Dr Derek Taylor from Altechnica weighs up the pros and cons of various renewable energy sources and shares his thoughts on whether you should be generating at home. He also talks about his role in creating one of the UK's most energy-efficient homes.
Interview with Dr Derek Taylor
Dr Taylor trained at the Architectural Association but got interested in renewable energy and low energy building design in 1972. From then he started to pursue more of a renewables orientated career and did a masters in designing wind turbines and renewables, and came to the Open University. He is particularly interested in bringing together renewable energy and architecture to try and make it much more effective.
There are still Fossil Fuels Available But CO2 Emissions are the Problem
A lot of people believe we have reached peak oil and that we are now at the point of depletion. There’s still a lot of coal in the ground and a fair amount of gas available but their CO2 emissions are a big concern for climate change. It's clear we need to make a step change. The scientists say we need to cut CO2 emissions by 80% in the next few decades.
UK's Best Renewable Energy Source is Wind
In terms of renewable energy Dr Taylor believes wind energy and offshore wind energy offers the most promise to the UK. He explains that 40% of the potential wind energy resource in Europe is actually in the UK. That figure is looking at land based resources, with even more potential offshore.
Phenomenal Increase in Wind Power
Dr Taylor has recently been updating the wind energy section of the Open University renewable energy course. He noted that in the year 2000 there was about 30,000 MW of wind energy globally whereas in 2010, there was 38,000 MW installed in just one year. Now globally there is over 200 GW. Dr Taylor is impressed with the progress. The UK currently has the largest offshore wind farm in the world, which is off the coast of Thanet (installed by Swedish company Vattenfall), and they’re currently building a third offshore wind farm in the Thames Estuary, called the London Array, which will produce a fair proportion of London’s electricity needs.
Floating Wind Energy Technology Has a Huge Potential
Tapping into floating wind energy technology, the wind energy resources in UK waters would be equivalent to the Gulf Oil reserves but every year.
Renewable Energy Solutions Fit into Different Scales
Generally there are three types of solution: building scale, an intermediate scale – which Dr Taylor calls neighbourhood or community scale – and large scale.
Solar Makes The Most Sense For Buildings
In terms of buildings, solar energy often makes the most sense for electricity generation, hot water and also for reducing space heating loads. In the summertime it can be used for cooling.
The temperature of the ground below a certain depth is constant throughout the year, so this provides another ambient source of energy.
Wind Energy Isn't Normally a Good Solution for Urban Areas
The usability of renewables depends on the location as to whether they will perform effectively. Wind energy can make sense but in most cases it doesn’t in urban areas. Wind energy technology usually starts to make sense at community scale upwards, for example, a medium scale turbine might be appropriate for a village or a town. Costs can then be spread amongst householders.
Former Watermill Sites Could Have Potential for Hydro Power
The best sites for hydro tend to be in mountainous areas, but Dr Taylor suggests that former watermill sites could be good places to generate. It's important to note that when watermills were in use there was less water extraction so there was more water running through the system. Dr Taylor did a renewable energy study for Merton Council which found that a short stretch (19km) of the River Wandle once had about 90 watermills in operation.
Biofuels Make Most Sense When it's a Waste Product
Growing energy fuels is very difficult to justify when you haven’t got much land. A forested area can obviously provide wood as a fuel. Dr Taylor believes the situation with biofuels probably makes sense if you can use it as waste, such as food waste and oil waste. You can then process that with biology to produce gases and fuels. In Denmark there are community digesters where manure, food waste and sewage combine to produce methane – the process mimics a cow's stomach and produces gas that can run small power stations.
Tidal Barrages Expensive to Build and Maintain
The main problem with tidal energy is that it's been exploited using tidal barrages, like a big dam across an estuary. These are very expensive to build and can impact on the rich eco systems. In France, there is an example of a successful barrage called La Rance.
Tidal Stream Technology Shows Promise
Essentially they are underwater wind turbines which capture the currents as they flow around the coasts. One of the big advantages is that because water is 800 times denser than air for a given size of rotor diameter you get a lot more power out compared to wind turbines because air is very low density. This means much smaller devices can give more power output. The downside is that these devices are situated in difficult locations and have to be able to cope with the water reliably. They’re still in the early stages of development.
Devices Built to Harness Wave Energy Have to Survive The Stormiest Seas
Dr Taylor reckons that wave energy is an even more difficult one to achieve. The energy resources from the waves are substantial but you have to build devices which can survive 24/7 in the most stormy seas.
Failures Important to Progressing the Technologies
Very few of the wave energy projects actually go through the iterative stages that are needed to develop a technology. Lots of funding goes into building one device and that fails and there’s no money to carry on. Those failures are vital to progressing the technology.
We Can Use Fossil Fuel Reserves Much More Effectively
While fossil fuels might still be available, Dr Taylor believes that the price will be the main constraint to using them. He stresses how in other countries they’re actually much further on with many aspects of design, performance of houses and also the use of wind energy.
Combined Heat and Power Makes Use of Waste Heat
One approach for district heating is to use the waste heat from power stations to heat houses. Dr Taylor calculated that if you add up all the energy being lost from the cooling towers around Britain, it amounts to more energy than is used to heat all the houses in Britain. Currently this energy is just allowed to go into the atmosphere or into the sea at coastal locations. In Denmark 65% of houses are heated this way or from large scale boilers. To achieve this heat mains are laid under roads or gardens and each house is then connected up. Part of the difficulty is that electricity networks are privatised and they would rather do what they've always done.
Heat Stores Play an Important Part
Dr Taylor explains that Battersea Power Station was a combined heat and power station when it was operating. There was a pipe under the Thames which provided heat for 4000 houses in Pimlico. They’ve subsequently re-installed a small combined heat and power station at Pimlico which delivers the same thing. Part of that scale of development enables very large heat stores to be built in, so that heat can be stored when you’re generating electricity for use later. Heat from other sources such as solar or wind energy can also be used to charge up the heat stores.
Nuclear Energy is Expensive and Funding Must Be Offset to Look After The Waste
In France about 80% of their electricity comes from nuclear, but this doesn't mean its future is clear. Not only is it expensive but disposing of nuclear waste is still a big problem. How much money will be needed in the future to look after nuclear waste from the past? There are also discussions about what’s going to be the most useful type of fuel after uranium.
Low Energy Buildings Fall into Two Strands
Historically there are two strands of developing low energy buildings. One is known as the super insulated approach that tends to be a lightweight construction with lots of insulation. The other approach is known as passive solar, which is reliant on lots of solar orientation, lots of glazing and high thermal mass. The solar gains are trapped in the thermal mass so that it acts like a storage heater.
Super Passive Solar
In the UK passive solar hasn't worked well in the spring or autumn times when there tends to be quite high cloud cover. There is also not much benefit in the winter time whereas super insulation then works well. So a super passive solar approach combines the two so you have a high level of thermal mass but it’s inside a super insulated envelope. Dr Taylor worked on a house in Herefordshire which might be one of the UK's most energy efficient homes.
Super Passive Solar Goes a Step Further Than Passivhaus
Dr Taylor really likes the Passivhaus standard although he finds it unfortunate that they chose the name Passivhaus as it's easily confused with passive solar. It is really an ultra super insulation approach. The Passivhaus design system doesn’t really take into account the thermal gains from thermal mass, so you can’t get that extra point further of actually optimising the design to get to zero space heating, although a lot of Passivhaus buildings are getting pretty close to that.
With New Builds, Push the Envelope as far as You Can
For new buildings Dr Taylor thinks you have to push the building's envelope as far as you can because it’s much more difficult to upgrade. If you can design as much insulation as possible and get to Passivhaus standards then it will be well worth doing and shouldn’t cost you a great deal more on top of the building.
If You Have The Money, a Passivhaus Retrofit Can be a Good Investment
Upgrading an existing building to Passivhaus is not a cheap option. However it's probably better using that money to go into the building's fabric rather than getting an expensive new kitchen!
Internal Insulation Must be Done Correctly or You Risk Damaging the Building
External insulation is a much easier solution but risks affecting the aesthetics. The problem with internally insulating walls is that there will be a reduction of floor area. Also, with solid walls, for instance, prior to that wall being internally insulated, it’s been kept warm by the space heating of the house but once the insulation is between it and the heating then it’s obviously a cold object and it’s a cold surface. So, unless the internal insulation is done correctly, if any vapour gets into that structure it will hit the cold wall and condense. This can cause rotting problems.
Combined Heat and Power Could Buy us Some Time to Retrofit
Dr Taylor refers back to how we might reduce the CO2 emissions from buildings. Investing in combined heat and power, and district heating would enable the existing buildings to start to use heating which is actually low carbon. It would also buy some time to upgrade the performance of the existing housing stock.
We Only Have One Chance to Make our Homes Energy Efficient
In order to reach 80% reductions in CO2 Dr Taylor believes that we must go beyond a little cavity wall insulation. He thinks we only get one shot at this and it should be done properly. The challenge will be funding it. If there were a scheme where everyone was connected to a heat network then there’s a potential revenue stream for the sale of that heat to people which could be used to fund insulation of buildings down the road.
Incremental Improvements Should Have a Long Term Plan
Try and have a plan or a strategy so you’re not going to foreclose on the options. Do the thinking upfront so that improvements compliment each other. If you have a loft that can be insulated then certainly the more upgrades you can do to that the better.
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