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©FEC Services Ltd 2007 Low Carbon Technologies for Greenhouse Horticulture What are the options for Growers in the UK? Chris Plackett FEC Services Ltd
©FEC Services Ltd 2007 Topics Results from two recent HDC projects PC256 –A review of closed greenhouse technology PC265 –Biomass heating systems
©FEC Services Ltd 2007 Closed Greenhouse Technologies Interesting concepts Complex engineering solutions Impressive headlines Commercially, where are they now? –Do they offer anything to growers in the UK?
©FEC Services Ltd 2007 Where is the technology now? Themato project has been a flagship –Successfully grown tomatoes –Moved to other crops - strawberry Commercial focus now on semi-closed greenhouses –Similar advantages –Reduced investment –Lower risk?
©FEC Services Ltd 2007 What about the UK? Aquifer thermal energy storage is not viable No other commercially attractive energy storage options currently exist But! –Air handling / heating technology has good potential
©FEC Services Ltd 2007 How Does Semi Closed Work?
©FEC Services Ltd 2007 Air Movement Technology The Benefits –Uniform greenhouse conditions »temperature, humidity & CO 2 –More efficient heating? »Better response »Use low grade heat »Increased opportunities to use alternative heat supplies
©FEC Services Ltd 2007 Fan & Duct Systems
©FEC Services Ltd 2007 New HDC Project – PC278 Adapting the Dutch approach …… –And doing it better! –Meeting the needs of the UK grower R&D with a commercial installation –1Ha Tomato Nursery –Side by side comparison with conventional system Partnership between –HDC –Mill Nursery Ltd –Industry suppliers
©FEC Services Ltd 2007 Project Objectives Reduce energy use & cost Reduce CO 2 emissions Expand the opportunities to use alternative heat sources Improve yield & quality Reduce disease incidence & the use of crop protection chemicals
©FEC Services Ltd 2007 Project Status Installation complete Work ongoing –4 year project Look out for results –All of the normal HDC communications routes –Website for HDC members
©FEC Services Ltd 2007 Summary – Sealed Greenhouses Not likely to be economic in the UK –Aquifer thermal storage not widely available –Long paybacks Semi-sealed offers better opportunities –Air movement technology –Opportunities for low grade heat A new HDC Project is investigating the potential –PC 278
©FEC Services Ltd 2007 What about biomass heating? Options? –Wood pellets –Miscanthus –Wood chip –Straw
©FEC Services Ltd 2007 One Potential Problem CO 2 enrichment –not currently commercially available What impact does this have on boiler utilisation? What are the alternatives?
©FEC Services Ltd 2007 Options for CO 2 enrichment Pure CO 2 –Not currently economic Biomass for winter heating only? –Heat with biomass when CO 2 demand is low –Use mains gas to produce CO 2 in summer
©FEC Services Ltd 2007 What size boiler? Choose the biggest possible? –Satisfy peak winter heat demand –Low output most of the year Smaller boiler? –Wont meet all of the heat demand but… –Lower capital cost –Higher utilisation
©FEC Services Ltd 2007 Heat Storage Helps to maximise boiler use Connect as open buffer What size?
©FEC Services Ltd 2007 Finding the answers Data from commercial nurseries –CO 2 demand –5 minute data –complete cropping season Scenarios –Low CO 2 demand, moderate heat use –High CO 2 demand, high heat use
©FEC Services Ltd 2007 Scenario 1 1 Hectare Energy efficient –Thermal screen etc. Low CO 2 user Ignoring the need for CO 2 Boiler size (kW)Buffer size (m 3 ) Heat from biomass % 1,4200100 80015099.2 80020099.4 80025099.6 60020090.9 50020083.9 40020073.4 200 40.5
©FEC Services Ltd 2007 Scenario 1 No CO 2 demand 500kW, 200m 3 – 84% biomass
©FEC Services Ltd 2007 Nursery 1 CO 2 demand – 423 tonnes/Ha p.a.
©FEC Services Ltd 2007 Scenario 1 CO 2 demand satisfied by mains gas 500kW, 200m 3 – 42% biomass
©FEC Services Ltd 2007 Scenario 2 Higher energy & CO 2 user 697 tonnes CO 2 /Ha p.a. Biomass heat = 31%
©FEC Services Ltd 2007 Some simple economics Assumptions –600kWh/m 2 /year heat use –Low CO 2 demand –42% heat provided by biomass Comparative fuel costs –Mains gas 2p/kWh (60p/therm) –Wood chip 0.7p/kWh (£25/t) Fuel cost saving = £32,760/Ha/year.
©FEC Services Ltd 2007 Simple economics 3Ha nursery –Total fuel cost saving = £98,280/year. Cost of 1.5MW boiler & infrastructure –£200k - £300k –2 - 3 year pay back, ignoring O&M costs Economies of scale & fuel cost sensitivity are high –Gas price 1.5p/kWh, payback up to 6 yrs –Lower capital cost /MW for bigger boiler
©FEC Services Ltd 2007 Also consider Boiler selection –Fuel flexibility –Ease of use Fuel –Cost now & in the future –Reliability of supply –Ease of storage & handling Operation & maintenance –Labour Rules & regulations
©FEC Services Ltd 2007 Summary - Biomass Lack of CO 2 enrichment is a barrier to uptake –But not a complete lock out The technology is not fit & forget There are opportunities –Do your homework –The economics are very site specific
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