Mark Diesendorf, Associate Professor and Deputy Director of the Institute of Environmental Studies at the University of New South Wales, has posted a detailed and convincing article in The Conversation this morning about the potential for a 100% renewable electricity supply in Australia.
His conclusion (with my underlining):
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.
That’s right: we could start implementing 100% renewable electricity generation RIGHT NOW, and with no financial burden on the economy, just a temporary shift of the political sacred cow of hydrocarbon fuel subsidies to the renewable energy sector. In fact Diesendorf doesn’t say it, but there would be a significant positive impact on the economy from very significant increases in both temporary and long-term employment in the renewables sector. And, you never know, when the renewable sector no longer needs the subsidy the government of the day may decide not to reinstate it for the hydrocarbon fuel sector. Very big win for the economy and possibly the climate if that happened.
Could we do this with current renewable technologies, or would we have to wait for the development of some currently unproven approach? It’s can all be done with today’s technology. Here’s Diesendorf again:
“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:
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.”
“BASELOAD POWER! You’ll need baseload power!”, I hear the coal and gas industries shouting. Well, clearly such a system would NOT require baseload power in the form that they understand.
I like it too that he has addressed the bogie inherent in the use of biofuel powered gas turbines: the possibility that they will require unacceptable volumes of timber from forests or the allocation of unacceptable areas of food-producing farmland to grow the fuel to run them. Keeping the gas turbines in reserve, to be used only for periods of a few hours a few times per year would mean that not only would fuel demand be low, but the fuel could be sourced from wastes over a longer period and stockpiled for later use.
Do we know whether it would work in reality? How about on hot summer evenings, or on those cold, windless winter nights? Diesendorf’s team used real figures from the National Energy Market (presumably the ones published daily by the Australian Energy Market Operator), to model many different mixes of current renewable energy technologies to come up with the proportions set out above.
“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.”
Read the full article on The Conversation.