Thanks for your replies to this query - and apologies for not responding sooner, I've been away for a week so only just been able to read your replies.
I think the major issue I had missed that is relevant is dfference in employment generation between PV solar panels and biofuels - taking into consideration the local skills that are available, it's probably fairly unlikely that remote villagers will have skills at running complex electrical systems. So that would tip the balance in favour of biofuels, which would not require a significant amount of external input. And PV systems are unlikely to generate significant local employment - which if employment is generally high in the area, would not be a problem but this is often not the case in such rural locations. Of course you are absolutely correct that what people want is a fridge and a television, not electricity per se - that is just a convenient way of fulfilling the requirements, with an easy path to expansion. Having said that, certain countries (particularly in Asia) were poor until a few decades ago, but have made a deliberate effort to become technologically savvy - and have become richer as a result. So there is a good argument in favour of giving remote villagers the skills that will enable them to participate in a high-tech world. This is of course a slow process, and if done wrongly can of course lead to environmental disasters on the way (I think of China and its big dams here as an example). Technology, as with so many things, can be both good and bad depending on how it is used. As an aside, I am puzzled as to why there is so much emphasis being placed on the "Hydrogen Economy" at the moment, especially by the US government. Hydogen is just a way of storing and transporting energy, just as are biofuels. OK, I realise that fuel cells can theoretically deliver a greater whole-cycle efficiency than biofuels, but it seems to me that a lot of money is being spent on something that probably won't give us a cost-effective solution for at least 20 years - given that there are still a large number of technical hurdles without totally satisfactory solutions. On the other hand, biofuel technology is pretty mature - most of it is at least 100 years old - and is available now. Biofuels could be used on a very wide scale without making any major changes to the infrastructure, such as the supply chain. While it does make sense to fund research into technology that one day may be even better, it seems that this is a poor excuse for not promoting technologies that can provide real benefits today. I do sometimes wonder whether it's more about 'image' - in other words, talking about Hydrogen is trendy, in a way that for example biodiesel is not. Donald --- Darryl McMahon <[EMAIL PROTECTED]> wrote: > Donald (and all), I certainly don't have all the answers (maybe > none), but it is a > complex topic, and I can certainly muddy the waters a bit more. > Comments inserted > below. > > Donald Allwright <[EMAIL PROTECTED]> wrote: > > > I have a question that some of you might be able to shed some light > on. > > > > As well as having an interest in biofuels, I also have an interest > in > > Third World development issues and other technologies, including > Solar > > energy collection and storage. So when trying to find an 'energy > > solution' for a remote village for example, there are a number of > > possible options. Of course, you have to ask, "what problem are you > > looking to find a solution for?" For the purposes of this post, I > will > > assume that we are trying to provide electricity to power > > refrigerators, lighting, miscellaneous equipment such as telephones > and > > computers (even remote villages can have satellite connections to > the > > internet these days!). This would be a light load and not include > > industrial use nor electrical heating/cooking. > > Let's think about the loads a bit, particularly refrigeration. In > this case, we > don't really need to store electricity, but "coolth". So one > approach would be to > develop a solar-powered icebox. Have the PV panels run a > conventional > refrigeration unit when the sun is shining to make ice in the top of > the "icebox". > A sensor can control a fan to pull air through the ice into the > refrigerator when > required to maintain temperature. Some electricity is still required > for the fan > (the sensor could be a simple bimetallic switch), but much less than > for the > compressor, so that would reduce electrical storage requirements > significantly. > > > > So I will propose two solutions, both of which are used in various > > places: > > > > 1) Grow an oil crop, use it to power a diesel generator > > 2) Install photovoltaic solar panels and use a battery system to > store > > the energy overnight > > > > Now I'm trying to get an understanding of the pros and cons of > these > > two approaches, and which would be better for a particular > location. > > The issues I have thought of so far are the following: > > -- > > Photovoltaics and batteries are expensive in terms of capital > outlay, > > whereas biofuels are cheap to 'install'. > > > > Photovoltaic systems have a conversion efficiency of ~10% of the > solar > > energy, whereas biofuels have a conversion efficiency of about 1% > > > > Photovoltaic systems require more specialist knowledge to maintain, > > whereas biofuels require less. > > > > Photovoltaics require low labour input once they are installed, > whereas > > biofuels require planting, harvesting, processing etc.. > > > > Photovoltaic systems can store only small amounts of energy over > short > > timescales, whereas you can store large quantities of oil for a > long > > time > > > > Photovoltaics make less sense when sunshine levels are highly > > unpredictable, whereas biofuel crops are not significantly affected > by > > a few gloomy days > > A small wind turbine is another option for renewable generation of > electricity, and > usually cheaper to install per watt-hour produced. Of course this > assumes an > appropriately windy place, just as PV assumes an appropriately sunny > place. > Another option is low-head hydro, if a suitable stream is nearby. > > > > > Photovoltaics require less land to install than oil crops, because > of > > their higher conversion efficiency. > > -- > > > > I realise that this is an oversimplification of the issues, and I'm > > trying to gain a deeper understanding of the secondary issues. So > my > > specific questions are: > > > > 1) What are the implications of manufacturing Solar collectors, > > batteries, electronic control equipment and so forth in terms of > energy > > use, toxic materials (e.g. lead in batteries), sustainability? How > does > > this compare with manufacturing a diesel generating system? > > The batteries don't have to be lead-acid. For a remote, stationary > application, I > would seriously consider nickel-iron batteries (Edison cells). More > expensive > (mostly due to lower production I expect), but less toxic (there is a > caustic > electrolyte), and can be very long-lived, reducing the > disposal/recycling issue > considerably. > > > > > 2) Biofuels are often produced from crops that are grown in an > > unsustainable manner. What are the effects on biodiversity of this? > How > > can this be counteracted? Are there any comparable environmental > issues > > in the manufacture of solar systems? > > > > 3) Do the levels of expertise required to install and maintain a > solar > > system make it inappropriate for use in remote villages? > > PV panels are effectively non-repairable. Solid state controllers > are also > effectively non-repairable. However, in a simple installation (which > can be fairly > large), regulators are not really necessary, if someone is prepared > to monitor the > battery charge state on a daily basis (and do some discharging if the > batteries are > being overcharged). Batteries do require some maintenance, and > replacement > (typically every few years). However, installation and maintenance > is certainly no > more complicated than maintaining a diesel engine and generator. But > then, modern > refrigerators are also pretty much non-repairable without specialized > tools and a > supply of replacement refrigerant. And electric lights are pretty > hard to > manufacture at a rural technology level. > > > > > 4) Am I correct in assuming that the best (cheapest over all) > solution > > for a Diesel generator in such situations is to use SVO (straight > > vegetable oil) with a preheating system, rather than converting it > to > > biodiesel? > > > > 5) What are the effects on electricity usage patterns for each type > of > > supply? For example, if people know that their battery system can > only > > store a fixed amount that won't be replenished until the next day, > are > > they more efficiency conscious than if they know their supply won't > be > > replenished until next year's harvest? > > I know that folks living in PV-powered homes are very conscious of > the state of > their battery reserve. High-consumption activities (laundry, > vacuuming, etc) are > typically only done when the sun is shining. > > > > > My gut feeling is that due to the higher conversion efficiency of > solar > > panels, these would make a better overall solution for providing > > electricity than growing biofuels, with less environmental impact > > overall. However the high capital cost may rule this solution out > for > > smaller villages. (Of course if you are using the energy for > transport, > > then biofuels are much better because the energy can easily be > stored > > and transported over long timescales. But that is not what I'm > > interested in here). > > > > Does anyone have any other information, opinions, experience of > these > > types of systems? Have I overlooked any significant arguments on > either > > side? > > The real key is what resources are available locally. If arable land > is plentiful, > then grown fuel is likely more attractive. If sunlight is plentiful, > and land is > not, then PV is probably more attractive. > > Do the people have any objections to the noise and exhaust from the > diesel engine? > > Would the shade created by installing PV panels provide any benefit? > (e.g. roof > for a water storage tank, reducing evaporation). > > Is there an infrastructure in the country that can provide support > related to the > maintenance of the PV system, including batteries? Will the > transportation network > support taking away the old batteries when new ones arrive? (I > figure there has to > be some kind of transportation network now if they are using diesel > fuel). > > > > I may soon have an opportunity to visit a remote solar installation > > that is backed up with a Diesel generator (as far as I know using > > petrodiesel) so wish to find out as much as possible beforehand. > > > > Regards, > > Donald > > > > > > ===== > > -- > > 43 - slightly more than the answer to life, the universe and > everything. > > > -- > Darryl McMahon http://www.econogics.com/ > It's your planet. If you won't look after it, who will? > > > > > ------------------------ Yahoo! Groups Sponsor > --------------------~--> > Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar. > Now with Pop-Up Blocker. Get it for free! > http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/FGYolB/TM > --------------------------------------------------------------------~-> > > > Biofuel at Journey to Forever: > http://journeytoforever.org/biofuel.html > > Biofuels list archives: > http://infoarchive.net/sgroup/biofuel/ > > Please do NOT send Unsubscribe messages to the list address. > To unsubscribe, send an email to: > [EMAIL PROTECTED] > Yahoo! Groups Links > > <*> To visit your group on the web, go to: > http://groups.yahoo.com/group/biofuel/ > > <*> To unsubscribe from this group, send an email to: > [EMAIL PROTECTED] > > <*> Your use of Yahoo! Groups is subject to: > http://docs.yahoo.com/info/terms/ > > > ===== -- 43 - slightly more than the answer to life, the universe and everything. ___________________________________________________________ALL-NEW Yahoo! 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