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A phase shift to domestic d.c energy in the home

Commercially d.c energy is a reality, but why is this not so in our home environments.

Despite embracing a range of sustainable technologies, a myriad of new construction standards, and our continuing search for a demand side energy solution, we still appear to be searching for a solution within a haze of different concepts and future ideas. Perhaps therefore we should simply stand back and ask ourselves what really makes sense and what is achievable today to meet our current UK environmental dynamics. Until nuclear fusion or hydrogen generation delivers affordable energy, we must take stock of what is available, and to devise practical and pragmatic energy solutions we can install today. When we look at our national energy problem, we have already adopted and are striving to achieve the best energy model for the UK, but why not adopt the same principle at a demand level and introduce direct energy savings as a result.

Within the commercial building sector we have significant opportunities to save energy by adopting d.c energy as we have the scale of demand and the OEM products to support it. Adopting d.c energy across UK data centres for example could potentially save 5% or approximately 180Mwhrs of ICT equipment demand, and it’s achievable today using existing technologies.

Regrettably however, few want to be “first to adopt”, the old mavericks and innovators are all gone and those who remain are now playing the safe game adopting the status quo. However, we must sympathise with this view in our modern market driven world, we are all constrained by the evil of economics. Change costs money, time and resources not to mention the possibility of billion dollar a.c power supply markets disappearing with a transition to d.c energy. The business impact and wider commercial consequence to our economies in the short term is therefore difficult to imagine, change is therefore either on-hold or very slow.

Domestically how do we stand? The commercial & regulatory outlook remains a significant restraint, and with little imagination until now we have struggled to move proactively forward. Combining our national energy model at a sustainable demand level may actually allow us to embrace untapped energy savings, but as early adopters this has a cost attached initially anyhow. The adoption of d.c energy in new homes integrated with sustainable technologies can be a reality today, but we need a proof of concept and funding to realise its potential. If we are to build 337,000 new homes per annum over the next 5yrs, then a strategy of sustainable technology integration and squeezing the last % efficiencies at the point of demand has to be an area for investigation.

   
Figure 1 – Domestic Demand Side Management - d.c Energy

Sustainably and environmentally we have the technology to create a home that ticks all the environmental boxes (Fig.1), but how we live today will be different to how we live tomorrow, so we need to research. Our sustainable tool kit offers CHP fuel cells, solar photovoltaic, solar thermal and battery storage technologies integrated together to offer a demand side solution to deliver real benefits. Combining this with the adoption of domestic L.V d.c (Fig.2) offers possibly the most optimum solution, but it needs to be empirically modelled. The advantages and disadvantages of d.c energy however, (Table 1) will need to be investigated further before we can develop a new domestic strategy, as will the associated capital and life cycle costs to prove the concept commercially. Practically we have issues to overcome (Fig.2), but theses are primarily from an installation perspective, and are merely challenges for an electrical industry seeking a new step change.

 

Adopting d.c energy domestically will also require the white/grey/black good OEM’s to remove the a.c power supply units they need to translate a.c to d.c from their product, however, what voltage shall we all normalise? I feel a new standard coming on. The adoption of CHP fuel cells provides the option for direct d.c outputs at 24v, 48v or 72 volts enabling us to accept the d.c generated supply directly into the distribution system integrating directly with the solar P.V and battery technologies (Fig.1). Our only decision therefore is to which voltage level should we adopt >48V but <380v d.c. ?

 

Achieving a demand side domestic housing solution relies upon a combination of natural gas, solar and battery technology using grid electricity as a back-up or top-up source (Fig.1). The future home will rely upon gas cooking, fuel cell (CHP) for heating and domestic hot water services, LED lighting and d.c power outlets, but relies upon agreeing a harmonised d.c voltage particularly for white good OEM’s who will need to develop low energy d.c options. Some issues to overcome, but with research funding none are unresolvable or impossible short to medium term.

In summary, d.c is a working solution within commercial buildings and industry so why not domestically. With more domestic goods using battery technology even electric cars, we should not miss an opportunity to research the possibilities of adopting d.c directly within the home. Commercially their is a huge step change to make the technology affordable, but if we think back to when laptop computers first arrived, they are now a tenth of the cost of their day-1 launch costs and more powerful so let’s be more positive than negative.

Article by
Gary Middlehurst (Author) – Advanced Intelligent Buildings Ltd
Blane Judd (Chairman) – Built Environment Committee