• Energy Research

Shallow geothermal systems use the thermal inertia of the earth to provide a temperature gradient between the ambient conditions and the underground soil. This thermal inertia can be used by the heat exchangers to provide space heating and cooling during the winters and summers. This paper provides a brief but broad overview of the different active and passive technologies involved in the use of heat exchangers for HVAC in order to achieve a near net zero energy building. Firstly the different types of ground heat exchangers and heat pumps are introduced along with the relevant studies of significance in this field. It has been demonstrated that the different types of heat exchangers can be integrated with thermally active building envelopes and renewable energy resources to significantly minimize the building energy use. Finally a pathway has been devised for use of ground heat exchangers to realize a net zero energy building.

SUMMARY This paper analyses the transportation and delivery features of hydrogen as energy market evolves and approaches a fully functional Hydrogen economy. Initially physical aspects have been assessed that affect the flow of hydrogen through the existing pipeline infrastructure. Line pack and compressors are the only identified problems that need to be addressed. This is followed by an investigation into the mixing of hydrogen with natural gas gradually. It was revealed that a mix of up to 17% by volume does not have any significant effect, however higher concentration of hydrogen leads to a changeover of high-pressure grid pipelines as well as the end-user applications. It is suggested that initially hydrogen can be introduced in the distribution system, while emphasizing towards developing means for high-pressure transportation of hydrogen fuel gas. Government policies towards encouraging use of hydrogen in an evolving market is important for widespread and early assimilation in energy mix. Renewable sources of energy are recommended for distributed generation of hydrogen along the pipeline network. Copyright © 2011 John Wiley & Sons, Ltd.

Energy consumption and its resultant impact on climate change are inextricably linked, with the burning of fossil fuels being a chief contributor to greenhouse gas emissions, contributing to global warming. Mitigating these effects necessitates a two-fold approach: reducing energy consumption through enhanced efficiency and behavioural modifications, and concurrently transitioning to renewable and clean energy sources. Of particular concern is the domestic and commercial building sector, which currently accounts for a substantial 40% of the world's total energy usage. Conventional wind turbines, effective in harnessing wind energy, face limitations in urban areas due to the requisite wind speeds. Micro wind turbines, notably vertical axis wind turbines (VAWT), present a promising solution for achieving net-zero energy buildings in urban settings. VAWTs exhibit advantages such as higher efficiency and lower cut-in speeds. Despite their promise, challenges such as reliability, cost and environmental impact persist. This concise overview suggests potential applications for Pakistan, emphasising the imperative for further exploration in optimising VAWT design, developing hybrid systems and evaluating societal acceptance of rooftop wind farms.

Abstract The share of renewable energy resources is consistently rising in the global energy supply, and power-to-gas technique is being seen as the feasible storage of surplus renewable electricity. In this regard the sensitivity of hydrogen towards various elements of the P2G network needs to be assessed. The study provides an overview of a number of P2G projects mainly concentrated in Europe, and summarizes the results of investigations carried out on the effects of hydrogen injection on the existing natural gas pipeline infrastructure. It has been found that each element of the natural gas infrastructure has a varying degree of acceptability to hydrogen concentration; however the determinant element affects the overall allowable hydrogen concentration. In the transmission network, compressors are the determinant element and have a limiting value of 10% hydrogen admixture. Distribution network and storage elements allow a 50% concentration of hydrogen. End use appliances have a tolerant range of 20–50%. The second portion of the study demonstrates the effect of hydrogen injection on gas quality, which reveals that an introduction of 2% hydrogen in the distribution network has negligible effect however a 10% hydrogen mixture affects the calorific value of the supplied fuel gas below the desired level.

Offshore renewable energies are proposed to generate green hydrogen through PEM electrolysis. Power-to-gas process can be used to store hydrogen gas in synergy with existing oil/gas exploration companies. Offshore CCS is thereafter used to assist in the production of synthetic natural gas entirely offshore.

Net-zero-energy buildings have the potential to mitigate climate change through reduced energy use. Shallow geothermal systems use the thermal inertia of the Earth to provide a temperature gradient between ambient conditions and underground soils. This thermal inertia can be used by heat exchangers to provide space heating and cooling during winter and summer, respectively. This paper provides a brief but broad overview of the different active and passive technologies involved in the use of heat exchangers for heating and cooling to achieve near net-zero-energy buildings. Different types of ground heat exchangers (GHEs) and heat pumps are introduced along with relevant studies of significance in this field. It has been demonstrated that different types of heat exchangers can be integrated with thermally active building envelopes and renewable energy resources to minimise building energy use. A pathway is then presented for using GHEs to realise net-zero-energy buildings.

Abstract One of the ways to address the woes of energy crisis effectively in the developing world is through the use of Geothermal energy resources. This paper discusses the Geothermal technologies in use globally with emphasis on the development paths. The development efforts in Pakistan are discussed focusing on the areas requiring attention. It has been found that while considerable potential for Geothermal energy is available in the form of Hydrothermal resources and Hot Dry rocks, however no appreciable practical steps have been undertaken in this regard. Shallow geothermal energy and Direct-use of Geothermal energy that is independent of terrain and resource has also not been pursued in Pakistan. The study discusses the stages of development, the current status of Geothermal energy in Pakistan and identifies the steps for initiating progress. Further, it is an established fact that the maximum consumption of energy in the domestic and industrial sector is in HVAC and process heat respectively. Shallow geothermal energy can fulfill this demand efficiently. Government support can play an important role in developing the Geothermal resource of the country. A number of steps have been suggested for the Government as well as research institutions that can inject impetus and enhance the pace of development of this significant but ignored Energy resource in the developing world.

Abstract Pakistan's energy crisis can be diminished through the use of Renewable and alternative sources of energy. Hydrogen as an energy vector is likely to replace the fossil fuels in the future owing to the political, financial and environmental factors associated with the latter. In this regard it is imperative that conscious effort is directed towards the production of hydrogen from Renewable resources. Renewable energy resources are abundantly available in Pakistan. The need to produce Hydrogen from Renewable resources in Pakistan (or any developing economy) is investigated because it is possible to store vast amount of intermittent renewable energy for later use. Thus the introduction of Hydrogen in the energy supply chain implies the start of a Pakistan Hydrogen Economy. Many nations have developed the Hydrogen Energy Roadmap, and if Pakistan has to follow suite it is only possible through the employment of Renewable energy resources. This study estimates the potential of different Renewable resources available in Pakistan i.e. Solar, Wind, Geothermal, Biomass and Municipal Solid waste. An estimate is then made for the potential of producing hydrogen from various established technologies from each of these Renewable resources. A number of reviews have been published stating the availability and usage of Renewable energy in Pakistan; however no specific study has been focused on the use of Renewable resources for developing a Hydrogen economy or a power-to-gas system in Pakistan. This study concludes that that Biomass is the most feasible feedstock for developing a Hydrogen supply chain in Pakistan with a potential to generate 6.6 million tons of Hydrogen annually, followed by Solar PV that has a generation potential of 2.8 million tons and then Municipal solid waste with a capacity of 1 million ton per annum.