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Renewable Energies In Practice- Ashton Green And London


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The UK has outstanding possibilities of contributing to climate change (CC)
through wind renewable energy technology (RET). Further development is expected from
geothermal source heat pumps (GSHP), biomass, hydroelectric and passive solar design`RETs. The UK has a limited quantity of resource for solar power. Hydrogen RET
possibilities are still unknown.
Ashton Green (AG) and London are examples of rural and urban developments
respectively renewable energy (RE) developments. Both approaches depend on the availability of resources in-site. AG approach bears the economics more than London, which targets to be in the vanguard of RETs development.
Technology has evolved significantly since AG project was started. This can lead to
a review of the technologies to be implemented. London, on its side, may consider the possibility of settling an Energy Service Company (ESCO) to serve the city as energy service provider.

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Renewable Energies In Practice- Ashton Green And London

  1. 1. 1 Alejo Etchart January 2009 RENEWABLE ENERGY IN PRACTICE: ASHTON GREEN and LONDON 1. Executive Summary The UK has outstanding possibilities of contributing to climate change (CC) through wind renewable energy technology (RET). Further development is expected from geothermal source heat pumps (GSHP), biomass, hydroelectric and passive solar design RETs. The UK has a limited quantity of resource for solar power. Hydrogen RET possibilities are still unknown. Ashton Green (AG) and London are examples of rural and urban developments respectively renewable energy (RE) developments. Both approaches depend on the availability of resources in-site. AG approach bears the economics more than London, which targets to be in the vanguard of RETs development. Technology has evolved significantly since AG project was started. This can lead to a review of the technologies to be implemented. London, on its side, may consider the possibility of settling an Energy Service Company (ESCO) to serve the city as energy service provider. 2. Introduction: UK aims and goals This work analyses the practice of renewable energies (RE) through the cases of a rural site like Ashton Green (Leicester) and a capital like London. The AG and London analysis are introduced by an explanation of the current British situation in the energy field and a more detailed analysis of the different renewable energy technologies (RET) available. The UK is currently responsible for around 3% of the world’s greenhouse gas (GHG) emissions, despite having only 1% of the world’s population. The UK was assigned by the Kyoto protocol a target of 12.5% reduction in average annual emissions in the period 2008-2012 below the levels of 1990. Being that this goal has largely been surpassed (Table11), the UK government seeks to reduce emissions to 20% below 1990 levels by 20102.
  2. 2. 2 Table1 In spite of EU’s general binding target of 20% of energy consumption coming from renewable sources, the UK was exceptionally proposed a level of 15% by the European Commission. The UK occupies the 19th place in the EU-27 for its RE share in total energy generation (Table23) Total Hydro* Wind Biomass Solar Geo- 2010 Share thermal TARGET EU27 14.5 9.2 2.4 2.7 0.074 0.2 21 (…) 1 Austria 56.6 49.6 2.4 4.5 0.021 78.1 2 Sweden 48.2 41.3 0.7 6.2 60 3 Latvia 37.7 36.5 0.6 0.6 49.3 (…) 19 United 4.6 1.1 1 2.5 0.002 10 Kingdom (…) 25 Estonia 1.4 0.1 0.8 0.4 5.1 26 Cyprus 0 0.021 6 27 Malta 5 Table2
  3. 3. 3 The House of Lords, in their report 12/11/083 comments the effects of the 15% proposal for the UK: 1) It implies an enormous change from the current 1.8% of total energy consumption coming from RETs to 15% in 12 years, coinciding with the need to replace old coal and nuclear plant and to meet demand increases. The UK energy flows in 2007 are shown in the Figure 1 3. Figure 1 2) Most of the increase is expected from wind turbines, which only produce electricity intermittently, so other REs are needed to cover the demand due to the lack of advance in electricity storage -technology that the House of Lords proposes to encourage. Hydroelectric, domestic biomass and solar energy approaches are said to be insufficiently scoped by UK government, while tidal barrage and wave are seen as in an early stage of development. 3) The Government support is needed to promote investments. Following the EPSRC4, buildings are responsible for 45% of UK carbon emissions, so a reduction of 50% in the emissions associated with UK buildings by 2030 is considered key for success. 3. RETs available. Figure 2 shows the current share of RE sources in energy in the UK
  4. 4. 4 Figure 2- Generation from RE sources in the UK3 3.1. Wind Following the BERR, 20045, - The UK has the largest potential wind energy resource in Europe - Wind power is currently one of the most developed and cost-effective RETs (ibid.). Wind being intermittent, it is important to consider the load factor achieved by a wind generator when calculating its value to the system. The load factor is the actual electricity generated, expressed as a percentage of the potential amount had the turbines been permanently operating at full capacity. The House of Lords3 provides an overview of the current situation and perspectives of wind energy: - In 2007, the load factor was 27.5% for onshore wind farms, 28.3% for off-shore turbines and 1-2% for small generators in urban areas. - Wind power was up to 43% of RE generation electricity capacity in Britain at the end of 2007. Taking into account the load factor, the share in RE actual generation was 27% (23% onshore and 4% offshore). - 179 onshore wind farms existed in October 2008, with a 2.3 GW capacity (3% of Britain's electricity capacity). Another 424 farms are planned, adding up a capacity of 13.8 GW. - Only eight offshore wind farms are nowadays in operation (0.6 GW capacity). The currently existing projects and the plans announced could generate up to 33.2 GW.
  5. 5. 5 Calculation of the Annual electricity production (e): e=KVm3AtT Where: - K= performance factor, normally valued 2.5 - Vm= average annual wind speed - At= turbine swept area - T= number of turbines. 3.2. Biomass- Combined Heat Power (CHP) Biomass includes a number of renewable fuel sources derived from organic matter, such as landfill gas from decomposition of organic material in landfills, sewage gas from biodegradable waste, wood, forestry wastes and energy crops. Biomass is not intermittent. Therefore, generators from biomass are used more intensively than most other RETs. Its share of electricity generation is therefore greater than its share of capacity. Following the House of Lords3, - Biomass provided 2.3% of the total electricity and almost 50% of the renewable electricity of the UK in 2007 (24% from landfill gas). - Most landfill sites are already being exploited. Growth in biomass might come from waste or energy crops. Figure 36 Combined Heat and Power (CHP) generation technology converts these renewable inputs into energy as shown in Figure 3. It uses a gas or steam turbine or an engine to drive an electricity generator, making practical use of the heat necessarily generated in
  6. 6. 6 the electricity production. When the input is biomass, the process is carbon neutral, because the CO2 emitted during the combustion equals the CO2 previously captured by the biomass. The energy is released by burning the fuel with air, producing large amounts of combustions gases at high temperature. Part of the heat is used to pressurize the gases, providing the force to drive an engine or turbine to produce electricity. Fuels can be solid, liquid or gaseous. Installations can be designed to accept more than one fuel. For solid fuels, dryness is a key factor to efficiency. Following the GPG437, the efficiency of CHP plants with latest technologies exceeds 80%, compared to standard fossil fuels plants which are typically 35%. Larger CHP schemes require up to 4,500 yearly working hours to be economically efficient; for smaller sizes, the minimum can be 4,000 hours. To calculate the energy generated (e) with biomass, the conversion efficiency per type of biomass used (c.e.) must be known: e=∑(biomass resource*c.e.) 3.3 Passive solar design Passive solar design involves the application of design principles such as south- facing windows to make sure that excessive heat loss is avoided and solar radiation is captured, in order to minimise the need for heating and lighting. The reverse is also true, so that minimising the capture of solar radiation, coupled with the use of natural ventilation, helps to reduce dependency on mechanical systems such as air conditioning. 3.4. Solar Hot Water (SHW) SHW technology uses collectors, usually placed on the roof of a building, to capture and store the sun’s heat via water storage systems. The collectors gather solar radiation (direct, scattered and reflected), providing heat to a fluid that circulates to a water tank. This hot water serves to heat the water allocated in a collector cylinder. The system is used for heating water in buildings and swimming pools. SHW systems have three main components8: 1) Collectors (solar panels) can be: a) Flat plate systems (Figure 4)
  7. 7. 7 Figure 4- Flat-plate SHW system9 b) Evacuated tube systems (Figure 5) Figure 5- Evacuated tube SHW system 9 2) Heat transfer system: uses the collected heat to heat water; 3) Hot water cylinder: stores (for a limited period of time) the hot water that is heated during the day and supplies it for later use. The orientation for SHW collectors must be within 30º south, and tilt must be maximum 45º, in a site with minimum shadowing, to reach its best performance9. Both PV and SHW have the limitation that the UK have a very limited resource for solar power, and the likely capacity factor was of the order of 11% 3. The installation cost for a domestic system is £3,000 - £5,00010. Energy output (e) calculation: e=ArE
  8. 8. 8 Where - A= Area of solar collector - r= Radiance of the sun falling - E= Efficiency of the solar water heater 3.5. Solar Photovoltaic (PV) Solar photovoltaic technology converts daylight into electricity by means of a semiconductor material such as silicon. When light comes to the semiconductor, the energy contained in the light breaks the electrons in the semiconductor free from their atoms. Electrons flow then through the semiconductor material, producing electricity that can feed the building or be sent to the grid. PV technologies include polycrystalline, mono-crystalline and thin-film materials. Latest technologies allow cells to be integrated directly into the roof tiles. Energy is only produced during the day, and varies depending on the cloud cover. For small-scale applications, batteries can be used to store the excess of electricity generated when the demand is lower than the output. In 2007, solar PV provided 0.3% of the UK's renewable generation capacity and 0.1% of its renewable electricity3. The energy output is calculated in the same way than for SHW. The comments about orientation and tilt are also valid for PV. Efficiencies in sun energy conversion into electricity are around 15-20% in PV. The inverters needed to convert the DC to usable AC are very efficient, and their effect on the power generated is almost nil11. 3.6. Water- Hydroelectric A short explanation of these technologies follows for reference, as they are not applicable to the case studies of London and Ashton Green. Water flows and ocean currents, waves and tides contain energy that can be harnessed for electricity production. The House of Lords3 reports the situation and perspectives in the UK: - Hydroelectric power makes up 27% of RE generation capacity in Britain (24% in large-scale schemes with dams and reservoirs in mountainous areas; 3% in installations with capacity below 5 MW, mostly in rivers). - The possibilities for further large-scale hydro-electric schemes are very limited, due to the lack of suitable sites. - Technologies based on ocean movements are in the first steps towards practical development, although the knowledge is already available.
  9. 9. 9 3.7. GSHP Ground source heat pumps use a series of underground pipes laid about 1.5m below the surface to transfer heat from the ground into a building (Figure 6) . This way, it provides space heating and, in some cases, pre-heats domestic hot water. Figure 6 For every unit of electricity used to pump the heat, 3-4 units of heat are produced, making it an efficient way of heating a building12. GSHP can also be driven in reverse to provide comfort cooling. It is a cost effective and environment-friendly technology. Three basic elements exist in a GSHP: - Underground pipes. The pipe is a closed circuit filled with a mixture of water and antifreeze, which is pumped around the pipe absorbing heat from the ground. - Heat pump. It extracts heat from the ground for home heating. It has three main parts: o Evaporator, to absorb the heat o Compressor, to move the refrigerant round the heat pump o Condenser, to heat a hot water tank which feeds the distribution system. - Heat distribution system: radiators or under-floor heaters for space heating or water storage for hot water supply. In the strict sense of the word, geothermal energy might not always be called renewable in case the source is extinguishable, although some authors13 think that to all purposes GSHP are renewable because the latent quantities of energy are so large we cannot imagine them running out. The largest GSHP installation in the UK is at the IKEA in Peterborough14. Eight kilometres of underground pipework in 45 vertical bore holes (70m deep) provide the heating and cooling required for the building. A normal 8-12kW system costs £6,000 to £12,000 (distribution system excluded) 15. Vertical ground loop systems are significantly more expensive to install than horizontal ground loops. The estimated savings in pounds and CO2 emissions for heat pump installed in a semidetached property and providing 50% of domestic hot water and 100% of the heating are:
  10. 10. 10 Fuel Displaced £ Saving per year CO2 saving per year (tonnes) Gas 410 1.2 Electricity 1000 7 Oil 750 1.8 Solid 350 6.5 16 Source: Energy Trust 3.8. Hydrogen and fuel cells Hydrogen is not inherently renewable. It is the most common chemical element on the planet, but it does not exist alone in nature. It must separated from chemical compounds: from water by electrolysis, from hydrocarbon fuels by reforming or thermal cracking, or from other hydrogen carriers by chemical processes. The hydrogen industry does not only involve production and use of hydrogen but also packaging, storage, delivery and transfer. Eliason et al17 say that: - These extra activities consume 10% of the energy traded, and that technical solutions exist or can be developed for a hydrogen economy. - Hydrogen promoter’s claim that a ‘hydrogen economy’ will solve all problems of energy and environment. - The cost of hydrogen remains irrelevant as long as the final products find markets. Today, enormous amounts of hydrogen are used in the chemical industry for economic arguments. - Nevertheless, the future hydrogen economy is unlikely to be based on pure hydrogen only. It will certainly be based on hydrogen, but most likely, the synthetic fuel gas will be chemically packed in consumer friendly hydrocarbons. The House of Lords3 thinks that in the near term, the most likely sources are fossil fuels, resulting in CO2 emissions unless accompanied by CO2 abatement or capture technology. It is seen as an immature technology that is now finding cost effective applications, developing hydrogen production infrastructure and ensuring that the power to make the hydrogen does not come from polluting sources. 4. General economics Following the House of Lords3, the cost of generation critically depends on: - cost of fuel (for non-renewable primary sources like biomass for CHP plants) - load factor (amount of output expected from the plant) - rate of return required by the generator - capital cost of the power plant, - transport required (specially for biomass) - cost of land, building raw materials, ground conditions - financing costs.
  11. 11. 11 Therefore, the cost range in pounds for kWh generated varies widely within a range as the Figure 7 below shows. Figure 7 - Cost of different type of electricity generation (excluding back-up and grid integration3 The economic interest of RETs depends heavily on the cost of traditional alternative sources: fossil fuels and nuclear plants. Renewable and nuclear plants have high initial capital costs but most of their costs are fixed The cost of electricity from fossil fuel burning power stations depends critically on the highly volatile price of (Figure 8). Figure 8- Source: OPEC18
  12. 12. 12 The House of Lords3 gives the Table3 below to estimate the range of prices for some RETs, stating that their prices are expected to reduce dramatically, following innovation and economies of scale. Table3 The BERR funded Low Carbon Buildings Programme19 provides grants to help with the costs of installing all kind of RETs. 5. Ashton Green and London 5.1. AG 5.1.1. Background Leicester was prized as UK’s first environmental city in 1990. Since 1994, Leicester participates in the UK’s Council for Climate Protection Pilot Programme. In 1994 its first energy strategy was launched. In October 2003, Leicester City Council drew up an action plan to cut its own carbon emissions by 50% by 2025, prepared by the Institute of Energy and Sustainable Development, De Montfort University, Leicester. Acknowledging the effect of past GHG emissions, it proposes measures to adapt to the
  13. 13. 13 unavoidable CC and sets an integrated approach to its mitigation across the city20. Leicester has settled for 2020 an objective of 20% from renewable sources. The energy management is carried out from centralized offices. AG project started an in 1997 with the concept of ‘sustainable community’ as its leading goal. The plan establishes 4,000 houses, 3 small sized shops, 1 convenience store, 1 school, 1 sports centre with swimming pool and 1 library in an area of 100 Ha. Phase 1 is for 500 houses. AG project aims to provide in situ integrated 100% RE solution, which involves settling several sources to complement each other overtime, so that an insufficient quantity from any of them is covered by another. The building standard selected is ‘zero CO2’, which provided energy savings of 63% over average 1998 houses and of 48% over the Building Regulation 2005. The Table21 below shows each RET’s share in meeting the total needs, for each of the three REs deployment scenarios. Scenario S1 S2 S3 Output % Power % MW % MW MW CHP 61.4% 2.46 74.3% 2.97 82.9% 3.32 SHW 17.1% 0.68 17.1% 0.68 17.1% 0.68 Wind 8.6% 0.34 8.6% 0.34 - - PV 12.9% 0.52 - - - - Total 4.00 4.00 4.00 Table4 5.1.2. Perspective assessment The Final Report21 informs the authors’ opinion about the best options available for the AG project development at the time when it was written (summer 2001). Things have changed much since. - The ‘zero heating’ standard for the constructions might become an interesting option from both the environmental and the economic viewpoints, in an era of growing energy prices. - Even though seven years have passed since the report was written, PV energy remains expensive, the high capital costs21 probably still being unattractive to AG developers. Nevertheless, cases exist in the region where PV technology has demonstrated its economic benefits (e.g. Beacon Farm22).
  14. 14. 14 - The increasingly big investment being made on RETs can make the option of GSHP feasible. It was disregarded in the report. Beacon Farm is also an example. - Municipal waste is a reality that needs a solution. As stated by the House of Lords23, energy produced from non-biodegradable materials such as plastics is not counted as renewable, although burning them may relieve the pressure on landfill sites. Its economic analysis should consider that if they are treated as energy, there will be costs savings from alternative treatments avoided. - Energy losses must be considered before any final decision is taken. - The CHP plant is to provide a minimum of 2.46MW. Figure 9 shows that a minimum of 12,500Ha of land are needed for crops. The total available place for AG is 100Ha, so the total crops will be far from being grown in-site. Figure 921 5.2. London 5.2.1. Background “Green Light to Clean Power” is the name of London’s Mayor ten year energy strategy, published February 2004. It aims to meet the essential energy needs of people living and working in London while minimising the impacts on health and the local and global environment. One of its four targets is to reduce London’s contribution to CC, with a 20% target reduction of CO2 emissions for 2010. The leading points to be strengthened are - Energy efficiency. London buildings are responsible for 44% of CO2 emissions. The minimum SAP (standard assessment procedure) accepted for houses will be
  15. 15. 15 30 in 2010 and 40 in 2016. Improving the insulation and the heating systems are the main measures for the change. - Renewable energy. 665 GWh of electricity and 280 GWh of heat are the goal for 2010, through: o 7,000 PV domestic installations, o 250 PV in commercial and public buildings o 500 small wind turbines o 6 large turbines o 25,000 SHW domestic installations o 2,000 SHW in swimming pools o Anaerobic digestion plants with energy recovery o 4,000 Biomass-fuelled CHP plants These targets are triple for 2020. - Hydrogen and fuel cells technologies. Hydrogen is seen by the strategy as the clean energy source of the future. London intends to incorporate it as it steps forward. A major opportunity is seen in CHP units run from fuel cells. Three London buses were already being run by hydrogen cells in 2004 (ten in 2010) - On the Mayor of London’s website24 it can be read that also passive solar design and ventilation, as well as GSHP, could be developed in London. Nuclear energy is explicitly discouraged for being very expensive and risky for environment and health. 5.2.2. Perspective assessment The Mayor of London three-step strategy (use less energy, use renewable energy, supply energy efficiently) shows a determination to be a leading city in the definition of strategic goals to sustainability and in the implementation of in-site generated RE. The strategy provides awareness about sustainability, a guide to installing RETs and to obtaining funds25, and a practical guide to strengthen the support given to households26. Currently, 40% of London’s power is generated at large (primarily natural gas- fired) power plants located in the city, the balance being imported via the high-voltage transmission grids27. The RETs proposed in the strategy form a varied net of sources that prevents dependence on one source. - Hydrogen economy is included not as an immediate quantified objective like in the rest of the cases, but as a field to investigate. - The small wind turbines proposed need to have special placement in order for them to be efficient. Large obstacles disturb the air flow downwind for a distance equivalent to at least ten times the height of the obstacle and up to a height twice that of the obstacle. - Lehmann27 says that the need of land for biomass crops to feed the CHP plants and the transportation involved may make this source more difficult than expected for London.
  16. 16. 16 - Lehmann also says that London could have followed other big cities in using building requirements to get his goals in energy, like Barcelona, where all new and rehabilitated buildings up to a certain size had to generate at least 60% of their hot water needs through solar thermal collectors. 6. Conclusion: comparison AG-London The perspectives for AG and London case studies differ importantly. While AG is a rural development by a medium-sized city, the London strategy is a proposal by one of the world’s most influential capitals to improve its energetic performance and serve as one of the world’s references as a sustainable city. AG pretends a 100% of its energy needs generated on-site and by renewable sources, while London aims it to be only 10%, but remarks the importance given to the latest technologic developments, as in the case of hydrogen. London’s objectives are much smaller in terms of RE share, but are more aggressive in terms of support to new technologies, reflecting the city aim to remain progressive and influential. As AG development is new, passive solar design is an important energy saving option that might be imposed to constructors. London can only have in mind passive solar design for the limited number of constructions that could be built. The creation of an ESCO is foreseen by Ashton Green. The advantages of it should not be disregarded by London, following the example given by Woking Borough (Surrey) or Southampton. It would give London’s authority the capability to influence the power portfolio delivered to customers, to subsidize or provide technical support for RETs and to implement policies to discourage the use of electricity, as well as to buy equipment and services to resell them to Londoners pursuing the city energy goals. REFERENCES 1 Department for Environment, Food and Rural Affairs (2008), “UK Greenhouse Gas Inventory, 1990 to 2006 Annual Report for submission under the Framework Convention on Climate Change”, April, 243pg. Also available under 06_main_chapters_UNFCCCsubmission_150408.pdf (Last accessed 11/01/09) 2 Department for Business Enterprise and Regulatory Reform (BERR) (Last accessed 10/01/09)
  17. 17. 17 3 House of Lords (2008), The Economics of Renewable Energy, London, 25 November 2008, 90pg. Available at (Last accessed 10/01/09) 4 EPSRC- Engineering and Physical Sciences Research Council, (Last accessed 10/01/09) 5 BERR- Department for Business Enterprise & Regulatory Reform,, (Accessed 17/12/08) 6 DMU- De Montfort University, IESD- Institute of Energy and Sustainable Development, MSc Climate Change & Sustainable Development, Lesson 5.2- Renewable Energies- Biofuels & CHP. 7 ETSU (1999), Best Practice Programme- GPG43, p.7 8 Energy Saving Trust, renewables/Solar-water-heating (Accessed 16/12/08) 9 DMU- IESD, MSc CC&SD (2007), Lesson 3.1- Conversion of Solar Radiation for Heat Energy. 10 Green Book Live, (Last accessed 10/01/09) 11 Institute for Energy and Sustainable Development, De Montfort University, Leicester, UK 12 DMU- IESD, MSc CC&SD (2006), Lesson 8.2- Regional Renewable Energy Resource Assessment 13 Envocare, (Accessed 18/02/08) 14 Business Link, (Accessed 23/12/08) 15 Energy Savings Trust, renewables/Ground-source-heat-pumps (Accessed 22/12/08) 16 Energy Savings Trust, renewables/Ground-source-heat-pumps (Accessed 22/12/08) 17 Eliasson, B. and Bossel U. (2002), “The Future of the Hydrogen Economy: Bright or Bleak? 18 OPEC(2008), (Accessed 23/12/08) 19 BERR- Department for Business Enterprise & Regulatory Reform, (Accessed 24/12/08) 20 Leicester Partnership (2003), “City of Leicester- Climate Change Strategy” 21 Ajiboye P., Fleming P., Devine-Wright, P. (2001), “An Energy Strategy for Ashton Green. Final Report”. Institute of Energy and Sustainable Development, De Montfort University. 22 See (Accessed 14/12/09) 23 House of Lords (2008), The Economics of Renewable Energy, (Accessed 14/12/08) 24 See (Last accessed 10/01/09) 25 Energy Savings Trust, (Accessed 15/12/08) 26 See (Accessed 15/12/08) 27 Lehmann, S.(2008): “Urban Energy Transition. From Fossil Fuels to Renewables”, Oxford, UK.