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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorCWatters
    • CommentTimeNov 22nd 2015

    "BRITAIN’S green energy barons are getting huge taxpayer subsidies to install diesel generators — exactly the kind of polluting energy source their wind and solar farms are meant to replace.

    Wind and solar power firms are being encouraged to install the generators, which pour out CO2, a greenhouse gas, and toxic nitrogen dioxide, on their sites in order to provide standby generating capacity and prevent the lights going out during periods of peak demand.

    The giant Roundponds solar farm, near Melksham, Wiltshire, is among the first green generators to take advantage. The directors of Hive Energy, which owns it, have won permission to put diesel generators near the solar panels — despite local objections.

    Similarly, First Renewable has won permission for a diesel farm next to its wind turbines and solar panels at Kettering Energy Park in Northamptonshire."

    The full story says 1000 diesel generators the size of a container have been installed in the past 18 months with a similar number planned.
    Yep - that would be the downside of the lack of planniing that has characterised our energy policy for the last dozen years.
    Too many people who should have known better have been bedazzled by the low carbon solar and wind energy systems (mmm... shiny....) without properly working out how to handle their intermittency.
    • CommentAuthorringi
    • CommentTimeNov 22nd 2015
    Given that a large part of the cost of installing a winfarm is putting in the grid connection, does it not make since to also use the same connection for the backup generator when the wind is not blowing…..

    These diesel generators may not be the lowest CO2 way to generating power from none renewable methods, but at least they don’t use much energy when they are not generating.
    • CommentTimeNov 22nd 2015
    Many hospitals have diesel generators that the National Grid can call on for extra power.
    Now that would be a headline.

    "Hospital flicks switch and earns a £1000"
    • CommentAuthorCWatters
    • CommentTimeNov 22nd 2015

    "Diesel generation won’t be used as renewables backup, despite critics’ claims"

    "...the diesel scheme isn’t meant to back up renewables..."

    Shouldn't we build gas plants rather than diesel?
    There was a scam in Ontario with solar feed-in tariffs. People just bought diesel generators and used those for their net metering. Some people made a fortune before they were found out.

    Paul in Montreal
    'green energy barons' that's a new one
    As oppose to the morally angelic 'press barons' that we all know and love
    • CommentAuthorCWatters
    • CommentTimeNov 23rd 2015
    These diesel generators are being promoted as backup but what if they burn biodiesel? Does that make it economic to run them more frequently?

    This mentions a 20MW plant...


    "Its 52 generators will consume more than 1.1m litres of diesel a year"

    So does anyone know how efficient diesel generators are so we can work out what percentage of the time they expect to be running?
    • CommentTimeNov 23rd 2015
    About 40% efficiency
    So about 44,000 MWh/year or 5 MW installed capacity (that depends on how it is run).
    That BBC report says they have 52 generators, so they are going to be tiny ones, so possibly not that efficient.

    We already use diesel for grid balancing, I think the Carbon Intensity is better than coal, but not as good as gas (CCGT anyway).
    Looking at the Gridwatch figures, it looks like there is a consistent 1 MW of oil generation (this may not be IC engines as some power stations also burn oil).
    There was a peak of 1.3 GW on the 12/12 12, I wonder what happened then. The day before and the day after there was no oil burning. OCGT usage was different to that day, as was hydro, so probably some planned maintenance.

    The real beauty of IC generation is that it can come online in a few seconds. This can save major problems. If you suddenly loose 1 GW of generation, then you need to get 1 GW of generation on line in the next 10 to 20 seconds or you start to overload the network.

    Burning bio diesel is no more environmentally friendly that burning anything else and has large scale long term effects to agriculture and food price stability.

    The main thing to remember with electrical generation is the order that the National Grid tries its hardest to keep too.
    Top of the list is reliability
    Then carbon intensity
    Then price

    It may seem odd that price is last, but there are different prices for different supply times.
    No one wants to run a diesel generator 24/7, they are not reliable enough or cheap to do so.
    It works out cheaper to pay them to do nothing for most of the time and then pay them even more when they are needed. The alternative is to have larger coal or gas plants being paid to have what they call 'hot spinning reserves'.
    HSR can be online in about 20 to 30 minutes, so not fast enough for a large coal plant or a nuclear coming off line.

    Think of it as a bus. We often think that it is total madness that a bus is run for just a few passengers, while at other times, you can't get on, but over the year, it works out best for everyone. Everyone can get a bus, but just occasionally you have to wait a little while for the next one.
    • CommentTimeNov 23rd 2015 edited
    Posted By: SteamyTeaThat BBC report says they have 52 generators, so they are going to be tiny ones, so possibly not that efficient.

    As I understand what I read today, they are existing backup generators in hospitals and other public sector sites. Definitely won't have been designed with efficiency as a consideration, unless there are special models for constrained fuel tank sizes that everybody happens to have chosen! Reliability, reliability and performance to spec would be my top three criteria for those type of generators.
    • CommentTimeNov 23rd 2015
    Yes, reliability is the important bit. They have to kick in in seconds, then perform as needed.

    I suspect that it was a bit of a non story that is just making a monkey out of the general public. No idea why really. I can't see what is being gained by playing on the general public's ignorance of the electrical energy market.
    Not as if it is top most on peoples minds how electricity is supplied reliably or if we got rid of every bit of renewable energy our pockets would be overflowing with gold and we could walk to work on baby polar bears.
    • CommentAuthorCWatters
    • CommentTimeNov 24th 2015
    So about 44,000 MWh/year

    So if it has a 20MW capacity that means they plan to run it about 25% of the time.
    Yes agree with that calculation. But sounds wrong as I thought these should only be used to ramp up supply while the slower ramping generators took over. Six hours a day seems a lot for that.

    • CommentAuthorwookey
    • CommentTimeNov 25th 2015
    Are we talking about generators getting capacity payments? There was an auction held early this year to ensure that sufficient dispatchable capacity existed on the grid. The price came out quite a lot lower than expected at £19/MWh, because it turns out that there are a lot of (mostly diesel) small generators that already exist and bid in.

    Capacity payments make sense because as you install more renewables (and nuclear) which both have negligible fuel costs and thus want to run as much as possible, so will take whatever price is going, the fueled generators get to run less and less. This is the 'merit order effect'. Eventually the owners cannot make any money because they run so few hours so want to close up shop without a capacity payment to make it worth their while to stick around.
    • CommentAuthorCWatters
    • CommentTimeNov 25th 2015
    The issue for me is that _new_ diesel plant is being installed on the premise that it's needed to back up renewables, when in fact it's needed to make up for a general lack of generating capacity eg not enough gas and nuclear. How else can you explain the need to run them as much as 25% of the time?
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