rss
21

WA grid could reach 85% renewables – and cheaper than ‘clean coal’

Print Friendly

Repowering WA’s South West Integrated System (SWIS) grid with renewables would not increase the wholesale electricity price. This is the conclusion of modelling by the WA research group Sustainable Energy Now (SEN), using hourly NASA wind and solar data over 10 years.

WA generation has been more expensive than the eastern states because more than 40% is from gas generators less than 30 years old and still being paid off.  There is sufficient gas capacity to provide standby power for 60% renewable energy (RE) generation, enough to replace all coal.

The two oldest coal generators (Muja A and B) are 52 years old and will be closed next year, despite $300 million being spent to refurbish them.

By 2021, 75% of the remaining coal generators will be 31 to 40 years old.  Replacing these with new wind and solar generation would deliver electricity at less than the current cost (Figure 1) and reduce CO2 emissions by 45% (2.1 t CO2 per head).

A high penetration RE generation mix of 85% wind and PV with 15% gas and 6,000MWh of battery storage would cost about $117/MWh, only $3/MWh more than the existing coal/gas/7% RE generation mix, and less than so-called ‘clean’ coal.

Contrary to the AEMO being indifferent as to what ‘strategic reserves’ are used, SEN believes that fast ramping open cycle gas turbines (OCGT’s) with dual-fuel capability are the most effective and proven standby fuelled generation technology.

SEN’s modelling for the 85% scenario shows that about 2500 MW of OCGT capacity and 1000 MW of DSM will be required in addition to the battery storage. All of this is included in the above costing as is the cost of new 300 kV transmission lines to wind and solar farms.

Coal transition scenarios include a conservative cost estimate of $0.5 billion for refurbishment of old coal and liabilities under the 2020 RET.

clean coal graph

Figure 1 shows that when a 1.2% annual demand growth to 2030 is taken into account, the 85% RE scenario (blue arrow) reduces CO2 emissions to 15% compared to 2017. New supercritical (so-called ‘clean’) coal with gas (grey line) would cost $2/MWh more and emissions would increase.

Scenarios that maximize nuclear ($203/MWh) and new supercritical coal with carbon capture and storage (CCS) ($146/MWh) are nowhere near cost competitive with the RE scenarios. Retrofitting of the old coal generators with CCS would cost more than the 85% RE scenario and still incur 52% of existing emissions.

Assumed RE technology costs are based on 2016-17 PPA’s reported in Renew Economy (Table 1 below). All RE is costed although up to 30% may be spilled in the high penetration scenarios. Fossil fuel, nuclear and solar thermal generation LCOE’s are calculated using BREE (2013) predicted 2025 CAPEX with cost of capital (WACC) cited from the Finkel Review Report (2017).

clean coal 2 graph

The SWIS is an isolated grid about 1/5th of the area of the NEM and it currently has virtually no storage. It has the advantage of large gas pipelines connecting to NW Shelf gas producers. The 85% scenario assumes 6000 MWh of ‘behind the meter’ battery storage is installed, costed as a $40/MWh subsidy, with the remaining costs recovered by owners reducing their power bills and some income from energy arbitrage.

Another scenario (green arrow in Figure 1) shows that 92% renewable energy could be provided for $129/MWh by including 600 MW of concentrating solar thermal (CST) with 10 hours of molten salt (MS) storage. This is the same cost as ‘clean coal’ with only 7% of the CO2 emissions.

There is potential for pumped hydro storage (PHS) from 2 of the water supply dams and in locations along the coast using the ocean as the lower reservoir.

However, large flows would be required to compensate for the low available heads (< 150m) necessitating very large diameter pipes and large reservoirs, which would increase the cost of these projects. SEN has also modelled a scenario with PHS (Figure 1), but it is more expensive than the CST/MS option.

Regardless of whether or not CST /MS or PHS is added later, 85% wind and solar with battery storage is now the most economic plan for clean energy on the SWIS and it could be achieved by 2030.

SEN’s SIREN and Powerbalance software is free to use and downloadable from: http://www.sen.asn.au/modelling_overview. It can be used anywhere in the world by downloading NASA ‘MERRA’ solar and wind data for the location.

Ben Rose is Principal Energy Modeller for Sustainable Energy Now  

Share this:

  • Chris Drongers

    “The two oldest coal generators (Muja A and B) are 52 years old and will be closed next year, despite $300 million being spent to refurbish them.” And here we have a small example of what Malcolm seems intent on locking the NEM into with extending the life of Liddell. Major cost in the face of a cheaper or similar alternative that will be built eventually anyway.

    Interesting that pumped hydro in WA suffers from lack of elevation so pipes and pumps would need to be bigger.

    And alarming that coal plants in WA are nearing the end of their operational lives so quickly – in a lump rather than spread over decades.

    Fortunately WA has what seems to be a forward looking government, unfortunately the previous Liberal government left WA broke.

    • Joe

      What happened to all the dosh generated from The WA Mining Boom?

      • Chris Drongers

        The mining income boom is just starting. The WA boom was in construction, of mines, ports,rail, accommodation etc.
        The overrun in WA state debt was due to a fiscally illiterate Liberal-NP government losing control of infrastructure expenditure (massive road spending in the wheatbelt, becoming a future liability as wheat forced off rail breaks up the understrength road base, failure to look ahead at the costs of unfettered urban expansion instead of going for cost recovery on urban road and infrastructure use, buying an election by bribing police, nurses and teachers with big pay rises, and building circuses for mates).

        The mining income boom from royalties is only just starting as newly built mines come on stream. That is if the LNP hasn’t granted too many royalty holidays.

  • Brunel

    The WA grid should be connected to the Eastern states grid.

    • Andrew Scott

      Agreed.
      Our aim should be to progress ASAP to and beyond 100% RE for all of Australia and have ways to contribute RE to our northern neighbors.

      To this end we should be putting time and effort into conceptualising a continental grid with widely dispersed renewable energy farms and many very large energy storages.

    • Greg Hudson

      What would the power line losses be over such a long distance ?

      • Brunel
        • Greg Hudson

          I’m impressed, and had not considered the possibility of 1mV over Ultra Direct Current. Thomas Edison would be rubbing his hands thinking he had outwitted Nikola Tesla (eventually).

        • Andrew Scott

          Very helpful, much appreciated.
          Have you an idea of indicative capital costs per kilometre for each of these transmission alternatives?

          • Brunel

            One is under construction in USA. You can perhaps find out the price of that.

            Cheap enough for China and India. You certainly need way less pylons – as illustrated by the diagram above.

    • grantoz

      Via HVDC. If it passed through the Nullarbor region, as no doubt it would, there might be the opportunity to use the excellent solar and wind resources in that corridor. The west could provide solar to the east later into the day, which would no doubt be a welcome source of income.

      I wonder if the economics of it could be made to add up?

  • FeFiFoFum

    I believe its now called the “SWIN”
    Used to be the South West Interconnected System, but is not the South West Interconnected Network.
    Must have had a change of government or something …

    The Muja A/B units ( there are four in total) are 60 MW nominal coal fired steam turbine generators and are ancient.
    Those units once had the dubious honour of being the worse polluting coal fired generators in Australia.
    They are 1950s vintage.

    If you look at the live data on the AEMO website they come under “Vinalco” and are not running.
    They hardly ever run.

    https://www.aemo.com.au/Electricity/Wholesale-Electricity-Market-WEM/Data-dashboard#generation-map

    The enlightened decision to spend $300 million on taking them out of mothballs back in 2010 was based on a gas shortage issue when we had the Varanus Island explosion resulting in gas curtailment to Perth metro area,, as well as a bus tie transformer failure which ties the 330kV network to the 132kV network.
    The Muja A/B units are connected to the 132kV network.
    Initial budget cost to bring the units back into production was a fraction of the final cost.
    So I guess thats where some of the mining boom royalties went… on another wasted government sponsored project.

    • Chris Drongers

      I heard that Varanus was in part an ‘own goal’ in that the regulations were set to allow sour gas into the pipes even though it was known that this would rot the pipes sooner than later.

    • juxx0r

      Varanus was ’08

  • Geremida

    Congrats on the modelling effort Ben. I wasn’t aware of what you guys have been doing. Had a bit of a look and it’s AWESOME!

  • Thanks All for your comments
    Brunel, we did look at aHVDC or 500 kV AC inter-connector with the NEM but the cost was prohibitive, > $3 billion as I recall. Besides, we’d only gain less than an hour of sunlight in the mornings. And there’s very unlikely to be enough surplus wind when needed to make much of a dent in WA’s shortfall when we have still winter nights

    • Brunel

      What about UHVDC? That is cheaper than HVDC and has even less leakage or transmission losses than HVDC.

      China and India have several UHVDC transmission lines now and one is being built in USA.

      Nothing is costly compared to the 12 submarines in SA.

  • Andrew Scott

    Thanks for your glimpse of a WA grid at 85% renewables and cheaper – Heading in the right direction.

    However it was disappointing to read your statement “The SWIS …………. has the advantage of large gas pipelines connecting to NW Shelf gas producers.”
    Clearly this statement is incorrect. We now know that the allure of ‘cheap’ and copious supplies of fossil fuels is a costly curse – not an advantage.

    We are struggling to break away from parameters of the old fossil fuel mindset.

    We spend too much time and effort thinking and talking about transitions involving continuing use of these unsustainable energy sources.

    We are also too parochial in our vision of what we are seeking to achieve, too focused on our capital city residential consumers and generally too oriented to the eastern seaboard.

    Our aim should be to progress ASAP to and beyond 100% RE for all of Australia and have ways to contribute RE to our northern neighbors.

    To this end we should be putting time and effort into conceptualising a continental grid with widely dispersed renewable energy farms and many very large energy storages.

  • Andrew Scott

    Re Pumped Hydro Storage opportunities:

    Any potential site offering an elevation exceeding 100 metres and having the ocean as its lower storage is worthy of favourable consideration. In these situations the avoided capital cost of providing a lower storage can either be a project saving or the funds can be directed to providing an upper storage of larger capacity.

    A PHS system operating at a lesser head does enjoy some cost benefit due to the lower pressure ratings required of the pipework, valves etc. There is also a positive safety aspect to managing operations and maintenance at lesser pressures than those present in a system with heads of several hundred metres.

    Finally,
    higher water flows from lower heads, to achieve a desired power output, can be achieved by employing more penstocks of regular size, not necessarily by using fewer but necessarily very large pipes.

    • That’s a really good idea, assuming these 300-foot high seaside cliffs are erosion-proof in future decades.

  • Huh? Two curious data points:
    1. Rooftop PV is cheaper than utility-scale in Australia?
    and
    2. How can you say that concentrating solar thermal has 7% of coal CO2 emissions (solar is zero CO2) or that it costs $129/MWh: (It is now $78) http://www.solarpaces.org/port-augusta-cheapest-solar-thermal-power/

    “Another scenario (green arrow in Figure 1) shows that 92% renewable energy could be provided for $129/MWh by including 600 MW of concentrating solar thermal (CST) with 10 hours of molten salt (MS) storage. This is the same cost as ‘clean coal’ with only 7% of the CO2 emissions.”