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Monday, September 4, 2017

Future energy technology is here

Australia ran an expensive experiment to encourage investment in electricity generation and distribution capacity to ensure supply on a few days of the year when demand is at a maximum.

Electricity demand on the hottest days in summer is about double the average electricity demand on other days. To encourage investment in capacity that is idle on all but these few extremely hot days each summer, a very profitable incentive was created.

State-owned electricity generators and distribution network operators that were able to borrow $billions at discounted interest rates were guaranteed a high rate of return on every dollar they could spend. The inevitable result was excessive and extravagent spending. It is commonly known now as "gold-plating".

As an aside, it is sometimes misunderstood that switching from coal-fired power generation to low-emission electricity generation increases prices. Note that the US maintained low electricity prices while making rapid progress on replacing coal-fired power stations.

Wind adds the most new generation capacity, followed by gas and solar

Technology is available to solve the problem that Australia created with these incentives to spend up big on electricity generating and distribution capacity that is planned to be idle on all but a few of the hottest days each summer.

This technology also solves the problem of what to do with the surplus electricity supply when the sun is shining on solar panels and the wind is spinning wind turbines, but all available battery storage is filled and demand is being fully met...

Distributed power-to-gas plants can convert the surplus electricity into renewable natural gas. This can be fed into the existing natural gas distribution lines to flow upwards to liquified natural gas plants for export. On the few occasions each year when electricity demand is exceptionally high, as many distributed power-to-gas plants as required can be reversed within a few minutes to generate electricity from natural gas stored in the natural gas distribution lines.

Renewable natural gas produced from farm and urban waste can be fed into the natural gas distribution lines and, where carbon dioxide has been separated from biogas, it can be piped to power-to-gas plants that combine carbon dioxide with hydrogen to produce renewable natural gas.

Australia is in the fortuitous position of being able to use renewable energy for 100 percent of its electricity supply, 100 percent of its transport energy and 100 percent of its energy exports.

Saturday, August 12, 2017

Renewable energy technology is affordable and reliable

Incumbent electricity and transport fuel producers lobby to hold back the adoption of renewable energy, but innovation has now eliminated the logic of their concerns.

When the roll-out of Australia's first-generation electricity supply system was finalised in the 1960's it relied upon simple management strategies for economic use of the capital investment:
  • Coal-fired power stations met electricity demand during peak loads during the day and at night heated off-peak hot water systems and stored further energy in pumped hydro storage.
  • The pumped-hydro storage system was available to supplement the coal-fired power generation capacity during the highest peak demand periods during each day. 
With the low cost of small-scale energy storage that is now available, it is practical to transfer the 1960's experience with centralised  electricity generation into managing electricity supply for individual homes, businesses and villages...

A large household in Australia uses up to 20 kilowatt-hours of electricity a day - about the same amount of energy that a 5 kilowatt rooftop solar photovoltaic (PV) can produce reliably on most days of the year.

For reliable electricity supply, a household only needs to install enough battery storage to provide it with all the energy it needs for just one day. On most days, the solar PV system will recharge all the energy used from the battery storage, and the household can meet occasional peak loads by drawing energy from both its solar PV system and battery storage at the same time.

Solar Battery Storage Comparison Table
Solar Battery Storage Comparison Table
Extract from SolarQuotes table

On days where solar PV energy output is below the usual level, the battery storage system can be topped-up overnight from large-scale generators. The large-scale generators can be informed of the total overnight demand well in advance - from data transmitted from battery storage systems, and schedule generation and distribution at times to make use of unused distribution capacity. This is like having supermarkets restocked by trucks using roads at 3 am in the morning to deliberately avoid busy peak-hour traffic.

In periods of extreme day-time peak demands, the large-scale generators can be brought online to supplement the regular levels of demand that are met by solar PV and battery storage of homes, businesses and villages.

This strategy eliminates the need for 'gold-plating' which is the major cause of high electricity prices in Australia: idle capacity for generation and distribution that is kept in reserve for as little as a few hundred hours each year when peak demand reaches unusual, extreme levels.

Sunday, July 23, 2017

Energy storage and meeting peak demand

The cost of storing energy and meeting peak demand can be cut dramatically with a good combination of technologies and judicious use of available assets.

Depleted gas fields in South Australia have provided a return on investment over a number of years and when reused for new purposes, save the need for investment in locating and tapping similar geological structures.

Subsurface geological conditions which may be suitable for underground gas storage have been identified in the Two Wells - Port Wakefield area of the Northern Adelaide Plains. This area is within 100km of Adelaide. (See "Underground Gas Storage", Department of the Premier and Cabinet, South Australia)

Cutaway view of gas turbine engine
A cutaway view of Solar Turbines' Taurus 70 engine, which is similar to a jet engine, but is used to generate electricity in power plants on the ground.
In a solar thermal turbine compressed air is heated by concentrated solar energy...

CSIRO Solar Air Turbine Project
CSIRO Solar Air Turbine Project

Heat energy in a solar thermal turbine can be supplemented with natural gas when there is partial cloud cover. At night natural gas can take over from solar thermal heating.

Whether a turbine engine is run on natural gas or solar thermal energy, about half the energy available from the turbine is used to power the compressor, leaving the other half to run a generator to supply electricity.

That is, a gas turbine power station with a nameplate rating of 100 MW is actually able to produce 200 MW of energy - if it did not have to drive a compressor.

Energy from renewable energy generators may be stored by driving compressors to compress air that is stored in depleted gas fields.

Compressed Air Energy Storage
Compressed Air Energy Storage
The compressed air energy storage can deliver electricity to the grid when it is required by supplying it to a gas turbine generator, relieving the generator of the need to drive a compressor while it is being supplied with compressed air.

A solar thermal power station can store energy in a compressed-air energy store and use the compressed air at night to significantly reduce the amount of stored thermal energy or natural gas needed for operation.

During peak demand periods, output from existing gas turbine generation plant can be quickly increased by reducing the energy used to drive compressors while supplying them with compressed air from storage.

Saturday, June 3, 2017

Does Australia have the world's silliest mining industry?

Setting a new benchmark in silliness, the Australian mining industry made not one, not two, but three laughable media releases last month.

On 11 May 2017 Minerals Council of Australia made a bold "projection" on the future of coal mining in Australia. The "projection" made from data from the Resources and Energy March Quarterly of a government department report was that the coal industry had a great future - at least until 30 June 2017 - when the value of exports of thermal and metallurgical coal was expected to be almost $55 billion.

Not many investment decisions are made on the basis of a "projection" of the final two months of the current fiscal year. On this "projection" the Minerals Council of Australia made the silly declaration: "Myth 1 Australia's thermal coal exports are in decline...BUSTED "

The Resources and Energy March Quarterly the Minerals Council of Australia thought worthy of quoting contains real projections for the value of Australia's coal exports to 2021-22.

Those projections show a dramatic decline from the peak of $55 billion in 2016-17 to just $39.8 billion in 2021-22.
Australia's metallurgical coal exports

Australia's thermal coal exports

On 17 May 2017 Minerals Council of Australia issued another media release with the puzzling title "New Report: Low emission coal technology key to growth in South-East Asia".
What is puzzling about this title is that a report referenced in the media release, "Sylvie Cornot-Gandolfe, ‘The role of coal in Southeast Asia’s power sector’, Oxford Institute of Energy Studies, December 2016" notes that combined cycle gas turbine power plants are superior to coal power plants for Asia:
Natural gas-fired power plants are, however, cheaper and quicker to build than coal-fired power plants, have higher efficiencies and greater flexibility in plant operation, and above all emit less CO2 than coal power plants. (The cost of capital expenditure for combined cycle gas turbine (CCGT) plants is around half that of coal on a per kWe capacity basis and their CO 2 emissions are also half that of coal.)

The levelized cost of electricity generation (LCOE)14 is commonly used in national power development plans to compare the costs of different technologies. Based on IEA assumptions for the costs of capital, operation and maintenance, and finance, and using 2015 prices for coal and gas ($63.5/t for coal and $10.3/MMBtu for gas), the generating cost of a new supercritical (SC) coal plant is 35 per cent cheaper than the generating cost for a new CCGT plant (Figure 6). However, at August 2016 coal and gas prices, the generating costs for coal and gas are similar – even slightly cheaper for gas.

14The LCOE includes fixed costs, variable costs (operation and maintenance and fuel) and financing costs for new power plants. In order to make meaningful comparisons, it is necessary to make a range of assumptions about various costs and operating parameters of competing technologies, as well as assumptions on future coal and gas prices. coal and gas prices, the generating costs for coal and gas are similar – even slightly cheaper for gas.

Keeping the silliest announcement till last on 29 May 2017 Minerals Council of Australia issued another media release with the cryptic title "Government takes balanced view on low emission strategy".
The media release begins:
The Australian coal industry supports the government’s sensible policy which recognises the role of our high quality coal in helping to curb emissions.

If the policy intent is all about reducing emissions we should have a technology neutral approach and that means considering the opportunity coal offers when utilising both high efficiency low emission (HELE) and carbon capture and storage (CCS).

Including CCS in the Clean Energy Finance Corporation (CEFC) ambit strengthens our capacity to lower emissions in the supply of electricity.
It is what the media release doesn't say that is incredibly silly: if a power station operator can release CO2 into the atmosphere for free, then it is absurd to imagine any investment in capturing and storing that CO2.

The government which is led around by the Minerals Council of Australia has ruled out imposing any scheme to put a price on the release of CO2 into the atmosphere.

Saturday, May 20, 2017

Coal lobby pushing obsolete technology in Asia

The coal lobby tries to lock-in dependence on coal imports
The coal lobby tries to lock-in dependence on coal imports

Friday, May 19, 2017

Renewable natural gas

The Australian Petroleum Production & Exploration Association - "the voice of [one part of] Australia's oil and gas industry" - held its annual conference in Perth recently. The Twitter feed about the conference is under hash tag #APPEA2017

Approaches for increasing the supply of natural gas were on the agenda, but renewable energy production of natural gas didn't get a mention. The absence of Bioenergy Australia which is holding a Bioenergy Business Breakfast in Adelaide next week left the struggling oil and gas industry bereft of a host of ideas to address the intractable problem of rising costs of extracting natural gas. The problem it faces is that there aren't any more low-cost natural gas reserves to exploit.

New methods for producing natural gas from renewable energy are being developed and refined, continually lowering costs and improving efficiency.

At the same time:
  1. The cost of extracting coal seam gas is constantly increasing.
    Unconventional gas production involves significantly higher capital expenditure
  2. The domestic price of natural is continuing to rise.
    The wholesale price of natural gas in Australia has risen steeply
    The wholesale price of natural gas in Australia has risen steeply
These factors are making it more commercially attractive to produce natural gas from renewable energy. 

There are 3 underlying processes for making renewable natural gas no matter how the various technologies achieve them:
  1. Carbon dioxide can be converted into carbon-containing compounds and oxygen by algae and other plants using sunlight to drive photosynthesis.
  2. Carbon dioxide can also be converted into natural gas and water using hydrogen produced from electrolysis of water using electricity from renewable energy generation. Oxygen is produced as a by-product as in the first process.
  3. Any carbon-containing compounds including those produced by algae and plants in the first process described above along with farm waste and municipal waste, can be converted into a mixture of methane and carbon dioxide. About half the carbon in the input feed stock is converted into methane, and the other half into carbon dioxide. After the carbon dioxide produced as a by-product is separated, it can be converted into methane by recycling it into either of the first two processes. No "carbon capture and storage" required, avoiding a susbstantial cost of using natural gas from fossil fuel reserves.
    • Long established technologies use methane-producing bacteria that create methane and carbon dioxide in anaerobic fermentation ponds or tanks.
    • More recently plants have become available that use supercritical water as a gasification medium to create methane and carbon dioxide. These complete the gasification process more quickly and so don't need large tanks where methane-producing bacteria gradually transform the feed stock. This newer technology is especially well-suited for wet feed stock as there is no need to dry it.

These more recent technologies can also efficiently convert low-grade coal with high moisture content into natural gas. Existing coal-fired power could use this option to improve efficiency and lower emissions until it is feasible to decommission them.

Researchers at ENN Group, China and Carleton University, Canada recently investigated supercritical water lignite gasification technology. See "Coal-based Clean Energy Production", Advances in Energy Engineering (AEE) Volume 1 Issue 4, October 2013.

Supercritical Water gasification of wet biomass and low-grade coal
Supercritical Water gasification of wet biomass and low-grade coal

More recently the Lappeenranta University of Technology, Finland, completed an assessment of the option of Australia becoming a major exporter of renewable energy to Asia - making use of the Queensland LNG export facilities - to ship natural gas made with renewable energy. See "Can Australia Power the Energy-Hungry Asia with Renewable Energy?"

Sunday, May 7, 2017

Improving old coal-fired power stations

Existing coal-fired power stations using low-grade coal might continue to generate particulate and sulphur dioxide emissions until they are decommissioned. Some are fitted with scrubbers and other post-combustion filters to reduce these emissions. This approach reduces the efficiency of already inefficient coal-fired power stations:

The heating value of Indian coal is, on average, about 60 percent of the heating value of coal burned in the United States. This increases the amount of coal that must be burned to generate a given heat input, implying higher auxiliary electricity consumption to run coal grinding equipment, conveyors, and pumps.

Auxiliary generation... will also increase if electricity is used to run pollution abatement equipment, such as electrostatic precipitators ( ESPs ) and flue-gas desulfurization units ( scrubbers ) . We note although coal-fired power plants in both countries have ESPs, only three plants in India currently have scrubbers.1

In the meantime there are options to increase efficiency and reduce harmful emissions until it is feasible to decommission these coal-fired power stations.
Average Gross Thermal Efficiency of Coal-Fired Power Plants by Country

One of these options is to pre-process the low-grade coal before combustion. The technology available to do this has several advantages. It eliminates the particulate and sulphur dioxide emissions and, more importantly, increases the efficiency of these coal-fired power stations. Scrubbers and other post-combustion filters are no longer needed.

Low-grade coal contains relatively high levels of contaminants and moisture content. The moisture content reduces the energy available for power generation when its burned because energy is wasted converting the moisture into water vapour. The contaminants increase the energy that is used to run pollution abatement equipment.

To understand the available technology this simplified model gives a reasonable approximation of what takes place; Consider a process in which carbon and water are placed in a reaction vessel and an environment is created to promote a desired reaction that uses little or no external energy. The reaction breaks down some of the water into oxygen and hydrogen. The oxygen reacts with half of the carbon to form carbon dioxide and the hydrogen reacts with the remainder of the carbon to create methane. The energy released by the reactions with carbon provide the energy needed to break down water  into oxygen and hydrogen.
Hydromethanation - Carbon plus Water producing Methane plus Carbon Dioxide

The methane can be separated to use in place of low-grade coal in the existing coal-fired power stations. There are no particulates or sulphur dioxide to be removed from the exhaust gases. When methane burns, about half the energy is produced by the reaction of carbon with oxygen to produce carbon dioxide, and about half is produced by the reaction of hydrogen with oxygen to form water vapour. Note that the total amount of energy is the same as would have been produced if all of the carbon had been burned and not pre-processed into carbon dioxide and methane. The moisture content that was present in the low-grade coal has been separated, as water, before combustion. No energy is wasted converting that moisture into water vapour.
Supercritical Water Coal Gasification

Research on this technology was conducted in several countries interested in producing methane from biomass that contains significant amounts of water. That research has advanced into at least three commercially available products. These can be adapted to carry out the desired pre-processing of low-grade coal into methane:

Upgrading low-grade coal to methane
Upgrading low-grade coal to methane

1 Chan, Hei Sing (Ron), Maureen L. Cropper, and Kabir Malik. 2014. "Why Are Power Plants in India Less Efficient Than Power Plants in the United States?" American Economic Review, 104(5): 586-90. DOI: 10.1257/aer.104.5.586