James Hunt examines how the potential of solar power can be turned into a more widespread reality in the following article originally printed in European Power News Magazine, published by Voltimum Media Partner Highbury Business:
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Many mainland European countries have embraced renewable energy as a potential solution to environmental issues and security of supply. However, solar power remains low in the mix, particularly in the relatively unfavourable climate of northern Europe. Despite this, with average temperatures set to increase further throughout the 21st century, the picture is beginning to change. A good example of this is the UK Renewable Power Association's establishment of a working group to promote solar technology.
Today, with the onset of global warming - man-made or otherwise - now clearly well under way, the race is on to develop more 'eco-friendly' sources of power. Renewables, as they are termed, include solar energy. So-called 'sustainability' is the key and the ultimate aims are to reduce 'greenhouse' gas emissions (CO2) from the burning of fossil fuels, help global fossil fuel reserves last longer and reduce dependence on other countries' reserves.
It has been estimated that, if a mere two percent of buildings capable of having solar air-conditioning installed had it, the emission of CO2 into the atmosphere could be reduced by 27,000 tonnes.* Another estimate has it that 100 square miles of solar (photovoltaic) arrays would power the entire United States!
Solar energy conversion types:
Power from our sun is converted into usable energy in either one of two ways:
- To electrical power through solar cells (photovoltaics - or PVs).
- Directly to heating or energy storage systems through heat exchangers (solar thermal).
Both require sun-absorbing arrays of equipment to generate significant power. These, especially photovoltaic solar arrays, can be extremely large. Individual PV cells can vary in size from about 1 to 10 cm.
Photons from sunlight generate an electron flow proportionate to its strength. Each solar cell produces about 0.5V (1 to 2W equivalent) and connecting the cells in series makes for higher voltages. Therefore larger solar panels tend to be more efficient. A current trend is towards thin-film technology. This allows more efficient use of space - and should, therefore, increase applications.
PVs have been used at remote sites to provide local electricity. However, the trend is towards distributed generation with the unbundling of transmission and distribution costs because of electricity generation deregulation. Numerous small-scale PVs in distribution feeders could improve the economics and reliability of national grid systems.
Swimming pools, homes, and large buildings can all use solar thermal technologies to advantage to provide heat for water and heating systems. Heating a building needs rooftop solar collectors to collect the solar energy and convert it to heat energy. Stored water or air is warmed by the solar heat to be used when needed. A back-up conventional system is necessary for an extended period of cloudy days. This acts as a 'battery'. Current practice is to use flat-plate solar-energy collectors with a fixed orientation. Solar thermal arrays - suitably focused - could also be used to generate steam or to drive small Stirling engines for domestic CHP systems.
So far, solar energy conversion of whatever type has been relatively little used in Northern Europe. Why? One often quoted reason is that Northern Europe's climate is too dull with insufficient sun. Another is that, to gain sufficient power, many solar arrays may be visually intrusive. But is all this really a hindrance? It would be a good idea to check the advantages and disadvantages of using solar power energy conversion.
Solar energy advantages:
- It is emission-free.
- It comes free of charge - apart from capital expenditure.
- The energy from PVs is produced during peak demand.
- It is never going to run out.
- It is ideal for many applications.
- It can save money for businesses and householders alike.
- There are many incentives for using it - from tax exemptions to a clear conscience.
- Installation is straightforward.
- Users can sell excess electricity back into the national grid.
- It can be cheaper for remote households to install solar arrays than to connect to the national grid.
- Solar arrays do no long-term damage to the local environment.
- Independence and reasonable freedom from power outages.
Solar energy disadvantages:
- The energy density is low.
- Pay-back times can be lengthy.
- Wherever they are sited, solar arrays can be visually intrusive.
- Solar arrays can be significantly affected by overcast or rainy days, and by the dark.
However, while many current PV cells are about 10% efficient in converting sunlight, it is expected that, in the near future, this will be raised to 20%, making this last disadvantage less significant.
Legislation and initiatives:
Expedience and politics are determining both local and macro energy policies in the EEC. The Clean Air Act has been in force for many years but the UK Business Council for Sustainable Energy believes that this Act's regulatory framework is too uncertain and time-consuming. The BCSE promotes the economic and environmental benefits of clean energy. It also supports tax policies that promote clean energy supplies and technologies that help improve the environment and reduce reliance on imported energy.
"Reaching the CO2 emissions levels needed for sustainability - around three tonnes per capita annually - in time to avoid major environmental degradation becomes harder the longer one delays", comments Rian van Staden, Executive Director of the International Solar Energy Society, an international NGO headquartered in Europe. The European Solar Cities Initiative (ESCi) was launched in June 2003 at the ISES Solar World Congress, held by the International Solar Energy Society in Sweden. This initiative was founded by global, regional and local organisations interested in the 'built-environment' sustainability sector. The group, representing parties from academia, NGOs, the building sector, industry and policy groups, achieved strong consensus on the need to greatly reduce emissions in European cities to avoid environmental, economic and social disaster.
"ESCi is a coming together of all actors, including city networks" van Staden adds, "in the creation of a new force for sustainable cities and communities in Europe. It will make possible a co-ordinated and synergistic push towards a European urban environment that is fit for the future - by creating the next generation of European Solar Cities."
Renewable energy represents an important priority in developmental policies in Europe. The Union currently leads the way in the development and implementation of environmentally sound energy technologies. It has recently been estimated that global sales in photovoltaics could reach 3,500 MW annually by 2010 with a global turnover of £11 billion. The Association of UK PV Manufacturers has estimated that around 19,000 jobs could be created in the UK with just 15% of this market. So far, the UK has invested little in solar energy, while solar manufacturers in mainland Europe are more likely to set up plants in countries such as Germany where installation rates have apparently reached 11MW annually. A government programme for solar roofs has helped promote this. Forum for the Future aims to bring solar PVs to the UK market and estimates that capacity could be raised to between 392 - 500 MW by 2010. The European PV Industry Association has estimated that production, installation and maintenance of PVs could directly employ 294,000 people in the EU by 2010. First movers will almost certainly reap the rewards. **
In another, non-solar power specific initiative, an effort is being made to raise awareness of 'green' electricity. Local authorities and industrial consumers across Europe are being encouraged to switch to green electricity, as part of a campaign by Green Electricity Marketplace (www.greenelectricity.org) and the World Wide Fund for Nature. The project, 'Save the climate: switch to green electricity', which is part-funded by the European Commission's DG Environment, is only supporting green electricity products which comply with criteria defined by Europe's green electricity NGO coalition, EUGENE. The criteria aim to ensure that support is only given to those tariffs which lead to new capacity being built. Double selling of green generation is to be discouraged.
European Power News asked Graham Meeks, Deputy Director at the Combined Heat and Power Association (CHPA), about the organisation's attitude to solar power. He said: "In many respects the problems facing the development of solar energy are similar to those that continue to confront CHP.
"In the Energy White Paper, Government largely ignored the recommendations of the Royal Commission on Environmental Pollution to develop a comprehensive strategy for the supply and use of heat. The result has been that the opportunity to save carbon through sustainable heat sources, such as solar and CHP have been given little emphasis in policy terms.
"Micro-generation technologies, such as PV and micro-CHP offer major potential for the future, as volume production slashes unit costs. But both need a major policy driver to establish the proper commercial structures and technical standards to realise large scale exploitation."
Conclusion:
Solar suffers from many of the same problems as CHP. Firstly, as CHPA has pointed out, the Government's apparent fixation with electricity ignores the enormous contribution that solar thermal and CHP can make in developing sustainable thermal energy supplies. Moreover, the small scale of PV and micro-CHP face similar institutional and technical challenges that are all too often placed in the 'too hard' category by policy makers.
However, the conversion efficiency of PVs is likely to be nearly doubled in the relatively near future. In any case, there is a clear and currently increasing trend towards ever warmer weather with more sunshine in Northern Europe. This, combined with the still greater political emphasis on use of renewable energy generally, can be expected to lead towards greater application for solar energy systems.
*Ref: European ALTENER programme.
** Ref: Trade Union Sustainable Development Advisory Committee (from DEFRA)
All pictures of Solar Energy Installations' application were kindly supplied by the company.
An application - eco-friendly lighting solution
Stand-alone solar powered bollards have been piloted in Pembrokeshire to light a public footpath inside a disused railway tunnel - also home to some unusual residents. South Wales based SolarGen Solutions successfully completed the project, recently commissioned by Pembrokeshire County Council, by providing a cost effective and eco-friendly lighting solution to their problem. The brief was to design and install lighting to improve safety and reduce the incidents of vandalism at a walkway, while making sure it remained dark enough to house its other occupants - two breeds of bats.
The stand-alone bollards are powered by solar panels located on the frame above the tunnel. These store enough electrical charge in batteries during daylight hours to power the bollards, therefore requiring no expensive external cabling or electrical supply. Furthermore, the bollards are bright enough to illuminate the tunnel for the public, yet do not to disturb the bats' natural habitat.
Ashley Wood, sales manager of SolarGen, said the UK could receive as much as two thirds of its total energy requirement from solar power. He commented: "Our unique solar solutions can be applied to just about every public lighting requirement. These bollards for example, meet all regulatory standards, both in terms of adequate lighting for a public footpath and a suitable level of light for the bats to survive, are very durable, require very little maintenance, making them a very cost-effective solution.
In another recent SolarGen example, Monmouthshire County Council (MCC) has installed its first solar lighting panel in the village of Shirenewton in an area by the churchyard where it would have been impossible to bring mains supplies.
This article was originally published in European Power News magazine by Highbury Business Communications - a Voltimum UK Media Partner.
Contact: Steve Ducker
European Power News
Highbury Business Communications
Nexus House, Azalea Drive, Swanley, Kent BR8 8HY
Tel: 01322 660070
Fax: 01322 616376
Email: s.ducker@highburybiz.com
Web: www.hhc.co.uk
And: www.electricaltimes.co.uk
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