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Science Forum

  1. 22 Jul '14 11:53 / 2 edits
    Renewable energy is ready to supply all of Australia's electricity

    "...In a recent article on The Conversation, University of Melbourne Professor Emeritus Frank Larkins wrote that Australia's targets to increase renewable energy will make electricity more expensive, thanks to problems with consistency and storage.

    But Professor Larkins is several years behind developments in renewable energy and its integration into electricity grids. In fact, we already have technically feasible scenarios to run the Australian electricity industry on 100% renewable energy—without significantly affecting supply.

    When the sun doesn't shine…

    Professor Larkins states that hydro, wind, solar depend on:

    irregular weather patterns, which lead to uncertain and intermittent power output. This is a big challenge for electricity generators and retailers, and it can cost lots of money.

    But the problem of "consistency" or variability of some renewable energy sources is now better understood, both from empirical experience with lots of wind power in electricity grids, and from hourly computer simulations of electricity supply and demand performed for many states, countries and global regions.

    For instance, South Australia nominally has two coal-fired power stations, several gas-fired ones, and at least 15 operating wind farms. Wind now supplies an annual average of 27% of South Australia's electricity generation. As a result, one of the coal stations is now shut down for half the year and the other for the whole year. And the state's electricity supply system is operating reliably without the need for any additional non-renewable energy supply.

    In Germany, the northern states of Schleswig-Holstein and Mecklenburg-Vorpommern have about 100% and 120%, respectively, of their electricity generated from the wind. Of course they use their transmission links with neighbouring states (including each other) to assist in balancing supply and demand with such high wind penetrations.

    100% renewable—without supply problems

    But Australia's National Electricity Market (NEM) has no such links to other electricity supplies. How could it increase generation from renewable energy without hurting electricity supply?

    Ben Elliston, Iain MacGill and I at UNSW have performed thousands of computer simulations of the hour-by-hour operation of the NEM with different mixes of 100% commercially available renewable energy technologies scaled up to meet demand reliably.

    We use actual hourly electricity demand and actual hourly solar and wind power data for 2010 and balance supply and demand for almost every hour, while maintaining the required reliability of supply. The relevant papers, published in peer-reviewed international journals, can be downloaded from my UNSW website.

    Using conservative projections to 2030 for the costs of renewable energy by the federal government's Bureau of Resources and Energy Economics (BREE), we found an optimal mix of renewable electricity sources. The mix looks like this:

    Wind 46%;
    Concentrated solar thermal (electricity generated by the heat of the sun) with thermal storage 22%;
    Photovoltaic solar 20% (electricity generated directly from sunlight);
    Biofuelled gas turbines 6%; and
    Existing hydro 6%.

    So two-thirds of annual energy can be supplied by wind and solar photovoltaic—energy sources that vary depending on the weather—while maintaining reliability of the generating system at the required level. How is this possible?

    It turns out that wind and solar photovoltaic are only unable to meet electricity demand a few times a year. These periods occur during peak demand on winter evenings following overcast days that also happen to have low wind speeds across the region.

    Since the gaps are few in number and none exceeds two hours in duration, there only needs to be a small amount of generation from the so-called flexible renewables (those that don't depend on the vagaries of weather): hydro and biofuelled gas turbines. Concentrated solar thermal is also flexible while it has energy in its thermal storage.

    The gas turbines have low capital cost and, when operated infrequently and briefly, low fuel costs, so they play the role of reliability insurance with a low premium.

    No need for batteries

    Our research, together with similar extensive hourly computer simulations by others spanning up to a decade from Europe and the USA (reviewed in Chapter 3 of "Sustainable Energy Solutions for Climate Change", refute Professor Larkins' statement that "We need baseload electric power [from non-renewable sources] to guarantee security of supply".

    Many regions of the world could operate a 100% renewable electricity system reliably without any baseload power stations. Indeed, in electricity supply systems with a lot of renewable energy, inflexible coal and nuclear baseload power stations get in the way. What we really need to balance the variability of wind and photovoltaic solar are the flexible renewable energy power stations: hydro, solar thermal and biofuelled gas turbines.

    This mix needs only a little storage from hydro and solar thermal to maintain reliable supply. With enough fuel, biofuelled gas turbines could also be considered storage. Such a mix has no need for expensive batteries or hydrogen fuel cells.

    Using BREE's conservative projections for the costs of renewable energy technologies in 2030, we find that the cost of 100% renewable energy is A$7-10 billion per year more than that of the existing polluting fossil fuelled system. Although this is a 50% increase, it is likely to be less than the damage caused by the increased frequency of heatwaves, droughts and floods in a business-as-usual scenario.

    The renewable scenarios would be economically competitive with the fossil system either with a carbon price of A$50 per tonne of CO2 (reflecting part of the environmental and health damage from fossil fuels) or, in the absence of a carbon price, by removing the existing subsidies to the production and use of fossil fuels and transferring them temporarily to renewable energy.

    As an alternative to BREE's cost estimates, Bloomberg New Energy Finance calculates that wind and solar are already cheaper than new build coal and gas in Australia. If this is correct, 100% renewable systems are already economically competitive with a new fossil-fuelled system.

    Australia could be more ambitious

    Is Australia's Renewable Energy Target of 41,000 gigawatt hours per year in 2020 "ambitious"? Not on a world scale. The table below compares several countries' renewable energy contributions, as well as their official long-term targets.


    (I cannot copy and paste the table here so you will have to see the link yourself to see it )


    Considering that Australia has much greater solar energy and wind potential than the European countries, its present renewable contribution and its 2020 target are both modest.

    Moving to 100% renewable electricity is safe, technically feasible and affordable. It can cut greenhouse gas and other emissions and land degradation, while creating local jobs and energy security. It is ready to go!
    ..."


    I think this link does an excellent job of debunking the usual argument some people make against renewables. We are very rapidly running out of excuses to going 100% renewable.
  2. 22 Jul '14 12:00
    Originally posted by humy
    Renewable energy is ready to supply all of Australia's electricity

    "...In a recent article on The Conversation, University of Melbourne Professor Emeritus Frank Larkins wrote that Australia's targets to increase renewable energy will make electricity more expensive, thanks to problems with consistency and storage.

    But Professor Larkins is several years be ...[text shortened]... link does an excellent job of debunking the usual argument some people make against renewables.
    sooooo why isn't it?
  3. 22 Jul '14 12:03 / 6 edits
    Originally posted by robbie carrobie
    sooooo why isn't it?
    Bad politics + short termism + lack of imagination.
    But that might all change because, as I said, we are very rapidly running out of excuses.
  4. 22 Jul '14 12:20
    Originally posted by humy
    I think this link does an excellent job of debunking the usual argument some people make against renewables. We are very rapidly running out of excuses to going 100% renewable.
    Yes, excellent article.
  5. Subscriber Kewpie
    since 1-Feb-07
    25 Jul '14 09:12
    Australia has an attitude problem with wind power, which isn't shared by the rest of the world. Someone out there managed to convince the "general public" that wind turbines generate cancer-causing electromagnetic transmissions, and every attempt to develop a wind farm results in mass protests in the area concerned and far afield. The rest of us are quite aware that it's a nonsense - collected data shows nothing of the sort - but ignorance is so widespread here, and the cheap-coal power industry pays a lot of lobbyists and media people to keep that ignorance in place, that I doubt wind power will ever get the recognition it deserves here.
  6. 25 Jul '14 12:21 / 1 edit
    Originally posted by Kewpie
    Australia has an attitude problem with wind power, which isn't shared by the rest of the world. Someone out there managed to convince the "general public" that wind turbines generate cancer-causing electromagnetic transmissions, and every attempt to develop a wind farm results in mass protests in the area concerned and far afield. The rest of us are quite a ...[text shortened]... that ignorance in place, that I doubt wind power will ever get the recognition it deserves here.
    Someone out there managed to convince the "general public" that wind turbines generate cancer-causing electromagnetic transmissions, and every attempt to develop a wind farm results in mass protests in the area concerned and far afield.

    I did not know this. What a pity. I take it that this is rather similar to the totally paranoid hysteria against GM food that is similarly based on pure ignorance and misinformation. I am afraid we get a lot of that crap here in the UK.
  7. Standard member sonhouse
    Fast and Curious
    25 Jul '14 12:35
    Originally posted by humy
    Someone out there managed to convince the "general public" that wind turbines generate cancer-causing electromagnetic transmissions, and every attempt to develop a wind farm results in mass protests in the area concerned and far afield.

    I did not know this. What a pity. I take it that this is rather similar to the totally paranoid hysteri ...[text shortened]... ased on pure ignorance and misinformation. I am afraid we get a lot of that crap here in the UK.
    That two hour period of no energy from renewables could be met by just pumping air to underground caves suitably sealed up and have a supply of compressed air available 24/7 using compressors to pump up the air in the caverns till they reach some 'full' point. Then just refill as they leak away.
  8. 25 Jul '14 18:25 / 3 edits
    Originally posted by sonhouse
    That two hour period of no energy from renewables could be met by just pumping air to underground caves suitably sealed up and have a supply of compressed air available 24/7 using compressors to pump up the air in the caverns till they reach some 'full' point. Then just refill as they leak away.
    yes, just one example of many possible perfectly reasonable solutions. All it takes is just a little imagination to come up with them.
    I had thought of using wind turbines to pump up water from a lower water reservoir to a higher one and then later retrieve that potential energy hydroelectrically. This certainly would be reasonable where there is hydroelectric damns anyway but not sure if it could be made cost effective if you had to build reservoir especially just for this purpose -perhaps underground reservoirs? -probably the capital costs would be far too high due to their necessary huge size but not sure.
  9. 25 Jul '14 19:25 / 1 edit
    Originally posted by humy
    I had thought of using wind turbines to pump up water from a lower water reservoir to a higher one and then later retrieve that potential energy hydroelectrically. This certainly would be reasonable where there is hydroelectric damns anyway but not sure if it could be made cost effective if you had to build reservoir especially just for this purpose -perhaps un ...[text shortened]... -probably the capital costs would be far too high due to their necessary huge size but not sure.
    It is already cost effectively used for power storage in many parts of the world. We have one here in SA.

    http://en.wikipedia.org/wiki/List_of_pumped-storage_hydroelectric_power_stations


    Also see:
    http://en.wikipedia.org/wiki/List_of_energy_storage_projects

    There are several projects with underground compressed air as mentioned by sonhouse.
  10. 25 Jul '14 19:35 / 2 edits
    Originally posted by twhitehead
    It is already cost effectively used for power storage in many parts of the world. We have one here in SA.

    http://en.wikipedia.org/wiki/List_of_pumped-storage_hydroelectric_power_stations

    Oh brilliant. So my idea does economically work after all and isn't a new one although I had independently thought of it.
    However, I was thinking of terms of directly using the mechanic energy from wind turbines to pump water up hill without converting it into electrical energy first because that way it should be more energy efficient because you avoid having to have so many energy conversions each of which gives its own energy losses. I am not sure if that is done somewhere already.
  11. 25 Jul '14 20:38
    Originally posted by humy
    Oh brilliant. So my idea does economically work after all and isn't a new one although I had independently thought of it.
    However, I was thinking of terms of directly using the mechanic energy from wind turbines to pump water up hill without converting it into electrical energy first because that way it should be more energy efficient because you avoid having ...[text shortened]... ions each of which gives its own energy losses. I am not sure if that is done somewhere already.
    It might be possible in rare instances, but in most cases the wind turbines are not at sites suitable for this sort of project.
    Even at a site that has the right geography for water storage and has good winds, there is the problem of location. To pump water you have to be at the bottom of the hill (water cannot be sucked more than 7 metres vertically). The wind is best at the top of the hill. So somehow you have to transfer that mechanical energy down the height of the wind Turbine tower then further down the hill to the pump station.
  12. 25 Jul '14 21:06 / 3 edits
    Originally posted by twhitehead
    It might be possible in rare instances, but in most cases the wind turbines are not at sites suitable for this sort of project.
    Even at a site that has the right geography for water storage and has good winds, there is the problem of location. To pump water you have to be at the bottom of the hill (water cannot be sucked more than 7 metres vertically). T ...[text shortened]... energy down the height of the wind Turbine tower then further down the hill to the pump station.
    arr but that brings me back to one of my original ideas which is to build two reservoirs at different levels especially built for this job underground very close by to the turbines wherever they are. That way you could have turbines at the top of the hill and store the energy hydroelectrically underground without the mechanical energy having to be transferred through an unreasonable distance. To get the mechanical energy transferred down to a sufficient depth which would be all the way down to the lowest reservoir, you could use a long vertical rotating shaft.
    But, as I said, I think that might be too expensive to set up -think of all the expensive tunneling that would be required and the required large size of the reservoirs. But at least such a setup should still eventually pay for itself and be cost effective in the very long run.
  13. 26 Jul '14 11:47
    Originally posted by humy
    To get the mechanical energy transferred down to a sufficient depth which would be all the way down to the lowest reservoir, you could use a long vertical rotating shaft.
    Don't forget that the turbines must be spread out over a large area - unless you are talking about a small project with only one large turbine.
  14. 26 Jul '14 18:44
    Originally posted by twhitehead
    Don't forget that the turbines must be spread out over a large area - unless you are talking about a small project with only one large turbine.
    not if there is a pair of mini underwater reservoirs for each and every wind turbine directly under each one.
  15. 26 Jul '14 19:36
    Originally posted by humy
    not if there is a pair of mini underwater reservoirs for each and every wind turbine directly under each one.
    I think flywheel technology might be a better idea.
    But I am not convinced that the advantages of keeping it local are significant.