Wind and solar PV have won the race – it’s too late for other clean energy technologies


Andrew Blakers, Australian National University

Across the world, solar photovoltaics (PV) and wind are the dominant clean energy technologies. This dominance is likely to become overwhelming over the next few years, preventing other clean energy technologies (including carbon capture and storage, nuclear and other renewables) from growing much.

As the graph below shows, PV and wind constitute half of new generation capacity installed worldwide, with fossil, nuclear, hydro and all other renewable energy sources making up the other half. In Australia this dominance is even clearer, with PV and wind constituting virtually all new generation capacity.

Moreover, this trend is set to continue. Wind and PV installation rates grew by 19% in 2015 worldwide, while rates for other technologies were static or declined.

https://datawrapper.dwcdn.net/AMQdk/1/

PV and wind dominate because they have already achieved commercial scale, are cheap (and set to get cheaper), and are not constrained by fuel availability, environmental considerations, construction materials, water supply, or security issues.

In fact, PV and wind now have such a large head start that no other low-emission generation technology has a reasonable prospect of catching them. Conventional hydro power cannot keep pace because each country will sooner or later run out of rivers to dam, and biomass availability is severely limited.

Heroic growth rates would be required for nuclear, carbon capture and storage, concentrating solar thermal, ocean energy and geothermal to span the 20- to 200-fold difference in annual installation scale to catch wind and PV – which are themselves growing rapidly.

Both wind and PV access massive economies of scale. Their ability to saturate national electricity markets around the world severely constrains other low-emission technologies. Some of the other technologies may become significant in some regions, but these will essentially be niche markets, such as geothermal in Iceland, or hydro power in Tasmania.

Around 80% of the energy sector could be electrified in the next two decades, including electrification of land transport (vehicles and public transport) and electric heat pumps for heat production. This will further increase opportunities for PV and wind, and allows for the elimination of two-thirds of greenhouse gas emissions (based upon sectoral breakdown of national emissions data).

Storage and integration

What about the oft-cited problems with the variable nature of photovoltaics and wind energy? Fortunately, there is range of solutions that can help them achieve high levels of grid penetration.

While individual PV and wind generators can have very variable outputs, the combined output of thousands of generators is in fact quite predictable when coupled with good weather forecasting and smoothed out over a wide area.

What’s more, PV and wind often produce power under different weather conditions – storms favour wind, whereas calm conditions are often sunny. Rapid improvements in high-voltage DC transmission allows large amounts of power to be transmitted cheaply and efficiently over thousands of kilometres, meaning that the impact of local weather is less important.

Another option is “load management”, in which power demands for things like domestic and commercial water heating, and household and electric car battery charging, are moved from night time to day to coincide with availability of sun and wind. Existing hydro and gas or biogas generators, operated for just a small fraction of the year, can also help.

Finally, mass power storage is already available in the form of pumped hydro energy storage (PHES), in which surplus energy is used to pump water uphill to a storage reservoir, which is then released through a turbine to recover around 80% of the stored energy later on. This technology constitutes 99% of electricity storage worldwide and is overwhelmingly dominant in terms of new storage capacity installed each year (3.4 Gigawatts in 2015).

Australia already has several PHES facilities, such as Wivenhoe near Brisbane and Tumut 3 in the Snowy Mountains. All of these are at least 30 years old, but more can be built to accommodate the storage needs of new wind and PV capacity. Modelling underway at the Australian National University shows that reservoirs containing enough water for only 3-8 hours of grid operation is sufficient to stabilise a grid with about 90% PV and wind – mostly to shift daytime solar power for use at night.

This would require only a few hundred hectares of reservoirs for the Australian grid, and could be accomplished by building a series of “off-river” pumped hydro storages. Unlike conventional “on-river” hydro power, off-river PHES requires pairs of hectare-scale reservoirs, rather like oversized farm dams, located in steep, hilly, farm country, separated by an altitude difference of 200-1000 metres, and joined by a pipe containing a pump and turbine.

One example is the proposed Kidston project in an old gold mine in north Queensland. In these systems water goes around a closed loop, they consume very little water (evaporation minus rainfall), and have a much smaller environmental impact than river-based systems.

How renewables can dominate Australian energy

In Australia, if wind and PV continue at the installation rate required to reach the 2020 renewable energy target (about 1 GW per year each), we would hit 50% renewable electricity by 2030. This rises to 80% if the installation rates double to 2 GW per year each under a more ambitious renewable energy target – the barriers to which are probably more political than technological.

PV and wind will be overwhelmingly dominant in the renewable energy transition because there isn’t time for another low-emission technology to catch them before they saturate the market.

https://datawrapper.dwcdn.net/Gzs0a/1/

Wind, PV, PHES, HVDC and heat pumps are proven renewable energy solutions in large-scale deployment (100-1,000 GW installed worldwide for each). These technologies can drive rapid and deep cuts to the energy sector’s greenhouse emissions without any heroic assumptions.

Apart from a modest contribution from existing hydroelectricity, other low-emission technologies are unlikely to make significant contributions in the foreseeable future.

The Conversation

Andrew Blakers, Professor of Engineering, Australian National University

This article was originally published on The Conversation. Read the original article.

Advertisements

We can have fish and dams: here’s how


John Harris, UNSW Australia; Bill Peirson, UNSW Australia, and Richard Kingsford, UNSW Australia

Fish are the most threatened group among Earth’s freshwater vertebrates. On average, freshwater fish populations have declined by 76% over the past 40 years. Damaged fish communities and declining fisheries characterise global freshwater environments, including those in Australia.

Fish migrate to complete their life cycles, but water-resource developments disrupt river connectivity and migrations, threatening biological diversity and fisheries.

Millions of dams, weirs and smaller barriers – for storage and irrigation, road and rail transport and hydropower schemes – block the migration of fish in rivers worldwide.

These barriers serve our needs for water supply, transport and energy. But, by obstructing fish migrations, they also degrade ecological integrity and reduce food security.

This is bad news for those who depend on fish for food. For example, in the Mekong River fish supply over 70% of the people’s animal protein, but catches are falling drastically following dam building.

In our paper published today in CSIRO’s Marine and Freshwater Research, we take stock of the impact these barriers have on our freshwater fish, most (perhaps all) of which migrate, and how we can help them.

Dam it all

There are countless barriers across Australia’s rivers. Roughly 10,000 barriers of all kinds obstruct flows in the Murray-Darling Basin. Flow is unobstructed in less than half of the basin’s watercourse length.

Native fish numbers in the basin’s rivers have declined by an estimated 90% through habitat fragmentation by barriers together with altered flows, overfishing, coldwater pollution and invasive species.

Similar problems also affect coastal river systems. One or more barriers obstruct 49% of rivers in southeast Australia.

Local species extinctions and loss of biodiversity have occurred nationwide in developed regions, especially upstream of large dams.

Overcoming barriers

One way to help fish overcome barriers is to build fishways (or “fish ladders”).

Fishways are designed to aid fish travelling upstream or downstream at high (dams, weirs) or low (road crossings, barrages) barriers. These are classed as “technical”, with hard-engineering designs, or “nature-like”, mimicking natural stream channels.

The raised Hinze Dam on the Nerang River, Queensland, with Australia’s first trap-and-haul fishway.
Author provided

Recognition that dams threaten freshwater fish communities lagged well behind their construction. Nonetheless, European and American observations of declining fisheries for species moving from the sea to breed in rivers prompted early attempts in Australia to provide for fish passage.

The first Australian fishway was built near Sydney in 1913. By 1985, 52 had been built, but they adopted Northern Hemisphere designs for salmon and trout. These were unsuitable for Australian species, which rarely leap at barriers, and their flow velocities, turbulence and other aspects were excessive.

Seeing the failure of these fishways, New South Wales Fisheries sought advice in 1982 from George Eicher, an American expert, who advised on research to create designs for local species.

This led to expanding fishways research and construction in eastern states. The result was markedly improved performance, for example in the Murray-Darling’s Sea to Hume program.

Fishway performance

Our research shows that regrettably few Australian fishways have yet been shown to meet ideal ecological criteria for mitigating the impact of barriers. Furthermore, fishways are in place at relatively few sites.

In NSW, for example, only about 172 in total serve several thousand weirs and 123 dams. They can be expensive to build and operate, so costs retard mitigation at numerous important sites.

Fishways have seldom been built on dams (fewer than 3% of Australia’s 500 high dams have one); they have generally cost tens of millions of dollars; and most operate, with limited effectiveness, for less than 50% of the time. The need for much greater investment in innovation, research and development is pressing.

How to store water and also rehabilitate fish

To reduce the impact of dams on fish we need to look at resolving problems at river-basin scale; improving our management of barriers, environmental flows and water quality; removing barriers; and developing improved fishway designs.

The modern vertical-slot fishway at Torrumbarry, near Echuca, on the Murray River.
Author provided

One way to accelerate improvements nationally would be to pass legislation for routinely re-licensing waterway barriers at regular intervals. This would mean that older barriers are re-evaluated and upgraded or removed where necessary. Under the NSW Weir Removal Program, 14 redundant weirs have already been removed, with others under assessment.

We are developing an innovative pump fishway concept at UNSW Australia. It combines aquaculture fish-pumping methods for safe fish transfer with existing fishway technology.

Young Australian bass during trials of an experimental model of the pump fishway.

We hope the project may help transform past practices through less-costly modular construction, adaptability to a wide range of barriers and improved effectiveness.

Better fishway developments will mean that we can store and supply much-needed water while also restoring fish migrations. This will be increasingly important as climate change reduces streamflows in many regions, and will help rehabilitate fish populations.

The Conversation

John Harris, Adjunct Associate Professor, Centre for Ecosystem Science, UNSW Australia; Bill Peirson, Adjunct, Water Research Laboratory, School of Civil and Environmental Engineering, UNSW Australia, and Richard Kingsford, Professor, School of Biological, Earth and Environmental Sciences, UNSW Australia

This article was originally published on The Conversation. Read the original article.