By Joe Sheehan, Technical Director, i3 Solutions Group
With green hydrogen widely touted as the most desirable option for achieving climate change goals, the debate is heating up in the data centre sector, where proponents of hydrogen believe it could well be an ideal primary power source for putting the sector on a path to net zero.
But if hydrogen is the answer, there are important issues to address, not the least of which the necessary changes to the utility power and gas infrastructure. Additionally, we urgently need to gather data on the greenhouse gas (GHG) abatement benefits that might accrue from data centres using hydrogen.
For a data centre, the real GHG abatement value of hydrogen lies in decarbonising the electricity supply – swapping out the utility grid for primary power and using green hydrogen to fuel engines or fuel cells for continuous use. This would take the data centre’s electrical consumption and replace it with a genuine source of renewable energy, since hydrogen causes no carbon emissions in use and green hydrogen is generated using only power from renewable sources.
But achieving such a goal brings its own challenges. While many countries have developed a strategy for hydrogen, the hydrogen economy itself – in the form of production, transport and storage – is just not here yet. Practically no location yet supplies infrastructure or any piped hydrogen. It is certainly not yet possible to bring in vessels containing compressed hydrogen at a sufficient volume and rate to provide for full and continuous operation of a modern data centre.
One obvious solution to this challenge could be for data centres and other energy intensive users to become both hydrogen producers and storage facilities. However, there isn’t currently a viable on-site source of clean energy that would produce green hydrogen by electrolysis of water.
Where could such an energy supply come from? One possible answer is for data centres to tap into a renewable power grid and utilise such a grid’s surplus energy for the production of green hydrogen. When the wind is blowing or the sun is shining and/or demand is low, taking electricity from Renewable Energy Resources (RERs) means the carbon emissions associated with each kilowatt hour of energy supply are low. And in the opposite circumstances – when the wind is not blowing, the sun is not shining, and electrical demand is high – data centres could operate using its own reserves of locally stored green hydrogen rather than the utility grid topping up capacity using fossil-fuelled power plants to fulfil demand. Use of hydrogen stored on-site for peak shaving at times of high demand and low renewable supply levels out demand on the grid. This is a form of carbon trade-off, since drawing less power from the grid reduces the use of fossil fuels, achieving a net gain in emissions reduction.
But is the round-trip efficiency, using this strategy good enough to achieve a meaningful advantage?
Modelling the carbon benefits
The big question is whether on-site hydrogen production is economically and spatially viable and offers affordable benefits in terms of greenhouse gas abatement.
Using carbon intensity data which is publicly available from grid networks in the UK and Ireland, i3 built a mathematical model of the process and measured what GHG abatement benefits it might bring about. It factored in the storage and technology that would be necessary, with the model using a nominal 10MW data centre in different locations.
The model showed the returns are quite modest in terms of carbon emission reductions in places like Scotland, where there are a lot of renewables on offer. It is possible to reduce by about 10% a data centre’s energy or carbon emissions – approximately 500 tonnes of carbon per year.
Interestingly, the percentage reduction in the southeast of the UK was smaller, but that worked out to be the same carbon reduction in absolute terms because there is higher grid carbon intensity in the region. In other words, the carbon costs are higher, so a smaller percentage reduction is an equivalent saving.
These modest returns need to be weighted against the cost of applying the hydrogen technology to data centres at sufficient scale.
The i3 model provides useful insight about the need to coordinate with grid-level facilities. It has also aided understanding of how battery energy storage, and in future, hydrogen, could be used in conjunction with the grid for a range of technologies, including various forms of energy storage and electricity demand reduction in data centres.
The tool developed can be applied to data centre designs for many types of energy storage systems and reveal what potential benefits they bring about in terms of carbon reduction.
The amount of activity in the hydrogen market, from production to transport to storage is accelerating. The biggest cost is green hydrogen production, for which excess renewable energy is required. However, it is projected that these costs will come down. Some point to conditions where because grids are integrating increasing amounts of power generated using renewable energy sources this will lead to excess capacity at times of low user demand, making more clean energy available for electrolysis.
In addition, the huge growth in the scale of electrolyser production will aid the speed at which the economics of green hydrogen production will swing in favour of the consumer. As green hydrogen becomes more available, the economies of scale will start to improve, making hydrogen a more viable fuel source for electricity for powering data centres.
Like many countries, the UK is a long way from a national hydrogen gas transport network (pipes), and therefore local production in data centres and other energy intensive industries should be considered.
Designing and developing data centres with hydrogen in mind needs to happen. We can future-proof data centres for the growth of hydrogen production and supply, for example, by specifying the use of reciprocating engines or fuel cells which can be run using hydrogen as well as other fuels in data centre designs.
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