At present we have a subsidy-driven renewable industry which getsmoney for generation and also for not generating, which is a licenceto print money. It should be a requirement of all intermittent formsof generation to have a set percentage of available storage withinthe schemes proposed and so investing in the infrastructure ratherthan just sucking money out of the public purse.
Storage of intermittently produced renewable energy is the onlyway to remove baseline coal, oil and nuclear power production fromthe grid. An industrialised country working only when the wind blowsis not a possibility. There are few viable options. Gordon Murrayrefers to compressed air storage but this runs at an efficiency of40 to 50% and at present requires air-tight caverns produced bysolution mining of salt (Letters, May 7). I am aware of no suchsites available in Scotland. Pumped storage is possible and existsbut it is land-hungry and is about 65% efficient. Batteries can beused to even out load but are high-maintenance and have a limitedlife span. Fly wheels are useful for evening out wind production butuseless for long-term storage.
Hydrogen production is possibly the best use for surplus power asit can be stored for later utilisation and gas-fired power stationscan be built quickly and relatively cheaply. These displace normalfossil stations and produce only water as a by-product. If locatedin urban settings their efficiency can be improved dramatically byusing waste heat to heat homes and businesses. As a fuel source forvehicles, hydrogen could reduce or replace the need for oil andcould be used as a fuel in homes.
Offshore production would require the gas to be pumped ashore buta network of pipes exist for oil/gas collection already and we havethe expertise to do it. The present problem of balancing the gridwith more than 20% wind power is resulting in constraining of supplywhen there is too much wind for the grid to cope. Localised hydrogenproduction would reduce the strain on the grid and make it easier tobalance. Hydrogen can be stored in depleted oilfields as well as insalt domes. The efficiency rate is 50-60% if used to generateelectricity but it also creates a high-density storable fuel whichis easy to utilise. A hydrogen-based economy would provide energysecurity and we have much of the infrastructure and expertise tomake it work.
Renewable energy is expensive because it requires so much baseload to be kept in reserve to ensure continuity of supply. Onceproduced hydrogen can be stored and used when it is required eitherto produce electricity, or for heating, or as a renewable fuel forvehicles, thus producing multiple markets for the resource.
The production of hydrogen from renewables removes most of theirdisadvantages and could make us world leaders in a hydrogen-basedeconomy.
Cameron D Gibson,
The Green House, Hughton, Kiltarlity, Inverness.
Gordon Murray's letter is a perfect example of the reason we non-experts need unbiased information on the whole question of energypolicy. He advises us that the reserves of uranium are so limited asto make nuclear energy unsustainable in the medium to long term. SoI turned to the book Sustainable Energy - Without The Hot Air (whichcan be downloaded free on the internet) by Professor MacKay of theCavendish Laboratory, who seeks to address the issues in a totallyobjective fashion. It turns out that there is more to the questionof uranium availability than Mr Murray is prepared to acknowledge inhis letter; for instance Professor MacKay discusses the option ofrecovering uranium from sea-water and using thorium instead ofuranium.
I am not arguing from a pro-nuclear stance but from theperspective of a lay person asking for all the facts and not just aselection. I am anxious to know how much reliance I can put on thecurrent feasibility of the type of large-scale storage Mr Murrayseems to favour.
John Milne,
9 Ardgowan Drive, Uddingston.
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