Energy Storage: Filling the Generation Gap

By Carl Ennis, Siemens

Energy management gets more interesting or challenging, depending on your perspective. From buying electricity from Government run power stations, we moved to buying electricity from a range of providers and then to generating our own electricity, mainly with solar power or wind turbines. Now we are looking at selling electricity to the grid or alternatively storing electricity generated in low demand periods to use at busier times.

With electricity demand set to double by 2050, the UK’s energy system has reached a turning point and there is a shift underway. The energy system is developing into a more diverse network with many sources of power; combining the traditional centralised model of power generation and distribution with renewable generation and more local, decentralised distribution.

The increasing focus on the decentralised generation and storage of electricity, where multiple local sites – including buildings, campuses, hospitals, air and sea ports and local government estates, amongst others – generate and manage their own electricity. Consumers are now becoming generators and can develop new business models to make an income or massive savings from their energy – becoming pro-sumers. This calls for intelligent distributed energy management and interconnected microgrids.

Many of our facilities, and our client’s, are committed to zero emissions, in Siemens case by 2030, and seeking to become self-sufficient in energy in the process.

Options and opportunities

Because solar and wind power, the most common options for self-generation, are intermittent, we have to look at either using the grid to replace our own generated electricity when the wind drops or at night, or we have to generate and store the excess to balance out supply and demand.

One of the interesting opportunities for storage, much in the news at the moment, is the use of electric vehicle batteries. The proposition is that when electric vehicles are not in use, they are connected to the grid, national or micro, and through smart management able to supply electricity to the grid or draw power to be charged when needed. Since at any given time 95% of cars are parked, this is an attractive proposition; electric vehicles can generally store in their batteries more than an average home’s daily energy demand. Government policies are pushing the rapid development of ever faster charging and higher capacity vehicle batteries to make electric vehicles more attractive to consumers, so the potential can only become greater as all vehicles in the UK going electric could match or exceed the current 38 million.

Passenger cars, taxis, buses and light vans account for around 75% of transport CO2 emissions, which account for 15% of overall CO2 output. If the majority of vehicles are electric by 2050, the current target, which many feel should be reduced, that offers an enormous reserve of power held in the vehicle fleet. Using energy stored in the batteries of electric vehicles in the car park to power large buildings not only provides electricity for the building, but also increases the lifespan of the vehicle batteries. Researchers at Warwick University have demonstrated that vehicle-to-grid (V2G) technology can take enough energy from idle electric vehicle batteries to be pumped into the grid and power buildings, without damaging the batteries. V2G storage capabilities can also enable EVs to store and discharge electricity generated from renewable energy sources such as solar and wind, with output that fluctuates depending on weather and time of day. There is also consideration that electric vehicle batteries, when exhausted beyond effective use in the vehicle, could still be useful for electricity storage, thus extending their useful life.

Battery systems technology has advanced very rapidly and we have to hope that this will continue through the efforts of manufacturers like Siemens and others coupled with, and working alongside, the research efforts of universities. Ideally we should be moving away from rare earth metals, essential to the current wave of battery development. Lithium, cobalt, vanadium, copper and so on have a clue in their generic name, they are rare. Furthermore, these minerals are mostly found in countries with unstable or inimical political systems and where mining practices do not always meet the basic human rights standards we would wish for.

Elements for the future

While electrochemical battery systems have been the technology of choice in most of the storage

applications to date, our group of Siemens scientists continue to research and develop, with particular effort in the higher capacity technologies which will better compliment current capabilities and future system needs.

Hydrogen, one of the most common elements on earth, has always played a major role in the fuels we use but it is also a potentially very important fuel in its own right. We have produced hydrogen power cells for on-site storage of solar and wind generated electricity; off-grid charging of electric vehicles – including performance cars at the Goodwood Festival of Speed; to augment power connections in car parks or fleet vehicle parks for EV charging at multi story car parks, shopping centres, parking for buses, ambulances and police cars; for powering trains on the systems of many countries and for powering heavy goods vehicles. Others have used it to fuel internal combustion engine cars and, most famously, as the propellant for space rockets. Hydrogen fuel cells, generate electricity by combining hydrogen and oxygen. They are reliable and quiet, with no moving parts; have a small footprint and high energy density and release no emissions – when running on pure hydrogen, their only by-product is water. Fuel cell facilities can, therefore, produce hydrogen when electricity is cheap, and later use that hydrogen to generate electricity when it is needed. We have recently installed hydrogen fuel cells for storage at Keele University as part of a major demonstrator development to make it self-sufficient and save £2million per annum in energy bills. Hydrogen cells are also being used as primary and backup power for many critical facilities e.g. telecom relays, data centres and credit card processing.

Green Ammonia is another avenue we are exploring. In a world first, Siemens opened a £1.5m pilot project in Oxfordshire employing ammonia, produced using green power, as a new form of energy storage. We believe ammonia has potential advantages over other emerging storage technologies because it is repurposing existing technology and hardware.

Be ambitious

The success or failure of energy production and storage projects are not solely related to the technology. Much of the funding for these projects will come from private sector investment, which may be looking at 15 to 20 years for payback and profits. This means they will have to be convinced that policies at local and national level will be stable around subsidies or support; buying and selling transactions with grids over the investment period. The other problem that needs to be addressed is planning consent, which for many projects will involve several planning authorities; decisions need to be in a realistic time frame and avoid costly and time consuming appeals.

Storage, in all its forms, both existing and not yet developed, is a critical element in our ‘future grid’. We are underestimating the scale of the task but also the amount of relevant technology already in existence. We need to raise our ambition.