solar hot water system

Solar hot water systems use the sun's energy to heat water in liquid-based solar collectors; they are almost always used along with conventional water heaters. Solar collectors for these systems are typically 3–6 m² in area and the systems are sold as a standard package like appliances. A typical solar hot water system can provide about 50% of the water heating energy needs in a home.


How they work

Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't.

Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.

Three types of solar collectors are used for residential applications:

• Flat-plate collectors
  
  Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors – typically used for solar pool heating – have a dark absorber plate, made of metal or polymer, without a cover or enclosure.



• Batch collectors
  
  Also known as integral collector-storage (ICS) system, these feature one or more black tanks or tubes in an insulated, glazed box. Cold water first passes through the solar collector, which preheats the water. The water then continues on to the conventional backup water heater, providing a reliable source of hot water. They should be installed only in mild-freeze climates because the outdoor pipes could freeze in severe, cold weather.



• Evacuated-tube solar collectors
  
  These feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin's coating absorbs solar energy but inhibits radiative heat loss. These collectors are used more frequently for commercial applications.

Poverty and environmental degradation Formidable challenges

The twin process of poverty and environmental degradation are among the most formidable challenges facing humanity today. The Food and Agriculture Organization has reported that the 10 percent of world population face starvation, 70 per cent of the population live in inadequate sanitary conditions and 1.5 billion people still lack clean drinking water.

This vast majority of people live in the Third World and depend on agriculture for their livelihood. Moreover, the single most important input for agriculture is land and it is here that the situation is most critical. Nearly a thousand million people are either landless or have so little land that cannot produce enough food to feed their households. Thus, limited access to land is undoubtedly a major cause of poverty in the Third World.

Lack of resources is the first element of the local poverty trap. This is especially true in Nepal where the per capita land availability indicates a very tight situation as it has declined from 0.17 hectare in 1985 to 0.09 hectare by 2005. It is estimated that, given the present yields, an additional around 1million hectares of land should be brought under cultivation if the deficit in calorie intake is to be met by increasing the production of food grains. Similarly, grazing pressure is higher than the carrying capacity of the land as the shortage of fodder of the whole country has become as high as 33 per cent. The average hill family maintains four cattle and two buffaloes and requires about 3.5 hectares of uncultivated forest to sustain each hectare of land under cultivation. Fodder shortage translates directly into a lack of manure, declining soil fertility and declining crop yield. As a result Nepal’s agriculture is suffering from low and declining farm productivity.

Inequality in land ownership also has a dramatic effect in environmental degradation. It confines the poor to marginal areas, and intensifies population pressure there. Moreover, the geographical concentration of poverty on inhospitable land is driven partially as people move in, but more so by the heightened population growth rates that poverty itself brings. Land degradation is, thus, now becoming a global problem. But it is becoming more acute in Nepal where due to rapid population growth, peasants in the highland valleys are forced to expand their plots on to steep, forested hillsides where land is less productive and tenure least secure.

The heavy monsoon rainfall often triggers mass wasting and landslide. In this extremely vulnerable region, increased terrace farming often at the peak of the hill, overgrazing and over cutting of the forest have resulted in the problem of degradation and desertification. As a result, Nepal is losing 240 million cubic meters of soil which is well above the maximum limit of acceptable soil level loss. The sediment load in the Nepalese rivers is alarming as river-beds in the Terai are rising 15 cm to 30 cm annually with excessive sedimentation. It is said that in around 200 years the Kosi river has shifted 115 kilometers westwards destroying land which had provided subsistence to 6.5 million people. Similarly, it is estimated that about 10,000 sq. km. in Dolpa and Mustang districts are devoid of vegetation indicating the desertification process.

In all this, the energy sources need focus as it has ramifications on the environment and thereby the status of poverty. The energy consumption rates to a considerable degree characterize the scale and efficiency of any society’s productive forces. While the energy commodities of the affluent are commercial, poor people largely depend on traditional energy.

Traditional forms of energy supply about 90 percent of energy consumption in Nepal; in which the share of fuel wood consumption is about 80 per cent. Because of this the national deficit in fuel is severe in Nepal and forests are declining at a very fast rate. The increasing cost of fodder and fuel-wood provisions are borne by family labor. As forests and pastures became degraded, fodder and fuel-wood must be fetched from increasing distance from less productive sources, using time that could otherwise be spent in income earning activity. Because of this, the working days in the field has shortened, family incomes have fallen, and diets have deteriorated. As a further result of forest depletion, dung is increasingly burnt in poor families as fuel instead of being returned as fertilizer to the soil. It is estimated that 8 million tons of dung are burnt each year.

Poverty should be placed on the environmental agenda as co-operator rather than competitor of those seeking economic and social development. It is also important to be aware of the costs of farmers on environmental measures and to be prepared to compensate them if necessary. In the meanwhile, it is legitimate to consider sustained production and welfare-oriented programs of support to the poor to protect the environment.

Saving the rainforests

The U.N.'s forest carbon scheme which has formed part of the negotiations at the climate talks in Copenhagen has been one of the few areas where countries are broadly in agreement.

The U.N.'s REDD (Reducing Emissions from Deforestation and Forest Degradation in Developing Countries) program is a collaboration between the U.N.'s Food and Agriculture Organization (FAO) and Environmental (UNEP) and Development (UNDP) programs.

Yemi Katerere, head of the U.N.-REDD program explained to CNN how the REDD program proposals would work.

"In theory REDD is a system to provide incentives for countries not to cut their forests," Katerere said.

"The incentive system is essentially that your trees are worth more standing than they are cut. You get a reward for not cutting your forests."

The idea is straightforward; If the function of rainforests -- capturing carbon, water catchment, weather regulators and biodiversity -- is recognized their value will rise.

The destruction of the world's rainforests is estimated to contribute to as much as 20 percent of total greenhouse gas emissions.

REDD envisages a situation whereby "different services can be marketed and paid for, boosting the incomes of other wise marginalized communities". Many pilot schemes are already underway.

Back in 1997 when the Kyoto Protocol was adopted, the part rainforests play in carbon storage wasn't recognized. Proposals to reduce emissions from deforestation were first introduced by the governments of Papua New Guinea in December 2005 at the COP11 talks in Canada. Talks at Copenhagen are hoping to build on the progress made since.

REDD say that more than 30 models of how the program should work have been put forward by countries, groups of countries and NGOs. Katerere wouldn't be drawn on the outcome of negotiations at Copenhagen when CNN spoke to him on Thursday.

Critics of the REDD program argue that it allows richer countries to meet -- to buy essentially -- some of their emissions obligations without cutting them at all. Others argue trying to measure what is being preserved and how much carbon is being stored will prove incredibly hard to quantify.

But Katerere said an imperfect program which can be improved is better than none at all.

"We should stop focusing on the negatives issues of REDD and start looking at the positives. In the short term, REDD offers use the greatest mitigation potential at an affordable price and is the most cost effective."

World Future Energy Summit 2010

World Future Energy Summit, the world’s platform for sustainable future energy solutions, provides an ideal networking event for industry leaders, investors, scientists, specialists, policymakers and researchers to discuss the challenges of rising energy demand and actions to achieve a cleaner and more sustainable future for the world

In April 2006, Abu Dhabi took a bold and historic decision to embrace renewable and sustainable energy solutions. As the first major hydrocarbon-producing nation to take such a step, it established its leadership position by launching Masdar, a global cooperative platform dedicated to finding and deploying solutions to some of the mankind’s most pressing issues: energy security, climate change and truly sustainable human development.

Under the patronage of H.H. General Sheikh Mohammed bin Zayed Al Nahyan, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the UAE Armed Forces, Masdar hosted the inaugural World Future Energy Summit in Abu Dhabi from January 21 to 23, 2008. The highly successful debut edition paved the way for an even larger and better attended World Future Energy Summit 2009, also held in Abu Dhabi

The World Future Energy and Environment exhibitions, along with the Summit, covered an area of nearly 40,000 sqm, housing more than 600 exhibitors from 44 countries. Together, the Summit and Exhibitions have created one of the world’s must-attend events in future energy, an unmissable networking and business opportunity for the energy and environment communities.

Reed Exhibitions and Elsevier, the world’s largest exhibitions company and the leading publishers of science information, are proud to announce the World Future Energy Summit 2010, in AbuDhabi from January 18 to 21. The four-day summit will build on the successes of its predecessors, with more than 30 individual conference sessions and more than 200 international influencers addressing future energy strategies, policies and technologies.

Copenhagen climate deal meets qualified UN welcome

UN Secretary General Ban Ki-moon has welcomed a US-backed climate deal in Copenhagen as an "essential beginning".

But he said the accord, reached with key nations including China and Brazil, must be made legally binding next year.

After intense wrangling, delegates passed a motion simply taking note of the deal, without formally adopting it.

The pact did not win unanimous support, amid outrage from some developing nations who said it lacked specific targets for reducing carbon emissions।

US-LED COPENHAGEN DEAL

• No reference to legally binding agreement
• Recognises the need to limit global temperatures rising no more than 2C above pre-industrial levels
• Developed countries to "set a goal of mobilising jointly $100bn a year by 2020 to address the needs of developing countries"
• On transparency: Emerging nations monitor own efforts and report to UN every two years. Some international checks
• No detailed framework on carbon markets - "various approaches" will be pursued