Biotechnology for fuels: Past, present, and future

The use of biotechnology in energy production presents opportunities to produce renewable fuels more efficiently and effectively. Refocus U.S. Correspondent Don C. Smith reports from a recent symposium that has been addressing this area now for a quarter of a century.     

Plastic solar stills: Past, present, and future

Over 400,000 plastic solar stills have been sold commercially. According to the literature, highest yields for large-scale solar stills were obtained from those with plastic covers. The technology of plastic stills is changing; that of glass covers has remained basically the same for the past hundred years.

A review of technical and patent literature on plastic solar-still elements is presented. Recent experiences with plastic covers are summarized with emphasis on causes for reported failures and explanations of acknowledged successes. The advantages of plastic solar still covers are listed with details on the properties of various plastics. Trends and influences which assure better future performance are also mentioned.

Shortcomings to the present approach to desalination of community water supplies by solar energy are compared with the advantages for individual family water supplies. The integration of desalination with other tasks, such as air conditioning, is recommended. By having the solar still replace the ceiling and roof of a room, it may be possible to eliminate all capital costs for the still.     

Renewable power for China: Past,present, and future

This paper briefly examines the history, status, policy situation, development issues, and prospects for key renewable power technologies in China. The country has become a global leader in wind turbine and solar photovoltaic (PV) production, and leads the world in total power capacity from renewable energy. Policy frameworks have matured and evolved since the landmark 2005 Renewable Energy Law, updated in 2009. China’s 2020 renewable energy target is similar to that of the EU. However, China continues to face many challenges in technology development, grid-integration, and policy frameworks. These include training, research and development, wind turbine operating experience and performance, transmission constraints, grid interconnection time lags, resource assessments, power grid integration on large scales, and continued policy development and adjustment. Wind and solar PV targets for 2020 will likely be satisfied early, although domestic demand for solar PV remains weak and the pathways toward incorporating distributed and building-integrated solar PV are uncertain. Prospects for biomass power are limited by resource constraints. Other technologies such as concentrating solar thermal power, ocean energy, and electricity storage require greater attention.     

Renewable power for China: Past, present, and future

This paper briefly examines the history, status, policy situation, development issues, and prospects for key renewable power technologies in China. The country has become a global leader in wind turbine and solar photovoltaic (PV) production, and leads the world in total power capacity from renewable energy. Policy frameworks have matured and evolved since the landmark 2005 Renewable Energy Law, updated in 2009. China’s 2020 renewable energy target is similar to that of the EU. However, China continues to face many challenges in technology development, grid-integration, and policy frameworks. These include training, research and development, wind turbine operating experience and performance, transmission constraints, grid interconnection time lags, resource assessments, power grid integration on large scales, and continued policy development and adjustment. Wind and solar PV targets for 2020 will likely be satisfied early, although domestic demand for solar PV remains weak and the pathways toward incorporating distributed and building-integrated solar PV are uncertain. Prospects for biomass power are limited by resource constraints. Other technologies such as concentrating solar thermal power, ocean energy, and electricity storage require greater attention.     

Indirect evaporative cooling and economy cycle in summer air conditioning

The air‐side economy cycle has a large application in warm and dry climates, where the simple increase in the amount of outside air supplied to the conditioned space can substantially reduce the cooling load. Although the dry‐bulb economy cycle is the simplest implementation, requiring only a dry‐bulb temperature comparison to operate the air flow rate regulation, the greatest potential in cost reduction is achieved by the wet‐bulb economizer (WBE). Indirect evaporative cooling (IEC), based on energy recovery from the saturated exhaust airflow, is another technique to be applied in the reduction of a building cooling load. Preconditioning the outdoor airflow by IEC actually extends the applicability of the WBE. In such a way, specific synergies can be exploited when WBE and IEC are combined, even in humid climates. On the other hand, the largest benefits can be accomplished only by redefining the control strategy of the outside air flow rate. In the present paper, the outside air flow rate control strategies are described both for simple WBE and for preconditioned WBE cycles. Different regulation regions are defined on the psychrometric chart together with the relative control strategies. The incidence of these regions is evaluated for 14 different European and American climates. Finally, the seasonal cooling energy requirements are determined for the dehumidification by cooling process, which can be considered as mainly responsible for cooling energy costs in the considered localities. Traditional, preconditioned by heat recovery and IEC on the exhaust airflow, WBE and PWBE air conditioning cycles are compared. Copyright © 2003 John Wiley & Sons, Ltd.     

Review of carbon dioxide (CO2) based heating and cooling technologies: Past,present, and future outlook

Refrigerants bearing high global warming potential (GWP) and ozone depletion potential (ODP) were outlawed or facing time-beared permission under the Montreal (1987), Kyoto (1997) protocols, F-Gas law (2015), Paris Accord (2016), and recent Kigali Amendment to Montreal Protocol (2019). In order to modify followed by the paradigm shift of existing heating and cooling systems, American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) envisaged natural and synthetic refrigerants (Synrefs) are under investigation globally. Carbon dioxide (CO₂) is a popular natural refrigerant (Natref) replacing Synrefs used in commercial heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems globally. A rampant rise is observed in markets of Asia (Japan and China), North America (the United States and Canada), the Australian continent, and Africa (South Africa) by reaching 20 000 CO₂-stores around the globe. The European markets are leading the utilization of CO₂ in the heat pump, and refrigeration, CO₂ based markets estimate 14% of the total food retail stores (400 m²). Japan is the second leading market of CO₂ heat pump and refrigeration with more than 10 200 CO₂ condensing units. CO₂ transcritical systems have a share of more than 10% in only European market (large stores); however, their share is less than 10% of total stores in other major markets of the world. New pump and compressor-driven transcritical CO₂ systems integrate ejectors, condensers, and booster systems to reduce energy consumptions, enhance efficiency, efficacy, and coefficient of performance. This article reports a critical review of the CO₂ based heating, cooling, and refrigeration system and presents updated literature along with barriers and challenges on commercial use of Natref-based heating and cooling applications worldwide.     

Indirect evaporative cooling of air to a sub-wet bulb temperature

Indirect evaporative cooling is a sustainable method for cooling of air. The main constraint that limits the wide use of evaporative coolers is the ultimate temperature of the process, which is the wet bulb temperature of ambient air. In this paper, a method is presented to produce air at a sub-wet bulb temperature by indirect evaporative cooling, without using a vapour compression machine. The main idea consists of manipulating the air flow inside the cooler by branching the working air from the product air, which is indirectly pre-cooled, before it is finally cooled and delivered. A model for the heat and mass transfer process is developed. Four types of coolers are studied: three two-stage coolers (a counter flow, a parallel flow and a combined parallel-regenerative flow) and a single-stage counter flow regenerative cooler.It is concluded that the proposed method for indirect evaporative cooling is capable of cooling air to temperatures lower than the ambient wet bulb temperature. The ultimate temperature for such a process is the dew point temperature of the ambient air. The wet bulb cooling effectiveness (E_wb) for the examples studied is 1.26, 1.09 and 1.31 for the two-stage counter flow, parallel flow and combined parallel-regenerative cooler, respectively, and it is 1.16 for the single-stage counter flow regenerative cooler. Such a method extends the potential of useful utilisation of evaporative coolers for cooling of buildings as well as other industrial applications.     

Carbon sequestration by forestation across China: Past, present, and future

Plantation forests are the most effective and ecologically friendly way of absorbing CO₂ and increasing carbon sinks in terrestrial ecosystems; mitigating global warming and beginning ecological restoration. China's forestation rate is the highest in the world, and contributes significantly to the nation's carbon sequestration. We have applied empirical growth curves, scale transformations, field sampling plots, and forest inventory data, to our carbon estimation model, to analyze the carbon sequestration in living biomass and soil organic carbon pools in past and current plantations. Furthermore, the potential carbon sinks of future plantations, 2010-2050, have been simulated. From 1950 to the present, plantations in China sequestered 1.686 Pg C by net uptake into biomass and emissions of soil organic carbon. The carbon stock of China's present plantations was 7.894 Pg C, including 21.4% of the total sequestration as forest biomass and 78.6% as SOC. We project that China's forestation activities will continue to net sequester carbon to a level of 3.169 Pg C by 2050, and that carbon stock in plantations will amount to 10.395 Pg C. Spatial patterns of carbon sequestration were dissimilar to those of planting area. On the basis of area, carbon sequestrations were highest in North China, while changes were generally greatest in the Northeast and Southwest regions.     

Economics of nuclear power: Past record,present trends and future prospects

We examine the economic record of operating U.S. reactors, factors affecting the economics of nuclear plants under construction and opportunites for nuclear energy to escape from the predicament it faces today. The records of the 80 operating reactors indicate that they represent an indispensable asset, generating power at a lower cost than fossil-fueled alternatives. Yet many reactors under construction have suffered so much delay and cost escalation that they have become a financial burden to utilities and their customers. The technical, economic, and institutional reasons for this grotesque contrast between nuclear energy's potential and the problems it faces today are discussed. Changes necessary to improve the economics of nuclear power are also discussed. It is argued that the deployment of a meltproof reactor design, several of which are now under development, may solve the multifaceted problems of over-regulation, long schedules, and financial risks.     

Magnesium based materials for hydrogen based energy storage: Past,present and future

Magnesium hydride owns the largest share of publications on solid materials for hydrogen storage. The “Magnesium group” of international experts contributing to IEA Task 32 “Hydrogen Based Energy Storage” recently published two review papers presenting the activities of the group focused on magnesium hydride based materials and on Mg based compounds for hydrogen and energy storage. This review article not only overviews the latest activities on both fundamental aspects of Mg-based hydrides and their applications, but also presents a historic overview on the topic and outlines projected future developments. Particular attention is paid to the theoretical and experimental studies of Mg-H system at extreme pressures, kinetics and thermodynamics of the systems based on MgH₂, nanostructuring, new Mg-based compounds and novel composites, and catalysis in the Mg based H storage systems. Finally, thermal energy storage and upscaled H storage systems accommodating MgH₂ are presented.     

Solar energy use through biology—Past, present and future

Each year plant photosynthesis fixes about 2 × 10¹¹ tonnes of carbon with an energy content of 3 × 10²¹ J—this is about 10× the world's annual energy use and 200× our food-energy consumption. All the atmospheric CO₂ is cycled through plants every 300 yr, all the O₂ every 2000 yr and all the H₂O every 2 million yr. The magnitude and role of photosynthesis is largely unrecognized principally because we utilize such a small fraction of the fixed carbon and because we do not realize the important recycling phenomena. Fortunately for us plants are very adaptable and exist in great diversity—they could thus continue indefinitely to supply us with renewable quantities of food, fibre, fuel and chemicals. Photosynthesis in the past provided all our fossil carbon resources. It now seems time that we recognize seriously and evaluate what photosynthesis can do for us in the future via traditional and non-conventional mechanisms, e.g. H₂ production, carbon fixation.     

Past,present and future status of electricity in Turkey and the share of energy sources

With a young and growing population, low per capita electricity consumption, rapid urbanization and—until recently—strong economic growth, Turkey for nearly two decades has been one of the fastest growing power markets in the world. Prior to Turkey's recent severe economic difficulties, Turkey's electricity consumption had been growing much faster than its production. It forces Turkey make a rapid action to supply electricity demand. Installed power generation capacity in Turkey reached about 31.84 GW in 2002. However, the growth in electricity generation has remained below the electricity demand, which made Turkey a net importer of electricity since, 1996. Projections show that Turkey's electricity consumption would continue over the next 15 years.     

An evaluation of the installation of solar photovoltaic in residential houses in Malaysia: Past,present, and future

This paper examines solar energy development in Malaysia, particularly in relation to the installation of solar Photovoltaic (PV) in residential houses. It analyzes the past activities related to solar energy in Malaysia, in terms of research and developments (R&Ds), the implementations used as well as the national policies for the past 20 years which have pushed the installation of PV in the country. The Feed-In Tariff (FiT) scheme is discussed, showing comparative cost-benefit analysis between the PV installation in houses in the United Kingdom (UK) and Malaysia, and with other investment schemes available in Malaysia. To investigate the awareness of renewable energy policies and incentives, a preliminary survey of the public opinion in Malaysia has been carried out, and an evaluation of public willingness to invest in the FiT scheme by installing the PV on their houses is presented. The cost-benefit analysis shows that the proposed FiT programme is capable of generating good return on investment as compared to the one in the UK, but the return is lower than other investment tools. The survey suggests that most Malaysians are unaware of the government’s incentives and policies towards renewable energies, and are not willing to invest in the FiT scheme.     

Fuel cells: past,present and future

Some of the euphoria of the early 1960s, which led to over optimistic predictions of the future of fuel cells, has now worn off.Mr Tantram charts the development of fuel cells from early laboratory experiments to the highly efficient, but expensive cells used in the Apollo space programme and assesses their future commercial prospects.     

Electric power systems: past, present, and future

The author mostly discusses the future of electric power systems, mentioning the past primarily to point out mistakes and so, hopefully, to avoid repeating them. The author discusses frequency and voltage control, complexity of systems, energy sources, and structure of the electric utility industry     

Natural cooling of stand-alone houses using solar chimney and evaporative cooling cavity

In this study a low-energy-consumption technique to enhance passive cooling and natural ventilation in a solar house, using a system consisting of a Solar Chimney (SC) and an Evaporative Cooling Cavity (ECC) has been proposed. The capability of the system to meet the required thermal needs of individuals and the effects of main geometric parameters on the system performance has been studied. The dependence of the system performance on outdoor air temperature has been studied to determine the operative conditions for appropriate effectiveness, regarding thermal comfort criteria. To determine the heat and mass transfer characteristics of the system, a mathematical model based on conservation equations of mass and energy has been developed and solved by an iterative method. The findings show that the system is capable of providing good indoor air condition at daytime in a living room, even with poor solar intensity of 200 W/m². The results show that when the relative humidity is lower than 50%, the system can make good indoor air condition even at 40 °C, and a higher performance is achieved using ECC with cocurrent configuration. It is found that the proposed system may be applied successfully in hot arid climates to fulfill the indoor thermal comfort expectations.     

Cooling potential of an evaporative cooling tower: Parametric studies

Dependence of the cooling potential of an evaporative cooling tower on the tower parameters (height h, cross-sectional area A_t, evaporative pad area A_p, packing factor of evaporating pads F_p and flow resistance f) has been investigated. The performance of the tower is studied for two different climates, namely hot-dry and composite, typified by Jodhpur and Delhi.     

Photovoltaic technology in Malaysia: past,present, and future plan

This article presents solar energy or specifically the solar photovoltaic (PV) development outlook in Malaysia. The paper first introduces the massive potential of solar energy in the country, the key players in the solar energy development and the early solar energy policies, and programmes in the country. The most important to the PV development is the Malaysia Building Integrated Photovoltaic initiative, which is presented in this paper followed by an explanation on the Feed-in Tariff recently introduced in the country to encourage new solar PV projects. The outlook for solar PV in Malaysia is optimistic and as the uptake of solar PV increases, the unit cost is coming down rapidly. Solar PV is expected to be the most competitive Renewable Energy (RE) source, with the potential to achieve grid parity for electrical power in the country in the near future, and surpassing all other REs combined by 2050.     

Substation battery options: present and future

Whenever a new battery type is considered, it is important to use life-cycle cost analysis that weighs all costs associated with battery ownership over a certain period of time, including the replacement of shorter-life batteries and all associated maintenance and testing activities. This article discusses the benefits and drawbacks of some of the potential alternatives to vented lead-acid batteries in substation service. These include VRLA, nickel-cadmium (Ni-Cd), nickel-metal hydride (Ni-MH), lithium-ion (Li-ion) and lithium polymer (Li-polymer). The aim of the article is to provide an overview of ongoing battery development work and an idea of the time-frame for commercial availability