7.heating users 8.ground supplying water pipe  9.ground returning water pipe 10.Undergroundpipe

Figure 1 Schematic of district heating system combined with ground source absorption heat pump

2.2 Features of the new district heating system

Compared to conventional heating method, the new district heating system combined with ground source absorption heat pump system can increase the heating capacity of the system, reducing heating costs without increasing the capacity of the district heating source. On the other hand, compared with electric-driven ground source heat pump heating method, it is not used high grade electricity as the driven source of heat pump, but made use of the high temperature water supplied by district heating source.Thus it can significantly reduce power consumption and increase the primary energy efficiency of the district heating system. Also, such new district heating approach can more easily achieve the summer and winter seasonal heat balance.  

3 Analysis model of primary energy efficiency  

3.1 Comparison condition setting  

To analyze the energy efficiency and economy feasibility of the new district heating method, the conventional district heating system and the electric-driven heat pump heating system are selected as reference system.

In the condition of the same heating parameter of secondary heating network for building heating users, it is assumed that the buildings for heating users are all energy-saving buildings with low temperature heating parameters and the supplying and returning heating water parameters of secondary heating network is 45/35℃. Schematic diagram of different heating systems and its working parameters are shown as below.

Figure2Conventional district heating system

Figure 3 District heating system combined with ground source absorption heat pump

Figure 4 Electric-driven ground source heat pump system


3.2 Primary energy efficiencyevaluation

Primary heating efficiency of different heating system is calculated by equation 1.


Which ——Primary heating efficiency

——Heating amount of building users, GJ

——Heating amount of heat source, GJ

——Heating transport efficiency of primary heating network, %

——Heating transport efficiency of secondary  heating network, %

——Heatingefficiency ofcogeneration heat and power system, %

——Heating efficiency of boiler, %

——The power consumption ofprimary heating network pump, GJ

——The power consumption ofsecondary heating network pump, GJ

——The power consumption of underground water pump, GJ

——Electricity generation, GJ

——The average efficiency of power generation of coal power plant

ηe,net——The transport efficiency of power network

The flow charts of primary energy utilizationprocess for different heating systems in the design condition are shown as figure5 to figure 7, and all units in the charts are GJ.

Figure 5Energy flow chart of electric driven ground source heat pump heating system

Figure 6Energy flow chart of conventional district heating system with CHP




Figure 7Energy flow chart of the new district heating system combined with ground source absorption heat pump

3.3 Evaluation results

The primary energy efficiency of different heating systems is shown in figure 8. The figure shows that the primary energy efficiency of the new district heating system combined with ground source absorption heat pump is highest among three heating systems. Compared with the conventional district heating system with combined heat and power heating system, the primary energy efficiency of the new district heating system combined with ground source absorption heat pump can be increased about 20%.




Figure 8 Primary energy efficiency of different heating system in the design condition

Figure 9ground source absorption heat pump delayheatingload curve

Table 1 Primary energy consumption of different heating systems in all heating period



District heating system with ground source absorption heat pump

District heating system with CHP

Electric- driven ground heat pumpheating mode

Totalheat amount

Ten thousand GJ




Supplying heat amount from geothermal

Ten thousand GJ




Supplying heat from district heating system

Ten thousand GJ




Primary heatingnetworkpump consumption

Ten thousand kWh




Secondary heatingnetworkpump consumption

Ten thousand kWh




Heat Pump consumption

Ten thousand kWh




Undergroundpump consumption

Ten thousand kWh




Totalpower consumption

Ten thousand kWh




Equivalent primary energy consumption

Ton standard coal




Primary energy consumptionper unit heating area






4 Economic analysis

4.1 Economic model

The initial investment of the new district heating system combined with ground source absorption heat pump is calculated by equation (2).


The initial investment of electric-driven ground source heat pump heating system is calculated by equation (3).


For cogenerationheating system, the initial investment is calculated as follows.

The initial investment of district heating system with CHP system is calculated by equation (4).


The initial investment of the second network, indoor heating pipe network and the end of heating is the same in the above economic model.

The investment base prices of different components are shown in table 3. The cogeneration system is the heat source of district heating system and its investment price can be calculated as 4.5 million RMB / MW (electrical load).

Its power generation efficiency is 25% and its heating efficiency is 50%, and then the ratio of thermal to power is 2.0, thus the initial investment of heating system can also calculated as 2.25 million RMB / MW.

The initial investment price of primary heating network can be calculated as 30 RMB per heating square meter.

The initial investment price of absorption heat pump can be calculated as 0.6 RMB/W (heating load), and the underground pipe can be calculated as 2.5 RMB/W (heat load from underground). The plate heat exchanger and other equipment in conventional substation can be calculated as 0.2 RMB/W. The electric-driven heat pump can be calculated as 1.0 RMB/W and the investment of increasing electricity capacity can be calculated as 1,800 RMB/kW.

The construction and installation costs of the heating system can be calculated as 20% of the equipment initial investment. The construction costs of plant building can be calculated as 30% of the equipment initial investment. The prices of different fuels are shown in Table 2.  

Table2 Fuelprices




Standard coalprice



Electricity generation price



Business electricityprice



Heat price




4.2 Analysis results

As shown in table 3, the installation capacity of the electric-drivenground source heat pump heating system is the smallest because it has no heat loss of primary heating network. Also, as shown in table 4, the investment of the electrically driven heat pump heating system is lowest because of none primary heating network.

The primaryenergy efficiency of the new district heating system combined with ground source absorption heat pump is highest among them, because it can utilize the work capability of the hot water from the district heating system with CHP to extract the shallow geothermal. Also, its annual operating cost is lowest. While, the annual operating cost of the electric-driven heat pump heating system is highest, as shown in table 5.

According to the economics comparative analysis of different heating system, someresultscan be found as follows. Compared with conventional district heating system with CHP system, the investment of the new district heating system combined with ground source absorption heat pump will increase, but its annual operating cost will decrease because its high primary energy efficiency. So its investment recovery period is about 6.9 year.

Compared with the electrical-driven ground heat pumpheating system, the investment of the new district heating system combined with ground source absorption heat pump will increase, but its annual operating cost will decrease, because it can utilize the cheap heat supplied with district heating system with CHP system as its main heat source and also take advantage of the shallow geothermal energy as its auxiliary heat source. So its investment payback period is 4.0 year.

Table 3 Installation capacityof differentheatingsystem


Basic price


District heating system with ground source absorption heat pump

District heating system with CHP

Electric- driven ground heat pump heating mode

Heat source

2.25 million RMB/MW





Increased capacity of power

1,800.0 RMB /kW





Primary heating network

30.0 RMB /m2

Ten thousand m2




Increased thermal type units

0.6 RMB /W





Thermal Power Station

0.2 RMB /W





Electric Heat Pump

1.0 Yuan/W





Underground pipe

2.0 RMB /W





Secondary heating network

15.0 RMB /m2

Ten thousand m2




Indoor pipe

30.0 RMB /m2

Ten thousand m2




End of heating

40.0 RMB /m2

Ten thousand m2






Figure 10 Initial investment of differentheatingsystem

Figure 11Annual operation costs of differentheatingsystem

Table 4Operation costs of different heating methods (The unit is ten thousand RMB)




District heating system with ground source absorption heat pump

District heating system with CHP

Electric- driven ground heat pump heating mode

Heat cost

Heat cost of district heat system

Ten thousand RMB





Primary heating network

Ten thousand RMB




Secondary heating network

Ten thousand RMB




Heat pump system

Ten thousand RMB




Undergroundwater pump

Ten thousand RMB




Totalheatand electricity cost

Ten thousand RMB




Operating costsper heating area

RMB /m2




Annual operatingcosts (including investment depreciation)

RMB /m2




Table 5 Initial investment, operating cost and payback period




Case 1:Referenceobject

Case 2 Referenceobject



District heating system with ground source absorption heat pump

District heating system with CHP

Electric- driven ground heat pump heating mode

The initial investment of unit area,





Operating costper unit area





Payback period






5 Conclusions

(1)  The new district heating system combined with ground source absorption heat pump to extract shallow geothermal was presented. And it is driven by high temperature water supplied with district heating system.

(2)  Compared with conventional cogeneration district heating system in the same heating capability and heating parameters condition, the primary energy efficiency of the new district heating system combined with ground source absorption heat pump can increase about 22% in the design condition. Also its heating energy consumption can decrease about 15% in the whole heating period.

(3)  Compared with electric-driven ground source heat pump heating system in the same heating capability and heating parameters condition, the primary energy efficiency of the new district heating system combined with ground source absorption heat pump can increase about 42% in the design condition. And the its heating energy consumption can decrease about 30% throughout theheating period.

(4)  Compared with electric-driven ground source heat pump heating system in the same heating amount condition, the new district heating system combined with ground source absorption heat pump extractless heat from ground in winter, so the installation capacity and the initial investment of underground pipes are smaller.


Project supported by the National Natural Science Foundation for Young Scholars of China (Grant No 00351911032) and Beijing Municipality Key Lab of Heating, Gas Supply, Ventilating and Air Conditioning Engineering.



[1]       Xu Wei, Zhang Shicong. China's ground-source heat pump technology status and development trends. solar .2007,3:12-14

[2]       Fang Zhaohong, Diao Nairen, Yu Mingzhi, Cui Ping. Buried ground source heat pump technology and its application. Electrical Information .2005,21:15-22

[3]       Zhou Yasu, Zhang Xu. Ground source heat pump system of status and development prospects. New Energy .1999,12:37-42

[4]        Lu Jilong, Peng Jianguo, Yang Guang. Ground source heat pump research and the status. Refrigeration and Air Conditioning .2007,9:92-95

[5]       Wang Yuan. Ground source heat pump and central refrigeration, thermal methods compared. district heating .2009,6:23-24

Refrigeration Main Challenges

International Institute of Refrigeration (IIR)

1. Refrigeration is increasingly necessary

1.1. Refrigeration is necessary to mankind

Temperature is a magnitude and a key variable in physics, chemistry and biology.

It characterizes the states of matter in liquid, solid and gaseous phases and is therefore essential in material applications.

It is vital to all living beings and each living being (bacteria, plant, animal) has a temperature range within which it can live.

Temperature governs whether pathogens can develop, survive or not. Foodstuffs and health products are thus often chilled or frozen.

Refrigeration is everywhere, in:

•         Cryogenics (petrochemical refining, the steel industry, thespace industry, nuclear fusion…)
•         Medicine and health products (cryosurgery, anaesthesia, scanners, vaccines…)
•         Air conditioning (buildings, data centres…)
•         The food industry and the cold chain
•         The energy sector (including heat pumps, LNG, hydrogen…)
•         Environment protection (including carbon capture and storage), public works, leisure activities…

1.2. The Needs are increasing, particularly in developing countries

 We need to keep a few facts in mind:

- 1600 deaths/year in the USA (1), at least partly associated with temperature control, are due to pathogens. According to the World Health Organization (2), refrigeration and improved hygiene have reduced stomach cancer by 89% in men and 92% in women, since 1930 in the USA. Figures would certainly be much higher in less developed countries where there is huge leeway for progress.

- There is an increase in global population, particularly in Africa and South Asia (9,3 billion in 2050, 8 billion in developing countries) (3)

- 70% (50% now) will be in urban areas (doubled figures in developing countries) (3) and this will increase the need for cold chains, because of longer distances between production and commercialization sites and because of increasingly westernized models (meat,… )

- 1 billion people are undernourished (4); 23% of food losses are caused by a lack of refrigeration in developing countries (vs. 9% in developed countries) (5). The refrigerated storage capacity in developed countries is tenfold the refrigerated storage capacity per inhabitant in developing countries (5).

- There are needs for better health everywhere (good cold chains, air conditioning), particularly because of an ageing population.

This increase in emerging and developing countries will increase the impact on the environment.

2. Energy and the Environment are increasing challenges for the future

2.1. Refrigeration is a major energy consumer

Refrigeration, including air conditioning, represents 15% of global electricity consumption. And this figure will increase (The Netherlands: already 18%...). Refrigeration issues are clearly linked with electricity issues, which are:

- Global warming because of CO2 emissions (electricity production depending on fossil fuels): we need to take into account the TEWI (Total Equivalent Warming Impact), and the LCCP (Life Cycle Climate Performance) of the refrigerating equipment (the IIR recently built a Working Party to measure it)

- The price of electricity will increase (new sources of energy have higher costs)

- There is a lack of power infrastructures, particularly in developing countries

Overall system solutions (district cooling, trigeneration…) should certainly be developed and we need to review the coefficients of performance of the systems. For instance, heat pumps are considered as a renewable energy in the European Union, provided that they have a sufficient Coefficient of Performance because of their electricity consumption. There are and there will be new regulations on energy and on buildings in Europe, the USA or Japan with new constraints on energy and thus new constraints on refrigeration systems.

New sources of energy can be used, such as solar energy. Even if the coefficient of performance of solar equipment is still relatively low and if investment costs can be high, some systems are already in place and many experiments and research programmes are ongoing.

Refrigeration can also drive new sources of energy, like liquefied gases (Liquefied National Gas, Liquefied Hydrogen…).

In any case, changing a system because of refrigerant issues must take into account potential reductions in energy consumption: both issues are linked.

2.2. The impact of refrigerants on the environment

Vapour-compression systems will remain predominant in the short and medium term and thus we will require more refrigerants in the future.
Because of their impact on the stratospheric ozone layer, Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) are included in the Montreal Protocol and each country (whether developed or developing) had to build phase-out plans. That issue will thus hopefully soon be behind us, apart from the bank issue (refrigerants in existing equipment to be destroyed in the future). However, the main issue of phase-out plans is the kind of refrigerating equipment which is used to replace old equipment.

There are alternative refrigerants:

- Hydrofluorocarbons (HFCs), including Hydrofluoroolefins (HFOs) have no impact on the ozone layer but they have an impact on global warming (they are included in the Rio Convention and the Kyoto Protocol)

- Natural refrigerants (ammonia, CO2, hydrocarbons, water, air) have a very low impact on global warming.

- Mixtures, combinations (cascades, secondary fluids) are being developed in order to meet the various requirements.

The following table summarizes the impact of the main refrigerants on the ozone layer (Ozone Depleting Potential = ODP) and on climate change (Global Warming Potential = GWP). Even if CFCs have a very high ODP and GWP, HCFCs and HFCs have similar impacts.


CFCs and HCFCs are mainly replaced by HFCs, which generally have a high GWP

Source: UNEP

HFCs are mainly used in refrigeration and air conditioning

Source: UNEP
HFCs currently represent less than 1% of CO2 eq emissions. In 2050, they will represent 7-45% (more likely 7%) of CO2 equivalent emissions.

HFCs emissions in 2050 could offset the achievements of the Montreal Protocol related to the phase-out of CFCs.

Hence, discussions are held at an international level (Montreal Protocol and Kyoto Protocol meetings) on the future of HFCs: replacing HCFCs with HFCs could be a real threat to the climate.

3. How to reduce the impact of refrigerating equipment on environment?

3.1. Various solutions

a - There are other technologies: absorption, adsorption, solar refrigeration, magnetic refrigeration, thermoelectric cooling, cryogenics (nitrogen, CO2) but they still require technological improvements (in terms of cost, energy efficiency, capacity). Thus, they are currentlyonly niche technologies.

However, many technical developments take place. IIR Conferences on adsorption-absorption technologies, on magnetic refrigeration and on cryogenics are increasingly successful and people in universities and industries from America, Europe, Asia attend them. Prototypes of magnetic refrigeration are developed in all these regions. Solar cooling is experimented in Africa as well as Southern Asia and Australia.

New solutions will be found on a mid-term perspective.

b – We can reduce leakage

Refrigerant emissions are due to leakage and poor recovery at the end of life of the equipment. Both issues can be handled and it would certainly be part of the solution on a short-term perspective.

Because of important variability within similar equipment working in similar conditions, there are margins for progress. For instance, leakage rates in the European Union which were at 30% in the 1980s are now at 5% and less.

This is part of the solution the European Union decided to implement in order to reduce fluorinated gases emissions. The F-gas regulation was adopted in 2006. It is too early to assess the impacts of this regulation on refrigerant emissions and the regulation is currently under revision. However, some advantages and backwards of such a regulation can already be seen. The aim was to strengthen the control on leakage thanks to staff training, and the certification of staff and companies handling refrigerants in stationary equipment.

Training is necessary but it is the most important difficulty and it takes time. However, reducing leakage has clear advantages in terms of savings and on safety. For instance, a draft European proposal for the review of the F-Gas regulation proposes to extend training and certification to non-fluorinated gases which could be toxic and flammable. In any case, more training of staff handling refrigerants will be necessary in the future.

c – We can reduce the refrigerant charge

The aim is the same: reducing the refrigerant charge without changing the refrigeration equipment capacity and its efficiency would reduce leakage rates. Several technologies can be used and are currently developed: secondary refrigerants, micro-channel technologies… It is also both a Greenhouse-gas emission reduction issue and a question of safety.

d - Choosing a low-GWP refrigerant

There can be several definitions of a “low-GWP” refrigerant. People generally consider refrigerants as low GWP fluids when their GWP is lower than 20: natural refrigerants (ammonia, CO2, hydrocarbons, water, air) or some HFCs called HFOs (hydrofluoroolefins). However «moderate» GWP refrigerants (for instance R32) are also chosen by companies, since their impact would be much lower in casesof leakage than some higher GWP refrigerants. (1/2 to 1/7…). In any case, several issues should be considered:

- Most low GWP refrigerants have safety drawbacks: flammability, toxicity. Some of them require very different equipment than that used with HCFCs or HFCs, because of corrosion or pressure issues. They all require adaptations of the equipment.

- Equipment energy efficiency depends on the kind of equipment, the working fluid as well as working conditions, such as climate conditions. However, solutions with natural refrigerants exist all over the world for many applications with similar energy efficiency than in most common equipment.

- Investment costs can be higher for low GWP refrigerants especially because of safety reasons. However, the cost of the fluid and the maintenance must also be taken into account.

- Numerous current technical developments on low GWP refrigerants and on new technologies are underway and constantly updated information is required.


And this is precisely the aim of this publication: to present various issues related to refrigerating equipment, various technologies, whether currently used or still under development.


(1) Head PS. et al. Food related illness and death in the United States.

Emerging Infections Diseases, 1999


(2) WHO, World Cancer Report, 2008


(3) United Nations. World Population Prospects, the 2011 revision


(4) FAO World Agriculture: Towards 2015/2030 – Summarizing Report


(5) 5th IIR Informatory Note on Refrigeration and Food: the role of Refrigeration in Worldwide Nutrition


The role of flywheel energy storage in decarbonised electrical power systems

Electricity power systems are going through a major transition away from centralised fossil and nuclear based generation towards renewables, driven mainly by substantial cost reductions in solar PV and wind. This transition, accelerated by government subsidies, has reached a self-sustaining momentum which will only accelerate as markets are reformed to be more consistent with this new order. Intermittency in demand has always been present short duration events were balanced passively by virtue of the rotating inertia of steam turbines and generators of large fossil and nuclear stations. Anything more than 10s of seconds required starting or peaking stations and/or pumped hydro storage. With the replacement of large stations, the supply is now intermittent and the stabilising inherent inertia is steadily being removed.


Compressed air energy storage – A new heat-integration, liquid-compression approach

Professor Christos Markides    Ray Sacks

Featured image - energy efficiency in home

Compression energy in CAES systems

Energy storage is an important element in the efficient utilisation of renewable energy sources  and in the penetration of renewable energy into electricity grids. Compressed air energy storage (CAES), amongst the various energy storage technologies which have been proposed, can play a significant role in the difficult task of storing electrical energy affordably at large scales and over long time periods (relative, say, to most battery technologies). CAES is in many ways like pumped hydroelectric storage (PHS), which has the largest worldwide installed capacity, quoted as 130 GW by Perez-Diaz et al. (2015) . In PHS, water is pumped to an elevated storage reservoir when excess electricity is available, and then allowed to flow downwards by gravity and through turbine generators when electrical power is required. For very large power capacities, PHS requires large natural-land features to hold the water, whereas CAES requires large underground sealable caverns which can hold high-pressure air.


Optimizing Natural Gas Generation with Energy Storage: A Gamechanger for the Transition to a Cleaner and More Affordable Power Sector

natural gas

The 21st-century grid is transforming faster than anyone imagined ten years ago, when natural gas seemed to be our power source of the future. Today, with ever-dropping prices in renewables and storage, the future is being re-defined.

A decade ago, the advent of horizontal drilling made natural gas the darling of the U.S. power sector, and for many good reasons. Natural gas lends itself to providing both steady baseload and easily dispatchable peak load power. Inexpensive, domestically produced and significantly lower in emissions than coal, natural gas was lauded as an abundant, cost-effective vehicle for enabling the lengthy transition to a renewables future that the domestic power sector faced. However, it now appears that the transition is happening much sooner than anticipated. As the deployment of renewables plus energy storage accelerates exponentially across the country, utilities are recognizing the proven ability of storage resources to supplement and, in some cases, completely replace gas-fired generation.



Central America's Energy Transition

costa rica

When considering the places that have embraced renewable energy, one typically thinks of affluent, highly developed regions, such as Denmark, Germany, or California. However, the transition from conventional power to wind, solar, biomass and other forms of renewable energy is happening around the world1.

A region that is frequently overlooked is Central America. While Costa Rica’s achievement of procuring 98-99% of its electricity from renewables on an annual basis is widely celebrated, Nicaragua and Honduras have also been among the global leaders in the use of wind and solar to satisfy their electricity demand.And while each of these three nations has its own trajectory, together they can provide lessons for other regions.


Human electricity – a solution?

George Loumakis

The ruler of a hypothetical small island faces two very serious problems. The inhabitants of the country are unemployed and at the same time, the island's power station, using diesel generators, has to import diesel at a price of £1.2 per litre. Thus, the ruler comes up with a plan. He wants the population to work as a labour force in order to produce electricity through high efficiency hand crank dynamos and stop importing diesel altogether, killing two birds with one stone. Is this a plan worth doing?


Sensing Domestic Energy Use

Brian Davison

Most countries in the world recognise the threats associated with global warming, and have committed to binding targets to reduce their greenhouse gas emissions. In very general terms, there are two parts to a solution: cleaner energy which does not produce emissions in the first place, and reductions in energy demand so that any remaining emissions are minimised. The former is more exciting in many ways since it involves the development of new technologies, stand-offs between fossil fuel companies and environmentalists and a great deal of political wrangling. The latter in contrast is much more staid, and often comes down to tightening construction regulations and improving the fabric of existing buildings. A quick look at official statistics however demonstrates the importance of improving energy efficiency. In the UK in 2016, for example, domestic energy use was second only to energy used for transportation (Figure 1).


The Age of the Electric Car?

Gillian Harrison

In this article we explore what is an electric vehicle (EV), how owning an EV may differ from our current conventionally fuelled personal passenger cars, and what we should expect in an age of the electric car.

electric car


In 2016, worldwide stock of electric vehicles (EV) rose over 2 million, currently with 750,000 sales in that year alone (IEA 2016). Although varying across countries, Norway by far leads the world in electrifying its fleet with a 29% share of new registrations, due to a series of political efforts. Many countries have ambitious targets for EV market penetration, with China setting a target of 10% of sales by 2019 and 20% by 2025. Various other countries have proposals plans to phase out conventional vehicle sales including UK and France by 2040 and Norway by 2025. In the EU 1.5% of all new vehicle sales were electric in 2015. This is supported by a network of around 120,000 public charging points across Europe (EAFO 2017).


Flywheels: An economic and sustainable solution meeting the growing need for the electrical energy storage

Keith Pullen

carbon emmisions

Increasing penetration of renewables is creating supply and demand balancing problems across all timescales. This penetration, initially encouraged by government subsidies, is accelerating due to substantial cost reductions in solar voltaic and wind in particular. These balancing timescales range all the way from milliseconds affecting grid stability to hourly, daily and seasonal. Large coal fired steam engines possess stored energy in their rotating equipment which helps keep the AC frequency stable plus such engines could operate according to demand. Their removal from the system and replacement by renewable sources requires storage in order to maintain grid system stability and matching of supply and demand.


Heat Pumps For Decarbonizing the Building Sector

Hermann Halozan

carbon emmisions


The building sector is responsible for about 40% of the total energy demand and 33% of the CO2 emissions. Until 2050 the building sector should become CO2 free. Measures are improving the building envelope, proper architecture and advanced heating and cooling systems, based on renewable energy sources.

In the case of new buildings a lot of standards and codes exist to minimize the energy consumption, at least for heating operation.


Project Finance, Energy Efficiency and Implications for Project Managers

Dr Yiannis Anagnostopolous


Featured Project Management article from Dr Yiannis Anagnostopolous from Kingston Business School

Within the last twenty years there has been a marked increasing and destabilising trend in energy prices with such trend forecasted to continue in the long-run. As an example, in the UK, gas and electricity prices have increased by over 80 per cent on average. According to DECC’s (Department of Energy and Climate Change, 2014) energy projections, electricity prices in the services sector are forecasted to increase by 66 per cent over and above inflation compared to the base of 2013 prices, whilst over the same period, gas prices are expected to increase by 31 per cent by 2030 (see Chart 1 below).


PV Systems at the Module Level

Martin Herzfeld

Solar Module Installation


"The continued growth of MLPE technology in PV arrays is influencing system design an installation practices."

Support for module-level power electronics (MLPE) has grown recently in the U.S. solar market in comparison with other solutions, such as traditional string inverters.  There are not only new code requirements that promote MLPE solutions, but also design, installation and support considerations, including ongoing operations and maintenance (O&M). In addition, there are performance and availability factors that support the use of MLPE systems with practical safeguarding.


90% of Domestic Solar Generation Usable with Batteries

Prof Susan Roaf


Opinion piece by leading authority in Solar Energy
Professor Susan Roaf

The citizens of Britain have been building the foundations for a sustainable solar future for two decades, under the radar, and against many odds, not least the barriers placed before them by many of the interested vested in Big Energy. UK now has over 8GW of installed PV energy of which around 2.3 GW is in domestic systems. The UK has only 9.4GW of installed nuclear capacity much of which is scheduled for cripplingly expensive decommissioning over the next decade or so. Solar energy is the People’s Power of choice: Safe, Clean and increasingly affordable for all.  


C02 Refrigeration and Winery Operations

Francois Simon    Prof. Aymeric Girard

Figure 2 - Energy Use Benchmarks by process step and serviceOperating a CO2 refrigeration system in a winery offers several benefits compared to traditional refrigeration technologies that utilize chlorofluorocarbons (CFC’s), hydro-chlorofluorocarbons (HCFC’s) and hydro-fluorocarbons (HFC’s). This article analyzes how winery owners and winemakers can benefit from lower costs and more efficient operational solutions that sustainable CO2 systems offer. CO2 refrigeration systems consume 20% less energy per year than existing systems and offer a total life-cycle cost savings of 25-35%.


Intelligent Buildings and Their Role in the Future Global Energy System

Jonathan Allcock ELC

Image 1


The global energy system is undergoing a massive change due to an overwhelming amount of evidence relating to climate change; in order to continue to reduce carbon emissions and increase overall energy efficiency, it is important to look at where and how the energy is consumed. Buildings are the largest energy consumer by sector and account for over one-third of global final energy consumption [1], it is important to recognise this because it shows a need for intelligent energy management within the building sector in order to decrease carbon emissions, increase building energy efficiency and energy security.


Energy Efficiency in Homes

Francois Simon    Prof. Aymeric Girard

Featured image - energy efficiency in home

Interactive investigation of building energy performance

The work presents a methodology, based on a simulation model and graphical figures, for interactive investigations of building energy performance. The investigated examples illustrate how decisions in the early stages of the building design process can have decisive importance on final building energy performance in United States' (US) climates.


The behavioural modelling and simulation of PV modules under real weather conditions in PSPICE

Chandrika Ramiah - University of Mauritius

Polycrystalline silicon solar cellsAbstract

In this article the behavior of the solar cell with respect to solar irradiance has been studied. Solar cells have been modeled, simulated and analyzed through graphical interpretations. Three types of photovoltaic modules from different companies (50Wp monocrystalline, 50Wp polycrystalline and 50Wp amorphous silicon) have been modeled based on the one-diode model and their maximum power point has been simulated in PSpice AD. The performance of the solar modules has been evaluated in terms of their response variables namely short-circuit current, open-circuit voltage, maximum power point voltage and maximum power point current with respect to real weather data.


COP21 Global Climate Summit: A Review of the Paris Agreement

Professor Scott Sklar, George Washington University

Paris Agreement - COP21 Global Summit

Prof. Sklar is an EEC Expert Lecturer of the Solar Photovoltaic and the Renewable Energy Management & Finance courses, organised jointly by the EEC Accredited Centre and The George Washington University. Prof. Sklar recently presented an inspiring TEDx Talk on the future of personal energy use.

The 21st Council of the Parties (COP21) ended in Paris as the first time in history where most of the countries in the world actually agreed to very public and somewhat ambitious actions to significantly reduce greenhouse gas emissions.


Non-Conventional Solar Energy Technologies

George Loumakis

Image3Whenever the public hears about solar energy technologies, their mind revolves mostly around two specific applications. One of them is solar photovoltaics, also known as solar PV, and the other is solar thermal collectors. Solar PV produces DC electricity and has been predominantly used in domestic applications in the past – both standalone and grid connected – as well as a component in portable electronic appliance chargers, pocket calculators, and so on. Solar thermal collectors produce heat, either in the form of hot water or hot air, and are used for heating applications such as hot water heating or space heating. Both forms are very well established and have been around long enough so that they are now considered to be the norm in solar energy applications.



History and Function of Polymer-Based Organic Photovoltaic Cells

Alexander M. Schneider

Solar PV Cells

Introduction to OPVs and comparison with traditional PV technologies


As populations outside of Europe and North America begin to enter the global middle class, one of the most notable effects of that transition will be a skyrocketing worldwide demand for electricity. This can already be observed in the worldwide trends in electricity consumption (Figure 1 [1]). In order to build this new growth on a sustainable foundation, much of this energy must come from renewable, nonpolluting sources.


Energy Investment Risk and Future Climate - Part 2

Rachel Jonassen

Climate Risk to Energy Projects

Figure 4 - Damage to Wind Turbine From Tornado Winds

Part 2: Climate Risk to Energy Projects

(Read Part 1 here)

Rachael Jonassen, Department of Engineering Management and Systems Engineering, George Washington University, Washington, DC 20052, USA.

A Compilation of Climate Risk to Energy Projects

In the first segment of this sequence of articles,[1] you read lots of recent examples of how climate has affected every different type of energy project, usually in multiple ways. In this segment, you will read about using those experiences to develop a more formal picture of the specific risks that your energy project faces. We’ll begin with a simple example and explain the concepts as we go along. As we go, we’ll take a look at the relevant risk assessment input to a financial analysis. 


Interview with United Nations - UNEP – by the European Energy Centre (EEC) – Part 2

Dean Cooper - UNEP

Dean Cooper - UNEP - United Nations - Wind Power

Part 2: Practical Steps & Getting Involved

(Read Part 1 here)

Recently, the EEC sat down with Dean Cooper, Energy Finance Programme Manager at the United Nations Environment Programme (UNEP), to discuss 2015 projects and opportunities for individuals and organisations to get involved with UNEP’s work in developing countries.

European Energy Centre (EEC): What are the next steps in order to advance the clean energy mini-grids?

Dean Cooper, United Nations UNEP: The first step is to involve both the public and private sectors, and to get the locals involved in stakeholder management. We then need to get the business model prepared to make sure we can demonstrate the investment potential most effectively. This could have been done via a report; however we didn’t think this would be enough to convince people of the investment opportunities.


Interview with United Nations - UNEP – by the European Energy Centre (EEC) – Part 1

Dean Cooper

Flag of the United Nations

Part 1: Opportunities for Stakeholders in 2015 – SE4ALL and clean energy mini-grids

Recently, the EEC sat down with Dean Cooper, Energy Finance Programme Manager at the United Nations Environment Programme (UNEP), to discuss 2015 projects and opportunities for individuals and organisations to get involved with UNEP’s work in developing countries.

European Energy Centre (EEC): What are the upcoming opportunities for stakeholders investing in clean energy projects in 2015?

Dean Cooper, United Nations UNEP: There are a wide range of opportunities for stakeholders – in many ways, there are more opportunities than resources available to meet them all – and our challenge is to focus on the areas where we think we can have the greatest impact.


Energy Investment Risk and Future Climate

Rachel Jonassen

Figure 4 - Damage to Wind Turbine From Tornado Winds

Part 1: Energy Investment Risk and Future Climate

Rachael Jonassen, Department of Engineering Management and Systems Engineering, George Washington University, Washington, DC 20052, USA.

Introduction to Future Climate Risk
If you’re an engineer designing new PV systems, or an entrepreneur installing them, or a financier planning a large offshore wind turbine farm, you know the practical challenges you face day to day getting renewable energy to the client. And you know how these new systems can help in the fight against climate change. But do you think about how that climate change will be fighting you and your business? This article gives you some weapons to prepare for that battle. 


A View on Hydropower Training

Title imageBHA logoA View on Hydropower Training
by Prof. David Williams on behalf of
the British Hydropower Association


The fight against climate change has brought global incentives for renewable energy resulting in the growth of new hydropower projects and refurbishment and upgrade of existing ones over the last decade.

With this increase in activity, the hydropower sector has grown rapidly in all types and size of projects. Equipment manufacturers, consultants, civil contractors, grid companies and other related activities have had to rapidly expand especially in manpower resource.

So why has there been an absence in mainstream training in hydropower in response to the growth in the industry?


Major Changes for the Renewable Electricity Market: a focus on UK Contracts for Difference (CfD)

C. McNaught

CfD principles illustrated

Author: C. McNaught

Managing Consultant at Ricardo-AEA

Recent UK trends

Renewable electricity generation in the UK has increased from 10TWh in 2010 to almost 54TWh in 2013.  As shown in the following figure, UK renewable electricity generation includes:

Read more... 

Opportunities and Challenges for the Adoption of Clean Energy Technologies.

Interview with United Nations – UNEP – by the European Energy Centre (EEC)

During a visit to the UNEP Offices in Paris to discuss 2014 opportunities, EEC Director Paolo Buoni conducted a short interview with UNEP Energy Finance Programme Manager, Dean Cooper, to discuss the current opportunities and challenges for the adoption of clean energy technologies.  

From left: Dean Cooper, United Nations UNEP; Paolo Buoni, European Energy Centre (EEC); Marco Buoni, Centro Studi Galileo (CSG), Vice President AREA.


Pumped and Waste Heat Technologies in a High-Efficiency Sustainable Energy Future

Pumped and Waste Heat Technologies in a High-Efficiency Sustainable Energy Future

C.N. Markides*

Dr Christos N. Markides, Imperial College London, collaborates with the European Energy Centre (EEC) and is the author of the below article entitled:

Christos N. Markides, The role of pumped and waste heat technologies in a high-efficiency sustainable energy future for the UK, Applied Thermal Engineering, Volume 53, Issue 2, 2 May 2013, Pages 197-209. (

Department of Chemical Engineering,ImperialCollege, South Kensington Campus,LondonSW7 2AZ,UK

*Corresponding author. Email: This email address is being protected from spambots. You need JavaScript enabled to view it. ; Tel. +44 (0)20 759 41601; Fax. +44 (0)20 759 45700


Intergovernmental Organisation Partners with EEC

Intergovernmental Renewable Energy Learning Partnership to partner with global leader in training, European Energy Centre (EEC).

The European Energy Centre (EEC), global leader in renewable energy training and host of the 15th EU European Conference with UNITED NATIONS (UNEP), has announced they have entered into a partnership with the Abu Dhabi based IRENA Renewable Energy Learning Partnership (IRELP), who are funded and supported by governments of 160 countries worldwide, on a number of projects aimed at improving renewable energy education in Europe and across the world.


Energy Management: Opportunities for improving monitoring

Author: Andy Smale, lecturer for the Energy Efficiency in Buildings Course run by European Energy Centre. The course is available distance learning, and also as a two day classroom based course held at major Universities.

The European Energy Centre (EEC) promotes best practice in renewable energy and energy efficiency with major universities and in partnership with the United Nations Environment Programme (UNEP).

Monitoring is a cornerstone of any energy management strategy – a paucity of data related to energy use makes any effort to reduce consumption much more challenging.  Without this kind of information it is impossible to compare performance against industry benchmarks for a particular type of building or industry sector, and to determine whether BREEAM targets are being met.


The Role of Training in Supporting SME and Community Development of and Financing for Projects in Energy Efficiency for Housing.

Author: Douglas Prentice, lecturer in Masters Degree at Edinburgh Napier University and lecturer of European Energy Centre (EEC) management, finance, carbon and green deal courses.

Economic issues regarding Sustainability

The BBC reported that atmospheric C02 concentrations at the Earth System Research Laboratory Mauna Loa Hawaii exceeded 400ppm for the first time.  Its daily average concentration figure on Thursday 9th May 2013 reached 400.03.


Development of Flexible Solar Cells on Fabrics

John I B Wilson and Robert R Mather, Power Textiles Limited, Upland House,Ettrick Road,Selkirk,TD7 5AJ,UK.

A Helena N Lind and Adel G DiyafSchool of Engineering and Physical Sciences,Heriot-Watt University,Edinburgh,EH14 4AS, UK.


Present day photovoltaic (PV) modules are mostly rigid panels of standardised sizes that are not readily integrated into buildings or other large structures without compromising the architect’s design. Although thin-film solar cells have been available for many years, they are often based on metal or glass sheets and do not provide any adaptability in shape. We are developing thin-film solar cells that are fabricated directly on woven polyester fabric in an effort to address these limitations of conventional PV modules. After a brief explanation of how photovoltaic cells operate, we describe how the required layers are produced with plasma enhanced chemical vapour deposition (PECVD) and other coating technologies. Finally we envisage how the performance of these innovative renewable energy devices is anticipated to improve.


United Nations at Scottish Government to find green energy projects for developing countries

The first of a series of Global Round Tables organised by the United Nations Environment Programme (UNEP) and the European Energy Centre (EEC) will take place at the Scottish Government in Edinburgh next Monday (11 March.)

At these events, the UN will gather industry leaders in renewable energy and finance, in order to create green energy projects which will benefit developing countries.

The Round Tables comprise five such events in financial centres around Europe, at locations including the London Guildhall, the United Nations offices in Paris and Frankfurt, and the University of Milan, between 11 and 26 March.

The EEC has a history of working closely with Edinburgh-based organisations including Heriot-Watt University and Edinburgh Napier University.


Development of a High Pressure Control Logic for CO2 Tap Water Heat Pumps

E Fornasieri, F Mancini, S Minetto
Dipartimento di Fisica Tecnica, Università degli Studi di Padova

This paper presents the development of the upper cycle pressure control system of a CO2 tap water heat pump. The system is designed to satisfy the domestic hot water requirement of a residential building located in the northern part of Italy. The heat pump works according to a single-stage transcritical cycle with internal heat exchanger.


Clear Up Confusion Over Electric Vehicles With the UK's First Training Course

The Edinburgh-based European Energy Centre (EEC) has launched a 2-day training course for professionals and individuals who want to understand the cost saving opportunities and environmental benefits of switching to electric vehicles.


Partners: European Energy Centre | European Centre of Technology | EnergyCPD | Galileo Master Certificate