Power to Gas

Scaling up clean renewable energy systems will generate more electricity than we need. The Centre for Alternative Technology (CAT) have put forward proposals [1] which would generate about 1,160 TWh of electricity in an average year. The average total demand would only be around 770 TWh per year. However, the problem is that the electricity isn't necessarily generated when we need it. There will be a mismatch between supply and demand, with both large surpluses and shortfalls.

The key is to develop large amounts of energy storage which can be saved until needed. At the moment technologies like fly wheels, compressed air, batteries and pumped hydro plants can't store enough energy to keep the lights on when there's reduced amounts of renewable electricity. For example, in 2010 there was little wind but a high demand for electricity due to the cold weather.

The solution is to develop a technology called Power to Gas or P2G.

Hydrogen
Hydrogen can be made by the electrolysis of water – splitting H2O into hydrogen (H) and oxygen (O) using electricity. Electrolysers can use electricity at times when there is abundant surplus of electricity, to create hydrogen gas for storage. In principle, hydrogen can be stored and then used directly to produce electricity using gas turbines or fuel cells. However, hydrogen is a very light gas that needs to be highly compressed for storage. Itis also quite explosive and can even corrode metal. It is possible to store relatively large amounts of hydrogen (a few 100 GWh) over long periods of time, for example in salt caverns. However, compared to natural gas (primarily methane), hydrogen is difficult to store and transport and there is almost no existing infrastructure suitable for it.

Biogas & Synthetic Gas
Biogas and synthetic gas are both produced from renewable sources. Biogas, a mixture of methane and carbon dioxide, can be produced by anaerobic digestion (AD) – the decomposition of biomass (for example, grass, animal manure or food waste) in an oxygen-free environment. Carbon neutral synthetic gas is made via the Sabatier process. Here, hydrogen (made by electrolysis) and carbon dioxide (from burning biomass, or from biogas) are combined to produce methane. Methane is easier to store than hydrogen. The Sabatier process can be seen as ‘upgrading’ hydrogen to a gas that is easier to handle. The process of using electricity to produce gaseous fuel is sometimes referred to as ‘power to gas’ (GridGas, 2012).

Methane gas is also the primary component of today’s fossil fuel natural gas. The methane in biogas and synthetic gas can be stored in very large quantities just as natural gas is currently. The UK today has a highly developed gas infrastructure that includes storage facilities, such as the Rough gas store off the coast of Yorkshire, which has a capacity of 35,000 GWh. However, methane is a powerful greenhouse gas, so it is very important that any escaping from pipelines or storage is kept to a minimum.

Biogas and synthetic gas, once stored, can be burned in power stations (again, like natural gas today) to provide energy when electricity supply from renewable sources is insufficient to meet demand. Gas power stations burning biogas or synthetic gas can be flexible – we can turn them on or off quickly. We can use them as ‘back up’ generation to meet demand when electricity supplies from variable renewables fall short. They can also supply industry for very energy intensive processes which would be difficult to run on electricity.

It is important to remember that burning methane is only carbon neutral when it is produced using biomass and/or renewable electricity. When methane gas is produced from biomass, the amount of CO2 released by burning it is reabsorbed when new biomass plants are grown, resulting in no net increase of GHGs in the atmosphere. Synthetic gas is carbon neutral when the hydrogen used is produced using renewable electricity, and the CO2 used is from non-fossil fuel sources (like
biomass).

The processes involved in creating a significant biogas and synthetic gas back up system have many losses associated with them. As energy is converted between forms (electricity and biomass to gas, and back to electricity), we lose energy in the process – about 50%. However, the ability to store energy in this way forms an integral part of an energy system powered by renewables, and is a good way of using electricity which would otherwise be surplus to requirements.

Who is making the technology happen?

A Sheffield company called ITM Power [2] is developing and installing technology to make Power 2 gas a reality.

References:
[1] http://www.zerocarbonbritain.com/images/pdfs/ZCBrtflo-res.pdf for the full report
[2] http://www.itm-power.com/energy-storage/power-to-gas-energy-storage-solution/

Heating from old Mines

Glasgow could soon become the latest city in Europe to develop a renewable underground heating system, after researchers unveiled plans to tap into water stored in a network of abandoned mines. A team at Glasgow Caledonian University, backed by Scottish Power, are launching a project to identify underground reservoirs in the tunnels that could be used to harness geothermal energy.


The research aims to build on the findings of a study by the British Geological Survey last year, which found almost 40 per cent of Glasgow's heat could be provided via geothermal energy.

The network of abandoned tunnels left by Glasgow's miners now hold huge amounts of water. Using heat pumps, researchers reckon Glasgow could "concentrate" heat energy from lower temperature waters in the mines to make water hot enough to heat buildings.

The heat could then be harnessed to warm the city's houses and offices, while the system could also be reversed in summer to provide cooling. If successful, the technology could help Glasgow meet its target to provide 11 per cent of its heat from renewable sources by 2020.

Geothermal energy is already being used in a small scale project in Shettleston, Glasgow, providing heating and cooling for 17 houses. However, the researchers now want to map the geothermal potential of the entire city over the next three years.

Geotechnical specialist Dr Nicholas Hytiris hopes the findings will allow Glasgow to install under-street heating systems, similar to those pioneered in Hamburg and Stockholm. "We believe this technology will, in the long term, be able to provide cheaper and more sustainable heating, which could be an answer to fuel poverty issues prevalent in many areas of Glasgow, particularly those with a mining past and a legacy of poor-quality housing and high unemployment," he said.

"In three years' time we will have a full and accurate record of what is going on beneath our feet and then we can go on from there."

See
http://www.businessgreen.com/bg/news/2243470/glasgow-mines-geothermal-heat-to-tackle-fuel-poverty
http://www.bgs.ac.uk/research/energy/geothermal/expertiseHeatEnergyGlasgow.html

This link also has a video
http://www.bbc.co.uk/news/uk-scotland-21443745

Off-Shore Wind Turbine Suction Bucket Support Structure

The Danish company Universal Foundation has developed a gigantic steel suction bucket which will act as a support structure for off-shore wind turbines. It has been engineered to sink rapidly into the sandy sea floor. Once in place, it will become stuck fast and form a rock-solid foundation for a wind turbine above the waves.

The structure works by creating quicksand around the rim of the 16-metre-diameter bucket, so it slips easily into the seabed. When the inverted steel bucket reaches the bottom, a pipe running up through the stem above sucks water out of the bucket. This causes water to flow into the bucket through the sediment, creating a sloppy quicksand at the rim. But when the bucket is in place, the pump is turned off, forming an extremely strong foundation. Trying to pull it out creates a vacuum in the bucket, like when you try to pull your foot out of wet sand on the beach.

Conventional foundations for offshore wind turbines are either a giant steel rod, driven into the seabed, or a steel jacket resembling an electricity pylon. Both need more steel – an expensive material – bigger, more specialised ships for deployment and are more prone to costly weather delays.

Two of the foundations left the Harland and Wolff shipyard in Belfast in January 2013 and will become the first deepwater deployment of the technology once planted 25 metres below the surface at Dogger Bank.

If all goes well, the technology may provide a secure basis for the thousands of giant offshore wind turbines planned for UK waters. The benefits include:

• It can be installed faster and at lower costs than conventional foundations
• It could save developers more than £5bn if used for the 6,000 turbines planned in the next decade or so, because it is 20% cheaper than conventional foundations, which make up about 30% of the cost.

For more details, see the following websites. The Guardian website has good videos, graphics and pictures:

• http://www.guardian.co.uk/environment/2013/jan/22/suction-bucket-offshore-wind?intcmp=122 
• http://www.universalfoundation.dk/
• http://www.harland-wolff.com/Services/Design-and-build-offshore-foundations/Universal-Foundation.aspx

Dynamic Demand Electricity

Dynamic Demand Control is a technology that could help stabilise the National Grid, reduce carbon dioxide emissions associated with power generation, and allow more intermittent renewable energy (like wind and solar power) than is currently possible.

The government has promised to connect significant amounts of renewable energy to the National Grid but many renewable sources are variable. Take wind: sometime it's windy sometimes it's calm. Already the Grid has to be continually balanced because the demand fluctuates all the time (we randomly switch kettles, lights etc. on and off). The National Grid company therefore has to pay for power stations to change their output continually on a second-to-second basis. This "response" service costs around £80 million a year (on top of the actual power supplied) and involves part-loaded generators which are less efficient and polluting. An important question is: "What will happen when large amounts of intermittent renewables are on-line? How do we keep the system balanced?" This is an important issue for system operators and the Government.

But what if we could design appliances that demand most of their power at times when there is excess power available on the grid? Take a fridge. It needs electricity but it doesn't really care exactly when it gets it as
fridges have large thermal storage. The good news is that you can measure the excess power on the National Grid from any plug socket in the country. (You just measure the "50Hz" AC frequency because it drifts a little as generators slow down and speed up). The device you need to do this would cost less than £5 and would fit into a matchbox.


It should be possible to provide the same stabilising service to the National Grid more cost-effectively using dynamic demand fridges. This means such a fridge could earn money throughout its life. The organisation Dynamic Demand has been founded to promote this technology. They want to see Government, regulators and industry seriously debate the possibilities. After all, if such a technology could reduce the carbon dioxide emissions associated with power transmission and allow more renewable energy onto the power grid, can we really afford not to have it?

See www.dynamicdemand.co.uk
Also see http://gridwatch.templar.co.uk/ for near real time information about the grid

North Sea Renewables Grid

Although critics of wind power suggest that wind is a variable energy source and can’t be relied upon to keep the lights on, this isn’t actually the case when wind power is distributed over a large area like the North Sea. Variations in production at one wind park can be partly balanced by that of another park several hundreds of kilometres away.

To demonstrate this concept, Greenpeace commissioned a report based on what would happen if real wind speeds over the North Sea were applied to more than 100 envisioned wind power projects with 10,000 turbines. If all projects from Belgium, Denmark, France, Germany, Great Britain, Netherlands and Norway were built there would be an installed capacity of 68.4Gw.

The top graph below shows how the power output of the propose London Array would fluctuate with changing wind speeds. When combined with all wind farms around the British east coast, the power production starts to level out as a dip in generation around London could be offset by heavy winds around Scotland. The final graph shows how wind production stabilises even more when combining all wind farm output from countries bordering the North Sea.

To capitalise on the balancing nature of distributed wind farms, a large North Sea grid spanning 3,850 miles would be required to connect all of the wind farms together. Such a grid would facilitate trade and increase security of supply by dispatching power from offshore wind farms to different countries depending on the highest demand. Moreover, an offshore grid allows the import of electricity from Norwegian hydro power plants to Britain and other countries. For some hydro plants, excess power (when the wind blows and sun shines) can even be used to pump water back into reservoirs, working like a huge water-battery. Biomass from European countries could also be fed into this grid.

A system of this nature with many thousands of wind turbines is more reliable, and energy production more secure because the impact of maintenance or defects will be negligible when compared to a large coal or nuclear plant going off line. Another advantage of a North Sea grid is that any future wave power, floating wind Turbines and tidal power stations could also be connected up to provide more power, stability and distribution of power between countries.

If this proposal were to be implemented then 70 million homes or 13% of the annual electricity consumption of the seven European countries could be met.

For the full report, see
http://www.greenpeace.de/fileadmin/gpd/user_upload/themen/energie/offshorewindgrid_final.pdf

Green Bio-Gas

According to the energy company, Ecotricity, it is about to launch a brand new initiative to supply green gas.

Green gas - or biogas – can be made during a composting-like process that breaks down food waste and other material that normally gets dumped straight into landfill or burnt in incinerators. Britain currently wastes around 18m tonnes of food alone a year, which could produce enough biogas to supply over 700,000 homes.

Ninety percent of homes in Britain are connected to the gas main and nearly two-thirds of us have a dual-fuel supplier (electricity and gas).

Householders who sign up to Ecotricity's deal will be supplied from January, although initially their gas will come from conventional natural gas. It is hoped that a small percentage of biogas will be injected into the national grid later in the year.

The company, which has about 30,000 electricity customers, said it wanted to eventually source 50% of its gas tariff from biogas and would match British Gas on dual-fuel pricing.

The owner of Ecotricity is reported to be planning to invest about £50m to build two green gas plants to make the biogas, but would also look at buying in biogas from other sources, including suppliers in Holland.

The National Grid recently produced a report on biogas suggesting that between 15% - 48% of our domestic gas supplies could be met in this way. Some materials such as wood are included in these figures so it isn’t clear if the materials destined for bio-mass projects are counted twice.
  
Extra momentum for UK biogas should arrive in 2011, when the government is due to introduce a renewable heat incentive, giving financial assistance to generators of heat from renewable sources, from householders using ground-source heat pumps to companies supplying green gas such as Ecotricity.

See www.ecotricity.co.uk for more details on green gas.
See www.nationalgrid.com/uk/Media+Centre/Documents/biogas.htm for a small report on the feasibility of using green gas.

Electric Car Charging Points

Elektromotive has developed a generic electric vehicle refuelling point called the  Elektrobay which has been designed to be a stylish and durable piece of street furniture. With its contemporary lines it blends in naturally to the surroundings, whether installed at the road side or multistorey car parks.

The elektromotive transport system is secure and extremely user friendly, offering a safe, dedicated power outlet.  The unit can be used by electric scooter, car or van.

To access the Elektrobay the commuter uses an electronic key that communicates wirelessly with the unit. When a valid key is read, the charging post automatically opens the weather proof access panel, where the recharging lead from their electric vehicle can be inserted. Upon closing the access panel, it locks securely and the power is turned on. The Elektrobay is a very safe design and as a security feature, once the access panel is closed and the unit charging, it can only be reopened by the same key or by one of the service engineers. When the access panel is reopened the power is automatically cut to allow safe removal of the charging lead.

The unit is fitted with an active display that shows the status of the charging post and is programmed to notify the user when their Elektrobay access is about to expire. It will also show the user’s name and registration number.
www.elektromotive.com