An Untapped Opportunity? - Solar Thermal for Industrial Process Heat

An EU research programme, So-Pro, has identified the enormous opportunity to utilize solar heating in industrial applications.  Many national markets across the EU boast levels of solar thermal deployment in residential buildings that leave the UK far behind (see earlier blog), but when it comes to industrial applications, we’re all absolute beginners.

The UK’s Renewable Heat Incentive is the first scheme of its kind in the world, and could act as a real driver for businesses that use heat in their industrial processes to consider using solar thermal to reduce their dependence on fossil fuel energy, save on bills and get cash-back from the government at the same time.

So-Pro estimates that 30% of total industrial heat demand is at temperatures below 100°C, and may therefore be suitable for solar heating.  The programme highlights a number of case studies where solar energy was successfully deployed in an industrial setting:

·         Food Industry

A producer of dried meat in Jerez de los Caballeros, Spain installed a 250 m² solar thermal array to heat 30,000 litres of hot water storage for washing processes in production, and for cleaning of vessels and machinery. 

·         Metal Processing

An electroplating company in Rahden, Germany installed a 220 m² solar array to support the heating of the galvanising baths to 80°C.

·         Drying

A brewery in Neumarkt, Germany installed a 72m² solar array to preheat air for drying processes in the malt house.

·         Washing

A specialised truck washing company in Villamuriel de Cerrato, Spain installed a solar thermal system of 140m² to heat water for washing tankers used to transport chemicals, food and industrial oils.

·         Preheating Steam Make-up Water

A laundry in Marburg, Germany installed a 57 m² solar system to raise the temperature of make-up water feeding two gas-fired steam boilers.

The successful implementation of these bespoke renewable energy installations were found to require close cooperation between M&E contractors with a detailed understanding of their customers’ heating processes and technically competent solar suppliers or installers that could ensure the design achieved efficient use of the solar technology.

With the advent of the Renewable Heat Incentive, the stage is set for heating companies to help their customers cost-effectively reduce fossil fuel use in a wide range of commercial heating applications. 

To find out whether your application for industrial process heat may be suitable for solar heating, try this checklist of questions

Q: When is a roof not a roof? A: When you put a solar panel on it

The launch of a new roofing standard for solar panels in the UK aims to fix this

Not a roof?

                “Will these solar panels make my roof leak?”
                “Will they blow off the roof in the wind?”
                “Will the fire-safety of the roof be affected?”

You might think that being able to confidently answer “no” to the questions above would be a position that solar manufacturers would aim for, if only for their own peace of mind.  However, with the exception of a small number of companies that have tested their products, the solar industry has avoided the need to comply with important regulations that apply to all other roofing materials for years. 

With the release of new roofing requirements (MCS 012) from the Microgeneration Certification Scheme (MCS), in the UK at least, this ends now. 

Aren’t there existing standards for solar panels?

European standards exist for both solar thermal and solar photovoltaic panels.  While these are excellent tests of the durability of the panels, they do not consider their performance as part of a building.  For example the wind loading test in the European standards for solar panels doesn’t fix the panels to a representative roof – even though the weakest link is often between the fixing brackets and the roof itself.  The weatherproofing tests only check if water gets into the solar panel, not whether it gets into the building.

MCS 012
This new standard published by the MCS now requires that solar roofing installation kits are tested by an independent test laboratory which will issue a certificate declaring the resistance to wind loads and the fire rating.  In addition there will be tests to confirm that the installation doesn’t decrease the weathertightness of the roof.

MCS 012 now requires tests for fire safety, weatherproofing and wind resistance

Installers must calculate the maximum wind load on the roof and check that the strength of the panel and its fixings are adequate.  Depending on the fire rating of the solar panel kit there may be restrictions on where the panels can be placed and the maximum area that can be given over to solar panels.

For a briefing document with more details of the MCS 012 standard, click here.

For a technical note on how the Building Regulations for Fire Safety apply to roof-integrated solar panels, click here.

Do Heat Pumps Deliver?

Do heat pumps actually deliver the energy and carbon savings that housing professionals and energy assessors predict?  A study by the Energy Saving Trust (EST) appears to show that they don't.

The measure of the performance of a heat pump is the coefficient of performance (COP).  This is the ratio of the heat energy that it delivers to the electrical energy that the unit consumes to do so.  An electric fan heater or storage heater would have a coefficient of performance of 1.0 - every unit of electricity consumed in the device ends up as a unit of heat energy in the building.  Heat pumps use electricity more intelligently than this, driving a condensation cycle which cools the ground or air outside a building and delivers the energy as higher temperature heat inside.  The technology is similar to a refrigerator, which transfers heat from inside the fridge to the room outside using the same principle.

For a heat pump to produce a carbon saving relative to a gas-fired boiler in the UK, it needs to be operating at a COP higher than 2.35.  This is because grid electricity has a high carbon-intensity.  When you consume a unit (kWh) of electricity, 0.52kg of carbon dioxide are emitted at a power station.  When you use a gas boiler to produce a unit of heat for your home, around 0.22kg of carbon dioxide are emitted from its flue.

70% of homes would have had lower carbon emissions with a gas boiler

The chart above shows the range of COPs measured in the EST trials (white) compared to the range of COPs claimed by manufacturers (orange) and used to calculate household energy for building regulations.

Fully 70% of households in the EST field trial would have lower carbon emissions from heating their properties if they had instead selected much cheaper gas-boilers.  It also appears that building regulations calculations are over-stating the efficiency of heat pumps by around 60% compared to the real-life examples in the trial.

Can any professionals from heat pump companies offer an explanation for the EST trial results, or highlight errors in this analysis?  Please leave your comments below.  Check workings here if you like.

Note Added 28/03/2012:

Thanks for all the comments to the original post.  The explanation appear to be that  heat pump performance is strongly diminished if it is:

• attached to inappropriately sized heat emitters (for example too small radiators)
• sized wrongly for the heat load
• not used correctly (for example run hard for short periods)

Following on from the EST trial, a group of trade associations created a document to help with the first two issues.  The heat emitter guide helps installers of heat pumps ensure that they achieve more optimal system design and achieve heat pump performance that approaches the laboratory test conditions.

Solar Heating - Could Do Better - UK Ranks Lowest Among Major European Economies

The United Kingdom ranks last for solar heating installations among its european peer group.  Germany has installed twenty times more solar heating per head of population, and Austria sixty times more, figures from the Euroobserv'er 2011 Barometer show.



The chart above shows the amount of solar heating panels installed in each of the major economies in Europe per head of population.  The wide range is only partly driven by climate, with many northern european countries scoring among those with the highest installed base.

A spreadsheet with sources, data for all European countries and calculations can be found here.

After the Party - UK PV Industry in 2011

How to build a sustainable industry

The UK photovoltaic solar installation industry returns to work in 2012 with the mother and father of all hangovers.

The chart shows the amount of solar photovoltaic capacity added each week in megawatts during 2011. 

On October 31st, the Department of Energy and Climate Change (DECC) launched a consultation on the Feed in Tariff (see earlier blog post here).  Alarmed by the rate at which solar installations were using up the allocated budget, DECC also announced that tariff levels were to be cut by more than half from December 12th.

A sprint to the line ensued, with 382MWp installed in the six weeks leading up to the deadline - more than the total since the Feed in Tariff scheme began in April 2010.  In the last week before the cut, 126MWp was installed and commissioned - sixteen times the rate of installation through the summer.

Unfortunately, the finishing line for this race was set up on a cliff edge.  The week after the deadline, installations fell 98% to only 2MW.

It remains to be seen what the long term impact on PV businesses will be.  This deadline was always going to pull forward installations, suppressing demand for a time afterwards. 

However, scaling up a business by sixteen-fold over a few weeks while at the same time maintaining the quality of solar installations would appear to be a ferociously difficult challenge.  We must hope that this challenge was met; else it could damage the reputation of an industry for years to come.

Slippery When Watt

Don’t know your megawatts from your kilowatts peak?  You’re not alone.  Look no further for help.

What’s a Watt?

Some watts are more equal than others

The watt is the unit of power – the rate at which energy is converted from one form, for example coal, to another, for example electricity in a power station. 

According to its rating plate, my kettle at home converts electrical energy to heat energy to keep us going in tasty hot beverages at the rate of 2.2 kilowatts, or 2,200 watts.

1 kilowatt (kW) = 1,000 watts.

At the other end of the scale, my nearest power station at Little Barford, is busy keeping the nation’s television screens alight by burning natural gas to make electricity at the rate of 680 megawatts, or 680,000,000 watts – enough to run 300,000 of those kettles at the same time.

1 megawatt (MW) = 1,000,000 watts.
So if you read that 650 megawatts of photovoltaic solar panels were installed under the Feed in Tariff during 2011, you can compare this to a power station in terms of energy output.  Right?  Wrong!

Give me a ‘p’
A fossil fuel fired power station could in theory run day and night every day of the year at or near full rated output.  The decision whether to or not is typically economic, or influenced by down time for maintenance.

In contrast, a photovoltaic solar panel makes electricity during the hours of daylight, and the output will vary with the position of the sun and cloud cover.  Likewise a wind turbine will produce its maximum (rated) power for a limited range of wind speed.  As the wind speed increases or decreases from there, the power output falls.

The difference between a conventional power station and a solar or wind farm is one small letter that is often dropped from news articles and statistics about this kind of renewable energy.  The letter ‘p’.
A solar panel power output is rated in watts-peak (Wp).  The electricity output of the panel is measured under very specific conditions of light and temperature – equivalent to a clear summer’s day at noon with the panel at 25C.  It is a useful measure to allow comparison of one product from another – it absolutely does not reflect any kind of average power output.

The scale of a solar installation such as a solar farm is the sum of all of the watts-peak of the solar panels used.  Again, a useful comparison between solar farms, but not between solar farms and conventional power stations.

Capacity Factors

The ratio of the energy output compared to that which would be expected if operating at full “nameplate” capacity the whole time is termed the Capacity Factor.
 
For the entire generating stock of power stations, it is necessary to be able to meet the peak electricity demands of the nation.  This means that at all other times, some of that generating capacity stands idle, resulting in an overall capacity factor between 50% and 60%. 

(Figures from Digest of UK Energy Statistics -DUKES table 5.10)

The energy output from a solar panel installation will depend upon its location, orientation and shading.  For well-situated PV installations in the UK, a rough guide is to expect around 850 kilowatt-hours (kWh) of energy for every installed kilowatt-peak of PV panels.  This corresponds to a capacity factor of around 10%.

Wind turbines at sea benefit from higher average wind speeds.  DUKES table 7.1 allows us to add the average capacity factor for wind energy.

Technology	Average Capacity Factor
Gas fired power station	60%
Wind Turbine (offshore)	30%
Wind Turbine (onshore)	22%
Solar PV (UK, S Facing)	10%

(Calculations can be viewed on this spreadsheet)

 All Watts are Equal...

Based on the above, 1 MW of gas fired power station produces the same annual energy output as 2MWp of offshore wind, 2.7 MWp of onshore wind or  6 MWp of solar photovoltaic panels.

The 650 MWp or so of solar photovoltaic panels installed in the UK during 2011 causing such panic in government circles is equivalent to a sixth of Little Barford power station.

How Much Electricity does the Average House Use?

Q: How Much Electricity does the Average House Use?

When putting the scale of a renewable energy development into context, it is common to state something like “this would provide electricity for” followed by a number of houses.  So what is the electricity consumption of a household?

One way to get at the number is to use the energy reporting from the Department of Energy and Climate Change (DECC).  Their Digest of UK Energy Statistics (DUKES) is a mine of information relating to energy.

Specifically, Chapter 5 deals with electricity and Table 5B shows domestic electricity sales for 2009.

Domestic sector electricity sales (Great Britain)              112,064 GWh

Number of domestic customers                                  26,987,000           (based on number of meters)

Dividing the first figure by the second gives a value for the average electricity use of a house.

A: 4,150 kWh/year

Q: How About Electricity Use per Person?

When you’re not at home, you’re probably still using electricity.  At work?  You need to power your computer, telephone, air-con, lights.  Sitting in the cinema munching popcorn?  Pay your share of the electricity to run the projector and the electricity to pop that corn.

On top of this, the goods you consume used electricity to extract, process, manufacture, package and transport them to the point where you buy them.

Domestic electricity use only accounts for 27% of the total, but the rest that is used in agriculture, industry and public administration is only there because you are.

Without getting bogged down worrying about the “balance of trade” in energy – that is that the UK imports more energy intensive goods and materials than it exports, it is possible to get an estimate for the electricity used per head of population as follows.

Total UK electricity consumption:             328,318  GWh                    (DUKES Table 5.1)

UK Population:                                           62.219 million                     (Google public data)

Again, divide one by the other to get electricity use per person

A: 5,276 kWh/year