The Practicalities of Developing Renewable Energy

The Practicalities of Developing Renewable Energy

The Royal Society of Edinburgh (RSE) is pleased to respond to the House of Lords Science and Technology Committee Inquiry into the Practicalities of Developing Renewable Energy. This response has been compiled by the General Secretary, Professor Andrew Miller and the Research Officer, Dr Marc Rands, with the assistance of a number of Fellows with considerable experience in this area.

In the White Paper, Our Energy Future – Creating a Low Carbon Economy, the large role suggested for renewable energy, as much as 20% of electricity by 2020 is laudable, but may not be able to be achieved and the real engineering analysis and cost of this possibility has yet to be assessed.

The specific questions identified by the Inquiry are now addressed below:

Cost-effective technologies available now for the generation of renewable energy, and those that are likely to become available in the next 10 years or so.

Solar energy could be a good option if new, more efficient, cells can be produced and introduced into small factories and houses as a boost to grid energy. Similarly, wind power offers potential, with offshore winds offering promise for both technical (more sustained and powerful airflows) and environmental reasons (less visual intrusion and effect on landscapes). The building of new hydro plant will be limited due to difficulties in obtaining planning permission and large land-based wind farms are likely to experience similar problems.

In terms of fuel cells, the UK has a poor record in industrial take-up of these cells, but quite a good record of university research. The central problem has been that the low industrial interest has inhibited both the Department of Trade and Industry and Engineering and Physical Sciences Research Council from investing in thetype of long-term R&D really necessary in this type of technology. There have been several initiatives that have petered out. Relevant departments in universities such as Imperial, Oxford, Newcastle, Loughborough and Keele have been encouraged to set up fuel-cell groups only to find funding has evaporated, and the groups have, inevitably, moved on to other areas. Only if funding agencies are prepared to give substantial long-term commitments to R&D will the UK really develop the leading edge technologies needed in this area.

The concepts for generation from wave and tidal resources are quite well-developed, but the technology is not yet mature for either. Water-based technologies have an advantage over wind and solar in that the energy flux is an order of magnitude higher, typically 4kW per metre squared compared with 400W, and often much less for wind and solar technologies. Modern load management techniques have also substantially alleviated earlier intermittent load fluctuating problems pertaining to both tidal and wave power among other renewable sources. However, factors relating to system integration still have to be considered even now for both tidal power and wave power. Wave energy converters need hydrodynamic characteristics to enable them to operate at maximum efficiency over the normal range of sea conditions, yet they must be robust enough to withstand the worst storms. Despite its large potential resource for the UK of 40-50 TWh/year (approximately 15-20% of UK electricity generation output), no economic large scale wave energy device has yet been produced, and load management and integration problems are still quite severe.

Fuels of biological origin are making a substantial contribution to the reduction of use of fossil fuels in combined heat and power systems in some countries in Europe; for example Sweden. A more extensive use of biofuels in combined heat and power schemes could make a significant contribution to a basket of measures. Suitable biofuels include residues from normal forestry management operations and purpose-grown short rotation forest crops. Worldwide, an increasing number of sawmills, wood pulp plants and composite board plants utilise the residues resulting from their processing operations to provide energy and are thereby self-sufficient for heat and power and, in some cases, export electricity.

The number of sites potentially available for such technologies, and the obstacles to taking these up

Scotland is fortunate in having a lot of the basic resources for wind, wave, tidal hydroelectric and even solar energy. However, the present 2% of electricity in the UK generated from renewables is largely from the medium-to-large size hydroelectric plants, many of which are in Scotland. Given that present levels of hydroelectric generation took decades to install, doubts must exist over the possibility of installing more than double that capacity in other renewable energy forms in the time scales proposed, and perhaps the most practical application would be to meet relatively small local demands.

Wind energy

At present, if all the wind farms currently operating in the world were to be put on the South Downs, they would generate only 15 per cent of UK electricity, less than the aspirational target for the UK alone for 2020. To produce 20% of UK electricity, largely from wind, would require twenty, 2MW machines to be installed every week between now and 2020. The Danes are just completing the Horns Rev offshore field 11km out into the North Sea, and using the latest technology they have succeeded in installing one machine every two days. To achieve something similar in Britain, a huge capital investment programme to provide the necessary offshore infra-structure will need to be mounted, but there will be problems in getting the private sector to pay for this unless substantial price guarantees can be made. For example, the floating cranes necessary to install at a rate of 60 machines per week offshore will have to be built and the necessary undersea cabling installed.

Fuel Cells

The main thrust here is towards hydrogen-based fuel cells, which obviously pre- supposes that sustainable sources of hydrogen can be identified, and the hydrogen stored efficiently; but neither is straightforward. Sustainable sources of hydrogen could include biomass which is very expensive, or photovoltaic-driven electrolysis of water. The latter urgently needs research, as the last serious investigations were funded by the space agencies in the 1980’s in order to develop bipolar cells for satellites. Both cell designs and catalysts are, however, far from optimised. In addition, the cost of electrolytic hydrogen is some 4-7 times that of hydrogen derived from cracking making it an expensive fuel. Storage is also a major problem. There are various methods, from high-pressure storage, through absorption into metal alloys or into special forms of carbon, that have been proposed and tried, but, especially for transport, such methods all carry major penalties in either weight or low-temperature requirements.

The essential feature of fuel-cell research is that there are two major difficulties: the costs of the fuel cell itself, and the costs and complexity of the systems engineering required to fabricate a working device. The main costs of a low-temperature hydrogen-oxygen fuel cell are the catalysts (though this is no longer a major problem with modern electrode design) and the costs of the membrane (a perfluorinated sulphonic acid polymer which is difficult to synthesise, and is mainly used by the chlor-alkali industry). Modern membrane-electrode assemblies can be fabricated for a few hundred dollars per kilowatt installed power, but this remains high compared to current technologies. In the case of high-temperature fuel cells, the main difficulties are encountered with materials chemistry and engineering; attempts have been made to synthesise lower temperature electrolytes to reduce the materials difficulties, but catalyst costs then begin to rise.

For both types of cell, however, the systems engineering remains extremely expensive, partly because there are noeconomies of scale yet realised, and partly because there are, as yet, no standard solutions agreed upon. There is almost no indigenous fuel-cell industry in the UK, and no prospects of one developing unless, as * indicated above, there is the guarantee of really long-term funding. There is critical mass in the universities, at least in the science and electrical and power engineering areas, but there is a lack of electrochemical engineering that is extremely serious.

Wave energy

The most likely sources of wave energy are on the West coast of Britain, and at some considerable distance from likely large users of electricity. Hence the total costs for design and erection of the energy generators, and the power transmission system must be analysed and estimated in relation to the market, and the price which the market will pay. Too often in the past, seemingly attractive projects have foundered because of over-optimistic initial assumptions. The problem of grid connection is common to all renewable sources as distribution grids tend to be "tapered" towards their periphery, which is often where the renewable energy is available. The intermittent nature of the supply also puts it at a disadvantage with the New Electricity Trading Arrangements (NETA) under which fluctuating supply attracts a penalty.

The economic advantage of wave and tidal power will also depend upon the relative values of imported and exported energy and on the ability of the supply system to meet the pumping demand. It will be difficult for either to become commercially viable if the present economic indicators continue to be used. However, if a new approach is taken to assess the value of renewable resources, then viability may become possible. Recent moves towards 'green credits' are moves in the right direction but more could be done. These new arrangements require suppliers to provide 10% of their supply from renewable sources by 2010 or pay a penalty. However, at present the price of electricity produced by wave and tidal stream technologies comes in at above 5p per unit (the capped price of the renewable electricity to be supplied in this arrangement). It will be difficult, therefore, to see why electricity suppliers should enter into such contracts with wave and tidal power providers when they can buy themselves out at 5p per unit. In addition, tidal stream energy is not included in the Renewable Obligation list of acceptable technologies despite its potential.

The main wave energy project is a shoreline device, now called Limpet, on the Island of Islay and is run jointly by WaveGen and Professor Whittaker from Queen's University Belfast. It operated successfully for ten years and has now been superseded by the Mk2 device which has been operating since November 2000 and generates 500kW. While the concept has been proven, it is onshore and so limited in power rating and it requires specific shoreline characteristics. A significant problem has also been in transmitting the power to the grid, with the existing grid line to the main land requiring significant and costly strengthening. In terms of tidal stream energy, the science is well understood but the technology requires further development. One 300kW unit is being installed by Marine Current Turbines of Lynmouth in Devon and The Engineering Business has also demonstrated a small model device which they are seeking to upgrade to a demonstration stage.

Biomass energy

Purpose grown, short rotation forest crops (willows and poplars in particular) contribute a significant amount of energy in combined heat and power schemes in Sweden and Finland and with the expansion of such schemes in the UK they could also make a significant contribution. The problems which will arise when enlarging pilot operations to areas of approx. 2000 ha of land and power stations of more than 10 MWe will concern land ownership, continuity of supply from hundreds of farmers and competition for the feed stock from pulp and board mills. There are, however, a range of crops suitable; for example Willow, Poplar and Miscanthus (Elephant grass). Further work is required in developing these annual crops.

It is estimated that the theoretical energy cropping and forest residue resource in Scotland could contribute around 2.3 GW of electrical generating capacity. However, taking planning, cost and other electrical infrastructural factors into account, the actual resource may only be around 170 MW. More detailed research on the potential for short-rotation coppice alone suggests that whilst there is a theoretical potential for some 500 MW biomass-to-energy plants if all the suitable land was converted to coppice, a more likely scenario would be around 20-25 MW biomass-to-energy plants in Scotland, assuming a 5% take up by farmers on suitable land. If one assumes that, for the foreseeable future, patterns of electrical energy consumption in Scotland remain the same (i.e. peak demand around 5.6 GW) then biomass-to-energy projects will not contribute significantly (<3%). They are therefore likely to be only a minor element in achieving the UK government's policy objective and ranked third behind wind and hydro.

Environmental Factors

It should be noted that some renewable forms of generation also have the potential for quite severe environmental impacts (as previously reported). Wave power devices, for example, impinge on coastal environments, tidal barriers affect habitats and cause change, wind farms pose threat to bird life and cause major visual pollution, and even hydro can affect wildlife and river form.).

The logistics of providing stand-by capacity for times when intermittent sources are not available

Wave, wind and solar power are all subject to intermittency of supply, and necessitate substantial use of conventional standby plant operating for much of the time at less than optimum efficiency on part-load. Accommodating any intermittent electricity source into the grid distribution system presents considerable technical and cost problems which should not be underestimated. Denmark, with around 15 per cent of wind electricity on its distribution grid, has just removed subsidies for three proposed 150MW offshore wind farms, as any more wind power would have caused serious destabilisation of their grid.

The intermediate milestones that should be set on the way to achieving the White Paper’s aims.

Some important milestones that will need to be met to achieve the White Paper's aims will be:

Speeding up the planning permission process without "short circuiting" or damaging the democratic process.

Financially incentivise the distribution network operators to make it attractive for them to connect renewable generators to their systems. At present they have no financial incentives to connect new renewable generation. One result of this is that individual developers are experiencing serious difficulties in negotiating with the relevant distribution network operator relating to connection of their plant. Network operators are also generally wary of connecting large volumes of renewable generation.

Plan and develop future high voltage transmission network extensions in a way that allows the large volumes in remote areas, e.g. Northern Scotland, that are foreseen to be provided with access to the high voltage grid.

Given that all forms of renewable generation are currently uneconomic compared to more conventional sources look again at the Renewable Obligation Certificate (ROC) arrangements in a way that will ensure that investors will not lose money if the value of these falls in the future, as seems likely. ROCs have a par value of 3p/kWh and are currently trading at say 5p/kWh, but as a marketable commodity. If they fall below "economic" levels, investors will depart the scene and this will impact upon future development as all new large wind farms being built today are being developed by large companies on their own balance sheets.

Some other suggestions might also include:

Given the large number of people and organisations engaged in the debate, an Annual Report of progress toward the Government's target of 10% renewable electricity by 2010 could be published, with reasons given for exceeding or falling short of the intermediate targets. It should also make clear what premium industry and the public are paying for the benefits that arise from renewable generation, including the cost of standby generation and of the necessary modifications to the electrical power system infrastructure.

All serious technological competitors in the renewable generation field, such as wave energy and biomass crops, should be able to point to at least two demonstration projects so that confidence can be gained by those considering similar commitments.

Many of those currently promoting renewable energy projects are small companies who seem to have no common agenda or technical affiliation to one another, or are unaware of all the issues involved in developing their projects. The DTI and Ofgem have found it difficult to engage this small generator community in debate and although each technology seems to have a "technical society" there needs to be some kind of "trade association" to look at the wider issues.

One major casualty of the privatised energy market has been research and development. The world-renowned research carried out by the Central Electricity Generating Board and the Gas Council in the 1970s and 1980s has been abandoned by the privatised energy companies. While the Government has stimulated research in renewables, a comprehensive energy supply research programme needs to be put in place. Some urgent topics, in particular, would include: carbon sequestration; electricity/energy storage; hydrogen for transport; restructuring the grid system to accommodate embedded generation and the financial and stability implications; and the new gas supply infrastructure to provide for importing large quantities of gas. While some of these topics are being addressed by a variety of bodies, co-ordination is poor, with the environmental Audit Committee identifying 23 different grant giving bodies in this area.

Finally, while the policy paper makes some perfectly sensible suggestions about CO2 sequestration, we have found this section somewhat lacking in imagination. For example, it is interesting that the Government have not recognised the potential importance of CO2 as an energy vector in its own right; the chemical reaction:
CO2 + 3H2 ÛCH3OH + H2O

allows the inter-conversion of CO2 and methanol, the latter being a liquid that is far easier to transport and is easily converted by reformation back to hydrogen. The argument that this is not a zero-emission fuel is certainly true, but if, for example, the CO2 were sequestered from the combustion of coal, then there would be a substantial reduction in CO2 emissions whilst allowing the use of much current technology and fuel infrastructure. There is a danger that seeking to change everything will, in the end, lead to changing nothing.

Additional information

In responding to this inquiry the RSE would like to draw attention to the following Royal Society of Edinburgh responses which are of relevance to this subject: Energy and the Environment (December 1998); New and Renewable Energy (May 1999); Non-Food Crops (May 1999); Wave and Tidal Energy (February 2001).


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