JimW - CNG from landfill or AD plants would make some substantial contribution to alleviating the problem. Adding CNG pumps top existing filling station infrastructure need not be expensive or problematic, and of course the waste feedstock is available in abundance, close to the point of use opf the final CNG product....
We always seek to use an ORC unit as a back-end odd-on if a potential CHP project does not have an economically-viable heat off-taker. Whilst most ORC plants have a comparatively low electrical efficiency (generally 16%-18%)it often makes sense to be able to generate additional power, particularly if there is a decent RE tariff structure in place. In the UK, for example, we would be able to get ~£125/MWe for power generated from a biomass gasifier + ICE plant, plus ~£30/MWth (assumes £15/MWth price to end-user + £15/MWth RHI)exported heat. If we cannot sell the heat, then we can still earn ~£20-25 for the additional ~200kWe generated by the ORC unit and still have on-site LT heat for drying, heating, etc. Doesn't have to be a biomass gasifier, of course - we can use RDF too!
Whilst solar power/heating and wind turbines are an excellent approach to the issue, they will provide only a partial solution.
I would suggest that, for similar sites, you consider an option which includes the installation of a biomass gasification CHP plant running internal combustion generator sets. If you also consider adding an AD plant to handle the school's (and community) food and other putrescible waste and generating biogas (for use in gensets, or as CNG for the school's transport....), you'd end up with an integrated RE "campus".
These would provide power, heat (and chilling, if appropriate)at much higher efficiencies than the solar/wind installations but, more importantly, continuous generation with the option to supply the surplus to the regional grid or, if one is available, the local distribition grid - usually at premium tariffs.
Given that schools and other public sector bodies tend to shy away from "commercial" undertakings, this may best be implemented via the creation of an ESCo with a private developer (a la PPP), in which the school/community has a carried equity position. Result - the school/community gets low-cost/free energy, and an income stream from the dividends arising from the ESCo profits. It also addresses Victoria's point re "teaching tool", as it covers both the environmental and business elements of renewable energy delivery.
This is something on which my company both advises and structures - happy to discuss further with anyone who may be interested.
Chief Executive, W2 Green Energy Limited
Dr Hutton's article seems to be describing a variant of the Organic Rankine Cycle packages which are already in use (and have been for some time)here in Europe. We also have access to proven gasifier + ICE packages which work with economically viable syngas filtration systems.
To a project developer such as my company, one of the significant advantages of the gasifier+ICE configuration, despite the admittedly higher O&M costs of the gensets, is that we can use a wider range of comparatively high electrical efficency packages and that, if properly prepared, we can use a variety of feedstock (e.g. fibre from an autoclave pre-treatment phase, waste woods, etc.) provided that the (dry) CV levels are reasonable.
The current problem with gas turbines (some of which can run on syngas)is that they won't meet emissions limits without very expensive clean-up, and of course the present market for such turbine packages is below that which the majority of 500kWe+ OEMs will find attractive.
Our configurations (we focus principally on the 500kWe to 10MWe sector)are therefore planned using gasifier+ICE+ORC heat recovery, and generate attractive returns...
Chris Moore - CEO, W2Green Energy. firstname.lastname@example.org
Any move away from/substitution of traditional hydrocarbons has to be good, and this technology is yet another piece in what is a very large jigsaw - anyone who thinks that only one technology will provide a universal panacea is living in clud cuckoo land. The diversion of the biodegradable fraction of MSW, and farm slurries, to Ad plants can provide substantial decentralised CHP options, almost all of which can be at output levels which need not cause any major interconnection issues with the local grids and will meet the "proximity principle". Most farms, in particular pig and poultry breeders, could achieve near self-sufficiency, with a number of proven non-incineration, modluar, technologies being available.
There is also the possibility of usnig the AD biogas (following comparatively low-cost cleaning) as CNG for vehicles - a considerably cleaner fuel than almost any other alternative available within the near future at anything like economic cost.
It seems to me most likely that only close-to-shore projects (including barrages) are going to be viable in the near/medium term, as the issues and costs associated with a) tethering, and b) grid connection will take a considerable time to resolve. The UK has massive wind and ocean energy resources, but is unable properly to exploit these due to lack of infrastructure - the implementation of which requires planning consents, etc., so don't hold your breath! I have been associated in the past few years with certain proposed ocean power technologies, some of which comprised sizeable units (up to 7MWe), but needed to be located at depths and distances from shore which would have made the projects unviable due to the connection costs (not to mention the insurance costs...)
If you take the biodegradable fraction of municipal and food wastes (of which there a re milions of tonnes produced annually), together with the slurries produced by farms (in particular, pig and chicken effluent) and sewage produced by humans, and put them through Anaerobic Digestion systems (lots of systems around from which to choose - I currently favour the Maltin System), we can generate significant volumes of methane which can easily be convereted to CNG for automotive use (can also, of course, be used to feed into the gas grid or to generate heat & power in a CHP plant). We thus address two significant issues - energy security, and carbon emmissions (remembering that methane is 21 times more harmful as a GHG than CO2).
I'd be happy to show you how......
Glenn - I think the plant will be using the cobs (inedible), and not the edible part, so no impact on the food element of the agricultural industry, save for perhaps making rapid use of what otherwise might end up being considered as a waste....
Part of the reason you don't hear much about gasification as a solution for waste is that the media is dominated by the lobbyists pushing for large-scale plants (which almost certainly means incineration + steam turbines). The gasifier route provides smaller, decentralised solutions, but are not considered big enough in capex terms to be of interest to the big players. Plasma gasification is great for conversion of hazardous wastes but comparatively expensive in terms of operating expense when using it for "normal" wastes.
One of the other "problems" is that the sector is still suffering from the hangover of technology short-comings of earlier designs (which blocked the banks' ability to approve project finance structures), so that industrial/commercial sized demonstration plants are only now being built and commissioned.
The producer (or "syngas") gas generated by a single stage gasifier (or a two-stage pyrolysis and gasification) plant will allow you to do many things with the gas, including production of syndiesel (hats off to messrs Fischer and Tropf). Much depends on what the input feedstock contains. Whether or not this delivers an economically-viable end-product is very much market-driven - the safest bet at the moment is to use the gas in a CHP application, ideally with gas IC engines (comparatively high efficiency) or (if you haven't solved the gas clean-up issues) boiler and ST configuration (comparatively low).
It was notable that, at last week's BWEA Conference, none of the politicians seemed to be prepared to give any commitment to actually dealing with the underlying problem areas - grid connection and planning. The Government may well still be "listening", but if we are to have in place the requisite infrastructure to enable the off-shore (and major on-shore) developments to go ahead, real action is required now and that requires the Government to take direct control, using a "national interest" argument (as many of our continental European neigbours have done), over the grid upgrade and expansion and the planning process. Perhaps some of the mooted increased funding to "spend our way out of recession" could be allocated to the grid? Allowing the whole process to be delayed in a series of local and regional applications before eventually being able to go to appeal not only undermines the likelihood of a developer being able to commit to a major project (no sane private sector credit/investor committee would commit without knowing whether or not the project has an interconnection point and a transmission capacity to deliver the power to its end-users), but inevitably means that there is not the slightest chance of meeting the targets to which the UK is now committed. The expert panellists referred to in the article were evenly split as to wheter the targets "would" be achieved (3 yes, 3 no, and one undecided), but all agreed that the they "could" - the "no" camp being sceptical about the political will to actually implement measures which would deliver......