By HDK / Published on Wed, 2009-05-27 08:10
The development of photovoltaic (PV) panels has made solar-powered pumps a reality. The pump drivers are usually direct-current (DC) motors, which are fed by power electronic converters with maximum power point tracking (MPPT) to extract the whole energy that the PV panels can generate, depending on environmental conditions including irradiation and temperature. The implementation of the MPPT algorithm essentially involves sensing both an input current and an input voltage. Understandably, such realisation is expensive.
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By Bruno De Wachter / Published on Thu, 2008-07-24 05:30
Where is the catch?
Arthur C. Clarke’s famous paraphrase of J. G. Ballard 'that any sufficiently advanced technology is indistinguishable from magic' seems to gain in strength every day. So much that we are all — even the most sophisticated or sceptical of us — ready to accept almost any 'new advance of science' as fact without serious questioning.
Sometimes technology does indeed appear to be close to magic. The Japanese company Genepax claims to have constructed an eco-friendly car that runs on nothing but water. The press agency Reuters walked into the trap with open eyes and published their promotion video.
'It almost sounds too good to be true', says the British commentator on the video. Of course it is too good to be true. Can you find the catch?
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By Angelo Baggini / Published on Thu, 2008-07-17 09:00
Year: 2006
Policy Status: In force
Under the auspice of DEFRA, the Market Transformation Programme publishes Product Strategy Guides and Policy Briefs, which set out the measures required to reduce the energy consumption of appliances. These Policy Briefs are public consultation documents that inform UK Government decisions on product policy.
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By Sergio Ferreira / Published on Wed, 2008-05-21 17:08
It certainly can, but whilst heating to the high temperatures required, the efficiency reduces. However, even low efficiencies are far better than an electric immersion heater. Most of the latest heat pump units have the hot water function built in, so it is usual to use this facility.
As the insulation levels in buildings increases, the heat demand drops, but the hot water demand is, if anything, increasing. It is therefore becoming more important to optimise the hot water facility, i.e. the size and design of the hot water cylinder are very important.
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By Hans Nilsson / Published on Sun, 2008-04-13 21:55
We are now so used to talking about climate change in terms of policy, of technicalities, such as GHG-concentration in PPMs and of technologies/fuels, that we tend to lose sight of the object itself – the physical impact on everyday life. The latest IPCC-report is, however, of great help to understanding this. What will climate change do to me?
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By Hans Nilsson / Published on Mon, 2007-10-29 08:00
The Chinese leadership confirms, in the recent party-congress, its intention to change the economy for the better, not only in terms of volume, but also in terms of environmental quality. The question is, however, whether it will work, or if they have already passed some critical crossroads from which there is no turning back.
The energy situation is bad, but water pollution might be worse
The Magazine 'Foreign Affairs' has a broad survey in their latest edition that shows the state in several sectors and aspects, including water supply, deforestation, urbanization, air quality etc. The survey covers more aspects than we normally see in the reporting on China. It is still not comprehensive, but rather a gathering of snapshots. As such, it still gives more facets to the overall understanding on both why the leadership is so concerned and where the present development could lead.
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By Sergio Ferreira / Published on Fri, 2007-09-21 15:39
The worldwide run-off of fresh water to the sea is about 4 x 1013 m3 y -1 . Half of it is delivered by the 50 largest rivers. It is assumed that this will increase due to the effect of the global warming alone by 11% and an extra 6% by the reduced transpiration of plants due to the increase in CO2 content in the atmosphere. Earlier estimates of the River Elbe in Germany with an average run-off of 800 m3 /s over one year gives a 1900 MW mechanical power to be harvested.
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By Bruno De Wachter / Published on Mon, 2007-08-13 07:30
Desalination by either evaporation (EV) or reverse osmosis (RO) is very energy intensive. However certain methods have been developed for reducing energy usage and greenhouse gas (GHG) emissions, as well as for powering installations where it is not feasible or is impractical to connect to the electricity grid.
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By Sergio Ferreira / Published on Thu, 2007-08-09 15:49
Renewables are trendy, that is undisputable, but some concerns are being raised about the “invasion of nature” we need to do in order to meet our energy needs using renewable energy sources. The lacks of materials, workforce for maintenance or even land to install renewable technologies are some of the issues being raised.
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By Bruno De Wachter / Published on Thu, 2007-08-09 12:26
Closely linked to energy issues
Accessible fresh water resources around the world are severely limited. In fact they represent only 1 per cent of all water on earth. Desalination of abundantly available seawater is one solution for producing fresh water for drinking, cooking, sanitation, agricultural irrigation, and industrial applications. However, desalination is a very energy intensive process and its potential is therefore limited by the availability of cheap energy. Consequently, the global fresh water problem is directly coupled to global energy issues.
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By Bruno De Wachter / Published on Tue, 2007-04-03 07:30
Greater than direct domestic water usage
With all the concern about carbon dioxide emissions, it is easy forget that other major environmental issues exist in the electric power sector. One of them is the use of freshwater by thermoelectric power plants (coal, nuclear, oil, steam side of CCGT power plants). Water withdrawal by thermoelectric power plants is huge, averaging about 95 litres per kWh. Coal-fired power plants with once-through cooling systems withdraw 142 litres per kWh while nuclear power plants with once-through cooling systems require as much as 175 litres per kWh.
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By Hans De Keulenaer / Published on Sat, 2006-09-23 10:19
All energy technologies have major advantages and disadvantages, and hydropower is no exception. In this briefing paper, Juergen Giesecke from Energie-Fakten presents a comprehensive overview of pros and cons, and a message that dams can make a major contribution to mankind's energy (and food) supply, provided that we exploit the pros while mitigating and managing the cons.
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