Computer scientists at the University of Southampton have developed a system of computerised agents which can manage energy use and storage in homes. Having already developed agents that can trade on the stock market and manage crisis communications, a team of researchers, led by Dr Alex Rogers (left) and Professor Nick Jennings (right)  at the University of Southampton's School of Electronics and Computer Science, have now developed an agent-based micro-storage management technique that allows homes to adapt their energy use to match market conditions.

The ultimate aim of this system is to optimise individual electricity usage and storage, in order to improve efficiency of the electricity grid and to reduce emissions.

The system, developed by Dr. Krishnen Vytelingum, Dr. Thomas Voice and Dr. Sarvapali Ramchurn, is outlined in a paper Agent-based Micro-Storage Management for the Smart Grid, nominated for the Best Paper Award at the 9th international conference on Autonomous Agents and Multiagent Systems, taking place in Toronto, Canada next week.

According to Dr Rogers, who earlier this year launched an iPhone application, named GridCarbon  (right) to measure the carbon intensity of the UK grid, this system will make it possible to install smart software into electricity meters.

The agents will be able to optimise usage and storage profile of a dwelling and learn best storage profile, given market prices at any particular time.

“This approach focuses on the system dynamics where all agents in the system are given the freedom to buy electricity whenever they see fit and, building on this, they can then learn the best storage profile in a market place where prices keep changing,” says Dr Rogers. “Another advantage is that if most homes in the system start using storage and manage to reduce peak demand, the overall cost of generating electricity is reduced.”


Storing 'green' electricity  as natural gas
A German-Austrian cooperation wants in future, to store surplus electricity – from wind or solar generation – as climate-neutral methane, and store it in existing gas storage facilities with the natural gas network.

Electricity generation is increasingly based on wind and solar energy. The missing link for integrating renewable energy into the electricity supply is a smart power storage concept. When the wind blows, wind turbines can generate more electricity than the power grid can absorb.

German researchers have now succeeded in storing renewable electricity as natural gas, converting the electricity into synthetic natural gas with the aid of a new process developed by the Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW), in cooperation with the Fraunhofer Institute for Wind Energy and Energy System Technology  (IWES)

Currently, Solar Fuel Technology, the Austria-based partner company, is setting up the industrial implementation of the process. One advantage of the technology is it can use the existing natural gas infrastructure. A demonstration system built on behalf of Solar Fuel in Stuttgart is already operating successfully. By 2012, a substantially larger system – in the double-digit megawatt range – is planned.For the first time, the process of natural gas production combines the technology for hydrogen-electrolysis with methanisation.

"Our demonstration system in Stuttgart separates water from surplus renewable energy using electrolysis. The result is hydrogen and oxygen," explains Dr Michael Specht (left) of ZSW.

"A chemical reaction of hydrogen with carbon dioxide generates methane – and that is nothing other than natural gas, produced synthetically.

"With the rapid expansion of renewable energies, the need for new storage technologies grows massively. This is of special interest for energy utilities and power companies.

"Surplus wind and solar energy can be stored in this manner. During times of high wind speeds, wind turbines generate more power than is currently needed. This surplus energy is being more frequently reflected at the power exchange market through negative electricity prices."  In such cases, the new technology could soon keep green electricity in stock as 
natural gas or renewable methane.

"Within the development of this technology, ZSW has been guided by two core issues,"  Dr Specht explains. "Which storage systems offer sufficient capacity for fluctuating renewable energies that depend on the wind and weather? And which storage systems can be integrated into the existing infrastructure the easiest?"

[WINGAS owns around 2,000 km of pipelines in Germany and Europe’s largest Rehden underground gas storage facility (over 4bn m3). Gazprom presently owns 50% minus one share in this joint venture. Thus, with an interest in WINGAS, Gazprom effectively owns a stake in Germany’s gas transmission networks.]

The storage reservoir of the natural gas network extending through Germany is vast: It equals more than 200 terawatt hours – enough to satisfy consumption for several months. The power network has only a capacity of 0.04 terawatt hours by itself. The integration into the infrastructure is simple: The natural gas substitute can be stored like conventional natural gas in the supply network, pipelines and storage systems, in order to drive natural gas cars or fire natural gas heating systems.

The new technology aims at facilitating the integration of high shares of fluctuating power generation from renewable energies into the energy system. One goal is to structure the delivery of power from wind parks on a scheduled and regular basis.

"The new concept is a game changer and a new significant element for the integration of renewable energies into a sustainable energy system," adds Sterner. The efficiency of converting power to gas is greater than 60%. "In our opinion, this is definitely better than a total loss," says Dr Specht. A total loss looms if, for instance, wind power has to be curtailed. The predominant storage facility to date – pumped hydro power plants – can only be expanded to a limited extent in Germany.

In order to push the new energy conversion technology forward, the two German research institutes have joined together with the company Solar Fuel Technology of Salzburg. Starting in 2012, they intend to launch a system with a capacity of approximately 10MW.

Japan: Grid parity anytime
In 2007, many agreed with the statement of US McKinsey & Co predicting that grid parity would be achieved in Japan around 2020. But the prediction by Fuji Keizai Co. Ltd. of Japan is that grid parity will be reached almost anytime now between "2010-2012." 

Solar cell manufacturing costs are dropping 5-10 years ahead of estimates. The low cost of CdTe solar cells overpowered other technologies in 2009, but it looks like thin-film Si solar cells may drop to about that level in 2010. Diagram by Nikkei Electronics based on material courtesy Fuji Keizai and First Solar.

2009 developments slash component costs
The recession caused by the Lehman Shock and the change in solar cell incentives in Spain (the "Spain Shock") occurred simultaneously, driving down costs. Sharp drop in Si prices had been expected, based on an Si oversupply, but it occurred simultaneously with the Lehman Shock, prices fell much further than expected. The manufacturing cost of a poly-Si photovoltaic (PV) cell module in 2009 was "about 30% less than it was in 2008," explains Norihiro Hashimoto, assistant manager, Osaka Marketing Div. of Fuji Keiza

The third event was the collapse of the existing price structure for photovoltaic cells triggered  by First Solar Inc. of the US which exploded into the market, fuelled by the cadmium-tellurium (CdTe)  solar cells with extremely low manufacturing costs. Volume production advanced in 2009 at the Malaysia fab and elsewhere, and the manufacturing cost in the 3Q of 2009 reached $0.85/W some 40% of the manufacturing cost of competing solar cell technologies. In addition to low manufacturing cost, adds Fuji Keizai, "The system sales prices dropped to about $2.40-2.50/W in 2008-2008."

This is about half the price of existing similar systems. In fact so low that it could well achieve grid parity for business rates, skipping over the residential price category. The numbers helped First Solar to achieve a shipment volume in 2009 significantly higher than other firms in the field.

The $1/W  lure by the end of 2010
The third shock, the price collapse brought about by First Solar, has had a major effect on companies throughout the industry. Most competing major solar cell manufacturers made public commitments to drop their manufacturing costs to the same level as First Solar by the end of 2010.

Q-Cells SE of Germany, for example, which lost its number one slot in photovoltaic cell shipment volume to First Solar, expressed confidence that it could drop manufacturing cost for CIGS solar cells to no more than €1/W by the end of 2010, at subsidiary Solibro GbmH of Germany.

QS Solar Inc. of China, a manufacturer of thin-film Si solar cells, promised to drop manufacturing cost to $0.70/W by the end of 2010, with retail at about $1.00-$1.20. Moser Baer PV Ltd. of India, now volume producing thin-film Si solar cells, claims to be able to drop manufacturing cost to $0.77/W if production volume can be boosted to

500MW/year.

Grid Parity attainment varies with region, and electricity rates and indicates when grid parity will be reached for various nations and regions. Horizontal axis shows annual generation, dependent on latitude and blue-sky ratio. If solar cell system price (inversely proportional curve) drops, more regions will reach grid parity. Diagram by Nikkei Electronics based on data courtesy McKinsey.

The Real Solar Cell Competition is Still to Come
Grid parity will also mean a variety of new problems.  Manufacturers supplying solar power generating systems will be caught up in intense global competition for cell performance, manufacturing cost and scale of production. Fuji Keizai estimate "The PV cell market will hit  ¥10trn in 2020, annual production volume at 85GW, 14 times higher than the 2008 level." In other words, being in first place in the market today does not  guarantee success in 10 years.

A number of major social issues for cities such as insolation rights could emerge. The sudden increase in the number of high-rise buildings in the 1970s and 1980s led to a number of suits by shadowed homeowners demanding sunlight. "This is going to be even more trouble than before, because now potential income from power generation is involved," warns one company involved in condo solar power systems. It is possible that solar power generation system evolution, including power conditioners, could alleviate the problem somewhat, though.

Battery-inclusive systems close to parity?
Grid parity achieved, PV generating systems will spring up like weeds which could introduce instability into commercial power grid and electric power utility operations, eventually leading to regulations on new solar power generation system installations.

In contrast to the German gas storage approach, Japan sees its solution to PV storage as batteries.  If solar power generating systems equipped with storage batteries achieve grid parity, the impact (including the reduction in fossil fuel consumption) will be enormous.  Already the Research Institute of Economy, Trade and Industry (RIETI) of Japan has released estimates that home solar power generating systems with storage batteries will reach grid parity in about 2022.