Putting 100% renewables on the table

In Climate Spectator on Tuesday Roger Dargaville informed readers about the Australian Energy Market Operator's (AEMO) plan to model scenarios assessing the feasibility and cost of supplying the National Electricity Market entirely with renewable energy by 2030 or 2050. A draft set of results are due in March next year with the final report released in May.

Since that article was published I've had time to look in greater detail over what AEMO and its consultants, ROAM Consulting and the CSIRO, intend to do. It is quite incredible and worth going into more detail.

The model will break down the NEM states into 40 regions, illustrated below. It then incorporates hour-by-hour historical data for wind speed, solar radiation (direct and indirect), and wave height and period for each region. This will enable the model to incorporate analysis of short-term weather variation and the extent to which this might affect the ability for the supply mix to match electricity demand as it varies from hour to hour. The historical data is quite comprehensive, stretching from July 2003 to June 2011, so it should be a reasonable reflection of the kind of variation, including extreme events, that we might expect into the future for these resources.

In addition annual resource assessments have also been undertaken by each region for biomass and geothermal.

What is very new and extremely interesting is that they've also investigated the potential for expansion in pumped-hydro, including the use of seawater-based sites.  Pumping water uphill into a storage reservoir and then releasing it to drive a conventional hydro turbine is one of the lowest cost and effective forms of energy storage available. With ocean pumped-hydro you'd build a dam site in an area of land with steep terrain close to the ocean and then pump seawater into it from the ocean.

All of these resource assessments are then overlaid by a variety of geographical constraints (for example they assume national and marine parks as well as urban areas are off limits for wind farms and concentrating solar), to then determine the realistic amount of megawatts of power generation capacity that could be installed within each region.

Then using data on each technology's energy conversion efficiency, they convert the data on natural resource energy into how much electricity could be produced within each region for each hourly block in time.

The researchers will then come up with mixes of the various technology options and regions that enable them to meet the hourly profile of electricity demand over the year of 2030 and 2050. This will take into account expected growth in electricity demand between now and then.

They will also overlay the transmission infrastructure that would be required to get the power from each region to demand centres while meeting reliability standards. The study will incorporate analysis on the use of other energy storage options beyond pumped hydro.

The model will then try to work out which mixes of technologies plus transmission and energy storage provide the lowest cost. 

As I was saying, this piece of work is incredibly impressive. All parties involved in making this project a reality should be commended for having the vision and insight to undertake such an ambitious initiative. Their next job is to expand the model to other areas of Australia, in particular Western Australia.

For far too long a number of media commentators and indeed some senior policymakers, particularly politicians, have written-off renewable energy based on gross simplifications like, ‘solar's not much good as the sun doesn't shine at night', and ‘wind isn't baseload'.  However once this model is complete, making policy on the basis of homespun wisdom or coarse rules of thumb will no longer pass muster. 

The model won't be perfect, and its results will probably cause difficulties for both those who think 100 per cent renewable energy is the only answer, and those who think renewables are a complete waste of time.

But if your ultimate goal is to work out how we can avoid dangerous climate change, far better to have that debate based on data, rather than screaming matches informed by speculative guesses.