A Shining Example

What is solar power and why do we need it? Paul Allen investigates:

1) What's the problem?

Like it or not, whenever we use energy from fossil fuels, we are dumping carbon dioxide into the atmosphere. From the beginning of the Industrial Revolution, the rate at which we burn fossil fuels has increased every year. The rise of the automobile and the easy availability of cheap petrochemicals in the 1950s and 1960s has made this increase exponential. Now, fossil fuels are used on such a vast scale that the planet is failing to cope. The build-up of carbon dioxide in the atmosphere is now recognized as a major cause of the instability in the global climate, placing vast areas of the world at risk.

The world population has doubled since 1950. By the year 2030, more than 10 billion people will inhabit the earth. There is now little doubt that we can no longer enjoy our present consumption patterns without putting at risk the future of life on earth. In the developed West, we currently enjoy the benefits of a disproportionately large share of the world's energy; yet the whole planet carries the burden of our emissions. As the global demand for electricity rises - particularly in China and the rapidly developing Eastern economies - there is little doubt that this vast increase in emissions will have dramatic consequences for the global eco-system.

The world cannot support our socio-economic activities. The time is ripe for consideration of alternative models of development.

2) What do we mean by being 'green'?

The roots of the modern ecological movement are diverse. Its development was an inevitable reaction against the effects of the Industrial Revolution. The energy of the Luddites, the voluntary simplicity of the Quakers, the views of nature developed by the Romantic painters and poets such as Blake and Shelley, the reaction against the rampant consumerism of the 1950s ..., all this came to a head in the early 1970s. In 1972, Peter Harper coined the term 'alternative technology' to describe attitudes and approaches to working with nature. This idea has been with us for over twenty-five years now, an intuitive reaction to our diminishing natural environment. Although self-sufficiency was once thought to be the solution, the past two decades have seen an increased emphasis on the notion of sustainability - engaging society, rather than dropping out of it.

3) Meanwhile out in Space

A most fascinating process is going on. Inside the sun, matter is converted directly into energy by the process of nuclear fusion, where small amounts of matter yield an enormous amount of energy. This potential is illustrated by Einstein's famous law E = mc², where E is the amount of energy created, m is the mass of matter destroyed and c is 3 x 10⁸ metres per second - the speed of light. In fact, the sun generates a massive 3.94 x 10²³ kW of power all day, every day.

This radiated energy takes about 8 minutes to cover its 93 million mile journey to reach us on earth. The total energy reaching the surface of the earth is about 80,000 x 10¹²W, or 10,000 times the current global energy demand. As it heats up the surface of the earth, it causes air to move around the planet, creating the global windpower resource. Some of this wind energy is concentrated by the sea, giving us the world's wave power resource.

Four-fifths of the sun's energy falls on the sea, driving the water cycle. Ocean evaporation causes rain to fall on the land, creating the global hydropower resource. The remaining fifth, which falls on land, is still about 2,000 times greater than the total world energy demand. This can be captured using a variety of solar technologies.

4) Technologies to capture solar energy (three different kinds)

There are three different ways we can capture the sun's energy:

a] Passive Solar; Space heating by conscious design of buildings.

Using buildings to collect the sun's warmth was a technique the early Greek and Roman builders developed into a serious form of solar architecture, as did the builders of the Pueblo villages in the American South-West and the Inca builders in Machu Picchu. Forms of solar architecture were also developed by Muslim architects, who used the minarets of mosques as solar chimneys. The exploitation of cheap fossil fuels made solar design too troublesome to bother with until the steep rise in oil prices, orchestrated by the OPEC countries in the 1970s.

Today, passive solar design is the most commercially mature of all the solar technologies, competing very well on direct cost terms with conventional energy sources. It can provide up to 70% of a building's energy needs by using sensible design and solar orientation; the increase in cost is marginal. Large glass windows or conservatories on south-facing surfaces take advantage of large amounts of free energy. Excessive heat is avoided by using overhanging balconies or planting trees nearby - these reduce sunlight during the summer, but let it in during the winter when the sun is low and the leaves have fallen.

b] Solar thermal; using solar energy to heat water.

A solar water heater is simply water pipes painted black to improve heat absorption. The small diameter of the pipes ensures that a large surface area of water is exposed to the sun. The pipes are placed in a small 'greenhouse' to insulate them. Originally developed in response to steep rise in oil prices in the 1970s, solar water heating got off to a very rocky start. The wild claims and poor engineering of many 'cowboy' manufacturers and installers undermined the credibility of the industry on both sides of the Atlantic.

Today, those problems are behind us. The UK alone has over 40,000 solar water heating systems. A survey in 1995 found that most were saving up to £200 per year, and around 75% of customers were 'very satisfied' with their systems. Solar water heating is commercially mature technology, competing very well with conventional energy sources - although, obviously, the payback time relates directly to the available solar resource of any particular site. Typical installation costs vary from about £800 for a 'Do It Yourself' system, to £3,000 for a commercial system which can provide approximately 60% of typical domestic hot water needs in the UK. Even though 500,000 square meters of panels are sold each year, there is room for improvement. 1.4 million households in Europe now use solar water heating, but this still only represents 1% of the potential market. The rate of installation in the UK could easily be increased with government incentives. The Dutch Ministry of Economic Affairs, for example, is working closely with industry and the energy utilities. Together, they are approaching consumers, housing corporations, property developers and municipal authorities with a campaign to ensure that some 400,000 domestic systems will be installed by 2010. Such cooperation has already put the Netherlands ahead of many of their European counterparts. The world's largest domestic solar hot water project to date was completed at Apeldoorn, where 1,000 houses were provided with systems. The project partners learned much about the reality of cost reduction through large scale installation and user feedback. In the UK, a project to install 100 systems will soon be completed in three developments in Swansea, Glamorgan, and Barry. It is part of a Thermie project aiming to install at least 3,000 systems in new-built properties in Germany, Denmark, the UK and the Netherlands before 1999.

c] The 'Photovoltaic effect'; generating electricity from sunlight.

Exploration of the photovoltaic effect began a surprisingly long time ago. In 1839, the French scientist Bequerel noticed that when light was directed on to one side of a simple battery cell, the generated current could be increased. Thirty-four years later, the British scientist Willoughby Smith discovered that selenium was sensitive to light. He found that selenium's ability to conduct electricity increased if it was exposed to more light. This discovery inspired scientists to carry out further experiments with this rare element. In 1880, Charles Fritts developed the first selenium-based solar cell. Research continued on the selenium solar cell throughout the first half of the twentieth century, despite its very low efficiencies and expensive production costs.

The real breakthrough came in the 1950s when Bell Laboratories discovered that silicon - the second most abundant element on earth - was also sensitive to light and generated a substantial voltage when treated with certain impurities. By 1954, Bell had developed a solar cell using silicon as the base material which achieved an efficiency of 6%. The first industrial use occurred soon afterwards: the powering of a remote telephone repeater station in rural Georgia.

In the late 1950s, NASA installed a 108-cell photovoltaic array on America's first satellite, Vanguard One. The costs for such systems are understandably quite high, reaching over US$100 per watt. For earth-bound applications, where environmental and size constraints are not nearly so severe, much cheaper devices have been developed.

Although economically it is not yet a fully mature technology, photovoltaic technology is now on the threshold of a performance-to-cost capability which would permit it to make significant advances in many new market areas. With costs falling each year, photovoltaics is already commercially mature in many remote applications, where it can compete with the higher installation costs of long links to the grid or expensive generation from diesel sets. Such applications already include healthcare in the developing world, telecommunciations repeaters, cathodic protection of pipelines, and marine buoys.

In grid-linked applications, photovoltaic electricity is currently almost five times more expensive than conventional electricity. This is mainly due to economic factors:

• The economies of scale support conventional technologies.
• There is still no levy on fossil and nuclear sources for polluting the environment.
• Direct subsidies to oil and gas (£9.2 million in the UK during 1996 - Greenpeace).
• Direct subsidies to coal (£6.3 million in the UK during 1996 - Greenpeace).
• Subsidies to nuclear (£11,544 million in the UK from 1990 to 1995 - Greenpeace).
• Renewables in the UK received only 2% of the subsidies directed at fossil fuels and nuclear energy in the UK from 1990 to 1995, the second lowest in the EU (Greenpeace).

During the past five years, grid-linked photovoltaic has gained cost advantages through the integration of electricity generation modules into the design of buildings. The costs of displaced building materials help offset the cost of the photovoltaic generators. Photovoltaic generators operate with no moving parts, noise or pollution, making them the most appropriate renewable energy source for use in urban areas. In the UK, there are at present only six photovoltaic roofs, in contrast to forward-thinking countries such as Germany where there are over 1,000 already in operation, with plans for many more. Such a long-term perspective builds up the skills base and technical infrastructure. Between 1976 and 1988 the cost of photovoltaic panels fell at a rate in excess of 15% per annum. As the costs approach those of conventional building cladding or roofing materials, solar power will allow buildings to generate their own electricity - selling it to the national grid when they have a surplus, and buying electricity back when they have a deficit.

To provide a PV power supply capable of meeting the demand from a typical domestic energy efficient house costs in the region of £20,000. Although this may seem quite high, it is not an unreasonable proportion of the cost of building a house.

5) The next move - to maturity and beyond.

If we are to see the necessary commercial maturity required to implement solar thermal and solar electric systems on the scale required to have a significant effect on global warming, we will need to see a more coordinated incubation process. In the Netherlands, for instance, the government, power companies, architects, planners, financial institutions, local authorities, scientists and manufacturers are co-operating in order to develop solar energy. Projects such as the Nieuw Sloten estate in Amsterdam show what can be achieved. By integrating PV modules into 34 low-level and 37 highrise properties, the project generates 250kW peak into the local grid, enough for 100 households. Needless to say, all the houses have been sold!

As electricity markets are opened up in 1998, new economic systems must be put in place. Plans are already underway for green electricity companies. This will make renewable energy available to all consumers for only a small increase in cost and offer a fair price to renewable energy generators. At first this offer may concentrate on large industrial users, but domestic consumers must also be given this choice through a 'green tariff' system. The Dutch energy company Nuon is currently using such a system to fund a six-fold increase in its solar electric generating capacity between 1996 and the year 2000, bringing it up to 6,000 megawatt hours per annum. The system has proved both cost effective and popular - so much so that the district council in Apeldoorn has recently switched to the green tariff for its public buildings.

6) The solar electric roof at CAT

At midday on the 9th May, Brian Wharmby, technical director of the UK's electricity regulation board OFFER, opened Britain's largest solar roof. It will generate over 13 kW into CAT's independent electricity grid. Covering an area of over 100m2, the roof will generate 9 megawatt hours of electricity each year. Constructed using an innovative mounting system developed by CAT and The University of Wales, the new system allows standard solar modules to be integrated into buildings, either as part of the roof or as cladding such as that used on prestige commercial buildings. The roof will be monitored using equipment supplied by Dulas Ltd of Machynlleth and the Energy Equipment Testing Service from Cardiff, providing performance data vital to the design of future large scale solar power projects. CAT's next step will be to export surplus electricity to the grid using the 'Powergate'. This device will also test ways in which non-critical loads can be switched off briefly to remove the need for large amounts of spinning reserve in the grid. Such moderation would smooth out the high peaks in demand, thus improving the overall energy efficiency of the grid system.

7) What's the solution?

Clearly, if solar energy is to make a significant contribution towards social, economic, and ecological sustainability, we will need to see a combination of the following factors:

• Pioneering solar projects such as CAT's solar roof, which illustrate what is possible and help kick-start the economies of scale.
• New economic systems such as the green tariff, making green electricity accessible to everyone regardless of where they live, and offering a fair price to solar generators.
• A large scale, centrally-funded energy-efficiency programme to help us all do more with less.
• Diversion of all subsidies away from fossil fuels into subsidies for renewables.
• A new era of cooperation between industry, local and national government, architects, planners, power companies and customers, to bring about the solar revolution.

In its election agenda, the new Labour administration made many claims regarding its support for renewable energy. Now is the time to demonstrate the Government's genuine commitment. Let's follow the shining solar examples set by the Netherlands, Germany, and our other European partners. Action is urgently needed from the developed economies to produce a mature programme for the advancement of solar and other renewable technologies. This is vital if we are to help China and the emerging Eastern economies 'leapfrog' excessive fossil fuel emissions and move directly to the sustainable alternatives. We must act now, before the global cost in terms of climate change becomes to high for all of us.

The information on this page has been taken from an article which originally appeared in the Summer, 1997 edition of Clean Slate Magazine.

 
 
 

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